With everything seemingly working it was time to inspect the other boards.
A pair of FETs, Q114 & Q119, on the AC assembly looked a little crusty with flux. I removed these, cleaned the board and reinstalled them. I also replaced C133 100uF 40V whilst the board was out.
The DC assembly also had a pair of crusty looking FETs, Q206 & Q207. The flux around the leads of these seems to have eaten into the top of the PCB a little. I removed them both and cleaned the board around them before reinstalling.
The final task was to replace the electrolytics on the Digital assembly.
I think i was just in time with this as the large electrolytics had started to leak. C004 was the worst but all of the large caps showed some electrolyte leakage.
The replacements I used are in the table below. Note that if you choose to replace with different parts that space is also limited here, but not as limited as with the Digital assembly. I stuck with 25mm capacitors as per the digital replacement parts, but you can probably just about squeeze in 30mm.
ID Original New Farnell #
C001, C004 1000uf 40V Panasonic ECA-1HHG102 1000uf 63V 9693009
C007, C012 220uF 63V Rubycon 100YXJ220M12.5X25 220uF 100V 2346277
C015 2200uF 16V Panasonic ECA1EHG222 2200uF 25V 9692851
C912 470uF 25V Panasonic ECA-1JHG471 470uF 63V 9693068
C002, C003,
C005, C006,
C009, C010, 1uF 63V Wurth WCAP-ATLL 860160672002 1uF 50V 2495115
C011, C014,
C016, C017
C309, C313,
C314 10uF 50V Wurth WCAP-ATLL 860160672009 10uF 50V 2495117
After the capacitor replacement the voltages were measured as:
TL001 = +15.215 (0.4mV RMS)
TL002 = -15.090 (0.4mV RMS)
TL003 = +35.542 (0.4mV RMS)
TL004 = -35.093 (0.4mV RMS)
TL005 = +5.038 (0.9mV RMS)
0V from U002 centre pin or heat sink.
With a little help from ManateeMafia I determined that the calibration key is this one from RS
“Key for Operated Switch” RS Stock no.: 319-792
All that is left to do is find a way of dumping the calram and convert to f-ram with one of ManateeMafia's converter boards.
Finally a big thank you to Mickle.T and ManateeMafia for answering the questions i had whilst working on this