:This capacitor analyzer (Sprague Tel-0hmike TO-5) has been recapped and I have reinstalled resistors to spec. The 6-60v electrolytic leakage scale works well. The 60-600v scale will not zero out with pot all the way counter clockwise. Immediately when pushbutton F (60-600v) is depressed I get a 140v reading (and the pot when turned clockwise will go to 600v with very good accuracy from 400v to 600v.)
:Now I have spent 2 weeks off and on troubleshooting this issue. Changed out tubes, changed out voltage pot, switched R7,8,9 and added additional jumper resistors to alter values, and took apart the push button switches and cleaned contacts, traced transformer connections…….to no resolution.
:So anyone got any ideas? Sure would appreciate advice.
:Thanks, Scott
:
Scott,
I looked up the manual at BAMA, check out resistors R16 and R17 for true aaccuracy and % of tolerance.
Section 4 of the manual explains how this part of the circuit operates. Read section 4, 4.1, 4.2, and 4.3. This section should help to solve your problem, also try installing a electrolytic capacitor rated at 450 VDC before operating the unit for test.
Best of luck,
Mitch