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Re: 453 trouble

Craig Sawyers
 

That would be typical if the chassis is ungrounded. Capacitance between the primary and shield (which
is connected to the chassis) in the mains transformer will cause this. First thing to do is connect
the ground in the mains plug - the previous user did a dangerous thing by disconnecting the ground.

There may be other problems to solve, of course - but make the scope safe first.

Craig

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of f4gny@...
Sent: 15 August 2018 06:02
To: [email protected]
Subject: [TekScopes] 453 trouble

Hello Folks,

Ive trouble on my 453, I discover that AC voltage is running on chassis +/- 75V .........
I opened the main plug and the ground pin was unconnected.
Does anyone experienced the same trouble ? is it normal when ungrounded or internal PSU show a
defective componement ? Thank for your help.
Regards
Alain


453 trouble

 

Hello Folks,

Ive trouble on my 453, I discover that AC voltage is running on chassis +/- 75V .........
I opened the main plug and the ground pin was unconnected.
Does anyone experienced the same trouble ? is it normal when ungrounded or
internal PSU show a defective componement ? Thank for your help.
Regards
Alain


Re: 422 AC power socket

 

Funny coincidence as I was out in the garage yesterday and saw my hedge trimmer cord. 10 seconds with my pocket knife and I now have a 50' power cord!

Thanks everyone for replying.


Re: 422 AC power socket

 

The non AC/DC version of a 422 needs the same kind of cord as most weed whackers n shit. I have had a few where I had to trim the edges a bit but they connect and they are safe. Some brands f them you don't even have to round the corners off.

Now if you got an AC/DC model that is a whole different story. If you really can't get the cords for those I reluctantly suggest a modification. There are many ways to do it.


Re: Concentric A and B time-base knobs/interlocking

 

On Tue, Aug 14, 2018 at 08:53 PM, Colin Herbert wrote:


the B time-base knob is a little imprecise in operation and doesn't seem to
quite click into its detents cleanly.
That sort of imprecise clicking thing normally is easy to correct by loosening the B knob, carefully adjusting the angle of the knob against the A knob, fastening it and repeating if necessary.

You do have a nice selection of equipment!

Personally, the 466 is one of my favorites in the series, if the storage is adjusted and used correctly.

Raymond


Re: Concentric A and B time-base knobs/interlocking

 

You may be right about the assembly error, as the B time-base knob is a little imprecise in operation and doesn't seem to quite click into its detents cleanly.

However, I have now checked both the A and B time-bases with my TG 501 and they look to be right, if not wonderfully calibrated. The A time-base is certainly showing the right rates as is the B time-base up to a point. By that I mean that beyond ~20uS/DIV the trace is so dim it can barely be seen. All of the beam-current looks to be in the first part of the sweep, which is the vertical line I mentioned before.

I am no electronic engineer, just a hobbyist, but I do have a working 464, 475A, SC502 and 7623A, as well as this 466 and a possibly ailing 468. I also have PG506, TG501, SG503 and an FG504 with issues. So, I am a little familiar with the operation of the 400-series, if not totally conversant with the theory of operation. But I have no problems with learning "new tricks" and I don't feel insulted. All help is gratefully received.

I am beginning to think that I might raid the parts-donor 466 for its B time-base control parts, if not the whole Timing board. I think my repair wasn't totally successful, considering the imprecise action of the B time-base knob.

Colin.

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Raymond Domp Frank
Sent: 14 August 2018 19:05
To: [email protected]
Subject: Re: [TekScopes] Concentric A and B time-base knobs/interlocking

Hi Colin,
Do you know if the time base speeds of A and B correspond to those indicated on the knobs? Did you try observing waveforms with both A and B? I'm thinking you may have made an assembly error: The max. A and B rotation and the freedom of rotation angles between A and B are mechanically limited by the knob assembly.

There is a less-intense portion which can be moved by the "Delay Time Position" control, but it's length isn't controlled by the setting of the
B (delayed) time-base knob, only it's position.
I have no idea how familiar you are with this model and 'scopes in general so please don't be insulted if you know all this: Just to make sure we're talking about the same thing, the smaller, grey knob controls the speed of the B timebase, the clear part behind it controls the A time base. The Delay Time knob controls the time after A's start until B starts. If all is well (assembled), A can never be faster than B.

