Re: 7587 Nuvistor Tetrode Substitutions in the Tektronix 184 Time-Mark Generator
Thanks for the link. It makes for interesting reading. At the very end, complete conversion kits are mentioned for specific instruments like the Tektronix 500 series CA amplifier and the Hewlett-Packard HP500 VTVM. Teledyne used the cascode configuration with internal bias since they were replacing triodes. They had their own high voltage JFETs which simplifies the design although high voltage enhancement or depletion mode MOSFETs could be used now. High voltage high frequency bipolars would be useful if they were available. In my case, I can just lower the anode supply voltage. On Sun, 27 Jan 2013 16:47:33 -0000, "Ed Breya" <edbreya@...> wrote: I just stumbled onto this blast from the past while looking for other info, and immediately remembered this discussion. It looks like Teledyne had the direct substitution problem solved in the 1970s. Hope this helps with cascode ideas - I don't know if the high voltage JFETs are available anymore.
)_Misc_Test_Equipment/FETRON_Solid_State_Vacuum_Tube_Replacement.pdf
Ed
|
Re: Need part 2232 CRT and source for a tube - update
Then why, when I installed the -00 tube into the 2232 scope with no
connection the pin 12, the display was completely unstable when the beam moved
around. The image size varied depending on where the beam was and with focus
changes. Very indicative of a floating element in the tube, When I installed the
diode, capacitor, and resistor on the board just like in the 2215A and connected
pin 12 to the -100 volts, everything worked fine.
?
I was thinking about connecting an external PS to the pin 12 and seeing
what effect varying the voltage on the mesh would have but I tired of working on
it. Maybe I'll go back and play with it. I'll also take a look at Sphere's
comments.
?
Thanks for your thoughts guys,
Tom
?
?
?
toggle quoted message
Show quoted text
----- Original Message -----
Sent: Sunday, January 27, 2013 12:59
PM
Subject: [TekScopes] Re: Need part 2232
CRT and source for a tube - update
?
I second Tom on this, the only difference between the -10 version
is a longer HT lead due to the updated multiplier having a built in socket
instead of a flying lead. I do have duff versions of both tube and neither
have the pin 12 connected. In the -00 as Tom says there is an unattached 3cm
wire, In the -10 the pin is used as a support for one of the glass rods, no
other connection. I've seen 2230's and 32's of all flavors with both versions
of tube interchanged, the only way you can't do it is if the scope has the
updated multiplier (requires a longer HT lead) and even then I've seen the HT
leads modified. The missing components referred to do allow the use of a 465
CRT See
about half way down the page. JC
--- In TekScopes@..., "Tom
Jobe" wrote:
>
> Hi Tom,
> Thank you for posting a nice
summary of your progress, but there is something wrong here.
> Pin 12 on
the 154-0861-00 CRT is not connected to anything inside that CRT unless I'm
confused (which is very likely).
> I have several broken samples of that
same CRT, and pin 12 comes into the CRT maybe 30 mm and then stops. It lays
against the side of one of the four glass rods that support the internal
structure, and touches no metal that I can see.
> Later today I could
post some pictures from my broken CRT collection.
> Pin 10 connects to
the metal can the expansion mesh dome sits on.
> tom jobe...
> PS
Maybe look at your -10 CRT and see where pin 12 goes internally?
> I
don't have a broken -10 CRT to look at.
>
>
>
>
----- Original Message -----
> From: Tom Miller
> To: TekScopes@...
> Sent: Saturday, January 26, 2013 10:22 AM
> Subject: Re:
[TekScopes] Need part 2232 CRT and source for a tube - update
>
>
>
>
> This is a follow-up to my repair of a 2232 scope
with a bad CRT, part number 154-0861-10.
>
> I was able to find,
for a very good price, a bad 2215A that seemed to have a good tube. It turns
out that the 2215A uses a 154-0861-00 CRT. This tube brings the mesh electrode
out on pin 12 of the CRT socket. The -10 tube either does not have a mesh or
it is internally connected to some other element. In any event, the -00 tube
must have the mesh connected to a -100 volt bias. Operating with the mesh
un-connected will cause all sorts of strange behavior such as the display size
changing with position control changes.
>
> The good news is that
there is track on the PC board to support the components needed to make this
negative supply. In essence, a high speed diode (UF4007) is connected to the
anode of CR955, C853. The cathode connects to this point. A 0.1/200 volt disk
capacitor connects the anode of this diode to ground. A 470K/ 1/4 watt
resistor goes across the capacitor. Run a wire from this point, (anode of the
UF4007) to pin 12 of the -00 CRT. Now the new tube will work fine. A careful
study of the power supply in this area will reveal that there is unused track
needed to do this mod.
>
> Good luck and email to the list if any
problems.
>
> As a side note, if I can find a way to re-weld the
connection from pin 5 to the astig electrode inside the tube, I will regain a
working tube. Anyone have a welding laser? :)
>
>
Regards,
> Tom
>
>
>
> ----- Original Message
-----
> From: Tom Miller
> To: TekScopes@...
> Sent: Tuesday, January 22, 2013 9:01 PM
> Subject: Re:
[TekScopes] Need part 2232 CRT and source for a tube
>
>
>
>
> Hi Tom,
>
> That's what I read somewhere, that
the -00 tube was for the early units. The one in my scope is the -10 and it
does not have the mesh. At least it is not brought out on pin 12 like in the
2215A. The HV multiplier has a short flexible lead and connector..
>
> I scored a "for parts" 2215A today for mostly shipping cost so we
will see. If necessary, I can add in the -100 volt supply.
>
>
Anyway, off to the archives.
>
> Thanks,
> Tom
>
>
> ----- Original Message -----
> From: Tom Jobe
> To: TekScopes@...
