Date   

Re: Scope, cooling ICs - refresh or not?

DaveH52
 

If you're talking about the hybrids with the 4 screws holding them, leave them alone. Other heatsinks may be thermal-epoxied to the chip and would be a lot of trouble to clean up and re-epoxy. Not to mention you've got to find and buy special thermal epoxy to use.


Re: 519 -- broken rate generator; stuck at a very high frequency?

Sean Turner
 

Tom,

It's all good; thanks for the explanation. I have not checked for dc level coming out of the multivibrator.

I turned R931 (avalanche control) some and observed the effects. There is, as expected, a threshold where no avalanche occurs. Beyond, this, turning the pot affects the frequency of the output considerably before it dies away again and the other end of the pot. Still no control with the multivibrator though. Maybe there's an open circuit hiding somewhere?

Sean

On Mon, Oct 19, 2020 at 03:14 PM, Tom Lee wrote:


Hi Sean,

Sorry for the truncated, uncpunctuated verbiage -- compression has obscured
the message. Here's a less cryptic version: Have you verifed that the swing of
the signal coming out of the multivibrator is correct (both in amplitude and
dc level)?

Either way, your avalancher is triggering on its own. The problem could be as
simple as the collector supply being set too high (there's a pot for that), or
possibly having a lot of noise on it. The way the avalancher is supposed to
work here is that the dc supply should be set just below the point where the
transistor will avalanche. The signal from the multivibrator kicks it over the
top of the hill, causing the transistor to avalanche in synchrony with the
multivibrator's triggering signal.

I don't have the schematic in front of me, but you should be able to
(mis)adjust the pot to prevent the avalancher from avalanching at all. Try
taking it to that point, and then gradually adjusting the pot to increase the
collector voltage until the transistor starts to avalanche reliably, and under
the control of the multivibrator.

-- Cheers,
Tom


5 photos uploaded #photo-notice

TekScopes@groups.io Notification <noreply@...>
 

The following photos have been uploaded to the 519 album of the TekScopes@groups.io group.

By: sdturne@q.com


Re: 519 -- broken rate generator; stuck at a very high frequency?

Sean Turner
 

Tom,

I put some photos in the album here: https://groups.io/g/TekScopes/album?id=255396

The trace shot is the output of the rate generator, at 10 ns/cm. The crt on this particular scoped is stated as 0.29 ns risetime and 9.1 V/cm.

On Mon, Oct 19, 2020 at 03:21 PM, Tom Lee wrote:


Also, you say that the avalancher seems to be doing the right thing. Would you
happen to have a screenshot or something to show what that output looks like?
Avalanchers can exhibit several pathologies (which is why not all transistors
-- even from the same production run --
avalanche similarly). Avalanching is very sensitive to surface effects, for
example, and not all surfaces age gracefully. A transistor can look otherwise
fine as a transistor, but stop avalanching well.

Just a thought.


Re: FTAGH: National Instruments DAQCard DIO-24 PCMCIA digital I/O card and cable

DaveH52
 

I (still) have a laptoop with a PCMCIA slot. I'll be glad to give it a try.
I'm in New Jersey, so if it's still available let me know, and if you take Paypal.
Dave - AC2GL


Re: smd precision resistor "paint layer" peeled off while soldering *** advice needed ***

Chuck Harris
 

Hi Roger,

The electrolyte is water soluble. Use hot water, dish detergent
and a soft toothbrush or paintbrush.

Put some electrical tape on the tops of trimmers and dip switches,
and scrub away.

The shine is an indication of corrosion. It tells you that the
electrolyte has been there... so you should scrub there.

When the board is rinsed, get the loose water off, and put it in
a warm oven... usually the oven light is more than hot enough...
for overnight.

-Chuck Harris

Rogerio O wrote:

Chuck,
Thank you for your reply.
Yes I could smell this while working on the components around the place where the are located.
Is it necessary to repair each and every solder joint that is not shinny?
I have washed these parts of the board with tap water and than with IPA.
I am letting the board dry while I wait for the replacement parts.
Roger






Re: smd precision resistor "paint layer" peeled off while soldering *** advice needed ***

Rogerio O
 

Chuck,
Thank you for your reply.
Yes I could smell this while working on the components around the place where the are located.
Is it necessary to repair each and every solder joint that is not shinny?
I have washed these parts of the board with tap water and than with IPA.
I am letting the board dry while I wait for the replacement parts.
Roger


Re: [HP-Agilent-Keysight-equipment] FS: S-100 stuff, electronic stuff, model railroad stuff, books and magazines!

momemeca
 

Hello Richard,
I thought that we were engaged in discussions leading to a deal?
Please confirm that S-100 is sold to someone else or is it to me?

