Re: Help required finding a Tek 466 power rail short
Just to clarify.
On the A10 Storage board, there are three tantalums which all read short when connected, yet fine with one leg disconnected.
They are, C1846 C1826 and C2097.
I am presuming that one leg of each is to ground and that the other must be to the 5v rail, so probably all ok (apart from the 5v rail short)
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Re: Looking for part 155-0042-03 Miller integrator to Japan
The Miller Integrators that I have in the parts mule 7B53A are 155-0028-00, but I also have a 5B10N parts mule in the right serial number range to be using a 155-0042-03 part. My notes say "the main selector switch needs cleaning, entire blocks of sweep speeds no working" which suggests that some sweep speeds are working, and hence that the Miller integrator is working. I can double check that instrument to be sure that it is working.
-- Jeff Dutky
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The serial number for my 7B53N is B052213 and U750 in it is a 155-0042-03. I haven't found a serial number range in the manual and presumed it covers all serial numbers for that model.
I'm not sure of all the differences, but comparing my 7B53N to a 7B53A or 7B53AN shows quite a bit of differences. For example, the trigger board in the N model has mostly discrete components whereas the A or AN models have several ICs there. There are other differences - mostly due to layout - but the schematics seem to be quite different as well.
I presume signals at similar (but differently-named) TPs should be close to the same between models but I haven't tried to correlate those yet.
Mine will display a trace in AUTO mode but won't trigger and, of course, won't display anything in NORM due to the same problem. It also won't sweep in the 5ms, 2ms, or 1ms positions. I've cleaned the finger switches but that didn't help and I suspect one of the timing resistors or capacitors is either bad or still not getting connected in those modes. I tested the timing caps while I had it apart and those looked good.
I'm still trying to determine where the problem(s) are in mine.
Thanks,
Barry - N4BUQ
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----- Original Message ----- From: "Jean-Marc Imbert" <jmimbert@...>
To: "tekscopes" <[email protected]>
Sent: Friday, December 10, 2021 9:24:33 AM
Subject: Re: [TekScopes] 7B53N sweep repair Thanks Barry ! this is useful information. I'd buy it from Artek asap;: can you
please check if it suits my serial number B051276 ?. Then I think I can work
out the voltage levels similarities with the 7B84, 7B92 which use the same
155-0049-00 sweep control IC. Regards .Jean-Marc
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Thanks Colin but it seems the 7B3N trigger part (and front face) is 90% inherited from the 7B52 in all cases.
For the sweep part, I can't generalize but mine (SNB051276) has a sweep part with a sweep control IC, 155-049-00, similar to the 7B53A. But the apart from this IC the 7B53N and 7B53A sweep boards have very different layouts and overall very different schematics and numbering.
So I dont think the trigger part of the 7B53A can help for the strangely named 7B53N. (everybody agrees that the sequential name should have been 7B52N).
But thanks for the offer.
I'm in France, Tours :)
Barry might be yes in North America.
Jean-Marc
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Re: Help required finding a Tek 466 power rail short
Hi Mark and thank you for your advice.
Any components from Mouser shall probably have to wait until I next go to Europe, as unfortunately the postal services here simply cannot be trusted to deliver any international item. Quality components such as low ESR caps are extremely difficult to find in Brazil so my goal is to just get the scope back to a working condition. I have repaired various of this series, which have always been just fairly simple component replacement. By the tme this one is back up and running I shall certainly have a much deeper understanding on analogue scope repair. :)
Anyway, CR1767 is fine although VR1726 is indeed open. So that is progress.
I have been primarily looking for shorted tantalums and diodes, and mainly on the A6 Interface board. So far, I have found three or four but seem to have run out of tantalums to test on that board.
On the A10 Storage board however, I do find that across certain caps it reads short, only for the caps to test good with one leg removed, although across the traces still reads short. C1846 being one of these.
@ Harvey...
