The xlr and rca has its own gnd connection on the pcb so there's no need to use a jumper. The zener Z1 - Z4 reading just won't stop after 5 minutes, it seems to be going up and up but can be measure by using AC value. I have also measured the bad channel's R41 resistor value, it is at 1.0 ohm. I suspect the fet is not accurately matched. I also suspect the capacitor C5 (No.43) is not doing its' job. The R7 (No.7) measurement seems to vary form 0.1mv between 0.6mv, so i put in the highest value. Please let me know your thoughts. Thanks.
Hi again,
No problem at R7. Looking at your chart I'm assuming that you misplaced the decimal point on the reading for the good channel for R15. Aside from that, your readings all look acceptable to me.
Apparently your fets arent matched at all, but the amp should operate OK.
There should only be one ground on the board, if your input ground is isolated from it that is the entire problem. Getting back to your XLR wiring, #1 is the signal ground and must go to the board ground. The 4th terminal you were referring to is chassis ground and most people dont use it. Also, if you are using the RCA inputs you need to tie the XLR - [cold] to ground . That's what the jumper does that you are referring to, I think
Bill
No problem at R7. Looking at your chart I'm assuming that you misplaced the decimal point on the reading for the good channel for R15. Aside from that, your readings all look acceptable to me.
Apparently your fets arent matched at all, but the amp should operate OK.
There should only be one ground on the board, if your input ground is isolated from it that is the entire problem. Getting back to your XLR wiring, #1 is the signal ground and must go to the board ground. The 4th terminal you were referring to is chassis ground and most people dont use it. Also, if you are using the RCA inputs you need to tie the XLR - [cold] to ground . That's what the jumper does that you are referring to, I think
Bill
Bill Fuss said:
Sorry, I did not mention this : there is only 1 gnd on the board which runs on the edge of the board and the xlr and rca and other circuit gnd is connected to this gnd.
The input gnd you are referring to is the IEC gnd, correct?
You do not suspect the C5 readings have anything to do with this.
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The input ground is the #1 pin on the XLR and the ground lug on the RCA. They should go to the board ground.
Actually, the voltage across C5 is another way of measuring the offset voltage on the output. They match quite well.
Now you have to apply a signal to the inputs and with your meter set on AC you must follow the signal through the amp, taking readings just as you did with the DC readings. You should be able to find the problem area. This time start at the input with no speakers.
Bill
Actually, the voltage across C5 is another way of measuring the offset voltage on the output. They match quite well.
Now you have to apply a signal to the inputs and with your meter set on AC you must follow the signal through the amp, taking readings just as you did with the DC readings. You should be able to find the problem area. This time start at the input with no speakers.
Bill
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