Date   

Re: SC502 With Display Issues

Stephen
 

On Sat, Aug 15, 2020 at 01:59 PM, Harvey White wrote:

Ok, that's actually part good news.  Not likely that you've damaged the
frame *if* the other modules use all of the frame slot's capabilities.
The 2 DC503 and DC505A that were inside the mainframe when this happened, shut down immediately.
Now that the 2 x 2.5A fast fuses have been replaced, they’re back on and properly working.

I’m so pissed at myself Right now for not being careful, and doing things when it’s late and I’m tired.
Not that I absolutely need this scope, but I just wanted to restore it and make it work.
On the other hand, it’s also very handy to have a little scope on the bench with just the TM506, so I don’t have to bring the big ones If I don’t need to.
I hope it’s fixable... Grrrr... :-(


Re: SC502 With Display Issues

Stephen
 

On Sat, Aug 15, 2020 at 01:59 PM, Harvey White wrote:

Interleaved

Then the thing to check is what's in the unit that happens before that
on/off switch.  Another question, however embarrassing, is if you can
figure out what went wrong (in terms of how the extender is put in), and
what the possible results might be.  That could tell you what might be
damaged.
I’m a bit out of my depth here, if not completely...
I’ve check the Vcc of U950 and I have -30.62 VDC at pin 4.
Output at pin 6 is -1.2VDC
U960 has nothing anywhere.

I suspect Q960 pass transistor (2N5401) to have blown along the the Mainframe fuses...

I hope no other transistors down the line blew as well, as I have no source for Q950 and Q955 (2N5086) and I’m not sure I can find equivalents (if there are any suitable for this application)...


Looking for a P6139A Schematic

JOE
 

Hi all,

I have a P6139A that appears to have a short in the compensator box. I've done the usual searches but have been unable to find a schematic.

Thanks Much
Joe


Re: 155-0035-00

Peter H
 

http://w140.com/tekwiki/wiki/155-0035-00 has details and links to data books.


Maybe OT: Battery for Tektronix RFM90

greenboxmaven
 

I am looking for a couple batteries for the Tektronix RFM90 signal level meter. I have been told it is the same as an old Nokia cell phone, but so far I have not had any luck finding any of them. Does anyone have batteries or a source recommendation?

Bruce Gentry, KA2IVY


Re: Tek 4654M; No Trace, No +5V, No +95V; Help

Dave Hills
 

OK. I will say 90% chance C741 is bad, 5% chance CR741, the bridge rectifier, has a shorted diode in it and 5%
chance something else. C741 is a single unit, it can be replaced with a part of equal or slightly larger capacitance
and voltage rating and it will work fine. Be aware the four tabs that read 0 volts may be conduction paths and likely
will need to be re-connected with jumpers if replacing with a two leaded replacement part. You can verify this by
checking for continuity between the four tab pads on the circuit board after the capacitor is removed. If there is
no continuity between them, they will require jumpers connecting all four pads together. Also, a modern part with
the same rating will be physically much smaller.

Dave


Re: SC502 With Display Issues

Harvey White
 

responses interleaved

On 8/15/2020 7:17 PM, Stephen wrote:
I’ve made quite a mess...
not sounding so good
I wanted to check the voltages. I plugged in the extender and forgot to power off the TM, and didn’t insert it correctly.
To quote RJS:  Gee Bullwinkle, that never works.
I blew the 2 +/- 35v fuses. Replaced them and now all the plugins work fine except this one.
Ok, now disaster control.
Nothing... No power at all. All the other plugins that stopped working when that happened, are now ok in all bays.
Ok, that's actually part good news.  Not likely that you've damaged the frame *if* the other modules use all of the frame slot's capabilities.
I checked the 2 fuses inside the unit, and they’re good...
BTW, the SC was in the OFF position when that happened.
Then the thing to check is what's in the unit that happens before that on/off switch.  Another question, however embarrassing, is if you can figure out what went wrong (in terms of how the extender is put in), and what the possible results might be.  That could tell you what might be damaged.

Another possibility when you do plug things in with an extender is to put the frame end first.  That protects the plugin.  That way, if you have BIG RED LEDS on the extender (hint... hint...) you can tell that power is on.


Grrrr. I shouldn’t be doing these things at 1:00am.
Been there, done that.  That includes soldering a 100 pin chip rotated 90 degrees from what it was supposed to be (IIRC).  We won't mention what happens on some designs...  Everything gets reviewed in the morning. (and I'll still need revisions).

You might look into some tektronix breadboard units, those might be an answer to homemade extenders.



PS: I was planning on replacing all the tantalums anyway, just for good measure.
not a bad idea, but consider the type (gumdrops likely will fail) and 7 volt parts used on 5 volt supply rails will likely fail as well.  On the other hand, a 35 volt part used on 20 volts is less likely to give you problems.

Harvey





Re: Looking for front cover for 465 and/or 485

Mike Harmon
 

I'd love to have a front cover for my 485 as well if someone is fortunate enough to find multiples!

