Someone forgot this poor DMM? That ain't me.
Yesterday night I replaced all components in earth-referenced area before the transformer, as well as 2xDG444,DG408 (interesting to note, 2002 using different switches there, instead of DG211 on K2001, shooting for lower leakage?), 1xAD711, 1xLM311, pair of 4094 SRs, 79L05 etc.
Also enforced few vias by putting small copper strand thru them and soldering both sides, as well as few traces were repaired as they were eaten away. One of pads of bridge rectifier was loose, so I had to jump wire it on bottom side. Blown resistors were fixed on same location above hi-temp mylar using piece of copper plate.
PCB was delaminated in few areas, but nothing we can do about that. Should be still fine, as these areas are not high importance of analog path.
End result look like this:
Power switch, Q101 transistor, 2 and 5 pin jacks, fuse holder, LM317T were checked, thoroughly cleaned and reused. It ain't looking pretty, but should do the job well.
Bottom side:
Every single resistor and cap were replaced here, some parts taken from my donor 2001, most of parts brand new from DigiKey.
And, first power on, smoke test passed, no surprises. Moment of truth, self-diagnostics test..
Yay, this fella want to play! I ran it 10 times in a row, all tests pass flying colors.
Hooked it up in parallel with 3458A, which is now calibrated to measured LTZ1000A module (
live log data), it read 10ppm high. Not bad, considering last calibration in 2009 and repairs
So the outcome of this project was just like I expected and hoped for, just fix of electrolyte mess, replace gunked parts and all is back again.
Seems it's time to sell few 2001's..