I will remember that on voltage measurements.
Negative rail is -18volts.
Having trouble getting my computer to load pics off my phone. I'll post pics as soon as I can.
Negative rail is -18volts.
Having trouble getting my computer to load pics off my phone. I'll post pics as soon as I can.
Post a photo of the area around the driver board. I think there should be a diode feeding 12v to the high-side drive.
Measure the DC voltage with a multimeter with the black probe on the Vs terminal and the red probe on the HO terminal. Battery on the IC. Confirm that you have low side drive before measuring the high-side voltage.
Are the relays engaging?
Are the relays engaging?
I don't know why but I all of a sudden have high side drive. I haven't changed anything and voltage still reads 0v at the chip. I read 3.35v at the driver transistors. Going to try a couple of outputs and see what happens.
Removed the battery and installed a couple of outputs. I have output to the speaker. I swear I know how to check for high side drive. I did not have any until now and I did not change anything. I wiggled components and pressed on the board. No change. Here's new pics of the high and low side drives.
Attachments
Okay, removed the two outputs. Moved the battery to the other driver chip. Checked drive signals. None. No high or low. Checked the chip. Shorted pin 6 to 7. Changed the driver chip. Good low drive on both chips. No high side drive on either chip. Zero DC voltage Vs to HO.
Well, I clearly don't understand this. The drive should be present. I thought that the lack of the diode between VCC and the VB could have been why the signal wasn't visible. That's why I suggested reading the Vs and HO voltage.
Are all of the drivers in the amp?
Do you have drive at the FET gates?
Does connecting a load to the amp make a difference? Sometimes, the high-side source is floating and the signal isn't visible on the scope.
What caused the IC to fail?
Are all of the drivers in the amp?
Do you have drive at the FET gates?
Does connecting a load to the amp make a difference? Sometimes, the high-side source is floating and the signal isn't visible on the scope.
What caused the IC to fail?
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Has me baffled as well.
All the drivers are in the amp.
I have the low side drive on the FET gates but no high.
I didn't try with a load until I saw high side drive.
Don't know on the chip. I was very careful not to short anything.
Tried a couple outputs to load one side. No drive. No output. Did nothing to the opposite side and now no high or low drive on that side. Chip checks shorted.
All the drivers are in the amp.
I have the low side drive on the FET gates but no high.
I didn't try with a load until I saw high side drive.
Don't know on the chip. I was very careful not to short anything.
Tried a couple outputs to load one side. No drive. No output. Did nothing to the opposite side and now no high or low drive on that side. Chip checks shorted.
Did you lift terminal 7 to eliminate the possibility that a capacitor or the regulator was shorted?
Changed the shorted driver chip. One thing good I guess I'm getting really good at changing those chips. Once again I have great low drive but no high drive.
No need if you already changed the IC. It's an easy way to determine which IC is defective.. or if it's something else.
Lifted pin 7 on one chip. Checked drive on the other chip. Then did the same to the other chip. No change. 12V regulators check good.
shoot me a email at serdafiedamprepair@gmail.com
I fix a lot of these amps on the regular and have seen some strange stuff...
I fix a lot of these amps on the regular and have seen some strange stuff...