Date   
Re: TM5xx/TMxxx Pass Transistors. SUBJECT CHANGE, WAS: DC-508 repair advice

Mlynch001
 

Dennis,

I was able to find the original specs for my particular unit and then found some replacements that I thought might work. It has 5 bays with the same NPN and PNP parts and the high power compartment used something different. I found some replacements and then used the curve tracer to match the old parts to the new parts as close as possible. I’m going to look at what you have written, to see how close I got by dead reckoning and using my Curve Tracer. I appreciate your guidance, I always learn something from the members of this group.

--
Michael Lynch
Dardanelle, AR

TM5xx/TMxxx Pass Transistors. SUBJECT CHANGE, WAS: DC-508 repair advice

 

Hi Michael and all TekScopes members,

As my late friend, Jerry Scheltgen (AKA Kilowatt on eBay), and I once documented, knowing which pass transistors are used in which TM500 / TM5000 mainframe, is not easy to figure out because Tek changed them often and some mainframes use different ones for no apparent reason. To make matters worse on some occasions Tek changed to a different transistor with ENTIRELY DIFFERENT lead order so they require contortions to reorient the leads to make them reach the holes the old leads went into.

To solve this mess in 8/2014, Jerry and I documented which pass transistors were used where and when you had to be careful because the lead orientation mattered.

I uploaded the list we created just now. It can be found at
https://groups.io/g/TekScopes/files/TM5xxx%20Pass%20Transistor%20List.pdf

If you search our archives of messages regarding any topic with "pass transistors" you will find several recommendations our members made for "better" or "more powerful" or "more sensitive" or "less expensive" or "more available" substitutes for what Tek used. The only consideration I would caution that you observe it is desirable (to prevent oscillation) that the pass transistor have a low cutoff frequency (Ft). Less than 1 MHz would be ideal.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Mlynch001
Sent: Sunday, December 15, 2019 11:51 AM
Subject: Re: [TekScopes] DC-508 repair advice

The hard part is finding replacement transistors for the pass transistors. I blew one up by plugging one of my plugins onto my extension cable upside down. The plugin extension did not have an indexing pin, so it would fit either way.
--
Michael Lynch
Dardanelle, AR




--
Dennis Tillman W7PF
TekScopes Moderator

Re: DC-508 repair advice

Mlynch001
 

The hard part is finding replacement transistors for the pass transistors. I blew one up by plugging one of my plugins onto my extension cable upside down. The plugin extension did not have an indexing pin, so it would fit either way.
--
Michael Lynch
Dardanelle, AR

Re: Paying it forward with David's Part's Exchange

 

David,

Please provide YOUR STREET ADDRESS for people to send to you for your list or include YOUR EMAIL ADDRESS.

Interested members PLEASE contact David Berlind directly if you are interested in his generous offer.
All inquiries should be handled OFF-LIST to keep unnecessary personal correspondence off of TekScopes.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of David Berlind
Sent: Saturday, December 14, 2019 9:18 AM
Subject: [TekScopes] Paying it forward with David's Part's Exchange

Hi Tekkies...

I have launched a Google Spreadsheet that I am very slowly updating with the inventory of all my parts. In an effort to pay it forward to you and others that have been so generous in helping me to get my fingernails dirty, I'm making 99% of the parts available to anyone for free. Personally, it drives me nuts I need one part and I have to pay more to buy it in bulk, or the shipping costs more than the part itself. I will never use most of these parts and so I'd rather give them away (not in bulk). All I ask is that you send me a self-addressed stamped envelope (or other packaging) and I will put the part in that packaging and return it to you. It's going to take me months to get this spreadsheet fully up to date. Maybe years. I don't know. But each week, I'm chipping away at the iceberg, adding new parts. So, let me know if you see something you need or like. I'm calling this David's Part Exchange. Let me know if you have any questions. https://docs.google.com/spreadsheets/d/1Q4M7dnS--TXb5PW1VqEBmM2Sxonknz0vVFVk_rfho_o/edit#gid=437389817




--
Dennis Tillman W7PF
TekScopes Moderator

Re: Paying it forward with David's Part's Exchange

 

PLEASE take requests like this OFF-LINE.

