well this didnt turn out to be much, apart from being filthy dirty and one of the leads had come off the volume control
it looks a bit black in the middle but its just a shaddow from the sponge protection on the filter caps
so repaired that, cleaned it all up, set the idle current back to 4mv on both channels (right was 0.5) and, well thats it im affraid.
sounds ok, no where as good as the creek i just repaired though.
It could realy do with a loudness function as the bass is almost non existant at low levels.
I presume it used to have a remote as it has a motor control for the volume
good sound though, if a little uninspiring.
it looks a bit black in the middle but its just a shaddow from the sponge protection on the filter caps
so repaired that, cleaned it all up, set the idle current back to 4mv on both channels (right was 0.5) and, well thats it im affraid.
sounds ok, no where as good as the creek i just repaired though.
It could realy do with a loudness function as the bass is almost non existant at low levels.
I presume it used to have a remote as it has a motor control for the volume
good sound though, if a little uninspiring.
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Nice to get an easy fix 🙂 That thing is filthy inside.
I really like the A6. Love the remote volume control. Heavily modified, it's my fave amp in the 50-watt class. They came out with a "6 Plus" version that addressed a couple of its shortcomings (all fixable) but still "built to meet a pricepoint". Their scheme to drop the 37V rails down to 15V for the preamp section is particularly stinky.
I really like the A6. Love the remote volume control. Heavily modified, it's my fave amp in the 50-watt class. They came out with a "6 Plus" version that addressed a couple of its shortcomings (all fixable) but still "built to meet a pricepoint". Their scheme to drop the 37V rails down to 15V for the preamp section is particularly stinky.
In the area below that shadow you commented on, we can clearly see the fiberglass in the PCB laminate. That should be invisible and does look like there is some delamination damage there, though no charring yet. It's where the main power supply rectifier is located so the amplifier must have had a hard life, running fairly hot for several years to do that. Being a mosfet design, normally the bias current would be significantly, as in 3 times higher than typical BJT designs but it calculates to only about 35mA and that probably explains the unimpressive sound quality.
If the damage it's what it looks like, I don't think it would be simple or economical to repair that PCB without it looking all too obvious as a home repair. If the amp. is yours and it's still working, not getting too hot after an extended period of testing (you can use a dummy load to avoid the noise), I'd move it as soon as possible.
If the damage it's what it looks like, I don't think it would be simple or economical to repair that PCB without it looking all too obvious as a home repair. If the amp. is yours and it's still working, not getting too hot after an extended period of testing (you can use a dummy load to avoid the noise), I'd move it as soon as possible.
Thanks for the explanation. I can't say that it's a shining example of quality control by the FR4 laminate supplier, board maker and Arcam's own inspection system though.