Tagged As: Yamaha Power Amp
Question:
I recently was given a 1985 vintage Yamaha M40 power amp that had the circuit board that leads to the speaker connections broken. I contacted Yamaha and they no longer have the parts for an amp this old. Does anyone know of any other sources besides finding another old nonworking M40 for parts? Anyone have any old Yamaha parts amps out there?
Answer:
I can't help you with any M40 spare parts but, if you have the circuit diagram, you can rebuild simple sections of older equipment with generic parts just using good electronics principles. If you cannot diy then a competent repair person should be able to do it for you. A simple example: I have a Yamaha M4 and the the square on/off and speaker switch filament lamps burned out (it's silly design, ran too hot anyway.) I replaced all three by LEDs via series resistors off the same supply (it's DC, white and orange leads on my unit.) The LEDs are in individual generic black plastic LED holders mounted under the original switches in new through holes (plenty of space, drill carefully.) Power On/off LED is red; speaker On/Offs (2) are green The results looks better than the original and, of course, will likely never fail. BTW, if you use LEDs to replace indicator lamps run off AC, use a small back-to-back diode across them to pull down the reverse voltage - LEDs are a bit low-rated on PIV (peak inverse voltage.)
Yamaha Power Amp
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Visitor Comments
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Comment #1 (Posted by Tomas
)
Hey, I have an m4 with the same lamp problem. yamaha obviously does not support these amps anymore. could you be a little more specific as to what type of led's you used and what value resistors? i am not a total tech nerd, so this would be very helpful (i guess i soucl measure the voltage going to the lamps, but i am a little afraid of having power on with the heavy duty stuff inside the chassis) thanks so much tomas -
Comment #2 (Posted by Tomas Valenti
)
i tried to post this once before, but it did not show up. i am not enough of a techno nerd to go and figure out what you did, but i have the identical problem with an m4, and wonder if you could tell me exactly what leds and what value resistors to get, and where you got them. are they just from radio shack? thanks a lot -
Comment #3 (Posted by emery
)
It's fairly easy to bypass the board. I've done it. You end up with a better amp.