Following up on the 400d "functional schematics" that omit details vs. a full schematic; here's the 400d from one of the BSP's that is commonly found:
![[Linked Image from seriss.com]](https://seriss.com/people/erco/tmp/400d-line-card-functional-schematic-page-13.jpg)
Now in comparison, here's a more detailed schematic; note part values and transistor arrangement details:
![[Linked Image from seriss.com]](https://seriss.com/people/erco/tmp/400d-schematic--bell-system-labs.png)
The transistor arrangement is important for someone studying tricks and techniques, as well as detailed part troubleshooting for dead boards. I tried to reverse engineer a 400D once, so as to make a page on how it all worked in detail, but it was too hard; reverse engineering makes me crazy unless I were to de-solder everything.. didn't want to go there. Figured I'd wait until documents turned up.. and they did!
If you know of a source for the actual WE service manuals for e.g. line cards and ComKey, I'd sure be happy to know about 'em..! I assumed they were few and far between because they probably never left the repair labs. Circuit descriptions are even more useful, as one can learn analog tricks/techniques. That patent I mentioned a few posts ago has a great circuit description, I learned quite a bit from that alone.
