My adcom GFA555-II won't power up,checked speakers they were fine.

There are several things that could be causing the lack of sound output from your Adcom GFP 710. Here are a few things to check:

1. Check the cables: Make sure that the cables connecting the preamp to the power amp and speakers are securely plugged in and in good condition.
2. Check the input selection: Make sure that the correct input is selected on the preamp.
3. Check the volume: Make sure that the volume is turned up and not muted.
4. Check the balance: Make sure that the balance is set correctly and not all the way to one side.
5. Check the output jacks: Make sure that the output jacks on the preamp are functioning properly.
6. Check the power supply: Make sure that the power supply is providing the correct voltage to the preamp.

If none of these solutions work, it is possible that there is an issue with the preamp itself. It may need to be serviced or repaired by a qualified technician.

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.

Obviously you are going to use the Front pre-out's on the Sony to drive the Adcoms. its pretty straightforward, just do not use a speaker that is less than 8 ohms. and make sure that you always have the power switch off on the adcoms, let them sit off for 5 minutes, THEN hit the bridge switch on the back of the adcom's and follow their instructions for bridging. it's pretty easy and tough to go wrong. Good luck...Rob

Hi,
please replace power switch to solve amplifier problem as power switch internal contacts seems stuck and does not disengage to turn power Off.
Thanks.

no this AMP is not bridgable to get more power out of this amp you need 4 ohm speakers.

Power rating
1 - 150 watts into 8 ohm speakers
1 - 225 watts into 4 ohm speakers

Register and download the sparse manual for free at retrevo.com

http://www.retrevo.com/support/Adcom-GFA-545-Amps-manual/id/582ci563/t/2/

Pictures:

http://www.audiocostruzioni.com/r_s/ampli/amplificatori-2/Adcom%20GFA%20545/adcom-GFA-545.htm

It has two clearly labeled inputs and TWO corresponding speaker outputs.

(Wincing) in-line volume controls???? For casual listening? Say it ain

Possibly. Most amps filter out line hum via low-pass filters. If you can locate a schematic, those would be the caps to check.

Check the Fuse. Unplug the AC first. If you replace the fuse and it blows again, disconnect all speakers, replace the fuse and turn on. If the fuse does not blow, chances are it is a speaker problem, Adcom builds some very solid product, I would suggest pulling the outdoor speakers and testing them.
Depending on what you are using, some outdoor speakers should never be taken out of the living room. If you still have an issue post a comment and I will help some more.

Try just the power amp on ..nothing connected
no Dakiom thingy either. It's a matter of elimination. Start at the output device and work back. Keep the Dakiom out of the loop.
If there's hum with just the Adcom..then it's the ADCOM

Running an amp in bridge mode requires a specific circuit design. It is not possible to combine 2 amps in this fashion.
Dan