> Sent: Tuesday, January 22, 2013 8:23 PM
> Subject: Re:
[TekScopes] Need part 2232 CRT and source for a tube
>
>
>
>
> Hi Tom,
> I think the CRT for your 2232 is identical
to the one in a 2215A (154-0861-00), unless you have one of those late 2232's
that has the shorter HV lead on the CRT (154-0861-10). The HV multiplier
changed on the last 2232's. It did not have a flexible lead coming out of the
multiplier, the CRT HV lead plugged directly into it on the front side. The
Tekscopes archive has some discussion about the later "dash 10" version of the
2232 CRT.
> I do believe that all of those 154-0861-xx CRT's use the
"expansion mesh" (or whatever it was called).
> tom jobe...
>
>
>
>
> ----- Original Message -----
>
From: Tom Miller
> To: TekScopes@...
> Sent: Tuesday, January 22, 2013 5:01 PM
> Subject: Re:
[TekScopes] Need part 2232 CRT and source for a tube [1 Attachment]
>
>
>
>
> It looks like the tube has a factory
defect where they failed to weld the pin 5 lead to the strap going to the
astig element. I wonder if there is any way to externally weld it? Induction
welding, laser, other? I can't use high voltage as there is no access to the
element. I attached a picture showing the fault. If I tap the tube, the screen
comes into focus. I verified all the connections externally.
>
>
Next question,
>
> Somewhere I read that a tube from a 2215A
would work. However, that tube uses a mesh electrode whereas the 2232 tube
does not. The only difference that I can see is they connect the mesh (pin 12)
to a -100 volt supply.
>
> I need to find a junker 2232 with a
good tube.
>
>
> Regards,
> Tom
>
>
> ----- Original Message -----
> From: Tom Miller
> To:
TekScopes@...
> Sent: Friday, January 18, 2013 9:48 PM
> Subject: Re:
[TekScopes] Need part 2232 CRT and source for a tube
>
>
>
>
>
> Looks like the same tube is used in the following
scopes:
> 2213A, 2215A, 2220, 2230, 2235, 2235L, 2236
>
>
> Tom
>
> ----- Original Message -----
> From: Tom
Miller
> To: TekScopes@...
> Sent: Friday, January 18, 2013 9:34 PM
> Subject: [TekScopes]
Need part 2232 CRT and source for a tube
>
>
>
>
> I received a 2232 scope with the UPS obligatory damage. Something in
the tube is loose and the display is way out of focus. A very light tap on the
tube seems to cause an internal connection to make and focus comes in very
briefly.
>
> Does anyone have a tube for the 2232 scope? Part
number 154-0861-00 or -10
>
>
> Regards,
>
Tom
>
|
Re: Need part 2232 CRT and source for a tube - update
Hi Tom,
?
Take a look at the schematic for the 2215A, the CRT page. It shows pin 12
connected to a negative bias generator off the 100 volt winding. In my tube,
there is a lead running to the front of the tube but is obscured from view.
Maybe that was a change Tek made before changing the part number?
?
In the 2232, the PCB track is still there but no components installed and
no wire to pin 12. In the 2215A, there is a wire to pin 12.
?
I'll put some more photos up later as I re-installed the bad tube into the
2215A chassis just to double check that the problem went with the tube. It did.
I moved the CRT photo to the photos section where you can see how Tek failed to
spotweld the electrode to the pin. I wonder if they honor warranty? LOL.
?
?
Tom
?
?
toggle quoted message
Show quoted text
----- Original Message -----
Sent: Sunday, January 27, 2013 12:32
PM
Subject: Re: [TekScopes] Need part 2232
CRT and source for a tube - update
?
Hi Tom,
Thank you for posting a nice summary of your progress,
but there is something wrong here.
Pin 12 on the 154-0861-00 CRT is not connected to anything
inside that CRT unless I'm confused (which is very likely).
I have several broken samples of that same CRT, and pin 12
comes into the CRT maybe 30 mm and then stops. It lays against the side of one
of the four glass rods that support the internal structure, and touches no
metal that I can see.
Later today I could post some pictures from my broken CRT
collection.
Pin 10 connects to the metal can?the expansion mesh
dome?sits on.
tom jobe...
PS Maybe look at your -10 CRT and see where pin 12 goes
internally?
I?don't have a broken -10 CRT to look at.
?
?
?
----- Original Message -----
Sent: Saturday, January 26, 2013 10:22
AM
Subject: Re: [TekScopes] Need part 2232
CRT and source for a tube - update
?
This is a follow-up to my repair of a 2232 scope with a bad CRT, part
number 154-0861-10.
?
I was able to find, for a very good price, a bad 2215A that seemed to
have a good tube. It turns out that the 2215A uses a 154-0861-00 CRT. This
tube brings the mesh electrode out on pin 12 of the CRT socket. The -10 tube
either does not have a mesh or it is internally connected to some other
element. In any event, the -00 tube must have the mesh connected to a -100
volt bias. Operating with the mesh un-connected will cause all sorts of
strange behavior such as the display size changing with position control
changes.
?
The good news is that there is track on the PC board to support the
components needed to make this negative supply. In essence, a high speed
diode (UF4007) is connected to the anode of CR955, C853. The cathode
connects to this point. A 0.1/200 volt disk capacitor connects the anode of
this diode to ground. A 470K/ 1/4 watt resistor goes across the capacitor.
Run a wire from this point, (anode of the UF4007) to pin 12 of the -00 CRT.
Now the new tube will work fine. A careful study of the power supply in this
area will reveal that there is unused track needed to do this mod.
?
Good luck and email to the list if any problems.
?
As a side note, if I can find a way to re-weld the connection from pin
5 to the astig electrode inside the tube, I will regain a working tube.
