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n8tron
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adcom gfa5300 left channel overheating

I have an adcom gfa-5300 that is causing problems. After about 10 mins of use the left channel overheats and shuts down from the temperature protection. The thing is the left channel is definitely very hot, the right never shuts off and is indeed cool. Does anyone know what could be causing this to overheat?

they are connected to b&w 683 speakers.

mrlowry
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Re: adcom gfa5300 left channel overheating

First I'd recommend checking to make sure that speaker cable connections are properly connected and secure both on the amp AND the speakers. Even one strand going from positive to negative is enough to cause problems. Second I'd make sure that each of the drivers in each speaker is functioning. For the lower frequency drivers do that by GENTLY putting you hand on the driver while it is playing full range music. For the tweeter you could do that by putting your ear near it to see if it is producing sound. One blown driver could make the amp see an electrical short. Finally to completely eliminate the speakers as a possibility disconnect both speakers and switch sides with them and reconnect and listen. Moving left to right and vise versa and reconnect. Did the problem switch sides? If it did it's in the speaker. You could also do that with the speaker cables too. Basically use the process of elimination (if you haven't already) to eliminate every variable except the amp.

n8tron
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Re: adcom gfa5300 left channel overheating

thanks for the suggestions.

I just went about first securing the connections, then switching the speakers to different sides, then switching cables. even switching which cable end I was using as the + and - end. In each test I got the same results... the left channel consistently overheated. Any other ideas? I wonder what else could make it overheat like this?

I should also mention that this is happening even when nothing is playing. Just turning on the amp will cause it to overheat.

JSBach
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Re: adcom gfa5300 left channel overheating

My advice is don't use it until you can get a technician to check it out. At a guess it sounds to me from what you've said as if the biasing of one channel has drifted and will end up destroying the output stage if used much longer.

Jan Vigne
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Re: adcom gfa5300 left channel overheating

There's nothing here you can repair yourself. As stated, the tolerance of parts has drifted over time and the amplifier is no longer running as designed, bias is the most likely cause for the overheating and then the amp shuts down to protect itself from immolation. Continuing to use the amp in this condition will push the chances the amp will decide its not worth continuing and put an end to it all. Like a crazy neighbor with a highpowered rifle, it might just think it's a good idea to take a few speakers and half your house with it on its way out the door.

At this point, when the amp is still operating with only a few minor parts causing problems, you shouldn't have to replace any major parts. Let this problem go without a technician servicing the worn out parts and you could very well see a picture of your ampifier on the front page of your local newspaper. "It was always such a nice amplifier, kept to itself alot and never caused no trouble", said the neighbor who wished to remain anonymous.

Speaking of which, anyone remember the Marantz ad from the '70's for the 2270B receiver they hauled out of the burned down house? Marantz claimed they only needed to replace the power cord and the charred receiver worked as ususal. What they didn't say was the receiver with the new power cord worked as usual, started to spark, caught their photo lab on fire and burned it down too!

n8tron
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Re: adcom gfa5300 left channel overheating

thank you so much for all the info.

I'm looking up stereo repair stores in the area right now. (anyone know of a good one in LA that's open on weekends?)

just hoping now that it's not an expensive fix...

mrlowry
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Re: adcom gfa5300 left channel overheating

I'd recommend getting in touch with Adcom and see who THEY recommend for repairs.

Jan-

Do you mean this ad?

You might love the classic Marantz site http://www.classic-audio.com/marantz/mindex.html

Jan Vigne
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Re: adcom gfa5300 left channel overheating

That's it! A classic even if the receiver isn't.

The classifieds are interesting. $2500 for a 2600 receiver?! Yikes!!!

I see someone is selling a light kit for the old receivers, $35 is $25 more than I paid for the 2225B I found on a yard sale. Think I'll pass.

Buddha
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Re: adcom gfa5300 left channel overheating

If it "played perfectly," the fire must have tweaked it in some beneficial way. Or, maybe it was the aftermarket power cord!

After that ad came out, many tweakers started to 'creme brule' their Marantz receivers all over the place. I disremember it well.

Jan Vigne
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Re: adcom gfa5300 left channel overheating

"Played perfectly" left a lot of room for subjective opinion when the listener chose the 2270 in the first place. But I think you're on to something. Possibly this guy was the first to market replacement power cables.

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