I recently acquired an inoperative 2182 nanovoltmeter for the princely sum of nothing, hoping to get it back in shape. This will be my first time working on something this complex (previously fixed a PB-503 for grins).
On power up, all display segments light up nicely, then it shows
REV:A06 A02. That's it for the good.
It then goes to
OVR.FLW V with a rapidly flickering period off to the far right.
I opened it up and took a look: everything looks good (all the caps look brand new with no apparent leakage).
I've gone through the repair manual trouble shooting steps (page 4-11 in the service manual).
Step | Item/component | Required condition | Remarks | Result | % |
4 | U304, pin 2 | +5V ±5% | +5VD, referenced to TP301 | 5.012 | 0.20% |
5 | U305, pin 2 | +37V ±5% | +37V, referenced to TP301 | 36.35 | -1.80% |
6 | CR313 anode | -6V ±20% | -6VD, referenced to TP301 | -7.59 | 26.50% |
7 | Q304, pin 2 | -5V, ±5% | -5VD, referenced to TP301 | -7.64 | 52.80% |
8 | U302, pin 3 | +15V ±5% | +15V, referenced to TP303 | 15.15 | 1.00% |
9 | U303, pin 3 | -15V ±5% | -15V, referenced to TP303 | -15.77 | 5.10% |
10 | U301, pin 3 | +5V ±5% | +5V, referenced to TP303 | 4.99 | -0.20% |
11 | CR305 cathode | +29V ±20% | +29V, referenced to TP303 | 31.49 | 8.60% |
12 | CR309 anode | -29V ±20% | -29V, referenced to TP303 | -8.88 | -69.40% |
13 | CR310 V+, pin 1 | +18V ±20% | +18V, referenced to TP303 | 21.17 | 17.60% |
14 | CR310 V-, pin 2 | -18V ±20% | -18V, referenced to TP303 | -20.75 | 15.30% |
15 | CR306 anode | -7V ±20% | -7V, reference to TP303 | -9.57 | 36.70% |
16 | CR308 cathode | +7V ±5% | +7V, referenced to TP303 | 7.87 | 12.40% |
So clearly something's off, particularly on the negative side. I replaced Q304 (ordered several of each of the out-of-spec parts) to no avail, then thought I might be getting ahead of myself.
I'd like to validate that the transformer is good, but I can't find any specs on what the secondaries should be.
Any inputs, guidance, donations, well-wishes... whatever would be more than welcome.