Hello,
first post here.
I have recently aquired a Solartron 7081, SN128 on ebay. Advertised with the "NVM FAIL" message.
First impressions:
- front/rear switch is missing
- some screws came loose
- both batterys are dead, the mempack is growing crystals
- CAL key is missing, as expected.
- some signs of bodges, like the SMD capacitor? soldered on R711 on the floating input board.
(those may be original/from previous services)
Exactly as advertised, it boots up to the NVM FAIL error message. Communication via RS232 and GPIB seems to work, but
dumping or refreshing the calibration constants caused no response from the instrument, aside from a 'ok'. Reinitialisation via the Monitor also did not bring any sucess.
After aquiring an replacement ER3400, the Solartron finally allowed initialising the EAROM. Instead of the NVM Fail message i am now greeted by the CAL INCOMPLETE Message,
as expected, according to the service manual.
This is where im stuck now. dumping or checking the test-constants remains unanswered. Poking around in the Monitor mode, i can read individual adresses, and the values are
as expected ( 0A 05 alternating).
Also calibrating, e.g. short-circuit conditions appears to be not working, at least the contents of the ROM dont change.
I noticed, that when printing out memory contents(P aaaa,bbbb) from the floating board, the first few characters (see attachements) are recognized and echoed back correctly,
but when writing more characters, some of them apparently get lost (p 0, 3FF is reliably losing either '3' or one of the 'f's).
This might be the reason why calibrate, dump et al are not working. (i can write them a few times, getting confirmed with 'ok', but after a few commands the instrument hangs up)
This smells like there is either a problem with internal UART communication or a problem on the floating processor.
Has anyone had the same problem here, or knows where to start looking?
My experience with older microprocessor systems is unfortunately rather limited.
Also, is it safe to probe the floating processor board with the input board on top unplugged?