The last two I worked on that had driver board failure had faulty 74HC02 chips. The first one I repaired and I’m currently waiting on parts to confirm the other.
I have to recheck my notes later today, I believe they had low resistances on a couple pins.
Seems you pulled the driver board already, prior to did you confirm the switching voltage on pin 3 and possible waveforms on pins 8 and 9?
I have to recheck my notes later today, I believe they had low resistances on a couple pins.
Seems you pulled the driver board already, prior to did you confirm the switching voltage on pin 3 and possible waveforms on pins 8 and 9?
I have 3 of these driver boards all not working, I've replaced the 74hc02 the lm292 and the lm6712 still nothing
No audio, do you have correct voltages on the power pins of the chips? triangle waves on pin 7 (lm292) pin 6 (6712)?
there are three transistors on the board 2X and D5 I believe, did you replace these?
I have to check my notes when I get of work tonight.
If you have the triangle waves and pins 1 and 7 (LM6172) should have square waves which are then fed to the inputs of the 74HC86.
I have to check my notes when I get of work tonight.
If you have the triangle waves and pins 1 and 7 (LM6172) should have square waves which are then fed to the inputs of the 74HC86.
You’ll need to determine where the 5v on pin 7 is coming from, pin 7 needs to have a square wave similar to 1.
A couple of notes:
The amp probably won't have a 100kHz signal until it's fully functional. When damaged or the circuit is open (no outputs), the drive signal frequency will be all that will be seen. This varies somewhat in that some of these circuits have dedicated integrators (triangle wave generators) and some (most) do not.
The two D5 components are diodes that are in parallel with 330 ohm resistors. These are used to build deadtime and aren't likely to fail.
The 2X transistor is the on-board muting transistor.
The 74hc86 isn't likely the right part number. Some manufacturers have the ICs mismarked. The actual number is likely a 74hc00.
The amp probably won't have a 100kHz signal until it's fully functional. When damaged or the circuit is open (no outputs), the drive signal frequency will be all that will be seen. This varies somewhat in that some of these circuits have dedicated integrators (triangle wave generators) and some (most) do not.
The two D5 components are diodes that are in parallel with 330 ohm resistors. These are used to build deadtime and aren't likely to fail.
The 2X transistor is the on-board muting transistor.
The 74hc86 isn't likely the right part number. Some manufacturers have the ICs mismarked. The actual number is likely a 74hc00.
I know the d5 are 4148 diodes and the board I have uses a 74hc02 I'm about to give up on this one and just try source a working driver Ive replaced everything on this board and still have no audio, fit a driver from a working amp and it works. I'm beginning to think there may be a pcb fault on this board somewhere