Anyone have a welding laser? :)
?
Regards,
Tom
?
?
?
----- Original Message -----
Sent: Tuesday, January 22, 2013 9:01
PM
Subject: Re: [TekScopes] Need part
2232 CRT and source for a tube
?
Hi Tom,
?
That's what I read somewhere, that the -00 tube was for the early
units. The one in my scope is the -10 and it does not have the mesh. At
least it is not brought out on pin 12 like in the 2215A.? The HV
multiplier has a short flexible?lead and connector..
?
I scored a "for parts" 2215A today for mostly shipping cost so we
will see. If necessary, I can add in the -100 volt supply.
?
Anyway, off to the archives.
?
Thanks,
Tom
?
?
----- Original Message -----
Sent: Tuesday, January 22, 2013
8:23 PM
Subject: Re: [TekScopes] Need part
2232 CRT and source for a tube
?
Hi Tom,
I think the CRT for your 2232 is identical to the one
in a 2215A (154-0861-00), unless you have one of those late 2232's that
has the shorter HV lead?on the CRT (154-0861-10). The HV multiplier
changed on the last 2232's. It did not have a flexible lead coming out
of the multiplier, the CRT HV lead plugged directly into it on the front
side. The Tekscopes archive has some discussion?about the later
"dash 10" version of the 2232 CRT.
I?do believe that all of those 154-0861-xx CRT's
use the "expansion mesh" (or whatever it was called).
tom jobe...
?
?
?
?
----- Original Message -----
Sent: Tuesday, January 22, 2013
5:01 PM
Subject: Re: [TekScopes] Need
part 2232 CRT and source for a tube [1 Attachment]
?
It looks like the tube has a factory defect where they failed to
weld the pin 5 lead to the strap going to the astig element. I wonder
if there is any way to externally weld it? Induction welding, laser,
other? I can't use high voltage as there is no access to the element.
I attached a picture showing the fault. If I tap the tube, the screen
comes into focus. I verified all the connections externally.
?
Next question,
?
Somewhere I read that a tube from a 2215A would work. However,
that tube uses a mesh electrode whereas the 2232 tube does not. The
only difference that I can see is they connect the mesh (pin 12) to a
-100 volt supply.
?
I need to find a junker 2232 with a good tube.
?
?
Regards,
Tom
?
?
----- Original Message -----
Sent: Friday, January 18, 2013
9:48 PM
Subject: Re: [TekScopes] Need
part 2232 CRT and source for a tube
?
?
Looks like the same tube is used in the following scopes:
2213A, 2215A, 2220, 2230, 2235, 2235L,
2236
?
?
Tom
?
----- Original Message -----
Sent: Friday, January 18,
2013 9:34 PM
Subject: [TekScopes] Need
part 2232 CRT and source for a tube
?
I received a 2232 scope with the UPS obligatory damage.
Something in the tube is loose and the display is way out of
focus. A very light tap on the tube seems to cause an internal
connection to make and focus comes in very briefly.
?
Does anyone have a tube for the 2232 scope? Part number
154-0861-00 or -10
?
?
Regards,
Tom
|
Re: Need part 2232 CRT and source for a tube - update
I second Tom on this, the only difference between the -10 version is a longer HT lead due to the updated multiplier having a built in socket instead of a flying lead. I do have duff versions of both tube and neither have the pin 12 connected. In the -00 as Tom says there is an unattached 3cm wire, In the -10 the pin is used as a support for one of the glass rods, no other connection. I've seen 2230's and 32's of all flavors with both versions of tube interchanged, the only way you can't do it is if the scope has the updated multiplier (requires a longer HT lead) and even then I've seen the HT leads modified. The missing components referred to do allow the use of a 465 CRT See about half way down the page. JC
toggle quoted message
Show quoted text
--- In TekScopes@..., "Tom Jobe" wrote:
Hi Tom,
Thank you for posting a nice summary of your progress, but there is something wrong here.
Pin 12 on the 154-0861-00 CRT is not connected to anything inside that CRT unless I'm confused (which is very likely).
I have several broken samples of that same CRT, and pin 12 comes into the CRT maybe 30 mm and then stops. It lays against the side of one of the four glass rods that support the internal structure, and touches no metal that I can see.
Later today I could post some pictures from my broken CRT collection.
Pin 10 connects to the metal can the expansion mesh dome sits on.
tom jobe...
PS Maybe look at your -10 CRT and see where pin 12 goes internally?
I don't have a broken -10 CRT to look at.
----- Original Message -----
From: Tom Miller
To: TekScopes@...
Sent: Saturday, January 26, 2013 10:22 AM
Subject: Re: [TekScopes] Need part 2232 CRT and source for a tube - update
This is a follow-up to my repair of a 2232 scope with a bad CRT, part number 154-0861-10.
I was able to find, for a very good price, a bad 2215A that seemed to have a good tube. It turns out that the 2215A uses a 154-0861-00 CRT. This tube brings the mesh electrode out on pin 12 of the CRT socket. The -10 tube either does not have a mesh or it is internally connected to some other element. In any event, the -00 tube must have the mesh connected to a -100 volt bias. Operating with the mesh un-connected will cause all sorts of strange behavior such as the display size changing with position control changes.
The good news is that there is track on the PC board to support the components needed to make this negative supply. In essence, a high speed diode (UF4007) is connected to the anode of CR955, C853. The cathode connects to this point. A 0.1/200 volt disk capacitor connects the anode of this diode to ground. A 470K/ 1/4 watt resistor goes across the capacitor. Run a wire from this point, (anode of the UF4007) to pin 12 of the -00 CRT. Now the new tube will work fine. A careful study of the power supply in this area will reveal that there is unused track needed to do this mod.
Good luck and email to the list if any problems.