It has been on my mind that perhaps there is a bridge rectifier issue because some of the readings are not as they were, and they are not consistent across all rectifiers. I have just been putting it down to something further along being shorted, however I shall have a deeper look just to clarify. It would be nice to remove the rectifiers but it was such a ball-ache changing the ones I replaced that I must say, it doesn't really fill me with desire to do it again.
There was a video I saw where the tech just used a pair of pliers to literally twist the rectifier off the board before desoldering the remaining legs/pins, it's just I can no longer find the vid and don't want to risk destroying the A6 board...
As for ESR testers, I have an MK 328 which stopped working this week. Having said that I found an old Wayne Kerr 4225 ESR/LCR tester yesterday in a junk shop for under 20 USD. It switches on and a quick look inside shows it's complete, so once I clean the contacts which hold the components under test, I'll give it a spin.
Need to head into town for components.
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Hi Guys,
I don't know if this is of much use, but my Tek hard-copy Service Manual for 7B53A/7B53AN has the s/n 107222 on the front page, is 070-1342-00 and also has pages marked "MANUAL REPRINTED APRIL 1980". It certainly includes typical signals and voltage values for TPs. I suppose this might be of some assistance somewhere. For instance, the "main trigger preamp" pages show TPs 50 and 59 and a third test-point at the R76/P70 junction. I live in London, UK and so can't easily send much to people in the USA even if the Tektronix patents would allow it, but if odd pages can help, I could try something.
Colin.
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-----Original Message----- From: [email protected] [mailto: [email protected]] On Behalf Of n4buq Sent: 10 December 2021 15:13 To: tekscopes Subject: Re: [TekScopes] 7B53N sweep repair Hi Jean-Marc, I happen to be working on a 7B53N as well (mine doesn't trigger). I purchased a scan of the service manual from Artek Manuals. It has the correct schematics, etc., and might be well worth getting one of those scans from Dave. I wish Tektronix had included some expected waveforms at the TPs and typical voltage values for pertinent points in that manual but, apparently, they did not so troubleshooting is a still a bit challenging. Thanks, Barry - N4BUQ ----- Original Message ----- From: "Jean-Marc Imbert" <jmimbert@...>
To: "tekscopes" <[email protected]>
Sent: Friday, December 10, 2021 8:57:33 AM
Subject: [TekScopes] 7B53N sweep repair Hello all from the great Tekscopes group,
My 7B53N has SN B051276 and the sweep board doesn't use the components showed in
the 7B52 service manual. It takes from the 7B53A because of the central
component (sweep control IC) which is 155-0049-(00). But it's not at all like
the 7B53A either and the schematics part numbering is entirely different
anyway.
So it is very difficult to follow the horizontal section flow (loop) without an
actual schematics and layout.
The 7B53N worked very well and suddenly wouldn't start sweeping (vert. defl. ok
on a 7633).
The trigger triggers OK but sticks lit. Trigger TDs CR470 and 475 arm and fire
OK.
The X amp works fine driven by a 7CT1N.
The trace is showing a very weak unblanked vertical (a non horizontally swept
sine) far left (2 virtual screen widths ? ) off the screen if recovered with
the 7B53N X position.
I am not sure whether the -15 V which reads -12.65 V after R128 (7B52 voltage
distribution - Schem. n¡ã10) is a problem.
I'd like to follow up with Holdoff and Unblank functions debug.
Does somebody please know a pdf schematics source for the version of the 7B53N
with 155-049-00 sweep IC ? Or could send a scan of the sweep board service
pages ?
Salutations.
Jean-Marc
ps excellent extender from John Griessen allows some repairs which would be a
chore without ! Thanks again John !
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Barry, If you want to discuss the trigger board maybe you can open a new thread because I just checked mine and I can maybe help. Everything is identical to the 7B52, schematics, voltages, waveforms except the the missing discrete AUTO MULTI. The discrete AUTO DRIVE is also an empty placeholder (with traces and holes) on the sweep board. This is because both functions are left to the sweep control IC 155-0049-00. Cheers . Jean-Marc
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Hi Carl,
I'm actively looking for these carts. Chesterton is pretty far away, but it's a strong maybe.
