I recently bought a m2 and corresponding c2a preamp. Problem with the m2 is that it does not work. Buttons don't light up. So I checked some of the test points inside. On the outermost boards I get 80 volts, which is correct. I don't remember which stage it is. But the inner boards get no power. Also, there are test points at the front of the amp that should be 12 volts and 100 volts. I get 30 volts and 175 bolts respectively. I can circle these points on a schematic if needed. Just seeing if anyone has run into this issue.
Need help diagnosing a Yamaha M2
- Thread starter RTBfalcon
- Start date
I'm not sure why it has me as a new member since I've had this account for several years now. But anyways, if the mods deem the subject be better suited to the Yamaha forum, I would not be opposed.
It's in your interest to raise the visibility of this thread so you get a quick, quality resolution. This is achieved by logging in the more appropriate forum.
Apolgies to wmgwizard but none of the yamaha guru's have posted, probably because they have not seen it. Use the report link at the bottom of the post
and request that the thread be moved
slimecity
Super Member
To get you started - refer to this and post your comments referring to the boards in the service manual:
https://www.hifiengine.com/manual_library/yamaha/m-2.shtml
https://www.hifiengine.com/manual_library/yamaha/m-2.shtml
Referencing chassis ground ?
Possibly just all burnt out lamps.
There were dedicated posts for earth on the boards. I tested all the fuses on the front board and they tested good. No relay click so I do not believe the amp is allowing a power up.
The service manual is as high quality as the build of this amp. Thankfully.
RTB, refer to page 12 of the service manual. Find the meter board. Test the output voltage at each pin (on either side of the "U" shaped notch. 12 pins to the left and 6 pins to the right).
Print out a hard copy of the schematic and record the values you measure. If any of those voltages don't match the schematic, we have at least narrowed it down to the meter board (potentially).
RTB, refer to page 12 of the service manual. Find the meter board. Test the output voltage at each pin (on either side of the "U" shaped notch. 12 pins to the left and 6 pins to the right).
Print out a hard copy of the schematic and record the values you measure. If any of those voltages don't match the schematic, we have at least narrowed it down to the meter board (potentially).
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There problpr is there. On thetmeter board where I shoush have 100 volts i get 175 and where I should haha 12 i have about 30.
Test whether you have voltage on the output side of the rectifiers. Rectifiers are immediately after the points where you measured the 175 and 30V. Keep testing points in the circuit until you read no voltage.
I'm not sure, but I suspect that you may have high voltages because some component (resistor or transistor) is open and so there is no current flowing.
If you keep testing down stream, you should eventually find the faulty part.
Seems curious that two different circuits are measuring higher voltage though.
I'm not sure, but I suspect that you may have high voltages because some component (resistor or transistor) is open and so there is no current flowing.
If you keep testing down stream, you should eventually find the faulty part.
Seems curious that two different circuits are measuring higher voltage though.
