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Post by 2600 on Jun 4, 2019 22:04:59 GMT -5
This is where a 'scope pays for itself. There are other ways to trace the progress of your audio signal from the mike jack to the final tube, but that's really not in my skill set. Been using a 'scope to answer this kind of question for so long it's the only way I know to troubleshoot a tough one like this.
Back in the bad old days when a 'scope was exotic and too expensive for a lot of folks, a gadget called a "signal tracer" was used for this sort of effort. It's an audio amplifier with the input on a probe at the end of a shielded cable.
Haven't used one of those since high school. Odds are you would pay as much for one of those as for a decent used 'scope these days.
Wish I had a better suggestion to offer.
73
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Post by n4dxx on Jun 13, 2019 8:14:10 GMT -5
I think i may be making some progress..I found i can get around 20% Clear modulation if i inject the mic signal at pin 2 of the 6bq5..I have as well tested that tube it's 100%
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Post by n4dxx on Jun 13, 2019 21:51:33 GMT -5
Found it..I over looked this and tested it more than once..It was the internal audio gain adjustment went to ground.I don't know why it tested ok the first time i checked it..I pulled it out and it was dead short..I would have never found it had i not fed input to pin 2 on the 6bq5..Thank you all so much..I will be making a donation to help keep this site up and going..
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Post by 2600 on Jun 13, 2019 22:16:32 GMT -5
Rock on!
Just goes to show there's always more than one way to skin a cat.
Congratulations for sticking with it!
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Post by n4dxx on Jun 13, 2019 22:35:26 GMT -5
Yea i was not giving up..I am so glad i found it but i still cant beleive i over looked that..I am sure i tested it more than once and it was testing ok..but when i removed it from the chassis it showed shorted to ground..Thank's a Million for all the help..2600 and Tubefan..
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Post by tubefan on Jun 14, 2019 16:56:40 GMT -5
Glad you got it. Tough thing tracing without all the equipment and knowledge. But asking questions and process of elimination can always get you there. Good work.
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