Re: Tektronix 475


Simon
 

Thanks for the information about the neons. I thought they might be for protection. I still do not understand how the beam finder works as it is a DC voltage, which is in specification on the test points, but it does not display any beam or spot. It looks as though the grid bias is obtained from grid leak through a 22 MΩ resistor and another winding on the HT transformer. I have not yet found that part on the circuit. I am still leaning towards the tube being bad.
Regards
Simon

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