开云体育

Thanks Mark. I ended up using a 470 uF cap rated at 250 volts. Turns out I
didn't need to perform the technique after all. In my haste checking
voltages, I missed the mV designation on my DMM. Looks like the voltages
are OK after all. Still, it was a great learning experience as now I know
how to check for faulty caps.

On Fri, Dec 5, 2014 at 5:17 AM, Mark Wendt mark.wendt.ctr@...
[TekScopes] <TekScopes@...> wrote:

On 12/04/2014 01:42 PM, Kevin Crossett kcrossett@... [TekScopes]
wrote:

That's what I figured. I will look in my junk box for an old power supply
or some other electronics gizmo for the 100 v cap. Assuming I find one in
the next day or so, I am now trying to determine the positive side of the
cap...
I found this image on the internet of someone with a similar problem as

me.

He laid out what he thought were the solder points for the 4439 cap. Is

he

right, and if so, how can I determne which one is positive?

You can also use a higher voltage cap too. Won't matter a bit. Just
don't go lower.

Mark


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Yahoo Groups Links

Yeah, I'm pleased that the voltages are OK. I will begin checking the
connections over the weekend, but I will have trouble with the transistors.
I know some scopes use sockets for the transistors, but mine seem to be
soldered to the board. I suspect my scope is one of the "newer" versions
and I have heard that the company moved away from sockets at some point
during the production cycle. Is it possible to check the B-E and B-C
junctions while the transistors are still on the board? I have a DMM that
can check diodes so I suspect I could reach the pins.

On 12/04/2014 01:42 PM, Kevin Crossett kcrossett@... [TekScopes] wrote:

That's what I figured. I will look in my junk box for an old power supply
or some other electronics gizmo for the 100 v cap. Assuming I find one in
the next day or so, I am now trying to determine the positive side of the
cap...
I found this image on the internet of someone with a similar problem as me.
He laid out what he thought were the solder points for the 4439 cap. Is he
right, and if so, how can I determne which one is positive?

You can also use a higher voltage cap too. Won't matter a bit. Just don't go lower.

Mark

Well, the good news is that it seems you won't have to replace one or more of the large el. caps.
If you're now certain about the voltages you reported, I'd say the power supply voltages are good enough to allow the 'scope to operate correctly.
With your limited set of instruments (yes, you do need a 'scope to repair a 'scope), you may now try some easy things i.e. check and possibly swap some transistors and see what happens. However, I'd first check if the left and right deflection plate connections are ok. Check the wires and clips that connect the CRT. Be careful and only use low force on the CRT pins and *don't* bend them, even if they're crooked.
By swapping transistors, there is a slight risk that you'll damage a good transistor but replacements are available and not expensive.
Depending on your DMM, you may do a diode test on the B-E and B-C junctions on each transistor (they're all in sockets) and swap like transistors in the horizontal amp (schematic 10). The physical location of the horizontal amp. is on the same board as the large caps but near the front of the 'scope.
Looking at the schematic diagram, you'll see a lot of symmetry. You may swap Q4146 with Q4341, Q4150 with Q4342 and Q4273 with Q4274 but *not* Q4161 with Q4361 nor Q4169 with Q4362. Please check this before actually trying (check on the schematics and check for identical type numbers printed on transistors to be swapped.
Where swapping changes nothing, put the original transistors back to avoid any possible loss of calibratio, though the difference should be minimal. Switch power off before any swapping.
U4269 is a DIL package containing five transistors. It has a Tek number but is just a CA3086. You may check the transistors in U4269, making sure that the substrate (pin 13) is at the most negative level. A replacement would cost less yhan a dollar.


BTW, did you wiggle all transistors in the horizontal amplifier in their sockets? Many "repairs" are performed by doing this...


Raymond

OK, so this is kind of embarrassing. Turns out the 15 v I said I saw last
night on the 110 v rail, was actually 15 mV. Sucks getting old. I hooked
up a 470 uF 250 v cap that I pulled out of an old power supply per Tom's
suggestion and it went down to about 14.5 mV AC. Is that still too high?
The other numbers on the remaining rails go down to <.4 mV AC.





On Thu, Dec 4, 2014 at 1:11 PM, Kevin Crossett <kcrossett@...> wrote:

Thanks for the insight Paul. I am familiar with parts removal, and would
probably have determined the best course of action would be destroying the
cap and removing the individual legs one at ta time. I will need to study
up a bit on the ground connections. i'm sure it will be very clear if and
when I get to that part of the board.

On Thu, Dec 4, 2014 at 3:11 PM, Paul Amaranth paul@...
[TekScopes] <TekScopes@...> wrote:

If you can't get to that file, I think I have a copy around that I could
mail you. It's a good writeup.

