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I have a couple of these amps and both have no output from the speaker outs. Speakers both good and headphone jack works. Found an old post here about this issue or similar because in that thread someone had rewired the amp to use the headphone out as the speaker out because of this problem. The rest of the thread is too technical for me but I'd like to learn, old guy could be taught new tricks I hope. Anyone got an idea of what could be wrong and how to describe the solution to me in layman's terms? Much appreciated.
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Check (replace) bad fuses in secondary PT.
https://elektrotanya.com/yamaha_g20-110_g50-110_iii_sch.pdf/download.html
https://www.audioservicemanuals.com/y/yamaha/yamaha-g/784592-yamaha-g20-110-g50-110-iiiIt's All Over Now -
From the schematic it looks like there is a relay protection circuit between the power (output) transistors and the speaker jacks (RY101). Do you hear a relay click after you turn on the amps? Looks like it probably is for both "power good" from the amp power supply and also disconnects the speaker outs if there is DC on the output, which would damage speakers and means there is something wrong with the power amp.Comment
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I have a working G50 and a few seconds after turn on it is easy to hear the relay click on this amp.Originally posted by glebert View PostComment
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Thanks for all of your quick replies, I didn't expect that and it is appreciated. Yes, I definately hear the relay click. The rest of the comments were above my current level so may I ask another uneducated layman's question. So because that relay clicks you think the protection circuit is doing it's job to protect the speakers and shutting off output to the speakers? If so, does that mean the power amp itself is bad or could it be some fuses mentioned above? Any idea where these fuses are and how I could check them? Again, much appreciated!Comment
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The relay clicking means it is coming out of protect, so that is a good sign. (That is assuming it's one click, a couple seconds after turn-on)
The amp turns on in protect mode, then if there are no serious power amp faults, you hear the click as the amp comes out of protect.
The headphone out in this amp does not have the kind of power needed to drive a speaker. So that other thread you mentioned must have been talking about using a powered speaker, or a different version of the amp.
Plug your guitar into the 'power amp Input' jack and check if there is any sound.Originally posted by Enzo
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If you don't know where the fuses are then you should consider doing some background reading and study before continuing. I appreciate that you want to learn and fix your amp but I really don't want you to get hurt in the process.
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