Cheers,

Rick

On 20 Oct 2020, at 08:29, Richard R. Pope <mechanic_2@charter.net> wrote:

Hello all,
The S-100 stuff is sold and paid for.
GOD Bless and Thanks,
rich!

On 10/18/2020 9:46 PM, Richard R. Pope wrote:
Hello all,
It looks like the S-100 stuff is available again. Sorry for the confusion!
GOD Bless and Thanks,
rich!

On 10/18/2020 12:36 AM, Richard Pope via cctalk wrote:
Hello all,
The S-100 stuff is sold pending payment. I appreciate the interest and help!
GOD Bless and Thanks,
rich!

On 10/17/2020 10:44 PM, Bruce wrote:
I believe there is an S-100 meuseum - think they specialize in Altare
- but they woul probably be a good home for the stuff

Cheers!

Bruce

Quoting Jeff George <driftwoodturning@gmail.com>:

Hi there, I’m sorry to hear about your expected diagnosis, that’s a tough
one. My neighbor Had cancer of the liver last year, he tried the “Rick
Simpson oil” treatment along with standard chemo and is cancer free today.
Maybe look into it?

On a selfish note, Im a high school physics teacher in Tn and would love to
find good price on some equipment so that my students could get their feet
wet with some actual good equipment. Scopes, frequency generators, vtvm’s,
dmm’s, etc.. I am a ham radio operator and tinkerer, some skills at
repairing equipment but not a whole lot.

Please let me know if you have anything appropriate for my students at a
high school budget. Happy to give you my info so that you can verify my
employment.

Jeff

On Sat, Oct 17, 2020 at 10:14 PM Richard R. Pope <mechanic_2@charter.net>
wrote:

Hello all.
I have 22 S-100 boards for sale. There are two backplanes. One is a
9 slot bare board and the other is a 19 slot fully populated board. Both
boards have active termination. There are 8080, Z80, FDC, HDC, Serial,
68030, a Display board, a Front Panel board. There are also 3 Mean Well
power supplies supplying the +9VDC and the +_16VDC. There are also
voltmeters and amp meters . I want $500 plus shipping for all of it. I
can provide a full inventory and pictures for anyone who is truly
interested.
I probably have cancer and if I do I am dying. I want all of this
to go to a good home and not to the landfill. If anyone is interested I
have some test equipment, electronic components, and model railroad
equipment Please only serious inquires for I tire very easily.
GOD Bless and Thanks,
rich!





--
Paying Attention, Not a Tutor!





Re: 519 -- broken rate generator; stuck at a very high frequency?

Chuck Harris
 

There is one other way, and that is motorboating.
The multivibrator multivibrates, causing a glitch
in the power supply, which triggers the multivibrator.

Just a thought...

-Chuck Harris

Tom Lee wrote:

Hi Sean,

Sorry for the truncated, uncpunctuated verbiage -- compression has obscured the
message. Here's a less cryptic version: Have you verifed that the swing of the signal
coming out of the multivibrator is correct (both in amplitude and dc level)?

Either way, your avalancher is triggering on its own. The problem could be as simple
as the collector supply being set too high (there's a pot for that), or possibly
having a lot of noise on it. The way the avalancher is supposed to work here is that
the dc supply should be set just below the point where the transistor will avalanche.
The signal from the multivibrator kicks it over the top of the hill, causing the
transistor to avalanche in synchrony with the multivibrator's triggering signal.

I don't have the schematic in front of me, but you should be able to (mis)adjust the
pot to prevent the avalancher from avalanching at all. Try taking it to that point,
and then gradually adjusting the pot to increase the collector voltage until the
transistor starts to avalanche reliably, and under the control of the multivibrator.

-- Cheers,
Tom


Re: 519 -- broken rate generator; stuck at a very high frequency?

