[volt-nuts] Fluke 732a concernes

[Igor]

Hello,

I am Igor and I am new to this forum. I have a Keithley 2002 and 3458A.

As probably a prerequisite for this list, I recently acquired a Fluke 732a and checking it our now. I do not have any history for the unit and it was shipped to me cold without batteries and with broken battery carrier.

After a warm up 10V read about 7ppm high and 1.018V read about 13ppm high. This is probably ok for a very old unit like this.  However 1V read 116ppm high! Is this typical? Would it be a sign of internal resistor drift?

I had to move an internal jumper for 5ppm adjustment and then adjusted 10V and 1.018V to proper value using a calibrated meter. I do not see any way I can adjust 1V output to be even close to spec. Is opening the oven and adjusting resistors an option? Should I just leave it alone and monitor drift?

When fully warmed up the thermistor measured 3.662KOhm. Is this a typical performance?

Additionally when inspecting the unit in more details I found a burned PCB patch on A4 Regulator board, right under R12 and R13 resistors in proximity to transistor Q4 and capacitor c8. It is literally burned to black crisp. The resistors themselves appear ok. Maybe they had been changed after the board burned.

When running the board I get transistor Q4 as hot as 220F, still below its 150C max running temperature. The PCB board and resistors get to 180F. Is this normal, or should I be concerned?


Thank you very much.