Accuphase P-300 needs some repair

agrajag9

New Member
I posted a few days ago on reddit about an Accuphase P-300 that I'm having some minor problems with and someone suggested I come here for more help.

A few years ago I came across an Accuphase P-300 amp for free on craigslist and immediately snagged it. Got it home and it wouldn't turn on, but a little PB Blaster on the power switch solved that. The thing sounds really amazing, but the left and right channels have never been balanced properly - I've tried at least 10 different sources and 3 different pairs of speakers, and in every case the left and right volumes have to be set wildly differently for the amp to produce the same output volume in each channel. I can't remember which is higher at the moment, but that's easy to check.

I'm not particularly comfortable dismantling and repairing it myself, but I'm willing to learn. I have some experience with EE - I can solder alright and I know what most things are called and look like IRL and in schematics - but mostly small things like RasPi boards and and gaming controllers.

I was able to find the schematics on HiFiEngine.

Help me Audiokarma, you're my only hope!
 
Welcome to AK and nice grab on the P-300! It's possible a good cleaning of all the switches with DeOxit could resolve the balance problem. You'll also need to check the DC offset ( see the third "sticky" from the top in the "Solid State" forum).
 
I owned one for a long time and had it rebuilt by one of the fantastic techs that frequents this site. It's well worth investing the money into having that done as I'm sure it needs it after four decades. It's one of the absolute best solid state amps I've ever owned.
 
I owned one for a long time and had it rebuilt by one of the fantastic techs that frequents this site. It's well worth investing the money into having that done as I'm sure it needs it after four decades. It's one of the absolute best solid state amps I've ever owned.

I agree, especially as you have no money in it.

There is a link on the bottom of this page to DeWick repairs;
I'd check w/ Terry (he was pretty backed up recently and may be narrowing the brands of gear he is currently servicing; or PM AK member EchoWars

Feel free to post gear pics too !
 
I read the outputs and it's reading ~90mV and ~37mV on the left and right channels, respectively. I'll pick up some DeoxIT this weekend and try that out first before I do anything else.
 
I like seeing Accuphase in the Kenwood forum. After all, the brands are related...
 
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Well, I got it MOSTLY apart, but I couldn't get the faceplate off. I think it may be glued on? It didn't feel like it was held on with screws.

I refuse to give up!!!
 
L & R endcaps come off (two screws for each endcap...the third screw on each side is the pivot point for the door; it stays). Carefully remove auxiliary door at the bottom front, taking care not to lose the nylon beads and springs that give the door its tension. Put some Scotch tape on these ends when the door is off to prevent losing these small parts. The pivot points for the door have some small plastic washers...stash them away to prevent loss as well.

Two screws at the top far L and R of the faceplate. Two (maybe three) more in the bottom, visible when the bottom cover is removed. The last two are at the far L and R under the auxiliary door, which you have already removed.

This may be of assistance: http://www.audiokarma.org/forums/showpost.php?p=982253&postcount=11
 
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