Tom Lee
 

Also, you say that the avalancher seems to be doing the right thing. Would you happen to have a screenshot or something to show what that output looks like? Avalanchers can exhibit several pathologies (which is why not all transistors -- even from the same production run --
avalanche similarly). Avalanching is very sensitive to surface effects, for example, and not all surfaces age gracefully. A transistor can look otherwise fine as a transistor, but stop avalanching well.

Just a thought.

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 10/19/2020 15:14, Tom Lee wrote:
Hi Sean,

Sorry for the truncated, uncpunctuated verbiage -- compression has obscured the message. Here's a less cryptic version: Have you verifed that the swing of the signal coming out of the multivibrator is correct (both in amplitude and dc level)?

Either way, your avalancher is triggering on its own. The problem could be as simple as the collector supply being set too high (there's a pot for that), or possibly having a lot of noise on it. The way the avalancher is supposed to work here is that the dc supply should be set just below the point where the transistor will avalanche. The signal from the multivibrator kicks it over the top of the hill, causing the transistor to avalanche in synchrony with the multivibrator's triggering signal.

I don't have the schematic in front of me, but you should be able to (mis)adjust the pot to prevent the avalancher from avalanching at all. Try taking it to that point, and then gradually adjusting the pot to increase the collector voltage until the transistor starts to avalanche reliably, and under the control of the multivibrator.

-- Cheers,
Tom


Re: 519 -- broken rate generator; stuck at a very high frequency?

Tom Lee
 

Hi Sean,

Sorry for the truncated, uncpunctuated verbiage -- compression has obscured the message. Here's a less cryptic version: Have you verifed that the swing of the signal coming out of the multivibrator is correct (both in amplitude and dc level)?

Either way, your avalancher is triggering on its own. The problem could be as simple as the collector supply being set too high (there's a pot for that), or possibly having a lot of noise on it. The way the avalancher is supposed to work here is that the dc supply should be set just below the point where the transistor will avalanche. The signal from the multivibrator kicks it over the top of the hill, causing the transistor to avalanche in synchrony with the multivibrator's triggering signal.

I don't have the schematic in front of me, but you should be able to (mis)adjust the pot to prevent the avalancher from avalanching at all. Try taking it to that point, and then gradually adjusting the pot to increase the collector voltage until the transistor starts to avalanche reliably, and under the control of the multivibrator.

-- Cheers,
Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 10/19/2020 15:03, sdturne@q.com wrote:
Tom,

Yes, that is correct. The output seems to not be correlated whatsoever with the multivibrator. The transistor is avalanching...the waveform that comes out is consistent with what it should be I think. It's just stuck at one frequency that is much higher than anything that the settings of the controls would suggest.

"Swing out" is a term I am not familiar with...perhaps I know it by another name?

Based on serial number, the rate generator should be the later revision.

Sean

On Mon, Oct 19, 2020 at 12:18 AM, Tom Lee wrote:

So, the multivibrator is producing the correct waveforms with controllable
frequencies, and the only problem is that the final output is running at
250kHz, independently of what the multivibrator is doing? Have you verified
that the swing out of the multivibrator is correct? And is your rate generator
an early or late one?

As you said, there isn't much left to check, so by definition you're close!

--Tom


Re: 519 -- broken rate generator; stuck at a very high frequency?

Sean Turner
 

Tom,

Yes, that is correct. The output seems to not be correlated whatsoever with the multivibrator. The transistor is avalanching...the waveform that comes out is consistent with what it should be I think. It's just stuck at one frequency that is much higher than anything that the settings of the controls would suggest.

"Swing out" is a term I am not familiar with...perhaps I know it by another name?

Based on serial number, the rate generator should be the later revision.

Sean

On Mon, Oct 19, 2020 at 12:18 AM, Tom Lee wrote:


So, the multivibrator is producing the correct waveforms with controllable
frequencies, and the only problem is that the final output is running at
250kHz, independently of what the multivibrator is doing? Have you verified
that the swing out of the multivibrator is correct? And is your rate generator
an early or late one?

As you said, there isn't much left to check, so by definition you're close!

--Tom


Re: smd precision resistor "paint layer" peeled off while soldering *** advice needed ***

Chuck Harris
 

As long as you cleaned the board of all of the corrosive (to copper)
residue, any solvent based paint would be fine. This is just a slow
computer, and as such it is all either dc or digital.

