On Mon, Nov 20, 2023 at 09:32 PM, Harold Foster wrote:

My board was a revision "D" and I uploaded pictures to the 3400A area of the files section.

Hal

Thank you Hal, those pictures should have all the missing information, I can see they removed a double thickness ground trace from the front and made a much wider trace on the back, it confirms the 1826-1381 for U602. I'll check the resistors another night, getting late tonight here in the UK.

And Artek did have the correct manual, very quick response to my email and I now have an excellent quality manual covering the 1982-84 versions.


David

On Mon, Nov 20, 2023 at 04:01 PM, factory wrote:

it confirms the 1826-1381 for U602

Which is an LT1012 - I was very surprised to see that they used such a precision amp on purpose - the precision is not needed there other than to possibly not have a negative output; even in the 3400B they used one section of a LM324. Doesn't hurt but just seems like an unnecessary expense and a departure from any other in the series.

Hal

I've had a good look at the differences between the Rev C & D boards and the pdf manual I bought.

Errors I found in the manual;

Parts list,
R601 should be 105k (was 174k) and R604 should be 174k (was 105k).
The circuit diagram, component layout & boards are correct.

Circuit diagram;
C10, missing '+' symbol
R615, decimal point missing from 61.9R

Differences between A6 Rev C and Rev D;

R608 was 22.1k, now 21k
R609 was 22.1k, now 21k
R610 was 2k, now 1.87k
R611 was 2k, now 1.87k
R616 was 1.21k, now 1.02k
R625 was 1M, deleted
R627 was 1k, now 500R
R629 was 100k, deleted

U602 was 1826-0310, now 1826-1381 (LT1012)

I haven't been able to verify all the diodes & capacitors, CR601 is not readable and some tantalum capacitors are facing the wrong way (both on my Rev C and Hal's Rev D).

---

I've now completed the Rev D design in KiCAD, I used the Rev C board for location measurements, then adjusted the traces for the Rev D design.

Most parts should be obtainable, the 2N4384 transistors seem to be obsolete, but I do have some BCY59X low noise NPN in my spares to try instead, the 1901-0518 Schottky diode I need to find some data for, Molex test point pins have been salvaged from some scrap SA plug-ins.

David

Received my three boards from Michael Muller, the Ebay seller in Germany.

Does anyone have his email address? The one he gave me is bouncing back and Ebay does not allow exchanging contact info.

Michael enclosed a note with order telling me to send him an email for updated BOM and other info.

I just did a redesign of these myself - for the chopper I used a 1N5817 for the diode and BC109Cs for the transistors because I already had a drawer full - although 2N3904s would work just fine in that application.? I used two 1N4151s for the input limiting, a NZX18B for the zener, a 2N3971 for the FET and a 2N6428 for the output.? Everything seems to work at least as well? as the original but I have not taken the time to really dig in and to more detailed testing. The response is a couple of percent high in midscale but I don't know if that is from the converter or is something from the input stage (which is all original.) I'll swap boards around with other units over the holidays and see if I can track that down - may be well be something related to the FET but we'll see...?

On a somewhat related note, I just made new versions of the boards for the 5087A - and relearned yet again that transistor footprints are **NOT** to be taken as a given. Sigh. At least boards are cheap now-a-days...

Hal

开云体育

Greetings,

on ebay when you purchase an item and pay for it, then you can exchange email/phone etc...
it will not block it

The board arrived with his instruction to contact him by his email address. It bounced back after I sent it.
I left him an Ebay message, he has always eventually responded so not a big deal at this point. Just thought someone might know a better email for him.

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