John Chi-town Posted July 12, 2015 Share Posted July 12, 2015 Fellow members, looking for some advice please. I bought an Adcom GFA 565SE about a year and a half ago. Currently Adcoms largest 2 channel amp rated at 250 WPC @ 8ohms. Why they named after their famous monoblock, I do not know. Any way, just the other day I powered up my amp and after the 10 second or so pre-warm I hear a very slight pop in the left channel from a cold start. Powered everything down, checked all connections, and re-started with no pop, however the very slight white noise that is always heard was louder and more crackly then the right. The next day I reversed speaker connections and on a cold start everything moved to the right channel. I repeated the process, shut everything down, checked connections and although again no Pop, still more white noise, and more crackly than left. Should I stop using until I have had looked at by a reputable tech? Obviously something is wrong with left channel, any ideas? The amp has instantaneous distortion warning for anything over 1%, yet neither channel light comes on or flickers. I had a GFA 555II, for over 25 years without a hiccup. Also, this is the second amp, the first I received had issues after about 90 days, sent back to Adcom and they replaced with another new, same model. This amp I have had for a year and a half, and if I need to repair professionaly think I might consider selling, unless it is a minor fix issue. Thanks in advance for any input. John Quote Link to comment Share on other sites More sharing options...
willland Posted July 12, 2015 Share Posted July 12, 2015 John, Sorry about the amp woes. Since the Adcom was new when you got it and you have owned it for only a year and a half, isn't it still under warranty? Bill 1 Quote Link to comment Share on other sites More sharing options...
John Chi-town Posted July 12, 2015 Author Share Posted July 12, 2015 Bill, Thanks. Not sure need to look into. The problem is, is that Adcom sources out repair to some outfit in NY. They had for over a month and could not repair, which is why Adcom replaced. I have a great tech locally that used to be an authorized repair center. Unfortunately Adcom is a shell of the company it was in the 80's and 90's. I would rather take to him to get diagnosed before waiting for over a month. If major will have him repair and dump. Midwest Audio Repair, in Arlington Heights IL. Just wondering if it is the beginning of losing a channel, or something minor? Best regards, John Quote Link to comment Share on other sites More sharing options...
willland Posted July 12, 2015 Share Posted July 12, 2015 Just wondering if it is the beginning of losing a channel, or something minor? Even losing a channel may not be that costly. I bought an Acurus 200FIVE that had a dead surround channel due to the previous owner's dog chewing through the speaker wire and sending DC back to the output transistors. It blew all four of that channel's output devices and luckily that was the only damage. Those OEM transistors were rare high quality($$$) and hard to find discontinued Toshiba bipolars and the total repair only cost me about $200.00. If it they were a more common and current transistor, the repair would have been less. Bill 1 Quote Link to comment Share on other sites More sharing options...
John Chi-town Posted July 12, 2015 Author Share Posted July 12, 2015 Thanks Bill. Just glad its not my forte II. LOL.... John Quote Link to comment Share on other sites More sharing options...
AllenTacey Posted July 15, 2015 Share Posted July 15, 2015 John if you can unplug and disconnect everything do so. then connect a good source, I found my CD Player to be bad and an IPod will work for this test. I connected my Nano Preamp and one amp. Reconnected my speakers checking wire from end to end. Sound was perfect so I tossed the CD Player. Make sure you have no metal objects inserting hum. Nothing no phones no lights nada. If it still has audible white noise and is solid state bang it bump it and see if that fixes the problem. Good luck I have a preamp that picked up a hum and repair shop could not find the source... Quote Link to comment Share on other sites More sharing options...
John Chi-town Posted July 31, 2015 Author Share Posted July 31, 2015 Well, I got my amp back. The problem was determined to be in the preamp of the amp, on the left channel. All boards tested clean. $50.00 in parts and 2 hours labor at $85.00 an hour. Adcom would have covered under warranty but would have taken 6 weeks and shipping to NY. Decided better to pay for than risk further damage by the boys in blue or brown. Hooked everytjhing up and works as new. Hoping no other issues in the near future. John 1 Quote Link to comment Share on other sites More sharing options...
willland Posted July 31, 2015 Share Posted July 31, 2015 Well, I got my amp back. The problem was determined to be in the preamp of the amp, on the left channel. All boards tested clean. $50.00 in parts and 2 hours labor at $85.00 an hour. Adcom would have covered under warranty but would have taken 6 weeks and shipping to NY. Decided better to pay for than risk further damage by the boys in blue or brown. Hooked everytjhing up and works as new. Hoping no other issues in the near future. John John, That is great to here. Hopefully you can enjoy your Adcom for many years. Bill 1 Quote Link to comment Share on other sites More sharing options...
babadono Posted July 31, 2015 Share Posted July 31, 2015 (edited) John, Just curious, was it an I.C. opamp in the preamp section that became the white noise generator? Or is this amp all discrete components? Edited July 31, 2015 by babadono Quote Link to comment Share on other sites More sharing options...
djk Posted August 1, 2015 Share Posted August 1, 2015 The only opamp in that circuit is a DC servo. Quote Link to comment Share on other sites More sharing options...
John Chi-town Posted August 3, 2015 Author Share Posted August 3, 2015 (edited) John, Just curious, was it an I.C. opamp in the preamp section that became the white noise generator? Or is this amp all discrete components? babadono; Not sure but following are the parts they replaced on the amplifiers left channel preamp: "Replaced defective parts on amplifier preamp board" SM IC-P88 1 @ $19.95 Q1 LT1006CN8#PBF-ND 1@ $14.46 Q2,Q3 2SC2713-GRLFCT-ND 2 @ $7.60 Does that tell you anything? Best regards, John Edited August 3, 2015 by John Chi-town Quote Link to comment Share on other sites More sharing options...
djk Posted August 3, 2015 Share Posted August 3, 2015 " LT1006CN8" Servo. When the servo goes it can damage other parts. Quote Link to comment Share on other sites More sharing options...
babadono Posted August 3, 2015 Share Posted August 3, 2015 Ok thanks for the info, I was just curious. DJK, Any idea what the first component, SM IC-P88, is ? Quote Link to comment Share on other sites More sharing options...
AllenTacey Posted August 20, 2015 Share Posted August 20, 2015 Well, I got my amp back. The problem was determined to be in the preamp of the amp, on the left channel. All boards tested clean. $50.00 in parts and 2 hours labor at $85.00 an hour. Adcom would have covered under warranty but would have taken 6 weeks and shipping to NY. Decided better to pay for than risk further damage by the boys in blue or brown. Hooked everytjhing up and works as new. Hoping no other issues in the near future. John John glad it is fixed. I asked around and found a local repair shop jem my Nakamichi cassette recorder needed a fix. Very reasonable. I'd stick with the shop you used. Adcom is not a tangle of wires and such. Rather many good companies make it easy to find the correct fix.I have one amp that is simple and the other well...looks to complicated fortunately the scematics are available online for free. $85 dollars an hour though is the base rate for an hour of car repair seems a bit stiff. I'd, while verything works find a more reasonable repair shop. Think $35 can be lopped off? Quote Link to comment Share on other sites More sharing options...
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