As a side note, if I can find a way to re-weld the connection from pin 5 to the astig electrode inside the tube, I will regain a working tube. Anyone have a welding laser? :)
Regards,
Tom
----- Original Message -----
From: Tom Miller
To: TekScopes@...
Sent: Tuesday, January 22, 2013 9:01 PM
Subject: Re: [TekScopes] Need part 2232 CRT and source for a tube
Hi Tom,
That's what I read somewhere, that the -00 tube was for the early units. The one in my scope is the -10 and it does not have the mesh. At least it is not brought out on pin 12 like in the 2215A. The HV multiplier has a short flexible lead and connector..
I scored a "for parts" 2215A today for mostly shipping cost so we will see. If necessary, I can add in the -100 volt supply.
Anyway, off to the archives.
Thanks,
Tom
----- Original Message -----
From: Tom Jobe
To: TekScopes@...
Sent: Tuesday, January 22, 2013 8:23 PM
Subject: Re: [TekScopes] Need part 2232 CRT and source for a tube
Hi Tom,
I think the CRT for your 2232 is identical to the one in a 2215A (154-0861-00), unless you have one of those late 2232's that has the shorter HV lead on the CRT (154-0861-10). The HV multiplier changed on the last 2232's. It did not have a flexible lead coming out of the multiplier, the CRT HV lead plugged directly into it on the front side. The Tekscopes archive has some discussion about the later "dash 10" version of the 2232 CRT.
I do believe that all of those 154-0861-xx CRT's use the "expansion mesh" (or whatever it was called).
tom jobe...
----- Original Message -----
From: Tom Miller
To: TekScopes@...
Sent: Tuesday, January 22, 2013 5:01 PM
Subject: Re: [TekScopes] Need part 2232 CRT and source for a tube [1 Attachment]
It looks like the tube has a factory defect where they failed to weld the pin 5 lead to the strap going to the astig element. I wonder if there is any way to externally weld it? Induction welding, laser, other? I can't use high voltage as there is no access to the element. I attached a picture showing the fault. If I tap the tube, the screen comes into focus. I verified all the connections externally.
Next question,
Somewhere I read that a tube from a 2215A would work. However, that tube uses a mesh electrode whereas the 2232 tube does not. The only difference that I can see is they connect the mesh (pin 12) to a -100 volt supply.
I need to find a junker 2232 with a good tube.
Regards,
Tom
----- Original Message -----
From: Tom Miller
To: TekScopes@...
Sent: Friday, January 18, 2013 9:48 PM
Subject: Re: [TekScopes] Need part 2232 CRT and source for a tube
Looks like the same tube is used in the following scopes:
2213A, 2215A, 2220, 2230, 2235, 2235L, 2236
Tom
----- Original Message -----
From: Tom Miller
To: TekScopes@...
Sent: Friday, January 18, 2013 9:34 PM
Subject: [TekScopes] Need part 2232 CRT and source for a tube
I received a 2232 scope with the UPS obligatory damage. Something in the tube is loose and the display is way out of focus. A very light tap on the tube seems to cause an internal connection to make and focus comes in very briefly.
Does anyone have a tube for the 2232 scope? Part number 154-0861-00 or -10
Regards,
Tom
|
Re: TDS-524A no trace need help
Thanks for your message,
I will try to answer as much as I can:
-the menus and graphics have no problem
-the full self test from the menu passes ok
-SPC passes ok
-reset executes but no help
-autoset works as it set the correct values to display the probe compensation signal
-the measurement values when active are correct(i.e. frequency, voltage, etc.) so I
think the acquisition is ok.
I am troubleshooting the unit with the help of the 520 service manual which has same architecture.
As far as I understood from the description of the schematic in the manual, the text and the waveforms use separate memory planes and chips (8 bit for text and 16 bit for wfm).
Regards
toggle quoted message
Show quoted text
--- In TekScopes@..., "baltimora86" wrote:
If the video RAM was bad, I would expect it to affect the on screen menus and graphics, not just the trace. It's odd that it passes the self test. Have you run the full self test from the test menu? Have you tried resetting the factory defaults? Does it still pass SPC?
--- In TekScopes@..., "iw0uwl" wrote:
Dear forumers,
I need help for my TDS-524A showing no trace on any channel.
Recap and board wash performed succesfully time ago.
Self test is OK, no error in the log.
I am pretty sure it triggers properly because the "T" symbol on screen moves according to the signal.
I am thinking a video RAM chip may be defective and I replaced 2 of them without result.
There are 8 ram chips related to waveform display.
Hope someone would like to offer some hint on where to investigate.
Many thanks in advance to all of you.
Enrico
|
Re: Need part 2232 CRT and source for a tube - update
It was in the attachments area. I created a new directory in the photos
section and put it there.
?
I'll add more info later.
?
?
Tom
?
?
toggle quoted message
Show quoted text
----- Original Message -----
Sent: Sunday, January 27, 2013 11:42
AM
Subject: Re: [TekScopes] Need part 2232
CRT and source for a tube - update
?
On 1/27/2013 10:41 AM, Tom Miller wrote:
>
>
> No Mark, I
did not get photos yet. I still need to open it up when I
> run through
the calibration and will take a few photos then.
> I did put up a shot
of the defect in the CRT.
> Regards,
> Tom
Tom,
I
must have missed that. What folder did you put the pic in? I can't
seem to
find it in the photo's section.
Thanks,
Mark
|
Re: Need part 2232 CRT and source for a tube - update
Hi Tom,
Thank you for posting a nice summary of your progress,
but there is something wrong here.
Pin 12 on the 154-0861-00 CRT is not connected to anything
inside that CRT unless I'm confused (which is very likely).
