Finished building Aleph J: one side biases up while the other gets a bias of 0. DC offset on the speaker output is ~18.6VDC.
Voltage is there. I checked and doubled-checked for bad solder joints, including reflowing every solder joint. No shorts - as far as I can tell - and I made sure all of the transistors ZTX550 and ZTX450 are in the proper sockets. Check resistors against the working board and everything is the same.
Where to next? Can provide voltages at any junction, pictures, etc.
I'm going to go out and walk this old Labrador for a few blocks and do some thinking.
Obviously current isn't flowing through the output transistors, nor the current source, which, to me, points to an issue at the latter part of the circuit.
Voltage is there. I checked and doubled-checked for bad solder joints, including reflowing every solder joint. No shorts - as far as I can tell - and I made sure all of the transistors ZTX550 and ZTX450 are in the proper sockets. Check resistors against the working board and everything is the same.
Where to next? Can provide voltages at any junction, pictures, etc.
I'm going to go out and walk this old Labrador for a few blocks and do some thinking.
Obviously current isn't flowing through the output transistors, nor the current source, which, to me, points to an issue at the latter part of the circuit.
pictures
be sure that both mosfets are isolated from heatsink
post link to exact schematic (or insert it here , even better) , so I can download it and write some voltages , if needed
orientation of bjts , diodes etc.
also check trimpots (resistance in cold)
just in case - both inputs shorted , no load on output
be sure that both mosfets are isolated from heatsink
post link to exact schematic (or insert it here , even better) , so I can download it and write some voltages , if needed
orientation of bjts , diodes etc.
also check trimpots (resistance in cold)
just in case - both inputs shorted , no load on output
Pardon my resoldering blobs - also pulling and inserting the power / signal leads multiple times doesn't help!
Images:
Imgur: The magic of the Internet
Imgur: The magic of the Internet
Imgur: The magic of the Internet
Schematic is the original on Post #1 but with a 1K resistor instead of the pot for R8
Images:
Imgur: The magic of the Internet
Imgur: The magic of the Internet
Imgur: The magic of the Internet
Schematic is the original on Post #1 but with a 1K resistor instead of the pot for R8
Correct. No problem other than needing to remember that adjustments will be happening in reverse. Ask me how I know.
Correct. No problem other than needing to remember that adjustments will be happening in reverse. Ask me how I know.
Meh, was worth a shot 😉
That's the spirit. Much more important to know what to watch that to
just think a particular direction means only one thing.
BTW, please measure and post the voltages ZM asked for. Also, what are you
getting as voltages across R7 and R8?
Cheers,
Dennis
all resistor values good ?
you have installed shortie in place of R27A , good;
further - you need to have installed either R27B or R27 trimpot, not both
I prefer R27 trimpot there (sans R27B) , pre-set to half value
if you have too small (resulting) resistance there , it can be confusing for novice
you have installed shortie in place of R27A , good;
further - you need to have installed either R27B or R27 trimpot, not both
I prefer R27 trimpot there (sans R27B) , pre-set to half value
if you have too small (resulting) resistance there , it can be confusing for novice