Also, look at the solder joints on the 4 capacitors. They should be
shiny as a mirror. If they are milky, or white, the capacitors have
not been replaced. If you touch one of the capacitor's solder joints
with the tip of a soldering iron, and you get the stench of boiled
radiator and rotten fish, there is electrolyte present.

-Chuck Harris

Rogerio O wrote:

Dear all,
I was doing a A5 board repair of a Tek2465BCT I bought some time ago.
This is a late unit, serial # B0577746 and the A5 board is the 671-0965-05.
I inspected the board when I bought the unit and there were no signs of corrosion, so I left it as received for quite a long time.
It seems the caps have been replaced ( I can't say for sure) but the board was not cleaned well enough so the corrosion started.

Near the ADC (U2101) the only pads "missing" are the ones for C2520, but I had to remover and solder again some SMD components in this area.
While doing this the "paint layer" of R2012 (RES,FXD,FILM:10KOHM,0.1%,0.125W,TC=T9) fell off, exposing the tiny traces.

I could not find a direct replacement for it so I am thinking of leaving it there and apply a layer of some isolating material (PCB varnish, for example).

My question is: Is it possible the the varnish would react with the exposed traces, changing the component characteristics?

|Is it better leave the component as it is? Any other coating material suggested?

Thank you in advance,
Roger







Re: [HP-Agilent-Keysight-equipment] FS: S-100 stuff, electronic stuff, model railroad stuff, books and magazines!

Richard R. Pope
 

Hello all,
The S-100 stuff is sold and paid for.
GOD Bless and Thanks,
rich!

On 10/18/2020 9:46 PM, Richard R. Pope wrote:
Hello all,
It looks like the S-100 stuff is available again. Sorry for the confusion!
GOD Bless and Thanks,
rich!

On 10/18/2020 12:36 AM, Richard Pope via cctalk wrote:
Hello all,
The S-100 stuff is sold pending payment. I appreciate the interest and help!
GOD Bless and Thanks,
rich!

On 10/17/2020 10:44 PM, Bruce wrote:
I believe there is an S-100 meuseum - think they specialize in Altare
- but they woul probably be a good home for the stuff

Cheers!

Bruce

Quoting Jeff George <driftwoodturning@gmail.com>:

Hi there, I’m sorry to hear about your expected diagnosis, that’s a tough
one. My neighbor Had cancer of the liver last year, he tried the “Rick
Simpson oil” treatment along with standard chemo and is cancer free today.
Maybe look into it?

On a selfish note, Im a high school physics teacher in Tn and would love to
find good price on some equipment so that my students could get their feet
wet with some actual good equipment. Scopes, frequency generators, vtvm’s,
dmm’s, etc.. I am a ham radio operator and tinkerer, some skills at
repairing equipment but not a whole lot.

Please let me know if you have anything appropriate for my students at a
high school budget. Happy to give you my info so that you can verify my
employment.

Jeff

On Sat, Oct 17, 2020 at 10:14 PM Richard R. Pope <mechanic_2@charter.net>
wrote:

Hello all.
I have 22 S-100 boards for sale. There are two backplanes. One is a
9 slot bare board and the other is a 19 slot fully populated board. Both
boards have active termination. There are 8080, Z80, FDC, HDC, Serial,
68030, a Display board, a Front Panel board. There are also 3 Mean Well
power supplies supplying the +9VDC and the +_16VDC. There are also
voltmeters and amp meters . I want $500 plus shipping for all of it. I
can provide a full inventory and pictures for anyone who is truly
interested.
I probably have cancer and if I do I am dying. I want all of this
to go to a good home and not to the landfill. If anyone is interested I
have some test equipment, electronic components, and model railroad
equipment Please only serious inquires for I tire very easily.
GOD Bless and Thanks,
rich!





--
Paying Attention, Not a Tutor!














smd precision resistor "paint layer" peeled off while soldering *** advice needed ***

Rogerio O
 

Dear all,
I was doing a A5 board repair of a Tek2465BCT I bought some time ago.
This is a late unit, serial # B0577746 and the A5 board is the 671-0965-05.
I inspected the board when I bought the unit and there were no signs of corrosion, so I left it as received for quite a long time.
It seems the caps have been replaced ( I can't say for sure) but the board was not cleaned well enough so the corrosion started.