The big fun comes in replacing the cap. The PCB is easy to damage. It's
probably easiest to disassemble things a bit so you can cut the offending
cap off at the board level, then desolder the terminals. The can is a
big heat sink and if you desolder it intact, there's a tendency to use too
much heat which lifts a PCB pad or two (although it can be done).

I'm probably getting ahead of things here, but as Tom mentioned, if you
replace the cap, you'll have to jumper the 3 negative terminals on the
PCB; Tek used the can as a jumper. When I do this, I use a little adapter
PCB that lets me plug in a snap cap and matches the pinout of the old
cap. Totally unnecessary, but it makes for a nice repair.

You can tell that lots of people have dealt with this problem, so don't
be shy about asking questions.

Paul

On Thu, Dec 04, 2014 at 02:41:42PM -0500, 'Tom Miller'
tmiller11147@... [TekScopes] wrote:

There is a file in the files section called Tek 465 Power Supply

Capacitor Replacement Guide.pdf that might help you find what you need.
Since the yahoo boobs went to neo, I am unable to open the file, so good
luck.

In any event, the capacitor has three negative terminals in a circle.

the positive terminal is within the circle.

- -
+

-

Watch your fingers when making measurements in this area or it can bite

you.

Also, when and if you go to change this cap, the capacitor can and the

three contacts are a part of the circuit. Also, you dont want to pull the
track and the plated through holes out when removing the bad cap. Come back
for some more advice when you get to that point.

Regards,
tom


----- Original Message -----
From: Kevin Crossett kcrossett@... [TekScopes]
To: TekScopes@...
Sent: Thursday, December 04, 2014 2:20 PM
Subject: [TekScopes] Re: Tek 465B woes



Makes sense. I'll report back my findings as soon as I locate a cap and
solder it on.

[Non-text portions of this message have been removed]





[Non-text portions of this message have been removed]

--
Paul Amaranth, GCIH | Rochester MI, USA
Aurora Group, Inc. | Security, Systems & Software
paul@... | Unix & Windows

[Non-text portions of this message have been removed]

Is there another plugin next to the stuck one ?Sometimes, if a PI side panel is not installed correctly, the front edge can get caught on an adjacent plugin, or on the left edge of the mainframe.
?HankC, Boston
WA1HOS

Cavid:

Thanks; that worked great!

Mike N4MWP

On 12/04/2014 05:47 PM, David DiGiacomo telists@... [TekScopes]
wrote:

On Thu, Dec 4, 2014 at 2:28 PM, Mike <mdinolfo@...> wrote:

2. Another poster (edbreya) suggested "you need to read... message
112514...then look at 96664..." If I log into the tekscopes yahoo group
site and do a "conversations" search on "112514" I can access the 112514
message, but if I attempt a similar search on "96664" I get nothing.
Can someone explain to me how I might get access to message 96664?

[Non-text portions of this message have been removed]

On Thu, Dec 4, 2014 at 2:28 PM, Mike <mdinolfo@...> wrote:

2. Another poster (edbreya) suggested "you need to read... message
112514...then look at 96664..." If I log into the tekscopes yahoo group
site and do a "conversations" search on "112514" I can access the 112514
message, but if I attempt a similar search on "96664" I get nothing.
Can someone explain to me how I might get access to message 96664?

Dear all!

I replaced the batteries BT150 (A18 Memory Board) and BT130 (A14 I/O
Board) on my 11801C.

Because the fact, that the NVRAM is completely cleared, the scope lost
also its ID#. Is there a way to set the ID#? Are there any other things
to be reset or values to be restored after battery change?

Thanks for your help, Simon

One more. This is what I order finally. Available at no extra shipping cost in Europe also.




;relevancy-data=636F3D3126696E3D4931384E525353746F636B4E756D6265724D504E266C753D656E266D6D3D6D61746368616C6C26706D3D5E5C647B337D5B5C732D2F255C2E2C5D5C647B332C347D2426706F3D313426736E3D592673743D52535F53544F434B5F4E554D4245522677633D4E4F4E45267573743D3130362D34353826 ;relevancy-data=636F3D3126696E3D4931384E525353746F636B4E756D6265724D504E266C753D656E266D6D3D6D61746368616C6C26706D3D5E5C647B337D5B5C732D2F255C2E2C5D5C647B332C347D2426706F3D313426736E3D592673743D52535F53544F434B5F4E554D4245522677633D4E4F4E45267573743D3130362D34353826

In connection with the concept of using the LH1262 (or similar) device,
I have two questions for the group members:

1. To implement the "regulation" suggested by raymonddf, applied to the
use of an LH1262 as proposed by mlitwack, would it be possible to feed
the output of the LH1262 (about 12 or 13 volts unloaded) to a resistor
in series with a string of 1n914 diodes (a shunt regulator) to obtain
the "target" 1.35V voltage (or close to it)? The Fairchild 1n914
datasheet indicates approximately 250 mV forward drop (at 25 deg C) in a
1n914 with 1.0 microamp forward bias; perhaps six 1n914 diodes in series
with a 10 megohm resistor would work?

