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Title: Help Sprague TO-6A Post by: AB3FL on December 11, 2011, 09:10:39 AM I recently acquired a TO-6A. It works fine on the top range 45-2000uf, but none of the other ranges work. Actaully they did work for a little then I banged the TO-6A and they don't work any more. Everything looks OK and I reheated all of the solder joints on the switches. Tracing the schematic, everything looks as it should and the tubes test fine. I even put a 50 ohm resistor inline to drop the line voltage to 115V in case this was causing a problem. The unit is properly grounded with a 3 wire cord. I have sprayed deoxit into the switches so they are all clean. All resistors and caps that didn't check good were replaced. The other functions (leakage and Insulation Resistance) work fine. Anyone have any ideas I may have missed? thanks Tom - AB3FL Title: Re: Help Sprague TO-6A Post by: Jim, W5JO on December 11, 2011, 10:30:30 AM Hope the range switches are OK. Have you checked the continuity?
Title: Re: Help Sprague TO-6A Post by: AB3FL on December 11, 2011, 10:34:17 AM Hope the range switches are OK. Have you checked the continuity? yes. All of he switches are fine Title: Re: Help Sprague TO-6A Post by: Jim, W5JO on December 11, 2011, 03:03:56 PM Be sure the switch section controlling C 6 is acturally opening when other swtiches are pushed. C6 is out of circuit on all measurements except the first range.
Title: Re: Help Sprague TO-6A Post by: AB3FL on December 12, 2011, 05:22:51 PM I found the problem! One of the calibration pots on the main dial pot was broken. Replaced it an all is good.
Tom - AB3FL Title: Re: Help Sprague TO-6A Post by: Jim, W5JO on December 12, 2011, 08:23:07 PM Congrats, you are, indeed, resourceful. That is a very useful piece of equipment. AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
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