...no bright-up indicating where the B (delayed) time-base will run from and to
This makes me think we are talking about the same A's and B's but the bright-up should be there.

...it's length isn't controlled by the setting of the B (delayed) time-base knob, only it's position.
That sounds strange: The B (delayed) time base knob (the smaller grey one) should control the length of B on A and not influence the starting position.
Sounds like assembly error.

Check the speeds of "A" and "B" relating to the indications on the time scale by applying a signal and see if they make sense.

Raymond


Re: Concentric A and B time-base knobs/interlocking

 

Hi Colin,
Do you know if the time base speeds of A and B correspond to those indicated on the knobs? Did you try observing waveforms with both A and B? I'm thinking you may have made an assembly error: The max. A and B rotation and the freedom of rotation angles between A and B are mechanically limited by the knob assembly.

There is a less-intense portion which can be moved by the "Delay Time Position" control, but it's length isn't controlled by the setting of the
B (delayed) time-base knob, only it's position.
I have no idea how familiar you are with this model and 'scopes in general so please don't be insulted if you know all this: Just to make sure we're talking about the same thing, the smaller, grey knob controls the speed of the B timebase, the clear part behind it controls the A time base. The Delay Time knob controls the time after A's start until B starts. If all is well (assembled), A can never be faster than B.

...no bright-up indicating where the B (delayed) time-base will run from and to
This makes me think we are talking about the same A's and B's but the bright-up should be there.

...it's length isn't controlled by the setting of the B (delayed) time-base knob, only it's position.
That sounds strange: The B (delayed) time base knob (the smaller grey one) should control the length of B on A and not influence the starting position.
Sounds like assembly error.

Check the speeds of "A" and "B" relating to the indications on the time scale by applying a signal and see if they make sense.

Raymond


Re: Concentric A and B time-base knobs/interlocking

 

Hi Raymond,

I probably didn't express myself clearly enough. The situation with regard to the horizontal display buttons is this:

1) A is fine and does what it should.
2) MIX shows both time-bases, but the start point is moved about a half of a large division to the left. The position of the changeover point is moved by the "Delay Time Position" multiturn pot as you would expect.
3) A INTEN shows the A time-base, but there is no bright-up indicating where the B (delayed) time-base will run from and to. There is a less-intense portion which can be moved by the "Delay Time Position" control, but it's length isn't controlled by the setting of the B (delayed) time-base knob, only it's position.
4) B DLY'D shows the B (delayed) time-base, but the first part shows a bright vertical line of the same amplitude as the signal at the vertical input. There is also some indication that some of the flyback is visible.

I think maybe I had the A Trig Holdoff control at "A ENDS B" before, but for these observations, it is at "NORM".
Other controls are:
A Trig mode Auto
A Coupling AC
A Source Norm
B Coupling AC
B Source Starts after delay.

I hope this is a bit clearer.
Colin.

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Raymond Domp Frank
Sent: 14 August 2018 14:59
To: [email protected]
Subject: Re: [TekScopes] Concentric A and B time-base knobs/interlocking

On Tue, Aug 14, 2018 at 03:39 PM, Colin Herbert wrote:


The "A" part of the display is given and is brighter than just showing the A
time-base on its own, but the supposedly intensified "B" part in too dim to
see, even if I turn the intensity up to maximum.
Colin,
Not sure if I understand exactly what you mean:
The "A" part of the trace (that's the part movable by the delay setting) is supposed to be intensified, not the "B" part.

Are you sure "B ends A" isn't set? It's the fully CW position of the Holdoff knob, which is just to the right of the Calibrator loop.

If that's not it, ISTR that there's a separate adjustment for the A and B part (one being the normal Intensity setting). Unfortunately, ATM I have no time to look it up in the Service Manual.

