Adcom GFA-565 Repair Service
GFA-565 is excellent power amplifier, but after 20years your amp may need a service or repair.
There could be several problems with the amp but most of the GFA-565 amps have a problem with leaky electrolytic capacitors. The problem is not a design issue, the amp is very well builded and has excelent characteristics. It seems that during production, the manufacture was supplied by bad quality batch of electrolitic capacitors. Typically there are few bad electrolytic capacitors on the input board. The electrolyte from bad caps spills over the board and make damages. First, the electrolyte is conductive liquid which causes servo DC and differential circuits to malfunction. At this point the amplifier can not properly control DC voltage at the speaker output terminals, which has to be about 0 volts. As a result you notice that the cold amplifier make loud turn on/off pop or has distorted sound, but works fine after warming. On the other hand, the electrolyte is corrosive liquid which cause damages of some components on the board. As a consequence after few weeks/months, the amplifier gets dangerous voltage at the speaker terminals, up to 70 volts, and can destroy the speaker.
This process is very slow and could take several months before the amp blows the speaker, so you have a chance to notice the problem and save your lovely speaker.
Typical noticeable symptoms of bad amp:
Does your amplifier have one of these symptoms? If so, service it ASAP before you get one of the following symptoms:
How to check the amp with a multimeter
Before you start please make sure you know what you are doing and how to use a multimeter. Set your multimeter to 200 Volts DC first, if the amp is ok you can lover to mV. Never switch the multimeter to ampers measurement you can badly damage your amplifier.
Be carefull, do not touch speaker terminals and wiring, bad amp can have 80 volts at the speaker terminals.
If your amplifier had developed a serious problem, fried a woofer or blew a fuse, or you have an unknown amplifier better to not power it up again but bring it to a repair shop for diagnosing - powering up bad amplifier even for seconds can cause more damages to the amplifier itself.OK. If you have some how working amplifier you can continue. Simply check DC voltage across the speaker terminals without input signal applied by using your multimeter. When you turn on the amp, the DC can jump up to 0.2 volts, then it slowly goes down. In 1 minute it must be stabilized at 0-30 mV (less than 0.03 volts). If your amp has more than 30mV DC, it must be repaired ASAP.
In any case, even the amp has just noticeable problem or just small output DC, it means that the caps leak process is started and amp must be repaired. The board has to be cleaned, corroded and bad parts replaced
Altough the source of the problem is simple, the repair is not so easy and not every repair shop can handle the problem. The electrolyte has been sitting on the board long time and usually bunch of parts are corroded, some parts can be burned because of amp malfunction, output transistors can be bad.
Long time we work with this model, since the first problems occured. We have extensive experience in repairing that amplifier. We used different methods of cleaning the preamp board and have found the best solution. Your amp will be 100% fixed. There are no amps which can not be repaired. We take good care about your amp, we protect your amp from any scratches during the repair. We use high quality components to prevent future problems. All known as weak or nonstable components also will be replaced. We provide 1 year warranty.
Note: Unfortunately all GFA-565 GFA-585 amplifiers have that problem, no exception, so you need to service all GFA-565 GFA-585 amps you have in your system.
For last 3 years we repaired more than 100 GFA-565 amplifiers. All of them were successfully repaired. No recalls. No amps left behind.
Do not want to fix your amplifier? We can buy it as is. Please contact us for more details.
Please if you have a question about this service.