Hickok 440 Curve Tracer Repair Help
On Tuesday, June 25, 2019 at 6:54:49 AM UTC-7, Don Brown wrote:
I have a Hickok 440 curve tracer that I am having difficulty troubleshooting, even though it is a relatively simple circuit.
The base generator staircase is not stable, and will not stay in calibration. It looks like noise comes and goes and distorts it. I have replaced most of the semiconductors. The 15v power supply is a bit low at about 13.9v, though the regulator transistor and zeners have been replaced.
I have the manual, schematic, parts and usual test equipment.
Thank you,
Don
I changed the two electrolytics in the 15v supply, and one polyester that is used in the base generator section (though it tested OK out of circuit). I did a quick run through on the resistors while in circuit, and they test within spec with nothing unusual.
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