Raymond


Re: Concentric A and B time-base knobs/interlocking

 

On Tue, Aug 14, 2018 at 03:39 PM, Colin Herbert wrote:


The "A" part of the display is given and is brighter than just showing the A
time-base on its own, but the supposedly intensified "B" part in too dim to
see, even if I turn the intensity up to maximum.
Colin,
Not sure if I understand exactly what you mean:
The "A" part of the trace (that's the part movable by the delay setting) is supposed to be intensified, not the "B" part.

Are you sure "B ends A" isn't set? It's the fully CW position of the Holdoff knob, which is just to the right of the Calibrator loop.

If that's not it, ISTR that there's a separate adjustment for the A and B part (one being the normal Intensity setting). Unfortunately, ATM I have no time to look it up in the Service Manual.

Raymond


Re: Concentric A and B time-base knobs/interlocking

 

Hi,
I removed both the Trig & Sweep Logic board and the Timing board. I could then remove the shielding covering the cams and the cam assemblies themselves carefully. I then extracted the appropriate B-time-base cam and actuating rod and applied just enough cyanoacrylate to the broken parts. After leaving this quite a long time to cure (while also actuating the pull-up actuator so that it didn¡¯t gum up, I checked it out and then re-assembled everything. I can now (sort-of) use the delayed time-base as well as the A time-base. The oddity remaining is that while I can use the A time-base, mixed and B delayed, the A intensified by B isn't working properly. The "A" part of the display is given and is brighter than just showing the A time-base on its own, but the supposedly intensified "B" part in too dim to see, even if I turn the intensity up to maximum. I have a Timing board from a parts-donor which I could put in, but I'm not sure whether the Timing board is the source of the bright-up pulse, despite trying to find this out from the manual. Of course, the parts-donor also has a Trig & Sweep Logic board which could be used. However, I don't know if either of these boards is functioning properly.....
Colin.

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Raymond Domp Frank
Sent: 16 July 2018 00:52
To: [email protected]
Subject: Re: [TekScopes] Concentric A and B time-base knobs/interlocking

Colin,
Usually, this is a symptom of the core of the plastic drum for the B-timebase being loose from the shaft that controls it from the front. Often forcing the knob beyond the extreme position breaks the injection molded bond between the aluminium shaft and the drum's core. Also, the plastic of the drum tends to become brittle with time, as I've seen in one case, where the complete assembly had disintegrated.
This problem and its solution have been described in this group in the past but I haven't tried looking things up.

I have used two methods for repair:

1. The safe way of removing the trigger and time base boards, disassembling the switch assembly and repairing the bond with cyanoacrylate glue. This is quite doable if you pay attention to what you're doing. Note that your 'scope may contain a spring-loaded cam-and-pin to prevent a few extreme combinations of the A- and B-timebase, as noted on the front plate. This part of the assembly is not present on later (?) units and AFAIK only prevents the selection of less-accurate combinations.

2. The adventurous way, as follows (read all steps through so you understand the procedure before doing anything):

a. Don't start by opening the 'scope, let alone disassembling anything!
Instead:
b. Remove the red variable time base button
c. Note the length of B-timebase shaft coming out of the 'scope in the pushed-in (no B-timebase) position and pull the B-timebase shaft out of the 'scope. It should come out easily if the problem is as suspected.
d. Try pushing the shaft in and out a few times. It should not bend with the surrounding (A-timebase) tube and see if you can get the same length of staff sticking out as noted in c.
d. Remove all grease from the shaft
e. Cover the shaft with a thin layer of silicon grease but leave about 1 cm at both ends free
f. Thinly cover the top end and ribbed tip of the shaft that is supposed to sit inside the drum with a layer of cyanoacrylate gel
g. Take a deep breath and push the shaft in as far as it was before (point c). You may want to rehearse this without grease and glue first.
h. Wait until the glue has set.

If you correctly followed this procedure, with a tiny bit of luck the shaft is now strongly stuck to the drum and *not* to the surrounding A-timebase tube, because the silicon grease prevented that.
Obviously, you basically only get one shot at this because if you pull the B-shaft out and push it in again, the glue-covered end will pass through the remaining grease in the outer (A-timebase) tube, killing the effectiveness of the glue.

