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Help with my trusty Pimeta (right channel is only static above low volume)

post #1 of 6
Thread Starter 

So I've had a pimeta for a long time now and it's served me well. I bought it from another forum member who made his own PCBs both for the main circuit board and for the diamond buffers. It has some very cheap looking volume pot, which I believe is the source of all my problems, but I'm not sure!

I few weeks back I noticed that at low volumes (well below what I listen at) the left channel was output was less than the right. However turning up the volume to anywhere near a reasonable listening level and the channels equalized and everything seems fine.

Last week I packed up my pimeta in my carry-on and brought it with me on a business trip. However upon hooking it up (same exact setup as before) the left channel seems to work fine but the right channel just sounds like static above anything but really low volumes! Basically if you start with the volume all the way down and slowly turning it up, first you hear both channels come in equally and increase in volume, but at a certain point the right channel just switches to low volume static while the left channel continues increasing as normal.

 

Seems to me that i've got a wonky volume pot, but is there anything else it could be?

Also, does anyone have any recommendations on who might be able to do repair work in exchange for money? :)

Thanks in advance for the help! Really disappointing to bring my rig with me and then not be able to use it!

post #2 of 6

Are you here in the DIY forum because you have a vaguely PIMETA-like amplifier, or because you actually want to Do It Yourself?  I mean, are you shopping for a repair technician, or are you willing and able to get in there and start troubleshooting?

 

There's a whole raft of basic troubleshooting steps you should take before you can expect anything but rank speculation in answer to your post.

post #3 of 6
Thread Starter 

Thanks for the info.

I posted in the DIY section because my amp was DIY ... seemed like it would be kind of strange to post in the regular amp sections.

As for what i'm looking for ... probably looking for a repair tech because nowadays i could only handle the most basic stuff myself, like swapping the opamps that your troubleshooting steps suggest (because my problem is isolated to the right channel right now). It kind of sucks for me because in the past I would have been able to really dig into this thing and almost for sure fix it myself, but nowadays i no longer have any real equipment to work on it.

I was hoping that the problem that I described would lead to some for sure solution like "for sure your volume pot is bad", and I could maybe find some way to borrow some stuff from people and handle it myself, but if it's going to be a more open ended troubleshooting thing then I almost for sure need someone to do it for me.

 

Thanks so much for the help so far, because it has definitely been helpful!

 

I think i'm going to swap these opamps, and if that doesn't work try to send it off to someone. I like this amp, and i'm attached to it because it's served me so well over the years, so i'd really like to keep it working.

 

Again thanks!

post #4 of 6
Thread Starter 

anyone have any suggestions for a "repair tech" or any place I should look?

post #5 of 6

You might have gotten lucky that way, but you have to realize that what you have there is truly a one-off item. If you were expecting someone to just know how to fix it from experience, the only one with direct experience with that specific build is the person who built it.

 

I and others here do know the PIMETA v1 and v2 circuits, but what you have there isn't that. It's kind of like saying "I have a Chevy" when what you actually have is a Baja buggy that was built on a Chevy chassis. If your local Chevrolet dealer can help you at all, it's only because the repair person has the thing in front of him and can apply his broad experience to figure out what the builder did while he simultaneously troubleshoots the builder's creation.

 

Even if you did have a "true" PIMETA, it's still a DIY project. DIYers are free to use alternate or non-recommended components, alter the circuit, etc. In effect, each DIY build still ends up being nearly a one-off even though it's built on the same PCB as all the other "true" PIMETAs.

 

Speaking very broadly, your symptom isn't common in "true" PIMETAs. Short of getting the test data lined out in the troubleshooting article I linked you to, I'm still left only with wild speculation.

post #6 of 6
Quote:
Originally Posted by floodo1 View Post

Seems to me that i've got a wonky volume pot, but is there anything else it could be?

From the description the chances are that that is exactly what it is. Other possible problems are dry or broken solder joints in the wiring associated with the volume pot. Since the problem changes with movement of the control, the chances are that the problems are being caused by some kind of mechanical problem in or close to the pot. Of course it's not a definitive diagnosis, but I would think that inspecting the joints near the pot and replacing it if nothing is found is a reasonable (cheap) risk to take.

Good luck.

w
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