Adcom thermal protection light stays on

autoconsortium

I am trying to repair a set of amps that were hurt during lighting. One of them seems like it will be ok. The other, a GFA555II, powers up, but the thermal protection light stays on constantly, and no sound is coming from either channel. I have replaced all external fuses, there are no fuses inside to replace, like the older GFA555 (with no thermal protection circuit). Anybody know where this circuit is? There is a little blue wire with a plug on the end coming out of the toroidial transformer area...is this where they plug in something to reset the circuit?

disneyjoe7

I that a stab at it Lighting damage / Short in bias transistors / per drivers / output drivers could be shorted causing a speaker output voltage to rail. Amp is doing the right thing and refusing to power up. Maybe fixable or not, seen TV's hit 1 was repairable 1 was NFT (Not feasible to repair) a complete frying. This set took the juice the other got the taste of it.

Good Luck

heiney9

The thermal protection light is on for a reason. There is no "reset" that I know of. Read many other stories similar and pretty sure the output trannys are cooked. It can certainly be repaired but I'd check on the cost and availabilty of original parts. The original Toshiba output trannys haven't been manufactured in about 5 or 6 years (or longer) although Adcom stated several years ago they bought up everything Tosh had and would be set for many years, FWIW. You maybe able to buy a used one for what it would cost to ship and repair.

Also check:

http://www.diyaudio.com/forums/index.php?s=

and do a search for Adcom in the solid state forum there are a few threads over there concering the same issue. Also some very helpful techs over there if you were to pose the same question.

H9