I am looking for a parts list for a Bogen C100 series classic amp. I have a good print, just need some component values. Specifically, I need the value of R67 thermistor. I meter it out at 31ohms, and would like to verify the value. I think this thermistor is the root of my problems with this amp
This seems to be a thermal shut-down. Shorting it should allow the amp to run. If not, then you have other problems. The right value will shut down the amp at the specified temperature. I don't see any way the thermistor could be burnt so it is unlikely it has changed. You should probably disconnect the output transformer while you are servicing the amp by removing the 4 Ohm-Link. R46 (?) and the thermistor should give something less than 0.65V on Q11 at operating temperature. And the thermistor should have a positive tempco??? 470@100C? Perhaps this is a PTC "thermal fuse" like those used for USB power.
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