I have 2 Adcom GFA-565 Monoblock Poweramps and while both turn on having power, they are not delivering any sound to connected speakers. The speakers work properly as well as the cables connecting them function. Also, there's no "pop" noise when turning the amps on from the speakers connected. There used to be this noise when switching on the amps, along with the sound being delivered to the speakers, but all of a sudden this has stopped. Any advice would be greatly appreciated.
You are using each amplifier in the bridged mode, correct? What ohm are the speakers these are driving? I would check the rail fuses first. Look up the owners manual and it lists acceptable fuses to replace them with.
Welcome to the forum!
I've attached what I believe is the service manual for your amp.
Would you confirm? Do you wish wish to repair your self? Do you have any test equipment and any repair experience?
I've attached what I believe is the service manual for your amp.
Would you confirm? Do you wish wish to repair your self? Do you have any test equipment and any repair experience?
I've seen what you’re mentioning stated in the manual but am unsure what's to be looked for per the rail fuses?
I see 3 fuses depicted in the last page of the manual, one near the AC power plug and two more between P036A and Z018A assemblies. The latter two are the on the "rails" that RickRay mentions, as they are fuses for the plus and minus DC power supply rails. The text mentions the fuses being chassis mounted but I've not spotted them in any mechanical drawings.
Thanks, yes that is the manual. If the fuses are simple to replace I’d be comfortable with trying that myself but anything more than that I’d probably be looking to bring it in somewhere. I’m also unsure where I’d be able to get replacement fuses.
You're not supposed to connect speaker with lower than 4 ohms to these amplifiers when they are bridged. Each side is seeing 2 ohms when bridged.
User Manual attached. Manual lists these specific fuses as acceptable replacements:
DC RAIL FUSES
Bussman AGC-8/250V
Littelfuse 3AG312008/250V
BEL 3AG 8A/125V
You can google them and find a source.
DC RAIL FUSES
Bussman AGC-8/250V
Littelfuse 3AG312008/250V
BEL 3AG 8A/125V
You can google them and find a source.
Don't think so. Pretty sure they are inside the amplifier case, looking at the pictures of the amplifier. The line fuse is replaceable from the outside. It is fine because the power light is coming on.
You did get lucky if that is the problem. The pictures of similar amps did not show the rail fuses on the outside. Do you know how to test fuses? Looking is not always accurate, those can blow at each end where you may not see the blown element. Not sure is those will be glass fuses or covered so you can't see inside. Use an ohmmeter and check resisitance from one end to the other with the fuse removed. Should measure .5 ohms or so.
Thanks for that information. Pretty sure the attached photo is the part.