I have several broken samples of that same CRT, and pin 12
comes into the CRT maybe 30 mm and then stops. It lays against the side of one
of the four glass rods that support the internal structure, and touches no metal
that I can see.
Later today I could post some pictures from my broken CRT
collection.
Pin 10 connects to the metal can?the expansion mesh
dome?sits on.
tom jobe...
PS Maybe look at your -10 CRT and see where pin 12 goes
internally?
I?don't have a broken -10 CRT to look at.
?
?
?
toggle quoted message
Show quoted text
----- Original Message -----
Sent: Saturday, January 26, 2013 10:22
AM
Subject: Re: [TekScopes] Need part 2232
CRT and source for a tube - update
?
This is a follow-up to my repair of a 2232 scope with a bad CRT, part
number 154-0861-10.
?
I was able to find, for a very good price, a bad 2215A that seemed to
have a good tube. It turns out that the 2215A uses a 154-0861-00 CRT. This
tube brings the mesh electrode out on pin 12 of the CRT socket. The -10 tube
either does not have a mesh or it is internally connected to some other
element. In any event, the -00 tube must have the mesh connected to a -100
volt bias. Operating with the mesh un-connected will cause all sorts of
strange behavior such as the display size changing with position control
changes.
?
The good news is that there is track on the PC board to support the
components needed to make this negative supply. In essence, a high speed diode
(UF4007) is connected to the anode of CR955, C853. The cathode connects to
this point. A 0.1/200 volt disk capacitor connects the anode of this diode to
ground. A 470K/ 1/4 watt resistor goes across the capacitor. Run a wire from
this point, (anode of the UF4007) to pin 12 of the -00 CRT. Now the new tube
will work fine. A careful study of the power supply in this area will reveal
that there is unused track needed to do this mod.
?
Good luck and email to the list if any problems.
?
As a side note, if I can find a way to re-weld the connection from pin 5
to the astig electrode inside the tube, I will regain a working tube. Anyone
have a welding laser? :)
?
Regards,
Tom
?
?
?
----- Original Message -----
Sent: Tuesday, January 22, 2013 9:01
PM
Subject: Re: [TekScopes] Need part 2232
CRT and source for a tube
?
Hi Tom,
?
That's what I read somewhere, that the -00 tube was for the early
units. The one in my scope is the -10 and it does not have the mesh. At
least it is not brought out on pin 12 like in the 2215A.? The HV
multiplier has a short flexible?lead and connector..
?
I scored a "for parts" 2215A today for mostly shipping cost so we will
see. If necessary, I can add in the -100 volt supply.
?
Anyway, off to the archives.
?
Thanks,
Tom
?
?
----- Original Message -----
Sent: Tuesday, January 22, 2013 8:23
PM
Subject: Re: [TekScopes] Need part
2232 CRT and source for a tube
?
Hi Tom,
I think the CRT for your 2232 is identical to the one in
a 2215A (154-0861-00), unless you have one of those late 2232's that has
the shorter HV lead?on the CRT (154-0861-10). The HV multiplier
changed on the last 2232's. It did not have a flexible lead coming out of
the multiplier, the CRT HV lead plugged directly into it on the front
side. The Tekscopes archive has some discussion?about the later "dash
10" version of the 2232 CRT.
I?do believe that all of those 154-0861-xx CRT's
use the "expansion mesh" (or whatever it was called).
tom jobe...
?
?
?
?
----- Original Message -----
Sent: Tuesday, January 22, 2013
5:01 PM
Subject: Re: [TekScopes] Need part
2232 CRT and source for a tube [1 Attachment]
?
It looks like the tube has a factory defect where they failed to
weld the pin 5 lead to the strap going to the astig element. I wonder if
there is any way to externally weld it? Induction welding, laser, other?
I can't use high voltage as there is no access to the element. I
attached a picture showing the fault. If I tap the tube, the screen
comes into focus. I verified all the connections externally.
?
Next question,
?
Somewhere I read that a tube from a 2215A would work. However, that
tube uses a mesh electrode whereas the 2232 tube does not. The only
difference that I can see is they connect the mesh (pin 12) to a -100
volt supply.
?
I need to find a junker 2232 with a good tube.
?
?
Regards,
Tom
?
?
----- Original Message -----
Sent: Friday, January 18, 2013
9:48 PM
Subject: Re: [TekScopes] Need
part 2232 CRT and source for a tube
?
?
Looks like the same tube is used in the following scopes:
2213A, 2215A, 2220, 2230, 2235, 2235L,
2236
?
?
Tom
?
----- Original Message -----
Sent: Friday, January 18, 2013
9:34 PM
Subject: [TekScopes] Need part
2232 CRT and source for a tube
?
I received a 2232 scope with the UPS obligatory damage.
Something in the tube is loose and the display is way out of focus.
A very light tap on the tube seems to cause an internal connection
to make and focus comes in very briefly.
?
Does anyone have a tube for the 2232 scope? Part number
154-0861-00 or -10
?
?
Regards,
Tom
|
Re: Need part 2232 CRT and source for a tube - 4xx
On 01/27/2013 10:41 AM, Tom Miller
wrote:
?
No Mark, I did not get photos yet. I still need to open
it up when I run through the calibration and will take a
few photos then.
?
I did put up a shot of the defect in the CRT.
?
?
Regards,
Tom
----- Original Message
-----
Sent: Sunday,
January 27, 2013 8:08 AM
Subject: Re:
[TekScopes] Need part 2232 CRT and source for a tube -
update
?Tom,
Most excellent! Did you take any pictures of the mod?
Mark
I would like to question the differences between the 22xx and the
465x CRTs.
Mainly because I have a few spares on these ( 465x) and, of course,
as the clock keeps ticking
the supply will continue to shrink.
