I got this monster a few weeks ago and after about a week the left channel started acting up. The owner I bought it from had it serviced 3 months ago from a reputable tech in my area and it worked flawlessly at first. Now the left channel gets intermittent distortion and continues to make a squealing buzzing noise even when I turn down the volume. I have hooked up a separate power amp through the pre main jumpers and the problem goes away. If anybody could help me get this beast running well again, I would be grateful.
Marantz 2325 left channel issues
- Thread starter TheStump
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- marantz 2325
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Bad cold solder connection in the L - channel amplifier perhaps. Or a transistor talking to ya.
So I have redone all solder joints as well as test all semiconductors and resistors for problems yet the problem still persists. I found that the voltage for the idle current will sit at about 0v to 0.1mv when it should be at 15mv. I am unsure of what to do since sometimes I can get it to 15mv before it goes back down to 0v. I have also checked r740 for problems and it seems to be working properly.
audio3000
Active Member
If luck is on your side, it could just be a dirty idle current trimpot. When the center wiper is open, it will reduce the bias current. Don't know how much exactly but could be zero.
How about with the power off:
1. mark the position of the idle current trimpot position.
2. drop some medical alcohol in it and let it sit for a minute.
3. turn it multiple times end to end and reset the position to the original.
4. wait until the alcohol is completely dry.
5. test.
I did the above steps for the bias trimpot too as a health check measure.
BTW, did the relay acts up as well? The amp's output DC bias voltage within normal range?
It's also a good idea to check the transistor mounting screw to ensure they are tight for good thermal transfer. When you play with the mounting screws, be aware that there are two nuts, one under the heatsink and one under the board. I did accidentally loose the nut under the heatsink without knowing it at the the time when I try to tighten the screws.
When I replaced the caps, I also apply new silicon heatsink compound as I found the original heat sink grease were pretty much dry up.
How about with the power off:
1. mark the position of the idle current trimpot position.
2. drop some medical alcohol in it and let it sit for a minute.
3. turn it multiple times end to end and reset the position to the original.
4. wait until the alcohol is completely dry.
5. test.
I did the above steps for the bias trimpot too as a health check measure.
BTW, did the relay acts up as well? The amp's output DC bias voltage within normal range?
It's also a good idea to check the transistor mounting screw to ensure they are tight for good thermal transfer. When you play with the mounting screws, be aware that there are two nuts, one under the heatsink and one under the board. I did accidentally loose the nut under the heatsink without knowing it at the the time when I try to tighten the screws.
When I replaced the caps, I also apply new silicon heatsink compound as I found the original heat sink grease were pretty much dry up.
The repair list I found on AK used KSA1381/KSC1503 to replace them. You have to tuck one leg under another to replicate the pinout, but otherwise they worked fine for me.