2. Another poster (edbreya) suggested "you need to read... message
112514...then look at 96664..." If I log into the tekscopes yahoo group
site and do a "conversations" search on "112514" I can access the 112514
message, but if I attempt a similar search on "96664" I get nothing.
Can someone explain to me how I might get access to message 96664?

Mike N4MWP

On 12/04/2014 01:42 PM, raymonddf@... [TekScopes] wrote:

The photovoltaic MOSFET approach would work of course. Current is more
than enough but regulation is compulsary at >13 V open circuit. The
sampler diodes in reverse bias hardly allow any current through.


Raymond


Another possibility on the photovoltaic approach is Vishay's LH1262
photovoltaic MOSFET drivers. It has two photovoltaic generators in a
DIP or SOIC package. You can get a minimum of 2.6uA each (3.4uA to
6.9uA typ, depending on drive current), with an open circuit voltage
of about 13.5V.

Regulation would still be needed, obviously, probably by loading the
output and controlling the drive current as in the referenced
artcicle. Or maybe that's enough current for an ultra-low power
regulator.


[Non-text portions of this message have been removed]

[Non-text portions of this message have been removed]

Thanks for the insight Paul. I am familiar with parts removal, and would
probably have determined the best course of action would be destroying the
cap and removing the individual legs one at ta time. I will need to study
up a bit on the ground connections. i'm sure it will be very clear if and
when I get to that part of the board.

On Thu, Dec 4, 2014 at 3:11 PM, Paul Amaranth paul@...
[TekScopes] <TekScopes@...> wrote:

If you can't get to that file, I think I have a copy around that I could
mail you. It's a good writeup.

The big fun comes in replacing the cap. The PCB is easy to damage. It's
probably easiest to disassemble things a bit so you can cut the offending
cap off at the board level, then desolder the terminals. The can is a
big heat sink and if you desolder it intact, there's a tendency to use too
much heat which lifts a PCB pad or two (although it can be done).

I'm probably getting ahead of things here, but as Tom mentioned, if you
replace the cap, you'll have to jumper the 3 negative terminals on the
PCB; Tek used the can as a jumper. When I do this, I use a little adapter
PCB that lets me plug in a snap cap and matches the pinout of the old
cap. Totally unnecessary, but it makes for a nice repair.

You can tell that lots of people have dealt with this problem, so don't
be shy about asking questions.

Paul

On Thu, Dec 04, 2014 at 02:41:42PM -0500, 'Tom Miller'
tmiller11147@... [TekScopes] wrote:

There is a file in the files section called Tek 465 Power Supply

Capacitor Replacement Guide.pdf that might help you find what you need.
Since the yahoo boobs went to neo, I am unable to open the file, so good
luck.

In any event, the capacitor has three negative terminals in a circle.

the positive terminal is within the circle.

- -
+

-

Watch your fingers when making measurements in this area or it can bite

you.

Also, when and if you go to change this cap, the capacitor can and the

three contacts are a part of the circuit. Also, you dont want to pull the
track and the plated through holes out when removing the bad cap. Come back
for some more advice when you get to that point.

Regards,
tom


----- Original Message -----
From: Kevin Crossett kcrossett@... [TekScopes]
To: TekScopes@...
Sent: Thursday, December 04, 2014 2:20 PM
Subject: [TekScopes] Re: Tek 465B woes



Makes sense. I'll report back my findings as soon as I locate a cap and
solder it on.

[Non-text portions of this message have been removed]

--
Paul Amaranth, GCIH | Rochester MI, USA
Aurora Group, Inc. | Security, Systems & Software
paul@... | Unix & Windows

[Non-text portions of this message have been removed]

If you can't get to that file, I think I have a copy around that I could
mail you. It's a good writeup.

The big fun comes in replacing the cap. The PCB is easy to damage. It's
probably easiest to disassemble things a bit so you can cut the offending
cap off at the board level, then desolder the terminals. The can is a
big heat sink and if you desolder it intact, there's a tendency to use too
much heat which lifts a PCB pad or two (although it can be done).

I'm probably getting ahead of things here, but as Tom mentioned, if you
replace the cap, you'll have to jumper the 3 negative terminals on the
PCB; Tek used the can as a jumper. When I do this, I use a little adapter
PCB that lets me plug in a snap cap and matches the pinout of the old
cap. Totally unnecessary, but it makes for a nice repair.

You can tell that lots of people have dealt with this problem, so don't
be shy about asking questions.

