Adcom GFA 555II
- Thread starter giovanni
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Nice amps...for some reason they don't seem to sell for a lot, and $299 CAN is about right.
There are problems with the small electrolytic caps (two on the voltage amp board, and 1 ea. on the output boards - six total, IIRC) beginning to leak on many of the 555's and 555II's. They should be replaced (fairly simple job).
There are problems with the small electrolytic caps (two on the voltage amp board, and 1 ea. on the output boards - six total, IIRC) beginning to leak on many of the 555's and 555II's. They should be replaced (fairly simple job).
I've heard this paper-thing too - sometime in the distant past, but I couldn't tell you by looking at the board if that's what it is. Anyway, the long-time Adcom techs will tell you that once they have leaked, it's a disaster to get cleaned up, and maybe this is because of the construction (paper) of the board.
Makes sense to me. Thanks for the insight grateful. :yes:
Makes sense to me. Thanks for the insight grateful. :yes:
grateful
Super Member
Sure thing I have a 585 sitting at work that has this problem. It gets on the servo ic section of the board. The repair estimate was too high for the customer and has not been approved. The paper boards are greenish white in color and look like mil epoxy fiberglass, but they are not. Most series 2 Adcoms have this type of board. Original 555 units do not.
JesusChrysler
...drives a Dodge ; )
So what the hell should I look for (newbie-style) inside my newly-acquired GFA-555 II again?
Speak slowly, and e n u n c i a t e...
Please.
Matt
Speak slowly, and e n u n c i a t e...
Please.
Matt
JesusChrysler
...drives a Dodge ; )
Thanks.
Matt
Matt
grateful
Super Member
If any brown stuff is leaking out of the caps clean it off the board without blotting it. Try to lift it off pehaps with a toothbrush. Any remaining scrub off with soap and water. Dry througly. If you are lucky that may do it. You can tell if the board is contaminated by smell. When you solder in the new caps soldering will be difficult and the fumes will smell like dead fish.Test unit for offset. If you have the problem you will have drifting offset perhaps from 40 mv to 3 or 4 volts with peaks up to the full rail. The final fix is to remove the board and the caps soak in a soapy water solution and scrub every inch, top and bottom. Oven dry and repeat as many times as necessary. Do not run a unit that has this problem. They have no protection circuit and can set your speakers on fire and burn down your house. I recommend a series speaker fuse in any case with these amps. 2 amps with a robust 8 ohm speaker 3 amps with a 4 ohm.
USA Soccer
Well-Known Member
That was my amp in college wow only $300, good deal.
specialidiot
Break Glass, Smoke Lucky
:lmao::lmao::lmao::lmao::lmao:
JesusChrysler
...drives a Dodge ; )
I sure set myself up for that one, lol.
Matt
Matt
thymanst
Minnesota morning
I picked up a Adcom 585 le cheap that had the caps leaking (and major DC offset problem) - EBC Electronics in New Jersey specializes in fixing these Adcom amps - the repair of mine was $240 (web site has package pricing for different Adcoms) plus shipping - They know what to look for and replace all problematic parts of the amp - they cleaned the board,etc - Not affiliated, happy customer - I have it driving a pair of B&W Matrix 802's and it does a very good job