Near the ADC (U2101) the only pads "missing" are the ones for C2520, but I had to remover and solder again some SMD components in this area.
While doing this the "paint layer" of R2012 (RES,FXD,FILM:10KOHM,0.1%,0.125W,TC=T9) fell off, exposing the tiny traces.

I could not find a direct replacement for it so I am thinking of leaving it there and apply a layer of some isolating material (PCB varnish, for example).

My question is: Is it possible the the varnish would react with the exposed traces, changing the component characteristics?

|Is it better leave the component as it is? Any other coating material suggested?

Thank you in advance,
Roger


Re: 577D1 Phantom base current

Michael W. Lynch
 

On Mon, Oct 19, 2020 at 01:30 PM, DW wrote:


Here is a idea

If someone with a 577 curve tracer try this test, install a transitor and with
the step generator set to single and increase the collector voltage does the
display indicate some current. Does moving the step generator amplitude
proportionally effect the amount of current displayed?

I am thinking if someone could duplicate this with a good known 577 we will
see if this is by design or if it is a fault.
DW,

I tried this with my 577 and with a PNP transistor in the standard test fixture. I have inverted the display so that the traces appear first at the bottom left of the CRT. With the # steps Control set to 1 step, I increase the collector voltage and I see the first line of the trace advance across the bottom at Zero (bottom graticule line), a single step appears above the ZERO Line, at whatever the step current control is set to. So I do not have any current offset indicating on the ZERO line. The ZERO Line remains at ZERO, indicating voltage being present with no current flow. Is that what you are looking for?

--
Michael Lynch
Dardanelle, AR


Re: 577D1 Phantom base current

DW
 

Here is a idea

If someone with a 577 curve tracer try this test, install a transitor and with the step generator set to single and increase the collector voltage does the display indicate some current. Does moving the step generator amplitude proportionally effect the amount of current displayed?

I am thinking if someone could duplicate this with a good known 577 we will see if this is by design or if it is a fault.

Thanks


DSA602A 11A72 ChksumTweak 1141 Error

wkibler
 

Greetings, after replacing the NVRAM in my 11A72 and resetting the SN and performing a few EA operations in my DSA602A. I am getting an 1141 ChksumTweak error.

I have tried manually setting an offset to a previous recorded value via RS232 with the cal jumper in place in the DSA and in the plug-in. Also various combinations of jumper settings and writing various values to NVRAM. All to no avail.

I just can’t seem to clear that error on that plugin. Can anyone help? Any advise would be greatly appreciated. Thanks in advance.

I have available the DSA and an 11301. I also have a virtual machine with TEKCATS if needed.


Re: Tek 468, X-Y mode not working, spot hard left, requires beamfinder

John
 

This issue has now been addressed. Thanks to all who provided comments.

Details here:
https://groups.io/g/TekScopes/message/172426


Re: Is my Tek 468 beyond repair?

John
 

On Sat, Oct 17, 2020 at 05:46 AM, <robeughaas@gmail.com> wrote:


I see the IPROM's are still on the way to you. I've started a survey of the 13
468's in the Museum's boneyard and of the first seven, found two with shorted
+5 Storage Supplies, as evidenced by blown F4007 and F4009, 5-amp picofuses at
the back of the trigger board. I've dismantled one and found a shorted CR169,
the catch diode in the supply. I'll go through the remainder tomorrow, and I
suspect I'll find more with shorted supplies. Of the six I've been able to
test ROM's on, I have found all the ROM's were good. I suspect that the power
supply problem is causing the failure that is thought to be ROM rot.
That's an interesting observation. Some time ago I came across a 465 that had an intermittent shorting -8V supply due to a faulty smoothing can but so far in the 468 all supplies are good and as it turns out, the ROMs are good as well. The problem turned out to be a non-running CPU. I don't know much about the history MOSTEK EEPROMs but can't help wondering how long these are likely to last although I am glad to have backup spares "just in case" courtesy of a helpful contributor on here. Still it is a testament to Teks' engineering that they can be brought back to life and still work 40 years later.... For sure the 468 is an interesting example of a vintage scope with early storage computing.

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