Let's dig into something rare. Not Keithley, not Fluke, but Time Electronics 9823 straight from England!
This beast was bought on eBay (seller still have lesser version, 30ppm/year
9822).
There is hardly any information on the web about this old beast, but from what is available, it's specifications are well competitive to monsters like Fluke 5500A/Datron 4808! I could not resist, you know.
Thing powers up, provide output but it's barely functional and have issues. E.g. if I set output 10.00000V, I get 9.845V. Adjustment to 10.1V making voltage jump and than quickly go back 9.845V. Sounds like digital/DAC issue to me. So, let's take it apart...
Construction is using aluminum frame with many boards. Most of parts numbers are dated 1988, some 1990. Everything is DIP and boards are 2-layer. Should be rather easy to recover schematics, yay.
Take a look on boards:
I let you guess which one is what.
Some cleaning would help...
Too bad DAC and reference are potted in large blocks
. Seems it will remain a mystery what reference is used in this machine.
Anyone had experience with this calibrator? Any manuals/service info?