ohbythebay
New member
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- #1
A while back, my alternate power amp was my Yamaha M65 Power amp. Pretty sweet. Due to age, I decided to recap due to age
It came out well but it seemed I have and imbalance. Well..it went on the shelf in the garage but decided to break her out
as a spare. I might recap the Velleman and JUST IN CASE, didn't want to be without music so...
Tackled the issue.
First thing I did was go over some SUSPECT looking solder joints. Then reset the idle voltage. 10mv
I was going to bypass the speaker switches and get that board out of there but keep the meters working...John gave me the steps and showed me on the schematic board drawings. Pretty easy and I had a bind post plate delivered today.. BUT I did not need to do this step...read on.
So after all this I tested using an 8 ohm resistor on the speaker terminals, a 1khz test tone as input. Hmm..still a bit of channel imbalance. measured and got .71 mv on one side and .48 on the other. Hmm..
well, decided to check idle voltage again...it was OFF. found instead of 10mv, one was 8.1, other 10.8...ahhh.. Reset and now at the terminals I got .52mv and .6 (which is really damn close). Turns out the 2 minute warm up the book says is not enough time to properly set this...15 to 20 minutes lets you set it correctly.
Hooked up to the system...everything is balanced. Sound, meters, everything...Yayyyy
Excuse the pictures but have to show off...LOL
soldering job from hell...LOL
inside the beast
Start with very clean power - Furman PS 8D
I can pick either amp
Behind the scenes...ability to totally isolate amps/speaker set
It came out well but it seemed I have and imbalance. Well..it went on the shelf in the garage but decided to break her out
as a spare. I might recap the Velleman and JUST IN CASE, didn't want to be without music so...
Tackled the issue.
First thing I did was go over some SUSPECT looking solder joints. Then reset the idle voltage. 10mv
I was going to bypass the speaker switches and get that board out of there but keep the meters working...John gave me the steps and showed me on the schematic board drawings. Pretty easy and I had a bind post plate delivered today.. BUT I did not need to do this step...read on.
So after all this I tested using an 8 ohm resistor on the speaker terminals, a 1khz test tone as input. Hmm..still a bit of channel imbalance. measured and got .71 mv on one side and .48 on the other. Hmm..
well, decided to check idle voltage again...it was OFF. found instead of 10mv, one was 8.1, other 10.8...ahhh.. Reset and now at the terminals I got .52mv and .6 (which is really damn close). Turns out the 2 minute warm up the book says is not enough time to properly set this...15 to 20 minutes lets you set it correctly.
Hooked up to the system...everything is balanced. Sound, meters, everything...Yayyyy
Excuse the pictures but have to show off...LOL
soldering job from hell...LOL
inside the beast
Start with very clean power - Furman PS 8D
I can pick either amp
Behind the scenes...ability to totally isolate amps/speaker set
