Topics

Current Probe Questions


 

Hi Mike,



Except for the AM503 the TM5xxx current probe plugins were introduced at a point in time when Tek was facing a bleak financial future. After 35 years of providing parts lists and schematics in their service manuals someone in management decided to remove them to generate additional revenue by forcing customers to return non-working instruments to the factory for repair.



Our members are experienced collectors of Tektronix products. We have many ex-Tek members. We have many circuit design engineers. We have many members with advanced degrees in other fields besides electronics. We provide free assistance to anyone who has a problem with, or questions about, their Tek instruments. Finally, several members of TekScopes own AM503A, AM503B and AM5010 plugins which they cannot repair or calibrate without schematics and/or parts lists.



I personally own several AM503B plugins which over the years have stopped working. With schematics I would be able to identify the cause of the errors displayed and track down the source of the problems. With this many plugins I would also be able to cannibalize one plugin to get the others working.



One of our members has located and scanned the schematics for the AM503A. Another member has provided us with the AM503B ROM code. I appreciate you willingness to assist us maintain our collections of Tektronix products. I hope you are able to find the time to become a regular contributor because we can certainly use your expertise.



Dennis Tillman W7pF

TekScopes Moderator



From: TekScopes@groups.io Notification [mailto:noreply@groups.io]
Sent: Wednesday, January 06, 2021 7:21 AM
To: dennis@ridesoft.com
Subject: [TekScopes] Message Approval Needed - mjmpdx1@gmail.com posted to TekScopes@groups.io



A message was sent to the group https://groups.io/g/TekScopes from mjmpdx1@gmail.com <mailto:mjmpdx1@gmail.com> that needs to be approved.

View this message online <https://groups.io/g/TekScopes/pendingmsg?pendingid=4491562>

Subject: Re: Details on 015-0670-00 Feed-Through Adapter for AM503B?

Hi Jared,

I was one of the designers of the AM503A, AM503B, AM5030 and newer TCPA300/400 products. Let me dig through my parts bins to see if I have one (I think I bought some from RAMs way back?) or at least check the service manual to see if there was a schematic. I remember there was a coding resistor from a pin to gnd and then a short between the output of the power amp into the input of the attenuator for one of the adapters. There was a coding resistor and a coax that went straight into the attenuator input for the other adapter.

Stay tuned,
Mike

A complete copy of this message has been attached for your convenience.

To approve this using email, reply to this message. You do not need to attach the original message, just reply and send.

Reject this message and notify the sender <mailto:TekScopes+reject+4491562+87017+7928225480618789892@groups.io> .

Delete this message and do not notify the sender <mailto:TekScopes+delete+4491562+87017+7928225480618789892@groups.io> .

NOTE: The pending message will expire after 14 days. If you do not take action within that time, the pending message will be automatically rejected.

_____

Change your notification settings <https://groups.io/g/TekScopes/editsub?id=1106251>


mjmpdx1@...
 

Hi Dennis,

Yeah, the early 1990s were bleak times. I was fresh out of school in 1990 and remember the round of layoffs in C1 a few months after I started. I remember the day like it was yesterday with my manager telling me what happened and that I was moving to Beaverton.

I thought I had an old service manual for the AM503B/AM5030 but cannot find it yet. I will keep looking through my books. I was able to reverse engr the AM503B/AM5030 calibration adapters though and was surprised what I still remembered about the design. Reminded me of Cliff Baker and Jeff Powell who were mentors to me. They were some of the best guys I worked with and learned from and miss them both.

Attached is my hand drawn schematics of the adapters for Jared and others. I hope this helps. I am happy to help out on the current probe side where I can.

Thanks for all your hard work on keeping this site alive.

Mike


Jared Cabot
 

Hi,

Fantastic information. Thanks a bunch for that!

I have two of the connectors and I already made the adapter for the AM503 (called 'special adapter' in the AM503 service manual) that consists of a BNC connected to pins J (shield), and M (center pin) via a 25ohm resistor.
I'll get myself another plug and build the two adapters you describe in the pdf for my AM503B modules.

If you remember or find any other interesting info, feel free to let us know. I have 3x AM503 and 3x AM503B to restore, so any pointers will be helpful.


Thanks again for the info and prompt reply! Greatly appreciated. :)

Jared

On Fri, Jan 8, 2021 at 04:29 AM, <mjmpdx1@gmail.com> wrote:


Hi Dennis,

Yeah, the early 1990s were bleak times. I was fresh out of school in 1990 and
remember the round of layoffs in C1 a few months after I started. I remember
the day like it was yesterday with my manager telling me what happened and
that I was moving to Beaverton.

I thought I had an old service manual for the AM503B/AM5030 but cannot find it
yet. I will keep looking through my books. I was able to reverse engr the
AM503B/AM5030 calibration adapters though and was surprised what I still
remembered about the design. Reminded me of Cliff Baker and Jeff Powell who
were mentors to me. They were some of the best guys I worked with and learned
from and miss them both.

Attached is my hand drawn schematics of the adapters for Jared and others. I
hope this helps. I am happy to help out on the current probe side where I
can.