Mike Harmon, WB0LDJ
mharmon at att dot net


Re: Tek 4654M; No Trace, No +5V, No +95V; Help

Harrison
 

Thanks gentlemen. I have read the voltages across both C741 and C761 as Dave has advised. I used the Beckman HD110 and read to ground. I.E. the black test lead was alligator cliped to the chassis and the readings were taken with the red test lead. The unit was powered through an isolation transformer and the unit was on. Only visual indication of being on is the "scale illumination". In the case of C741 DC volts on one pin was +8.5V. The other four were 0.00V. Regarding AC volts, the pin that read 8.5V DC read 4.2V AC. Again the other four were 0.00V. In the case of C761 DC volts; 4 of the 5 pins read -11.9V. The fifth pin read 0.00. Regarding AC volts; all five pins read 0.00V AC. In comparison it seems to indicate an issue with C741. If that is the case, is C741 a capacitor pack? Is something like that available or would one have to say cut it open and rebuild the internal circuit. Maybe I am getting ahead of myself here. I am interested in what the two of you, or anyone else for that matter, deduce from the above readings. Thanks again for your continued support and advice. I really appreciate it. There doesn't seem to be as much traffic or discussion/posts on something as old as the 465M. For me it is a good covid-19 time filler and training project. Once it is on line I will be passing it on to my son Michael NC1V or Brian KA1OMR or some other Ham needing a scope.Stay safe and healthy. Harrison N1FAM


Re: Oscilloscope Operator Training Kit - TNGTDS01

 

Roy,
Thanks,
Thanks; looking in the appendix; I see there's a comprehensive description of the generated signals included there.  While the 465 is a great scope,I am looking forward to the increased bandwidth and digital displays of frequency, voltage, and timing offered by digital models.  My expected applications will include both analog and digital signals.  Although most of the test signals provided by the training board can be quickly generated with instruments on the bench, the Tek training module seems to provide a rapid, and rather complete, introduction to these DPOs for folks like me that spent the latter portion of their career in administrative, rather than technical positions.
Bruce, KG6OJI


Re: SC502 With Display Issues

Stephen
 

I’ve made quite a mess...
I wanted to check the voltages. I plugged in the extender and forgot to power off the TM, and didn’t insert it correctly. I blew the 2 +/- 35v fuses. Replaced them and now all the plugins work fine except this one. Nothing... No power at all. All the other plugins that stopped working when that happened, are now ok in all bays.
I checked the 2 fuses inside the unit, and they’re good...
BTW, the SC was in the OFF position when that happened.
Grrrr. I shouldn’t be doing these things at 1:00am.

PS: I was planning on replacing all the tantalums anyway, just for good measure.


Re: Looking for front cover for 465 and/or 485

Dave Daniel
 

Most covers were separated from their ‘scope when the company that bought the ‘scope started using it. When the ‘scope was retired, the cover remained in a cabinet or whatever and was later tossed because there was no associated ‘scope with it (or, for all I know there are thousands of ‘scope covers still sitting in cablnets all over the world).

DaveD

On Aug 15, 2020, at 15:23, Roy Thistle <roy.thistle@mail.utoronto.ca> wrote:

On Fri, Aug 14, 2020 at 04:28 PM, John Brown wrote:


The whole world is looking for covers
.... well... I'm out here in the colonies (not in CONUS) ... so if someone has covers for 400 series scopes... out here in the colonies... P.M. me... I'd like to get some.
As an aside... it's odd behaviour, to throw out the oscilloscope; but keep the cover! (Keeping the probes is an annoyance I can contemplate.)



Re: SC502 With Display Issues

DaveH52
 

If you have a service manual, spend the time to read the functional description while following along in the schematics.
My starting point was smoke and lots of it. I'm going to be busy for a while replacing every tantalum capacitor and all of the A1-A5 HV caps because one of them had arced to a wet tantalum that spewed sulfuric acid. Once that was repaired, each power-up after that, would fail because another tantalum cap had failed and burned up a resistor. Therefore, not they're all getting replaced.


Re: 'Soft' transistor sockets

 

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Tim Phillips
Sent: 15 August 2020 21:13
To: TekScopes@groups.io
Subject: Re: [TekScopes] 'Soft' transistor sockets

Hi Egge; no, maybe I didn't explain myself very well - the 'sockets' I
referred to are actually three individual tiny contacts on the PCB into
which the transistor leads go directly. Not an actual socket as we
understand the word ! Imagine a very low-profile socket, but without the
surrounding supporting material, just the contacts.
regards
Tim


On Sat, 15 Aug 2020 at 20:23, Egge Siert <eggeja2@hotmail.nl> wrote:

Hi Tim,

This kind of sockets?


https://www.ebay.com/itm/4-Mil-Spec-S-Augat-8058-1G24-1437508-9-4P-PCB-Mount-Teflon-Transistor-Sockets/201234498862?epid=1236928307&;hash=item2eda82c52e:g:d54AAOSw4gpbyhtN

Greetings,

Egge Siert




Re: Tek 4654M; No Trace, No +5V, No +95V; Help

Chuck Harris
 

Definitely, it is exceedingly rare that you can adjust your way
out of total failure.

