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Has anyone worked on one of these (Phonic MK50)? Our church has one that's broken and they asked me to look at it. I can't find anything on the web related to repair or a schematic. It seems simply built. The power section has a transformer, diodes and caps and it does power up but it has no output. It appears that the power amp is Jfet driven. There are no markings on the two Jfets. Any thoughts or comments would be appreciated.
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Phonic is distributed by US Music Corp.
Contact them, maybe they can help with documentation.
U.S. Music Corp. -
And what about it are we trying to fix? Often we don;t need schematics.Education is what you're left with after you have forgotten what you have learned.Comment
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Well Phonoc (US Music Corp) won't give me anything other than a place to send it so i'm game for going w/o a schematic. I'll put a signal through it and trace it through the circuit this coming week-end and let you know what I find. As always, thanks for the input.Comment
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What is the symptom?
Isolate it to the speaker/speaker wires, the power amp, or the preamp, and verify power supplies are present for both preamp and power amp.Education is what you're left with after you have forgotten what you have learned.Comment
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What is the symptom?
All I know now is that the power section turns on and lights the "on" light. There are two speakers 1 12" and 1 2" which are good and their connections are tight. It has 1 fuse in the power section which is also good. It has 2 channels and a CD input. No sound comes from any of the inputs. I haven't yet traced anything through the amp which I plan to do this week-end. I'll post my results. thanks...Comment
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So the symptom is "no sound from speaker."Education is what you're left with after you have forgotten what you have learned.Comment
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There is a headphones jack, which presumably disconnects the speaker. SO do the headphones work?
Ther is an insert jack, which is an effects loop in one jack. Probe that, does it wake up the amp? APply a signal to the amp input, does anything come out that insert jack if you connect to another amp? And can you plug a signal into the insert jack and get anything out the speaker?Education is what you're left with after you have forgotten what you have learned.Comment
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No the headphone jack does not work either. I did not fiddle with the insert jack but I will. That's a real possibility! Thank you, Enzo. I'm working long hours this week but will tackle this in earnest this week-end. If I can't figure it out I'll post what I do know along with some pics...Originally posted by Enzo View PostComment
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