So, I got myself another bit of test equipment.
This one is a Yokogawa/HP 4276a LCZ meter, and it is huge, 2.5U or so high,, 19" wide...
I fired it up last night and hit the self test button, and was gifted with a few more errors than I was hoping for...
37, 38, 39, 41, 42, 43, 44, 45
Does anyone happen to know what these errors actually are? Maybe I need to dig deeper into the service manual, but all it seems to say is that they are related to the analogue section. No other info.
I also found that the brushless dc motor in the cooling fan is dead and been disconnected by the previous owner, so I'll replace it with a standard 12v San Ace brand 60mm fan.
And, the backup battery has leaked everywhere too, as is tradition. It's a 2.4V nicd, so I'll probably remote mount a couple nicd AA batteries to keep further mishaps a little more contained.
The battery is only used to save the front panel settings when you turn the machine off, so no calibration memory was lost like happens with the 3478A multimeters.
The main problem is one of the card edge connectors for the digital board is corroded pretty bad from the battery juice, but I'm sourcing a NOS exact replacement for that.
So, the first plan of attack is to clean up the battery residue and replace the card edge connector, and figure out what those error codes mean, hopefully some are magically resolved with the disappearance of the old card edge connector...
Second step is a full capacitor replacement, all electros are getting ditched, and a few dodgy looking poly caps too.
It looks like all the electrolytics are United Chemicon, many being SM series, an obsolete 85degree rated general purpose type. They'll be replaced with 105degree rated caps of an equivalent series and same brand.
Third step is to recreate my own Option 001 board to give me built in DC bias output.
The service manual has schematics, BOM and PCB layout so it should be relatively easy, pending the sourcing and substitution of obsolete silicon.
I'll add more photos when I'm back home tonight.