Any ideas?
|
Re: TDS-524A no trace need help
If the video RAM was bad, I would expect it to affect the on screen menus and graphics, not just the trace. It's odd that it passes the self test. Have you run the full self test from the test menu? Have you tried resetting the factory defaults? Does it still pass SPC?
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--- In TekScopes@..., "iw0uwl" wrote:
Dear forumers,
I need help for my TDS-524A showing no trace on any channel.
Recap and board wash performed succesfully time ago.
Self test is OK, no error in the log.
I am pretty sure it triggers properly because the "T" symbol on screen moves according to the signal.
I am thinking a video RAM chip may be defective and I replaced 2 of them without result.
There are 8 ram chips related to waveform display.
Hope someone would like to offer some hint on where to investigate.
Many thanks in advance to all of you.
Enrico
|
Re: 7587 Nuvistor Tetrode Substitutions in the Tektronix 184 Time-Mark Generator
I just stumbled onto this blast from the past while looking for other info, and immediately remembered this discussion. It looks like Teledyne had the direct substitution problem solved in the 1970s. Hope this helps with cascode ideas - I don't know if the high voltage JFETs are available anymore.
)_Misc_Test_Equipment/FETRON_Solid_State_Vacuum_Tube_Replacement.pdf
Ed
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--- In TekScopes@..., David wrote:
What I think is happening is the control grid circuit is rectifying
the positive input peaks to set the bias. A JFET replacement would
operate in the same way although I may have to change the grid bias
resistor or in the worst case, add a paralleled resistor and capacitor
for source biasing.
Vacuum tube design is before my time so I am just having fun reverse
engineering. The time mark outputs which work fine do most of what I
need.
The screen grid series resistors are 27K and connect to the 125 volt
anode supply so the currents are all about 1.8 milliamps which is well
under the 3.6 milliamp maximum. That makes the total cathode current
less than half of the 20 milliamp maximum at least on the 20 MHz
amplifier. The 50 Mhz and 100 MHz amplifiers operate with self biased
grid voltages closer to ground so their anode current should be
higher. On later units like mine, the screen grid voltage of
oscillator V10 is fixed by a zener diode at about 52 volts.
None of the carbon composition resistors I checked were out of
tolerance. Of course, everything up to the 100 MHz output *does*
work.
The 200 MHz doubler at least sort of works but the output looks low
and distorted to me. I may try replacing the germanium diodes with
1N270s or RF schottky diodes. The only information I have on the
152-0075-00 diodes Tektronix used is from the Tektronix parts book.
On Sat, 19 Jan 2013 18:44:49 -0000, "Ed Breya"
wrote:
Wow - that means the grid currents must be over -100 uA to get that much on 100k grid leak resistors. I don't recall what the screens were hooked to, but I think you should calculate the screen currents too, to see the total cathode currents.
If they only used 5 mA or so plate current, you can easily replicate that with modest JFET and cascode NPN current.
Ed
--- In TekScopes@..., David wrote:
I added a 10 ohm current shunt to the anode circuit of V20, the 20 MHz
amplifier, and used it to test all of the tubes. The anode currents
varied from 4.8 to 5.7 milliamps, the gate voltages varied from -10.3
to -12.6 volts, and the screen grid voltages varied from 72.2 to 76.0
volts except for one 7587 which had a screen voltage of 63.5 volts for
some reason.
That one also had the highest anode current but not the highest grid
voltage. I don't know if that is significant.
I can get 2N5950 JFETs and MPSH11 NPNs cheap at the moment so I will
start off with them.
On Wed, 02 Jan 2013 22:06:30 -0000, "Ed Breya"
wrote:
You may want to try swapping tubes from the other spots too, although it seems they're all biased for the same operating conditions, so should wear at the same rate - but if they are only on when needed for their specific function, then it all depends on the history of use. I think the only one that's always on then, would be the 10 MHz oscillator, so it should have the most wear.
I looked up the 7587 and see that it's rated for 20 mA max cathode current, but there were no charts showing what it should be near zero grid bias - unless the grid current gets pretty high, it doesn't seem that it will make much into 100k. It would be interesting to see what it is if you measure it and the actual plate currents.
I think your cascode version with a JFET and an NPN would be best, since you can then assure cutoff by pulling the base to ground. The double-JFET form won't positively cut off unless you can pull the gate negative, making it more complicated. You will have to watch out for the voltage ratings of the NPN to make sure it can handle the cutoff conditions.
I'd recommend around +15V or so for the bases (via small R so they won't oscillate on their own), and about +25V for the collector supply. Those should work with many types of VHF JFETs and small signal RF NPNs. For parts I'd recommend something like 2N5109 or MPSH10 for the NPN, and a J300 with around 15-25 mA Idss.
Ed
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Re: Tek 2445, 2445B for sale
The scopes have been spoken for.
Thanks
Bob
|
Re: Need part 2232 CRT and source for a tube - update
On 1/27/2013 10:41 AM, Tom Miller wrote:
No Mark, I did not get photos yet. I still need to open it up when I run through the calibration and will take a few photos then.
I did put up a shot of the defect in the CRT.
Regards,
Tom
Tom, I must have missed that. What folder did you put the pic in? I can't seem to find it in the photo's section. Thanks, Mark
|
TDS-524A no trace need help
Dear forumers,
I need help for my TDS-524A showing no trace on any channel.
Recap and board wash performed succesfully time ago.
Self test is OK, no error in the log.
I am pretty sure it triggers properly because the "T" symbol on screen moves according to the signal.
I am thinking a video RAM chip may be defective and I replaced 2 of them without result.
There are 8 ram chips related to waveform display.
Hope someone would like to offer some hint on where to investigate.
Many thanks in advance to all of you.
Enrico
|
Re: International mail rates USA -> China?
