Quote:
Originally Posted by stusnyder
Took the back off and noticed the crt gun had no glow to it, checked pins 1 and 14 and have no voltage, but the filament checks ok. It has 6 filter cans, single section. One got rather warm. Fuses are ok. Since this is 1971 vintage I'm guessing just replace all the cans???? Double sided circuit board, so lots of fun getting these cans out. If one or some of these cans were bad, would that interfere with the crt circuit?
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I don't have specific knowledge of the 475, but many Tek scopes power the CRT heater from a winding on the HV supply transformer. Usually the lack of heater voltage implies that the HV supply is not working. It is also likely that you could have encountered a fairly high negative voltage at the heater pins had the HV supply been working. BE CAREFUL!! get a schematic and know what you are doing before poking around the CRT base in an oscilloscope.
jr