Date   

Re: Purpose of Q32 in S-52

Ed Breya
 

"Digilog" is just a term I coined decades ago, referring to circuits that are both digital and analog, sometimes without clear distinction. In reality, everything is analog, including digital circuits, until you go deep enough, then it becomes kind of digital (discrete) at the quantum level.

Ed


Re: Tektronix 2465b Boo Boo

squirrel@...
 

Thanks satbeginner I hope that Toms solution may work thanks for the help


Re: Tektronix 2465b Boo Boo

squirrel@...
 

Wow what a great group thanks for that as soon as I get 5 mins I will give it go
Cheers Tom.


Re: Purpose of Q32 in S-52

Dave Daniel
 

What is “digilog”?

On Jul 7, 2020, at 17:32, Ed Breya via groups.io <edbreya=yahoo.com@groups.io> wrote:

Curiosity forced me to look at the S-52 schematics. I think Q32 is to prevent possible latch-up of the digilog circuitry during power-up. There are quite a few things going on back and forth, and with varying levels. so I can picture it maybe getting stuck during initial activation. while the supplies (including the shunt-regulated -5.1V) slew up at various rates. and the clocking system state is undefined. This is unpredictable in a mainframe, for example, with widely varying plug-in loads and combinations. It looks like once the oscillator and state control decoding are running, it should clear and cycle properly, but there may be some quasi-digilog state where the bias is partly on and the circuit is confused. I'd consider it a "power-up reset" function for now.

It could also protect against loss (permanent or temporary during power-up) of the -12.4V supply. In this event, Q32 will pull the control line down, forcing the TD bias current steering stage to dump it into ground rather than the TD. This forces a reset, regardless of the rest of the functions.

Ed



Re: Tektronix 2465b Boo Boo

 

Ok, try doing the exerciser 3 routine (cycle error clear). See the service manual for the procedure. It is on pdf page 237 on my Artek manual.

Regards,

Tom

On 7/7/2020 8:34 AM, squirrel@... wrote:
Hi guys my first post here be gentle.

I have made a big Boo Boo with my scope
Without reading or joining any Tek scope forums but just glancing through the manuals I decided to jump the "cal" and have a look at the settings that where there
I don't remember exactly what I did, but I think I just scrolled through and then exited I know for a fact that I have never adjusted any thing and I never set or entered any parameters.
But I now have the dreaded 2v????????/?? at the display bottom.
So the question is can I recover from this mistake or does the scope now require a full cal
thanks


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Re: Purpose of Q32 in S-52

Ed Breya
 

Curiosity forced me to look at the S-52 schematics. I think Q32 is to prevent possible latch-up of the digilog circuitry during power-up. There are quite a few things going on back and forth, and with varying levels. so I can picture it maybe getting stuck during initial activation. while the supplies (including the shunt-regulated -5.1V) slew up at various rates. and the clocking system state is undefined. This is unpredictable in a mainframe, for example, with widely varying plug-in loads and combinations. It looks like once the oscillator and state control decoding are running, it should clear and cycle properly, but there may be some quasi-digilog state where the bias is partly on and the circuit is confused. I'd consider it a "power-up reset" function for now.

It could also protect against loss (permanent or temporary during power-up) of the -12.4V supply. In this event, Q32 will pull the control line down, forcing the TD bias current steering stage to dump it into ground rather than the TD. This forces a reset, regardless of the rest of the functions.

Ed


Re: Tektronix 2465b Boo Boo

satbeginner
 

If you did not make a backup of the A5 Dallas contents, a full cal is what needs to be done....


Tektronix 2465b Boo Boo

squirrel@...
 

Hi guys my first post here be gentle.

I have made a big Boo Boo with my scope
Without reading or joining any Tek scope forums but just glancing through the manuals I decided to jump the "cal" and have a look at the settings that where there
I don't remember exactly what I did, but I think I just scrolled through and then exited I know for a fact that I have never adjusted any thing and I never set or entered any parameters.
But I now have the dreaded 2v????????/?? at the display bottom.
So the question is can I recover from this mistake or does the scope now require a full cal
thanks


1240 / 1241 Logic Analyzer Lithium Battery Removal

Andre D'Amours
 

Hello Everyone,

I just acquired a very nice 1241 logic analyzer with accessories. I'm aware that the 1240 and 1241 have a potentially nasty Catalyst Research Corp lithium iodine battery that should should be removed before it causes damage. Does anyone have any suggestions on the safe removal of this battery? Is it safe to remove the battery using vacuum de-soldering equipment such as Metcal or Pace? Is a CR-123A in a socket a good replacement for this battery?