This is interesting. With my small business, I've shipped lots of packages around the world; the vast majority of customers choose First Class because it's cheapest (these packages are 2-6 ounces usually), some choose Priority, and a few choose Express Mail. I've never had any trouble with Priority, and with First Class while sometimes slow, I think only one has gotten lost. But Express Mail I've had a lot of trouble with: two of them got lost (to Bulgaria and Spain), and one was very slow, out of only a handful of packages sent this way. Maybe I should just take Express off the options list and replace it with Fedex?
Dan
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--- In TekScopes@..., "dehav7" wrote:
None of my customers has ever reported having to comply with some of these strange practices mentioned here. The cheapest and fastest shipment method from the US to Israel, is Priority Mail (not Express Mail, due to severe well-known incompetence issues in this particular Israel Post department). Priority Mail delivery time is anywhere from 7-14 days, whereas the more expensive Express Mail can sometimes take over a month!!!
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I have two 2445's and one 2445B for sale for $150 (for all three) if anyone is interested. All are in working condition, hard copy 2445 manual and CD of the 2445B manual. Front covers with the 2445's, no cover for the 2445B. Pickup only in Moreno Valley, CA (Riverside area). Any interest please contact me off list.
Thanks
Bob
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Re: 475 progress but another road-block
I checked the triggering section some more and it seems to work as I would expect. Setting it to normal and adjusting the trigger point does change what I see on the screen (I just have to hold the beam finder button down the whole time). Single trigger works, etc.
I couldn't get the same "open" reading on the vertical plates in any subsequent tests. However I'm not doing anything differently either. I don't know what I did wrong there. I'll leave it on longer and test again to see what happens.
-Josh
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--- In TekScopes@..., "i814u2.geo" wrote:
Triggering first: If I mess with triggering controls, it does appear as though it is triggering properly. I'll need to check more tomorrow.
Voltages for the deflection plates are as follows:
Horizontal R (manual states 52.1): 48.5
Horizontal L (manual states 48.1): 50.6
I triple checked those readings. They are fairly steady and I was testing the proper points (based on matching parts and schematics).
The vertical off pin 9 (is this the bottom plate?) has a spec of 36.6. I read roughly 38 but that value fluctuates a bit while slowly decreasing. Pin 12 has a spec of 32.5 but starts around 30 and fluctuates while slowly decreasing.
Another item I notice: when first turned on, the scope shows channel 1 toward the top of the screen when pushing in beam finder button. I can't adjust over the normal range. Once it warms up more, I can at least center the beam (though it's a bit jumpy). Channel 2 doesn't have this issue. I assume this is a separate issue (since it only happens on one channel) but I mention it in case it's helpful.
After a while the vertical deflection plate voltages can't be read and my meter shows the circuit is open. This sounds like a cold solder joint type issue (or a part doing the same) but where would I start with that? Just trace voltages back from the deflection plates until things are stable again? Or am I totally off on that idea?
Also, I'm assuming the fact that the horizontal voltages appear swapped is simply a coincidence due to the spec values being so close to start.
Again, thanks for the help. I'm eager to finish this project up and get a working scope.
Josh
--- In TekScopes@..., "Tom Miller" wrote:
The 112 is ok for the 110 measurement.
Resistance measurements depend on several variables including lead polarity, meter type, and active device junction variables.
You need to make a dc voltage measurement on each of the deflection plates (left and right, top and bottom) and report the measurements. Let's see if the beam is anywhere near the center.
Next thing to check is the triggering. Are you getting a sweep?
That should keep you busy for a while :).
Tom
----- Original Message -----
From: i814u2.geo
To: TekScopes@...
Sent: Sunday, January 20, 2013 3:45 PM
Subject: [TekScopes] 475 progress but another road-block
So, with the help of the folks here and some troubleshooting, I've gotten my 475 closer to being usable again.
However, I'm stuck at a new spot now. I am getting almost perfect voltages at each test point except for the 110V TP which shows roughly 112.4 (which is still within tolerance, just not ideal).
The odd thing is that when I test resistance to ground, only about half of the points are within tolerance. 110, -15, U50, and 105 all show much more resistance than they should. Especially -15 which is showing several K of resistance (book shows it should be 480 ohms).
At some point, I also found a trace that was broken and made the repair. I now get a display if I use the beam finder button. However, I do not get a display without using that button. When I adjust knobs on the front, that "beam found trace" does move (mostly as I would expect). It doesn't seem to stay perfectly still in all cases, but I'm assuming that is because something is still bad and causing issues (including the resistance variances).
I do not have another scope in order to test ripple. I've been trying to follow the troubleshooting flow chart in the manual, but I may be getting confused. If I press the beam finder and adjust the trace to the center, but then release the beam finder button and still see no trace, should I be disconnecting the delay line as my next test?
Or have I gotten ahead of myself?
-Josh
|
Re: Need part 2232 CRT and source for a tube - update
No Mark, I did not get photos yet. I still need to open it up when I run
through the calibration and will take a few photos then.
?
I did put up a shot of the defect in the CRT.
?
?
Regards,
Tom
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----- Original Message -----
Sent: Sunday, January 27, 2013 8:08
AM
Subject: Re: [TekScopes] Need part 2232
CRT and source for a tube - update
?Tom,
Most
excellent! Did you take any pictures of the
mod?
Mark
|
Re: Need part 2232 CRT and source for a tube - update
On 1/26/2013 1:22 PM, Tom Miller wrote:
This is a follow-up to my repair of a 2232 scope with a bad CRT, part number 154-0861-10.