Thank you
Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of DaveH52
Sent: Sunday, December 15, 2019 11:05 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Paying it forward with David's Part's Exchange

Where would I send the SASE and wish list?
Dave





--
Dennis Tillman W7PF
TekScopes Moderator

Re: TDS684C "Cal Fails during initialization".

Siggi
 

Hey Reg,

I can't speak to these errors, but wonder if you know what you're getting
into with the TDS 6XX series. These are CCD-based scopes, meaning they
capture in real time at up to 5GS/sec per channel into a CCD FIFO, which is
then digitized at a pretty leisurely rate after a trigger hits.
The upshot of this is that they have a fairly limited memory depth, and
some other acquisition quirks. The selling point for those scopes
originally is that you get the full 5GS/sec for all the channels
simultaneously.
Another thing to watch out for is that the 6XX*A*s don't have a peak detect
mode, which might be a problem - though only if you're looking at the As.

If you contrast the 7XX series, those scopes capture at up to 4GS/sec
across all channels. This is however multiplexed, so the capture rate per
channel drops off as you turn on more channels. With all four channels
turned on, you're down to 1GS/sec each.
You do however have equivalent time capture for repetitive signals, hi-res
for slow signals, peak detect across the board, and (I'd guess) much less
dead time between acquisitions.

I don't know if any of this matters to you - and apologies if I'm preaching
to the choir...

Siggi

On Sun, Dec 15, 2019 at 1:23 PM Reginald Beardsley via Groups.Io <pulaskite=
yahoo.com@groups.io> wrote:

I've seen this error in a number of ebay listings. What does it mean? I
could find nothing in the service manual, 071062702 on Tek's web site. I"d
bought a LeCroy DDA-120, but FedEx dropped it, so I'm looking for another
cheap 1 GHz DSO.

Is this an NVRAM failure with error messages even worse than the 11801?
What is required to repair the fault? So far no search has turned up
useful information.

Reg



Re: Paying it forward with David's Part's Exchange

DaveH52
 

Where would I send the SASE and wish list?
Dave

TDS684C "Cal Fails during initialization".

Reginald Beardsley
 

I've seen this error in a number of ebay listings. What does it mean? I could find nothing in the service manual, 071062702 on Tek's web site. I"d bought a LeCroy DDA-120, but FedEx dropped it, so I'm looking for another cheap 1 GHz DSO.

Is this an NVRAM failure with error messages even worse than the 11801? What is required to repair the fault? So far no search has turned up useful information.

Reg

Re: DC-508 repair advice

radioconnection@...
 

Thanks... I have manuals on order for most of them. Will check to make sure.

I managed to blow up the DM-501 at 2AM playing around (installed it upside down, since I had
the slides removed for servicing.) Another project. I need to go to bed instead of doing bench work at 2AM half asleep.

The only plug in I care about is the tracking generator which is mated with the 497P. The others were free for the taking.
I ended up with the 504 since the 503 was getting filled up rather quickly. But, I am anal and will get them all working
eventually.

Re: Great video for 500 series Tek restorers

Kurt Rosenfeld
 

Lazyelectrons has continued the series of videos on the Tektronix 555. There are five of them up now. The latest is here: https://www.youtube.com/watch?v=A0-rZohmyjQ

Highly recommended!

-Kurt

Re: DC-508 repair advice

Mlynch001
 

Check your fuses on your plugins. They are prone to open when the pass transistors fail. Also check your voltages as well. Plugin crowbars are also prone to fail. Pay special attention to the complementary transistor in the plugin I.e, the one that’s mated to the failed pass transistor. For example, in a TG501 on the 15v Supply, this would be Q610.

--
Michael Lynch
Dardanelle, AR

Re: DC-508 repair advice

radioconnection@...
 

Well, thanks to the advice, I did find bad pass transistors, and a few plug ins seem to have some issues. This is turning into a larger than expected project. Those mainframes are miserable to work on!

