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Re: Purpose of Q32 in S-52
What is ¡°digilog¡±?
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On Jul 7, 2020, at 17:32, Ed Breya via groups.io <edbreya@...> wrote: |
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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.
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Regards, Tom On 7/7/2020 8:34 AM, squirrel@... wrote:
Hi guys my first post here be gentle. --
This email has been checked for viruses by Avast antivirus software. |
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Re: Purpose of Q32 in S-52
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 |
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Tektronix 2465b Boo Boo
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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1240 / 1241 Logic Analyzer Lithium Battery Removal
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 |
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GOULD SCOPE SUPPLIES
#file-notice
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 service@... and we'll sort this out if you are still in need. - Dan Brasier, Holland, Michigan |
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Re: R7704+7A18+7B53A in Newport Beach, CA to part with
Chris...i could come get it.
On Tue, Jul 7, 2020, 10:50 AM ChrisBeee via groups.io <chrisbeee= [email protected]> wrote: I have a leftover from my time in Southern California I want to part with: |
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R7704+7A18+7B53A in Newport Beach, CA to part with
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 |
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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? |
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8 photos uploaded
#photo-notice
[email protected] Notification
The following photos have been uploaded to the TM500 Front Panel Blank Project. album of the [email protected] group. By: Michael W. Lynch <mlynch003@...> |
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Re: Purpose of Q32 in S-52
On Tue, Jul 7, 2020 at 04:07 PM, Albert Otten wrote:
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 |
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Re: Purpose of Q32 in S-52
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 |
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Re: Tek TS-4353/U Distortion Analyzer and 500 series plug-ins
Hi Dick,
The Operator's Manual of this TestSet is in the File Section of this Group. /g/TekScopes/files/SG505%20MOD%20WR%20WQ%20AA501A%20MOD%20WQ.pdf More interesting is the Service Manual of this TestSet. Seen only once on eBay (old Tucker Store).The AA501 MOD WQ has special Custom Made Filters in it. Greetings, Egge Siert |
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Re: 7000-series plug-in power tester
Hi,
I the guy who is making a standalone power and signal adapter board. The original post is here /g/TekScopes/topic/74053244#168481 To answer your question, would be it worth doing? No it does not worth it at all for the trouble you go through, if the goal is only powering some plugins for troubleshooting. I have three flexible extenders, and one rigid extender with more than 4 working 7000 mainframes (even more if count broken ones). But I am still spending a significant portion of my night to make it happen. Why? The value is not in the power adapter board itself. The value is in that you enable these plugins to be used on modern digital scope. No company make 100 MHz differential amplifier anymore (at least not I am aware of) => 7L13 Low noise low frequency measurement with adjustable bandwidth=> 7A22 Hard to get capability for very low frequency spectrum analyzer for audio work => 7L5 Capability to get better noise floor than 1mVpp @ >100MHz => 7A26 is about 120uV level although not easily available due to limited 5mV/div max gain Sampling plugins 7S12, 7S14 TDR => 7S12 Curve tracer 7CT1N The above items are the ones that I can make sense of it. There may be other benefit to enable these plugins being used on digital scopes. |
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Re: Strange TM 500 plugin to ID
I'm going to find it a HOME!
You can use it ??? Make me an offer I can't refuse! On 6 Jul 2020 at 12:05, Michael W. Lynch via groups.io wrote: On Mon, Jul 6, 2020 at 01:07 PM, kim.herron@... wrote:John Goller, K9UWA & Jean Goller, N9PXFTekwiki.? I put Antique Radio Restorations k9uwa@... Visit our Web Site at: 4836 Ranch Road Leo, IN 46765 USA 1-260-637-6426 |
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