I was able to find, for a very good price, a bad 2215A that seemed to have a good tube. It turns out that the 2215A uses a 154-0861-00 CRT. This tube brings the mesh electrode out on pin 12 of the CRT socket. The -10 tube either does not have a mesh or it is internally connected to some other element. In any event, the -00 tube must have the mesh connected to a -100 volt bias. Operating with the mesh un-connected will cause all sorts of strange behavior such as the display size changing with position control changes.
The good news is that there is track on the PC board to support the components needed to make this negative supply. In essence, a high speed diode (UF4007) is connected to the anode of CR955, C853. The cathode connects to this point. A 0.1/200 volt disk capacitor connects the anode of this diode to ground. A 470K/ 1/4 watt resistor goes across the capacitor. Run a wire from this point, (anode of the UF4007) to pin 12 of the -00 CRT. Now the new tube will work fine. A careful study of the power supply in this area will reveal that there is unused track needed to do this mod.
Good luck and email to the list if any problems.
As a side note, if I can find a way to re-weld the connection from pin 5 to the astig electrode inside the tube, I will regain a working tube. Anyone have a welding laser? :)
Regards,
Tom
Tom, Most excellent! Did you take any pictures of the mod? Mark
|
Re: 7T11 with truncated trace in ET modes
You could grow old thinking about all of the things that could go wrong with a 7T11. As they say: Ain't that the truth!!! Dave
|
--- In TekScopes@..., Don Black wrote:
I remember a similar thread some time ago where one of the members who
had worked at Tektronix recalled the testing of new exotic equipment. He
mentioned the weeping and wailing (probably teeth being gnashed too)
when some mega bucks piece failed and an $8,000 CTR was reduced to
shards of glass laying in the bottom. I guess it's much more common now,
particularly in the auto industry where every model has to be crash
tested. Formula 1 cars also now have to be crash tested and the benefits
are very plain to see. Crashes into barriers at 150 MPH that once would
have been fatal usually now result in the drivers walking away. Indeed,
it's no longer permitted but divers would often sprint back to the pits
and get into the spare car to continue the race.
Don Black.
On 26-Jan-13 1:02 PM, Rob wrote:
Thanks Steve, all that makes sense to me. I also understand how the
rubber deformation method brings some meaning to the 20G over 1ms into
perspective (or the impulse). I also understand the disconnect between
my original post and the tens of thousands of G's others mentioned. I
did not try to translate the 20G over 1ms into an actual impulse. So I
do not know how it compares to others.
Anyway, do you have a feel for if or how the specifications changed
over the years? Said another way, where the same military specs
understood when the 647 specification was written (I know Tektronix
was enough on the leading edge that some specifications were written
to what there equipment was capable of vs. any real world
need/criteria.). Would a 647 and a 7000 series scope meet the same
requirements? How about modern solid state scopes?. Conversely as
people became more acquainted with both Oscilloscopes and solid state
electronics. Where they allowed to be manufactured less bullet proof
(for lack of better wording),
The biggest reason I am asking all of this is because of the trouble I
have had shipping my refurbished scopes after I have sold them. I
package them what I consider to be very well. However the post office
is capable of defeating even the best packaging it seems. Then again,
perhaps the 7000 series scopes (non-militarized especially) are more
fragile then they appear to be on the bench and my packaging is indeed
not adequate. Would one expect a 647 or other scope with the
specification they claimed to survive better than a 7000 series or 475
or??? Given the post offices apparent ability to reach well above a
20G threshold.
As always Thank you for your time and the bandwidth.
Rob
*From:*TekScopes@... [mailto:TekScopes@...]
*On Behalf Of *Steve
*Sent:* Friday, January 25, 2013 5:16 PM
*To:* TekScopes@...
*Subject:* [TekScopes] Re: Tentative 647 scan?
Almost all Tek instruments were tested for dynamics, both earlier and
later versions. This included acceleration and vibration.
Acceleration is tested as deceleration. The instrument is firmly
attached to a large steel plate in a test stand. The plate is dropped
from a standard distance. An elastomeric moderator (block of rubber)
is placed at the bottom of the test stand, where the plate will hit to
control the G force. The moderator integrates the peak deceleration
force over time. Different types and sized of rubber are used. Soft
rubber lowers the peak G force, spreading it over a longer time. As it
gets stiffer, the peak gets higher, but the duration of the
deceleration is lower (energy = Mass * velocity^2). If you took the
rubber out (never done in practical testing), the G force would be
huge (tens of thousands of Gs) with ultra-short duration. Basically,
the tiny flexing of the massive steel elements would limit the peak
force from becoming an impulse function (infinite peak with 0 time).
Changing the drop height allows fine tuning of the test forces. An
acceleratomer is attached to the plate to monitor the force and time.
Testing is either started at a low value and worked up, or a dummy
weight with the same mass as the item to be tested is first bolted to
the test stand to calibrate the force.
The dynamics specs were not listed in the later catalogs as they were
contained within the military specification that most instruments were
designed to, which was listed. Typically it was MIL-T-28800C -- class
5 for lab instruments, or class 3 for portable instruments.
(MIL-T-28800B preceded `C', and MIL-T-28800A precede B)
- Steve
The environmental and dynamic specs have not really degraded much over the years. When scopes started to include floppy disk drives, then embedded PC, then had to relax the operating temperature range, as these components are only rated for operation up to +40 degrees C, rather than the +50 that standard class 5 requires. Most of the vendors shifted to the +40 spec, because the drives were not available with the higher operating temp. Unfortunately, the +40 spec has become the defacto standard, and is applied to other instruments which don't even have these components. People say this is not a serious reduction in performance, as 40 degrees is not often encounter in a lab. While this is true, the +40 does limit operation in some rack mount setups, as the cooling air is often mixed with the exhaust air from other instruments. Active probes can be installed between cards in a rack, and situations where instruments with a +40 degree rating will overheat. - Steve
|
David Hess
David C. Partridge