-Chuck Harris

Dave Hills wrote:

Hello, Harrison.
I would not adjust anything at this point, as any adjustment can't correct for this much out of spec.
Take a look at the voltages across C741 and C761. Measure both DC and AC values. The DC
voltages should be around 10v or more and the AC voltage much smaller.
Please let us know what you find.

Dave




Re: 'Soft' transistor sockets

Chuck Harris
 

The thinking was:

... transistors are expensive, very variable in their gain
from one example to the next, and we are not so convinced
that they are any more reliable than vacuum tubes. So, we
need sockets for the transistors, ... a lot of sockets...
but the available sockets are so expensive, and take up a
lot of room, and are not all that reliable...

The little insert pin sockets that tektronix used are very,
very reliable, and the silicone gasket at their entrance can
take the heat of soldering, and keeps foreign materials out
of the socket... Plus, it adds a little more resistance to
the transistor falling out of the socket.

Tektronix found over time that transistors got cheaper, and
were much more reliable than any sockets you could use to
mount them, so they went to directly soldering the transistors
into the circuit board.

-Chuck Harris

Tim Phillips wrote:

from Tim P (UK)

What was the thinking behind the 'soft' transistor sockets used by
Tektronix in some of the 5000-series 'scopes? I am working on a 5113 / D13
that has these on the storage board. Seems to be a soft white-ish stuff
around the contacts, and it's not clear (to me) if the transistor is making
a good connection.
Also, the lead spacing on the transistor is very slightly different to the
usual T05, meaning a replacement has to be 'jiggled' into it's socket.

regards
Tim




Re: 'Soft' transistor sockets

Bert Haskins
 

On 8/15/2020 4:12 PM, Tim Phillips wrote:
Hi Egge; no, maybe I didn't explain myself very well - the 'sockets' I
referred to are actually three individual tiny contacts on the PCB into
which the transistor leads go directly. Not an actual socket as we
understand the word ! Imagine a very low-profile socket, but without the
surrounding supporting material, just the contacts.
regards
Tim


On Sat, 15 Aug 2020 at 20:23, Egge Siert <eggeja2@hotmail.nl> wrote:

Hi Tim,

This kind of sockets?


https://www.ebay.com/itm/4-Mil-Spec-S-Augat-8058-1G24-1437508-9-4P-PCB-Mount-Teflon-Transistor-Sockets/201234498862?epid=1236928307&;hash=item2eda82c52e:g:d54AAOSw4gpbyhtN

Greetings,

Egge Siert



I have used these and I like them except for the fact that they are obscenely expensive at least when I have been able to purchase them.

I have ended up pushing the pins out of machined pin IC sockets and using them instead.

There might be some difference at high frequencies but I will never see it.

-- Bert


Re: Oscilloscope Operator Training Kit - TNGTDS01

Roy Thistle
 

On Fri, Aug 14, 2020 at 10:32 AM, ebrucehunter wrote:


TDS3052B digital scope; however, it seems only very distantly related to my
465 that it might ultimately replace
Well... I'd claim the TDS2052B "trace" it is closer to the 465... than many other Tektronix DSO. (You've got the so called digital phosphor.)
Anyway... the signals the "Training 1 Signal Board" put out are described in Appendix A of the document you quoted.
Are you planing to work on modern digital systems? ... because you mention you are/were using a 465.


Re: 'Soft' transistor sockets

Dave Seiter
 

Are these the type that have a sort of rubber grommet at the top that the pin goes through?
-Dave

On Saturday, August 15, 2020, 01:11:20 PM PDT, Tim Phillips <timexucl@gmail.com> wrote:

Hi Egge; no, maybe I didn't explain myself very well - the 'sockets' I
referred to are actually three individual tiny contacts  on the PCB into
which the transistor leads go directly. Not an actual socket as we
understand the word ! Imagine a very low-profile socket, but without the
surrounding supporting material, just the contacts.
regards
Tim


On Sat, 15 Aug 2020 at 20:23, Egge Siert <eggeja2@hotmail.nl> wrote:

Hi Tim,

This kind of sockets?


https://www.ebay.com/itm/4-Mil-Spec-S-Augat-8058-1G24-1437508-9-4P-PCB-Mount-Teflon-Transistor-Sockets/201234498862?epid=1236928307&;hash=item2eda82c52e:g:d54AAOSw4gpbyhtN

Greetings,

Egge Siert




Re: 'Soft' transistor sockets

Stephen
 

This is what you’re referring to:
https://groups.io/g/TekScopes/photo/252113/0?p=Created,,,20,2,0,0

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