At high frequencies, even a short length of wire has enough inductance to cause problems.
Look more into the drive circuit.
Look more into the drive circuit.
Don't know if this tells you anything. I can put one output on that side and there is no noise. It doesn't matter which one.
Quick question Perry. Shouldn't the drive signal on R37 and R42 on the driver board be identical?
I thought the signal to Q9 and Q7 came off the same side of the resistors. It doesn't. I rebuilt a different driver board. Still have the same problem with the same amp. Trying to find out why.
I guess it's possible but unlikely.
Are the high and low drive signals identical to the adjacent IC?
Are you soldering these in with an iron or with hot air?
Are the high and low drive signals identical to the adjacent IC?
Are you soldering these in with an iron or with hot air?
I put all new driver chips in the board. Q3 was shorted base to collector. Q7 was shorted base to emitter. I replaced them. This is the same amp different driver board. When I put outputs in the section I've been having problems with, the amp pulls current. All three of the others run.
Signals are identical to adjacent chips.
I'm using a weller WD1 with the temp cranked down to 650. Being careful not to heat too long . I do a couple of pins, let the chip cool and move on to a couple more.
I'm using a weller WD1 with the temp cranked down to 650. Being careful not to heat too long . I do a couple of pins, let the chip cool and move on to a couple more.
Pull the outputs for the bad driver group and load one FET location in each bank with a small capacitor (0.01uF or something close) connected across the gate and source pads. How do the drive signals look?
If you move the capacitors to check all of the FET locations in that group, do they all look the same?
If you move the capacitors to check all of the FET locations in that group, do they all look the same?
I will do what you just posted. But I double checked the drive signals. On the one acting up I get 4.4 v on the gate. and 17v peak to peak. The good ones read 4.2 v and 11.5 peak to peak.
I know Perry. I can't get it to lock on to anything useful. I believe the problem to be with the high side. It just looks like ringing of some sort. The low side looks better. I can try to get better pics. When I put outputs on that amp, i get loud ringing in the output.
Trigger level?
Other channel of the scope?
External trigger?
Video horizontal/vertical?
Trigger polarity?
Other channel of the scope?
External trigger?
Video horizontal/vertical?
Trigger polarity?