Carver Amp Problems

[dthomps]

Alright, here's the story.
I have a carver amp (model TFM-24).
When I hook it up to me preamp and cd player, I get a lot of distortion. The preamp is fine, because headphones sound fine through it, as do other amps played through it. I have used various interconnects, and the speaker wire/speakers are from my bedroom setup that sees daily use. I am absolutely lost here- what could the problem be with the amp? Both channels sound the same. Like I said in my old thread, it sounds like a radio station that barely comes in. Lots of static.

I have tried playing with the bass/treble/balance adjustments, but really havent come to anything that I could draw a conclusion from. It just seems to be present no matter what.
I took the cover off the amp to check all the solder points, and I did see that a couple of points holding the RCA connectors to a little PCB were a bit coroded, and I tried to clean them a bit but I don't think it did anything. If anyone has any advice, tips, web sites... whatever, it would be more than appreciated.
Thanks a lot! Mike

My original (http://clubpolk.polkaudio.com/forum/showthread.php?s=&threadid=12579&highlight=tfm24)thread

[jcaut]

Hi Mike,

Have you checked the speaker outputs for DC offset?

I'm no tech, but the fact that both channels sound the same would make me tend to think it's a power supply problem. Possibly in the rectifier. Bad diode(s) or something. If that's the case, it should be an easy fix. That's just my best guess though.

I know just enough to be dangerous, as they say!

Good luck,
Jason

[dthomps]

Hey Jason
Thanks for the reply.
I have not, nor do I even know how to check for DC offset at the speaker outputs:D
If you could elaborate on how to go about doing so, or a link would suffice if you dont want to type it out it would be awesome.

The fact that you mention the power supply reminded me that there is a little tag stuck to it from a repair done, it says "3266 12-14-96 MSM" which might hint at a faulty repair, or something along those lines?
Anyhow, if anyone has any other ideas, or if you need a couple photos just let me know, I would love to get this baby rockin'. thanks. Mike

[amulford]

You could give these folks a call:

Carver Service (http://www.sunfire.com/carver.htm)

They are the real deal and could probably help you out, or repair it if found necessary, Good luck.

[jmasterj]

Hey dthomps,

sorry to hear about your TFM-24. I just reciently got my TFM-35 back from Carver service. Rita the service tech did a good job. It has been playing fine since I got it back. One thing though... you must pack it good. It is fragile. Mine left Carver playing, by the time it reached me in Atlanta UPS ground had shook a solder contact point loose. I had to resolder it. I was lucky it was easy to notice.

A friend wants to buy it from me I'm thinking about letting him get it because I have (2) of them.

Send it to Rita she'll fix it...

[jcaut]

Hi Mike,

Sorry I took so long to respond to your question about the DC offset. I kinda forgot about this thread until I saw it back on top.

For this you need a decent voltmeter that will read DC mV. Here's how to check it:

Disconnect the speakers and connect the meter leads to the speaker terminals. Polarity isn't important, as the offset can be in either direction. Set the input to an unused position, or in the case of a power amp, make sure there's no signal on the inputs. I don't think it matters whether there's actually anything connected to the inputs or not, so long as there's no signal (but someone can correct me if it does), I usually just disconnect all components from the main inputs. The offset will usually change a little as the amp warms up. Give it ten minutes or so before you read it. The reading should be less than +/- 50 mV; The lower the better. Most amps have protection circuitry that will kick-in and silence the output if the DC offset is half-a-volt, or so. Usually indicates output transistor problems, which I don't think yours has. I still vote for the rectifier or some other power supply problem. Hope you get it going!

Jason