Paul

--
Paul Amaranth, GCIH | Rochester MI, USA
Aurora Group, Inc. | Security, Systems & Software
paul@... | Unix & Windows

Raymond:

Thanx for all the info. When it's working properly, the 7S14 is a sweet
plug-in.

I also wish there were more retired Tektronix engineers who would do repair
and calibration of old Tek equipment. Most of the repair shops in the S.F.
Bay area wanted an arm and a leg to do a few hours work.

Gary
On Dec 4, 2014 9:26 AM, "raymonddf@... [TekScopes]" <
TekScopes@...> wrote:

I wouldn't consider zinc-air batteries a good choice for this purpose.
Zinc-air batteries have a relatively long shelf life unopened but once
opened (activated), they discharge rather quickly, even without load, since
the zinc-air reaction just proceeds.


Several good options are available:
I have replaced the batteries with a DIY photovoltaic solution, using LEDs
(4 sets total). This solution is easy to build and works well.
There's been a lot of traffic on this forum re. the replacement of these
bias batteries, some of it less than a month ago.


Have a look at Ed Breya's very useful article here:


7S14 repair - TekWiki


7S14 repair - TekWiki The
following document was authored by Ed Breya and originally posted on the
TekScopes Yahoo forum. Contents 1 Background 2 Design and construction 3
Findings and recommendations Background



View on w140.com
Preview by Yahoo






Raymond


[Non-text portions of this message have been removed]

[Non-text portions of this message have been removed]

So now it seems to be just fine. Last night I fired it up and it still had the problem. Then I took it out and poked around in the circuitry looking for anything suspicious, jiggling stuff around some more, and pondering how to measure some of the resistors.

Then I put it back in to make some measurements, and the trace was nearly the right width. I also learned that the "SWP CAL" pot has nothing to do with setting the width, only the actual sweep ramp velocity. I initially assumed it was a gain control, but no. The specs just say that the width should be at least 10.2 divisions, so that must be the minimum that it gets to considering tolerances and drift - there's no 1X gain adjustment or comparator setting. So the trace was just about 10 divs wide, and stayed good for quite some time. I could adjust the sweep cal and set it right on to match the calibrator signal, so close enough to call it done.

This morning I fired it up again, and the width was about 10.5 divs when cold, then warmed up to where it is now 10.2 divs and holding. So, it's a mystery exactly what caused it, but I think the combination of poking around in there, working the controls more, and running time has restored it to normal. So, I'll have to call this one a done deal - I'm sure it will be just fine until I need to use it.

Ed

There is a file in the files section called Tek 465 Power Supply Capacitor Replacement Guide.pdf that might help you find what you need. Since the yahoo boobs went to neo, I am unable to open the file, so good luck.

In any event, the capacitor has three negative terminals in a circle. the positive terminal is within the circle.

- -
+

-

Watch your fingers when making measurements in this area or it can bite you.

Also, when and if you go to change this cap, the capacitor can and the three contacts are a part of the circuit. Also, you dont want to pull the track and the plated through holes out when removing the bad cap. Come back for some more advice when you get to that point.


Regards,
tom

Thanks Mike. I think I'm thinking too hard about this. That makes obvious
sense.

Cheers
Kevin
KN4M

On Thu, Dec 4, 2014 at 2:35 PM, n2lym n2lym@... [TekScopes] <
TekScopes@...> wrote:

Use you dmm on the existing capacitor to verify the correct polarity
BEFORE attaching added capacitor.

Mike N2LYM

On Thu, Dec 04, 2014 at 01:42 PM, Kevin Crossett kcrossett@...
[TekScopes] wrote:



That's what I figured. I will look in my junk box for an old power
supply

or some other electronics gizmo for the 100 v cap. Assuming I find one
in

the next day or so, I am now trying to determine the positive side of
the

cap...

I found this image on the internet of someone with a similar problem as
me.

He laid out what he thought were the solder points for the 4439 cap. Is
he

right, and if so, how can I determne which one is positive?

On Thu, Dec 4, 2014 at 1:29 PM, raymonddf@... [TekScopes] <

TekScopes@...> wrote:

Kevin,

Don't try a 470 uF 35V cap. unless you're looking forward to an early

firecracker party a few seconds or minutes after switching on...

Raymond

[Non-text portions of this message have been removed]

[Non-text portions of this message have been removed]

Use you dmm on the existing capacitor to verify the correct polarity
BEFORE attaching added capacitor.

Mike N2LYM

Hello everyone!

I'm searching for two parts for my sampling scope (Tek 11801):

1) 2x knob for sampling plugin (part# 366-0673-00 (KNOB:O.096 ID X 0.24
OD X 0.299H)
2) 1x empty plugin slot cover (part# ???)

I would be pleased if someone could help me!

Best, Simon

Makes sense. I'll report back my findings as soon as I locate a cap and
solder it on.