20 Most Recent Adcom GFA-5500 2-Channel Amplifier Questions & Answers

Things to check: 1. With your multi meter, measure from left ground to right ground. What do you get? Measure from each input ground to chassis. What do you get there. 2. Get or make a pair of shorting plugs. Plug those into the inputs. Power on. Hum there or gone? 3. Turn the pre-amp on. Connect. Level of hum change with preamp on? 4 additional information. How efficient are your speakers? This is a big amp, high-efficiency speakers may show some noise, while low-efficiency speakers won't. A trip back to the shop may be indicated, too.

Adcom GFA-5500... • Answered on Dec 02, 2015

we don't sell fuses here, bro....

Adcom GFA-5500... • Answered on Aug 04, 2015

not unless it has a Bridge switch OR you design an inverter circuit for one of the inputs. If it has XLR inputs you can try to invert pins 2 & 3 on one of them, that might work...

Adcom GFA-5500... • Answered on Aug 04, 2015

The colour code or the value it states on R23 should give you the reading you will see on a test meter on the Ohm setting. If the value doesn't match the colour code of the resistor then you should replace it. It's best to take any resistor out of the circuit to test as strange readings can be caused in circuit. The same applies to the left channel one. Ohm meters are not expensive if you don't have one and can be got from various places that sell electronics parts etc. Some car part dealers sell them. They are a worthwhile investment and can be used for many types of problem.
It's likely that it's a basis resistor and failed when the power jobs went.

Adcom GFA-5500... • Answered on Jun 25, 2015

If you're friendly about it , the folks at ADCOM will probably give you a schematic
Call and talk to tech support

Adcom GFA-5500... • Answered on Jun 25, 2015

I's not a fuse, if it would have been one the entire amp would have been dead or severely affected. It can't be a bad connection, the warning light lights only when the input signal goes beyond a certain limit and forces the amplifier over it rate power.
If you see the warning light even without no input connections then something is wrong with the protection circuit - strangely it has failed before the amplifier it was suppose to protect. Since this is very unusual failure you should send it to be repaired at the dealer.

Adcom GFA-5500... • Answered on Nov 16, 2010

This sounds like an electrolytic capacitor that's discharging. Follow the wires from the speaker terminals in the amp to the PC board. This should lead you to the main amp board. If you look around it you might see what is called speaker coupling capacitors. I reckon they could be a bit larger than others and be around 220 to 470UF or perhaps higher. These capacitors will be the last thing the signal goes through before the output goes to the speakers. They can cause that. Otherwise it could be a capacitor in the power supply section.

Adcom GFA-5500... • Answered on Aug 24, 2010

Hi there,

Well it seems while transporting your Amplifier a sudden **** has resulted in some sort of disconnection inside. you'll have to open and check for it.

post further comments for more help or information..

Good Luck!!


Adcom GFA-5500... • Answered on Dec 04, 2009

go to radio shack near you and change the fuse with the same rate-------or any electronics store near you.

Adcom GFA-5500... • Answered on Nov 28, 2009

What I would do is look around inside and see if anything is burnt or broken, pay close attention to the heat sink area.
With neither channel working you have something that's common to both channels that is causing the trouble.
You should be able to see any fuse by looking inside, they might be covered up, but should be easy to get to.

Adcom GFA-5500... • Answered on Nov 27, 2009

Any fuse blowing is caused by a shorted component in either the power supply section or main audio amp part. Follow the fuse circuit and see where it leads you. Look around for burnt of damaged parts. Suspect anything sitting on a heat sink. The most common culprit is the audio amp main transistors, especially if someone shorted the speaker leads together. In the power part it could be the transformer, the large Electrolytic capacitors, rectifier, or voltage regulator. Some amps use an IC for amplification and this can blow the fuse.

Adcom GFA-5500... • Answered on Oct 19, 2009

Adcom makes a great amplifer! Usually broken highs and no bass means blown speaker. Try hooking it up to a completely different input source. Try different speakers also. If problem persists, check the fuse. Most will have a fuse on the back you can screw out. Some have two fuses (one for each channel) If this doesn't fix the problem it could be expensive to fix. Also, does this model ave the thermal protection light and if so, does it come on at all?

Adcom GFA-5500... • Answered on Sep 19, 2009

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