Unless you put an inordinate amount of glue on the end (almost impossible) or did not completely cover the shaft with silicon grease (possible), it'll be easy to pull the B-shaft out again from the A-shaft if the procedure didn't work and you'd still have to follow procedure 1.

I have had complete success with both procedures in several cases (3 or 4 with method 2. alone, no retries or going to procedure 1.) and no failures, apart from the case where the plastic drum assembly had almost disintegrated and the switch assembly had to be replaced by a donor unit.

Please report back which procedure you followed and its results. Good luck!

Raymond


Re: 464

 

On 2018-08-14 1:08 AM, Jim Olson wrote:
Roy it is also available on the KO4BB site as a clean PDF file down loaded it myself. they also have a lot of Tek manuals, the weekly pubs and tech notes too.

Jim O
A direct link for those interested.


--Toby


Re: 464

 

On Tue, Aug 14, 2018 at 04:14 AM, Roy Morgan wrote:

You should/must get a copy of the 1998 Tek Manual ; Troubleshooting Your Oscilloscope ; Getting Down to Basics, 068-0315-00. It is one of our Bibles

Ah I did find it at:

That version has 94 pages though the last page is numbered 88.
That would be the scan I made about 14 years ago and made available to this group:
/g/TekScopes/message/7215

It then has spread to various sites for free download which is OK. But it's annoying is that
it often comes up for sale on eBay. The original is off course in Letter format but for some
reason my scanner was set to A4 format leaving a white field at the bottom if each page.
Since then I have rescanned the whole manual with a better scanner and in the correct format:


BTW, it's from 1989 not 1998

/H?kan


Re: 464

 

Roy it is also available on the KO4BB site as a clean PDF file down loaded it myself. they also have a lot of Tek manuals, the weekly pubs and tech notes too.

Jim O

On August 13, 2018 at 7:13 PM Roy Morgan <k1lky68@...> wrote:


Jon,

I searched Tek Wiki web site:
w140.com/tekwiki/ <>

And did not find this manual.

Am I looking on the right place?
Is there a direct link to it? Or to the page or list of manuals it is found among?

Ah I did find it at:

That version has 94 pages though the last page is numbered 88.

Ah I also did find it on the proxy site manuals page:

And the direct link is:


Thanks, I can certainly learn a lot from that manual. My 547 seems to be working ok but its 1A1 has incorrect gain in one channel.

Roy
547 and 545B

Roy Morgan
k1lky68@... <mailto:k1lky68@...>



On Aug 12, 2018, at 4:37 PM, Jon Batters <jonbatters32@... <mailto:jonbatters32@...>> wrote:

... You should/must get a copy of the 1998 Tek Manual ; Troubleshooting Your Oscilloscope ; Getting Down to Basics, 068-0315-00. It is one of our Bibles. It's 82 pages and mine is maybe 120 pages with copies of data from my various Tek Scopes and annotations,




Re: 464

Roy Morgan
 

Jon,

I searched Tek Wiki web site:
w140.com/tekwiki/ <>

And did not find this manual.

Am I looking on the right place?
Is there a direct link to it? Or to the page or list of manuals it is found among?

Ah I did find it at:

That version has 94 pages though the last page is numbered 88.

Ah I also did find it on the proxy site manuals page:

And the direct link is:


Thanks, I can certainly learn a lot from that manual. My 547 seems to be working ok but its 1A1 has incorrect gain in one channel.

Roy
547 and 545B

Roy Morgan
k1lky68@... <mailto:k1lky68@...>

On Aug 12, 2018, at 4:37 PM, Jon Batters <jonbatters32@... <mailto:jonbatters32@...>> wrote:

... You should/must get a copy of the 1998 Tek Manual ; Troubleshooting Your Oscilloscope ; Getting Down to Basics, 068-0315-00. It is one of our Bibles. It's 82 pages and mine is maybe 120 pages with copies of data from my various Tek Scopes and annotations,


Re: Scope

 

On 2018-08-13 12:37 PM, Roger Evans via Groups.Io wrote:
Tom,

This is where I found mine. It is not a service manual in the traditional sense with schematics but it does have some useful information on removing boards and voltage test points. Despite the name it does include the 684A.

www.dennlec.com/images/manuals/tek-tds-784a-service-manual.pdf
For those curious what else is there:



--Toby

Roger




Re: Scope

 

I think the nearest you'll get to schematics is what H?kan has published <
>. You'll some schematics for the 644A
there, though ISTR there are significant differences to the 684A.