Please check your email.
Thanks,
Chris
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Thanks Barry ! this is useful information. I'd buy it from Artek asap;: can you please check if it suits my serial number B051276 ?. Then I think I can work out the voltage levels similarities with the 7B84, 7B92 which use the same 155-0049-00 sweep control IC. Regards .Jean-Marc
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Hi Jean-Marc,
I happen to be working on a 7B53N as well (mine doesn't trigger). I purchased a scan of the service manual from Artek Manuals. It has the correct schematics, etc., and might be well worth getting one of those scans from Dave.
I wish Tektronix had included some expected waveforms at the TPs and typical voltage values for pertinent points in that manual but, apparently, they did not so troubleshooting is a still a bit challenging.
Thanks,
Barry - N4BUQ
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----- Original Message ----- From: "Jean-Marc Imbert" <jmimbert@...>
To: "tekscopes" <[email protected]>
Sent: Friday, December 10, 2021 8:57:33 AM
Subject: [TekScopes] 7B53N sweep repair Hello all from the great Tekscopes group,
My 7B53N has SN B051276 and the sweep board doesn't use the components showed in
the 7B52 service manual. It takes from the 7B53A because of the central
component (sweep control IC) which is 155-0049-(00). But it's not at all like
the 7B53A either and the schematics part numbering is entirely different
anyway.
So it is very difficult to follow the horizontal section flow (loop) without an
actual schematics and layout.
The 7B53N worked very well and suddenly wouldn't start sweeping (vert. defl. ok
on a 7633).
The trigger triggers OK but sticks lit. Trigger TDs CR470 and 475 arm and fire
OK.
The X amp works fine driven by a 7CT1N.
The trace is showing a very weak unblanked vertical (a non horizontally swept
sine) far left (2 virtual screen widths ? ) off the screen if recovered with
the 7B53N X position.
I am not sure whether the -15 V which reads -12.65 V after R128 (7B52 voltage
distribution - Schem. n¡ã10) is a problem.
I'd like to follow up with Holdoff and Unblank functions debug.
Does somebody please know a pdf schematics source for the version of the 7B53N
with 155-049-00 sweep IC ? Or could send a scan of the sweep board service
pages ?
Salutations.
Jean-Marc
ps excellent extender from John Griessen allows some repairs which would be a
chore without ! Thanks again John !
|
Hello all from the great Tekscopes group,
My 7B53N has SN B051276 and the sweep board doesn't use the components showed in the 7B52 service manual. It takes from the 7B53A because of the central component (sweep control IC) which is 155-0049-(00). But it's not at all like the 7B53A either and the schematics part numbering is entirely different anyway.
So it is very difficult to follow the horizontal section flow (loop) without an actual schematics and layout.
The 7B53N worked very well and suddenly wouldn't start sweeping (vert. defl. ok on a 7633).
The trigger triggers OK but sticks lit. Trigger TDs CR470 and 475 arm and fire OK.
The X amp works fine driven by a 7CT1N.
The trace is showing a very weak unblanked vertical (a non horizontally swept sine) far left (2 virtual screen widths ? ) off the screen if recovered with the 7B53N X position.
I am not sure whether the -15 V which reads -12.65 V after R128 (7B52 voltage distribution - Schem. n¡ã10) is a problem.
I'd like to follow up with Holdoff and Unblank functions debug.
Does somebody please know a pdf schematics source for the version of the 7B53N with 155-049-00 sweep IC ? Or could send a scan of the sweep board service pages ?
Salutations.
Jean-Marc
ps excellent extender from John Griessen allows some repairs which would be a chore without ! Thanks again John !
|
Re: 7S12 diagnosis needed
Tim,
The Locate highlighted portion length should match the Time/div setting. For Time/div fully CCW (at a given range) the portion should be about 50% of the total length. Is Time/div also defective, apart from Time/Distance?
Albert
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Ok. That¡¯s too far away for me.
Thanks.