Thanks for all your hard work on keeping this site alive.

Mike




Clark Foley
 

Mike,

Thank you for your good citizenship!
I miss Cliff as well. He was a strong character, very bright, very practical and a good adviser.

As for Dennis' comment about Tek service manuals ditching schematics and limiting service to Tektronix only, he is correct that money was a strong motivation; however, the slippery slope began with good intentions (as will all roads to hell). When products such as the 7854, 492P and other of similar complexity were near introduction, the service people demanded and received extra support from the designer to include more service tools, hardware and software, to support field repairs. I know for LID (Large Instrument Division), this had a significant impact upon the design resources that could not move to the next new product design. The field service competence varied due to experience with the custom tools, elaborate calibration software and equipment (remember CATS?) for each new product. Service expenses were rising and the job was getting much more difficult. When the 7D20 was introduced, it was decided that it was more consistent to ship the units directly to the manufacturing line. Specifically using UPS Blue Label, we could get a unit in two days, repair it in one day and ship the same day. Guaranteed warranty turn was 5 days and it worked. Many times the manufacturing crew did it in 4 days. So much for good intentions!

Fast forward a few years and you get better shipping coverage, lots of more complex product designs and pressure to keep service expenses low, resistance to divert designers and the beginning of the annual layoffs. Someone then gets the bright idea to close service centers and protect Tektronix customers from non-Tek repair shops from poaching business. Schematics are no longer published and bound and the de facto project archiving is lost. No other paper record is kept unless the design manager insisted upon a local copy for his group and repair technicians. That's how I managed to get the 11301/11302 schematic books.

In short, Dennis is correct that money was the ultimate motivation, but quality of service drove the initial mile on the road to hell.

Happy New Year!


 

Hi Clark,
You deserve our thanks for sharing the schematics for the TVC 501 Time-Voltage Converter TM5xx Plugin with us.

Your detailed explanation of what led up to the demise of the schematics was very informative. I know from my conversations with Tom Rousseau that supporting the 7854 was going to cause the service centers fits. The sharper technicians would have been able to keep up with the analog portion of the 7854 but digital logic can be devilishly complex to troubleshoot and it requires an entirely different technical background. When you throw in the microprocessor software controlling most of the logic it becomes hopeless unless you have a technician who is good at analog troubleshooting, another one that's good at troubleshooting digital circuits, and a third one who knows how to troubleshoot microprocessor systems. It took me 30 years before I knew how to troubleshoot all three of those.

A few questions I forgot to ask you the last time I saw you:
* How did you manage to get a 3 letter designation for the TVC 501 plugin?
* How did you get Tek to forego the usual service manual cover for the VERY unusual front cover of the TVC 501 Service Manual with the nice gray scale sketch of the plugin and two 3D images that pop right out of the page even without 3D glasses on?
* Why is there no mention of the Chili Dog on TekWiki?

:) Dennis

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Clark Foley
Sent: Thursday, January 07, 2021 6:02 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Current Probe Questions

Mike,

Thank you for your good citizenship!
I miss Cliff as well. He was a strong character, very bright, very practical and a good adviser.

As for Dennis' comment about Tek service manuals ditching schematics and limiting service to Tektronix only, he is correct that money was a strong motivation; however, the slippery slope began with good intentions (as will all roads to hell). When products such as the 7854, 492P and other of similar complexity were near introduction, the service people demanded and received extra support from the designer to include more service tools, hardware and software, to support field repairs. I know for LID (Large Instrument Division), this had a significant impact upon the design resources that could not move to the next new product design. The field service competence varied due to experience with the custom tools, elaborate calibration software and equipment (remember CATS?) for each new product. Service expenses were rising and the job was getting much more difficult. When the 7D20 was introduced, it was decided that it was more consistent to ship the units directly to the manufacturing line. Specifically using UPS Blue Label, we could get a unit in two days, repair it in one day and ship the same day. Guaranteed warranty turn was 5 days and it worked. Many times the manufacturing crew did it in 4 days. So much for good intentions!

Fast forward a few years and you get better shipping coverage, lots of more complex product designs and pressure to keep service expenses low, resistance to divert designers and the beginning of the annual layoffs. Someone then gets the bright idea to close service centers and protect Tektronix customers from non-Tek repair shops from poaching business. Schematics are no longer published and bound and the de facto project archiving is lost. No other paper record is kept unless the design manager insisted upon a local copy for his group and repair technicians. That's how I managed to get the 11301/11302 schematic books.

In short, Dennis is correct that money was the ultimate motivation, but quality of service drove the initial mile on the road to hell.

Happy New Year!







--
Dennis Tillman W7pF
TekScopes Moderator


Clark Foley
 

Dennis,

The Tek nomenclature guidelines did not restrict us from using three letters. Using two letters for the earlier products was a convenience and a preference that became habit rather than policy. Many of the products could be described in two words, e.g. counter timer, power supply, etc. There were many accepted practices that were not codified into rules and policy. It was similar with the manuals. A user guide did not have many rules and not too many people were watching anyway!
I should send a photograph of Chili Dog to Kurt R. I owe him lots of stuff to add to his wiki pages.