All,
Got a Fluke 87 off fleabay for $20 as broken. Indeed, on firing it up, it behaves rather strangely.
So, knowing MrModemhead did some work with these, I immediately tested the 1K fusible resistor. Indeed, it's open. Great, so wired a 1K 1% 1/4w resistor in across it (with some leads), and now the ohms and diode read correctly. But, the ACV and DCV both read all over the place. ACV reads random mv's, and DCV reads about -34V. DCmV reads correctly. Pretty sure current measurements are correct too, but haven't checked. Range switch test checks out as well.
Interestingly, ACV reads random on all ranges (about -80mV to -100mV on 400mV range, about the same on the 4V range, .33V on 40V range, slowly decreasing to 0.5V on the 400V range, and 4V on the 4000V range (last couple seem to just slowly be decreasing to 0V)), and does nothing when you short the leads together. DCV reads -34.xx V on the 40V range, 0V on the 400V and 4000V range. OL on the 4V range. Makes me wonder if C1 might be bad (though, that shouldn't have anything to do with DCV since it's shorted out for those readings). RT1 seems to be good, as it's at 1.48K. I do only get 850K out of R2 (that's in circuit).
I'm really hoping there isn't something blown with the resistor network. I'll fully admit, I haven't tested the power supply(s) yet, but that's mainly because I haven't mapped out where the test points are yet (the service manual for these is great, albeit, a bit difficult to jump back and forth on).
Was mainly hoping someone had an idea to point at. Obviously if that fusible resistor is bad, then someone shocked this thing. It reminds me a bit of high input impedance, but it would zero out if the leads were shorted, and that isn't happening. Guess it also reminds me a bit of a digital issue (bad logic signals), but haven't gotten that far.
So, anyone seen anything like this? got any ideas? I thought at first the spark gap (E1) (guessing that's what it is) was bad since it had a big split in it, but that seems to be normal from pictures I've seen. =P Big hope is I don't have to order a replacement R1 until I figure out the issue, and can order whatever else at the same time. =)
Thanks!