Re: Paying it forward with David's Part's Exchange

Lawrance A. Schneider
 

Hi,

I have a: on the front RTD710/A - ADAPTER
on the back L9A-0450-00
671-1194-00

Looks to be some sort of parallel connection going from internal connections to outside connections. I see a lot of what appear to be terminal resistors. Not a very good description I know but...

If someone wants it, let me know. Just pay postage.

I see there is a spreadsheet of parts. If you would like, add this to the list and show my name as the contact point.

larry

Re: DC-508 repair advice

Carsten Bormann
 

On Dec 14, 2019, at 16:14, Mlynch001 <@mlynch001> wrote:

On the TM503 check your pass transistors. My TM506 had 4 bays out of 6 that had very weak or outright "bad" pass transistors. They will wreak havoc with your plugins.
And one problem is that some plugins are damaged by bad pass transistors, and these very plugins then proceed to break the pass transistors of the next slot they are in.

These things need condoms.

Grüße, Carsten

Re: Paying it forward with David's Part's Exchange

Tam Hanna
 

Hello,

let me join in by mentioning that I usually have at least one order from Mouser a month, and also have a working billing relationship with AliExpress.


If anyone of you ever wants to "ride" me and my wife, we are always glad to be at service. But sorry in advance, we are not fast.


Tam

--
- - - - -
With best regards
Tam HANNA

Enjoy electronics? Join 13500 followers by visiting the Crazy Electronics Lab at https://www.instagram.com/tam.hanna/

Re: Paying it forward with David's Part's Exchange

Mlynch001
 

David,

Very Generous of you. You have inspired me to consider doing something similar for those on this forum.

--
Michael Lynch
Dardanelle, AR

Does anyone have any PIC17C42A-16I/L to spare (ideally in UK)

 

Extended temperature range PIC17C42A version in PLC44 ...

Thanks David

Re: Paying it forward with David's Part's Exchange

EricJ
 

Very nice of you David, kudos.

--Eric

On Dec 14, 2019 11:18 AM, David Berlind <david@...> wrote:




Hi Tekkies...

I have launched a Google Spreadsheet that I am very slowly updating with
the inventory of all my parts. In an effort to pay it forward to you and
others that have been so generous in helping me to get my fingernails
dirty, I'm making 99% of the parts available to anyone for free.
Personally, it drives me nuts I need one part and I have to pay more to
buy it in bulk, or the shipping costs more than the part itself. I will
never use most of these parts and so I'd rather give them away (not in
bulk). All I ask is that you send me a self-addressed stamped envelope (or
other packaging) and I will put the part in that packaging and return it
to you. It's going to take me months to get this spreadsheet fully up to
date. Maybe years. I don't know. But each week, I'm chipping away at the
iceberg, adding new parts. So, let me know if you see something you need
or like. I'm calling this David's Part Exchange. Let me know if you have
any questions.
https://docs.google.com/spreadsheets/d/1Q4M7dnS--TXb5PW1VqEBmM2Sxonknz0vVFVk_rfho_o/edit#gid=437389817






Paying it forward with David's Part's Exchange

David Berlind
 

Hi Tekkies...

I have launched a Google Spreadsheet that I am very slowly updating with the inventory of all my parts. In an effort to pay it forward to you and others that have been so generous in helping me to get my fingernails dirty, I'm making 99% of the parts available to anyone for free. Personally, it drives me nuts I need one part and I have to pay more to buy it in bulk, or the shipping costs more than the part itself. I will never use most of these parts and so I'd rather give them away (not in bulk). All I ask is that you send me a self-addressed stamped envelope (or other packaging) and I will put the part in that packaging and return it to you. It's going to take me months to get this spreadsheet fully up to date. Maybe years. I don't know. But each week, I'm chipping away at the iceberg, adding new parts. So, let me know if you see something you need or like. I'm calling this David's Part Exchange. Let me know if you have any questions. https://docs.google.com/spreadsheets/d/1Q4M7dnS--TXb5PW1VqEBmM2Sxonknz0vVFVk_rfho_o/edit#gid=437389817

Re: DC-508 repair advice

Mlynch001
 

TM504. excuse me. Anyway, check them out, they can cause all sorts of issues.

--
Michael Lynch
Dardanelle, AR