I just got an Adcom GFA-585 and found that the left channel heat sink gets much hotter than the right heat sink, while playing at normal/low volume. I measured the left at 138F and the right at 105F. The unit seems to be working properly and the leaking capacitor issue was taken care of in 2014 by EBC Electronics. Is this a normal condition, or is there something wrong?
Thanks for the help,
Mark
Thanks for the help,
Mark
What he said^^, I try and keep the heat sinks at 120f or below.
But regardless of that temperature number, there should be a "bias" setting for that specific model that you would want to adhere to until you know other wise.
Search for bias adjustment and sort through that for starters.
But regardless of that temperature number, there should be a "bias" setting for that specific model that you would want to adhere to until you know other wise.
Search for bias adjustment and sort through that for starters.
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138F is really hot for this amp; much more than could be explained by a bias mis-adjustment, or drift.
More likely, the amp is suffering once again from the leaked capacitor issue. I see this all the time. Amps that were repaired once, will fail again years later. The problem is the electrolyte actually soaks into the fiberglass, and continues to leach out.
Do you have any DC offset on the speaker outputs? It should be less than 15mV on a GFA-585.
Also check your voltage on the output of the servo Op-Amp. (Pin 6) This pin can swing +/- 12V. In a perfectly tuned GFA-565 or 585, there would ideally be zero volts, meaning everything is perfectly in balance. Of course, this never happens in real life, but you should see less than 6V coming out of the servo. If it's reading 12V, that means it is trying as hard as it can to correct the DC imbalance.
I hope it's not improper to mention, but I do sell the solution to this problem. New circuit boards.
https://hoppesbrain.com/2016/05/09/how-to-fix-leaking-capacitors-in-adcom-gfa-565-for-good/
If you'd like me to fix it for you, I'm about 7 months out now.
More likely, the amp is suffering once again from the leaked capacitor issue. I see this all the time. Amps that were repaired once, will fail again years later. The problem is the electrolyte actually soaks into the fiberglass, and continues to leach out.
Do you have any DC offset on the speaker outputs? It should be less than 15mV on a GFA-585.
Also check your voltage on the output of the servo Op-Amp. (Pin 6) This pin can swing +/- 12V. In a perfectly tuned GFA-565 or 585, there would ideally be zero volts, meaning everything is perfectly in balance. Of course, this never happens in real life, but you should see less than 6V coming out of the servo. If it's reading 12V, that means it is trying as hard as it can to correct the DC imbalance.
I hope it's not improper to mention, but I do sell the solution to this problem. New circuit boards.
https://hoppesbrain.com/2016/05/09/how-to-fix-leaking-capacitors-in-adcom-gfa-565-for-good/
If you'd like me to fix it for you, I'm about 7 months out now.
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