On Mon, 13 Aug 2018 at 12:13 Thomas Dodge <tdodge2404@...> wrote:

Thanks for your email. Yes, it is a TDS 684A. I actually got it running
yesterday, and it is working very well. I think it had been in the surplus
place for a long time, and so it took a while for everything to initialize,
but it works great. It is in very good condition. Do you know where I can
get an original service manual for it? I will take a look inside it and
look at the condition inside. Thank you very much.


Re: Scope

 

Tom,

This is where I found mine. It is not a service manual in the traditional sense with schematics but it does have some useful information on removing boards and voltage test points. Despite the name it does include the 684A.

www.dennlec.com/images/manuals/tek-tds-784a-service-manual.pdf

Roger


Re: Scope

 

The clearest you will get is a service manual for TDS544A as I recall. None of the others have ever been released. Many of the sections are the same or similar though so it is still helpful.
--Eric
Sent from my Samsung Galaxy smartphone.

-------- Original message --------From: Thomas Dodge <tdodge2404@...> Date: 8/13/18 11:13 AM (GMT-06:00) To: [email protected] Subject: Re: [TekScopes] Scope
Hi Roger,
Thanks for your email. Yes, it is a TDS 684A. I actually got it running
yesterday, and it is working very well. I think it had been in the surplus
place for a long time, and so it took a while for everything to initialize,
but it works great. It is in very good condition. Do you know where I can
get an original service manual for it? I will take a look inside it and
look at the condition inside. Thank you very much.

Tom

On Mon, Aug 13, 2018, 8:49 AM Roger Evans via Groups.Io <very_fuzzy_logic=
[email protected]> wrote:

Tom,

Do you mean a TDS 684A?? I have one of these and it has serious problems
with leaking of the SMD electrolytic capacitors on the acquisition board
and subsequent corrosion.? There are not too many to change and you can
find the service manual which details the procedure for removing the
acquisition board.? Look very carefully around the other SMD components
near the attenuator assembly, this is where I have the most obvious
corrosion rather than near the electrolytics.? Best to fix these before
they cause damage to the PCB tracks and vias.

Roger




Re: Scope

 

Hi Roger,
Thanks for your email. Yes, it is a TDS 684A. I actually got it running
yesterday, and it is working very well. I think it had been in the surplus
place for a long time, and so it took a while for everything to initialize,
but it works great. It is in very good condition. Do you know where I can
get an original service manual for it? I will take a look inside it and
look at the condition inside. Thank you very much.

Tom

On Mon, Aug 13, 2018, 8:49 AM Roger Evans via Groups.Io <very_fuzzy_logic=
[email protected]> wrote:

Tom,

Do you mean a TDS 684A? I have one of these and it has serious problems
with leaking of the SMD electrolytic capacitors on the acquisition board
and subsequent corrosion. There are not too many to change and you can
find the service manual which details the procedure for removing the
acquisition board. Look very carefully around the other SMD components
near the attenuator assembly, this is where I have the most obvious
corrosion rather than near the electrolytics. Best to fix these before
they cause damage to the PCB tracks and vias.

Roger




Re: Scope

 

Tom,

Do you mean a TDS 684A? I have one of these and it has serious problems with leaking of the SMD electrolytic capacitors on the acquisition board and subsequent corrosion. There are not too many to change and you can find the service manual which details the procedure for removing the acquisition board. Look very carefully around the other SMD components near the attenuator assembly, this is where I have the most obvious corrosion rather than near the electrolytics. Best to fix these before they cause damage to the PCB tracks and vias.

Roger