Thank you!
Andre


GOULD SCOPE SUPPLIES #file-notice

MyTubeAudio
 

I have some NOS color plotter pen kits and NOS paper for Gould 400-series DSO's and I've recently posted them to EBAY.

Member Ken Chalfant on this message board was looking for Gould supplies and I think these are correct.

Ken - please send me a message at @MyTubeAudio and we'll sort this out if you are still in need.

- Dan Brasier, Holland, Michigan


Re: R7704+7A18+7B53A in Newport Beach, CA to part with

Abc Xyz
 

Chris...i could come get it.

On Tue, Jul 7, 2020, 10:50 AM ChrisBeee via groups.io <chrisbeee=
yahoo.com@groups.io> wrote:

I have a leftover from my time in Southern California I want to part with:
a nice R7704 including a 7A18 and a 7B53A plug in. It has been stored in a
dry garage lab after I bought it from Gov surplus somewhere in 2008 or 2009
(ex-NASA unit). This unit has not been run for quite a while, so please be
prepared to revive the PS carefully! No warranty for meeting manufacturer's
specs of course ;-)
I would like to give it in good hands because shipping across the pond
does not really make sense.
Price: what you feel it is worth for you, first come first serve.
The only caveat: this unit is for local pick up only (location: San
Joaquin Hills area, Newport Beach, CA.).
Please contact me off-line, thanks!
Chris




R7704+7A18+7B53A in Newport Beach, CA to part with

ChrisBeee
 

I have a leftover from my time in Southern California I want to part with: a nice R7704 including a 7A18 and a 7B53A plug in. It has been stored in a dry garage lab after I bought it from Gov surplus somewhere in 2008 or 2009 (ex-NASA unit). This unit has not been run for quite a while, so please be prepared to revive the PS carefully! No warranty for meeting manufacturer's specs of course ;-)
I would like to give it in good hands because shipping across the pond does not really make sense.
Price: what you feel it is worth for you, first come first serve.
The only caveat: this unit is for local pick up only (location: San Joaquin Hills area, Newport Beach, CA.).
Please contact me off-line, thanks!
Chris


Another 7D20 attenuator question

Dallas Smith
 

My second 7D20 attenuators started acting up. Cleaned relays and substrate to no avail. I noticed that the 'A12 & A13 substrate PCB has tarnished relay contacts. there are a dull gray (lead?). I thought Tek gold plated PCB contacts for non corrosion and good contact resistance? Is there a way to gold plate the contact areas. Were they ever gold? I think this is the root problem with these plugins, cleaning seems to have no effect. Reluctant to buy another unit with this factory design error.

What do you say?


Re: More Tek Calibrators and 11K spares added to Stuff Day, plus a Tek 2216

@0culus
 

Walter,

I hope all is well. I sent Susan an email about two items listed and haven't heard back.

Sean


Re: Purpose of Q32 in S-52

 

On Tue, Jul 7, 2020 at 05:33 PM, Raymond Domp Frank wrote:


Just a hunch, didn't study the schematic much nor thought this through
... nor the motivation to dive into it...

Raymond


8 photos uploaded #photo-notice

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

The following photos have been uploaded to the TM500 Front Panel Blank Project. album of the TekScopes@groups.io group.

By: Michael W. Lynch <mlynch003@...>


Re: Purpose of Q32 in S-52

 

On Tue, Jul 7, 2020 at 04:07 PM, Albert Otten wrote:


Anyone an idea? Some kind of protection perhaps, but against which condition?
Just a hunch, didn't study the schematic much nor thought this through but low -12V (closer to 0V) would lead to Q32 conducting from ca. -7.5V (?), pulling down on R30 (point 10). Could this stop the TD from permanently being in the triggered state (carrying I > Ip) with risk of being damaged? The other negative supply voltages will remain present to say at least -6V instead of -12V.

Raymond


Re: Purpose of Q32 in S-52

unclebanjoman
 

Against excessive positive (+15 V) supply I presume.
If for any reason the positive suplly voltage is too high, the TD can be damaged by an excessive current.
It is veeery small and must tolerate 50 mA peak....
Doing so, with Q32 conducting the TD never fires. A some kind of minimal security.

Max


Purpose of Q32 in S-52

Albert Otten
 

Hi all,

A recent topic (ending at message #168946) about S-52 repair brought up the mysterious role of Q32. During normal S-52 operation Q32 will never conduct .
Anyone an idea? Some kind of protection perhaps, but against which condition?

Albert


Re: Hakko FR-301 alternatives?

EJP
 

I will have a supply of ZD985 pump diaphragms in a few weeks. Please context me off list if interested.

EJP