DaveD
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On Dec 9, 2021, at 21:58, Carl Hallberg via groups.io <n9ess@...> wrote:
?Chesterton Indiana
On Thursday, December 9, 2021, 03:41:00 PM CST, Carl Hallberg via groups.io <n9ess@...> wrote:
Anybody need a cart? Pickup only.
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I have a 7S12 that 'half-works', in that I see the pulse from the S52 / S6
combo and I get the step-response from a length of cable BUT, the Time /
Distance crank does nothing to the display and the Locate button just
gives a bright dot at far LHS.
I have done basic tests on the horizontal circuitry, and re-seated the ICs
on the Horizontal board. These have 'proper' sockets, not the T*x*s ones. I
don't have any extenders, and anyway, the H and V boards need their own
extender cards so I can't probe any of the TPs. And it's not a loose screw
on the T / D shaft.
Has anyone been here ? I sort-of suspect one of the ICs on the H board but
don't want to tear into it without asking advice.
TIA
Tim
--
"Success is a collection of well-curated failures"
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Re: Looking for part 155-0042-03 Miller integrator to Japan
Oh, I¡¯m also not sure if they are -03 parts: do you absolutely need an -03?
¡ª Jeff Dutky
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Re: Looking for part 155-0042-03 Miller integrator to Japan
I have a couple from a badly abused 7B53A, but I don¡¯t know if they are good. Is there a way to test them on the bench? If they prove to be good I can send you one.
¡ª Jeff Dutky
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Hi Carl,
I'd love to have it for my 7409.? I'm in Columbus, can you put it on a bus?? 9 hours RT is kinda a stretch.
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On 12/9/2021 9:58 PM, Carl Hallberg via groups.io wrote: Chesterton Indiana
On Thursday, December 9, 2021, 03:41:00 PM CST, Carl Hallberg via groups.io <n9ess@...> wrote:
Anybody need a cart?? Pickup only.
.
--
Bruce Atwood PhD
Sponsored Guest, Department of Astronomy
The Ohio State University
Phone 614.314.0189
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Re: Help required finding a Tek 466 power rail short
James,
It appears you have shorted tantalums. Also check CR1767. The 5V and -15V supply resistance is too low. Get 647-ULD1E470MDD1TD for the 15V supplies and 647-ULD1C470MDD for the 5V supplies. The former is due in sometime this year and latter is in stock at Mouser. These are electrolytics that will work to replace the 6.8mfd tantalums. If you want tantalums, get 25V types for the 8V and 15V supplies and 10V minimum for the 5V supply. Raising the capacitance is fine. I did this in my 466. Raising the value of decoupling is fine. These are not critical in value. The ULD types are very low ESR, long fie and high temperature. I use this series when possible. C1737 can be increased in value, e.g. 15-33mfd 100V Nichicon UHE type or 22mfd 100V ULD type. Replacing the main filters with long life high temperature long life types is advised. I found that the 1200mfd I replaced with a 2200mfd type because this value is available in the specs mentioned before. These values are used in the 46/7X types.
Testing the other side of the series pass means that you test the resistance at the TP points instead of at the collectors. You could have a bad series pass transistor.
I will suggest to change R1726 to 2W and VR1726 to 85-BZX85B9V1. There are other resistors that should be increased in wattage. The zener is highly likely open.
Mark
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Re: Help required finding a Tek 466 power rail short
I believe I have the relevant manual in .pdf form, it is just not the clearest reproduction.
Just to help fill in more details, with no power to the scope, the resistance readings across the various low voltage rails are as follows;
140v ... 24 K¦¸
65V ... 7.3 ¦¸
15v ... 13.7 ¦¸
5v ... 0.2 ¦¸
-8v ... 47.4¦¸
-15v .. 2.5 ¦¸
So connected the scope up at 100mA but nothing heated up.
When you say to test on the other side of the 'pass' transistor, are they the ones bolted under the bar at the rear of the scope? And when you say disconnect everything from the supply, are you talking about disconnecting the boards beyond the main A6 board?
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James55