Well, you've narrowed it down. You'll have to look at that part of the circuit to see where the short is.
Desolder the next components in series or parallel with the output of that resistor to see if you can find the short.
Desolder the next components in series or parallel with the output of that resistor to see if you can find the short.
I found the shorted capacitor, replaced it and the amp idles fine.
The Class D section has clean audio.
The AB section has no audio output. Protection light is green/good.
I have audio to the muting transistor but no negative voltage at its gate to turn it off. This amp uses 1 ea J108 for each channel.
I removed the J108 in one channel and I get clean audio on the speaker terminal for that channel. So I know I need to find out why the correct voltage is not being supplied to turn off the muting transistor, but I am having trouble finding where it should be supplied from.
I have both sets of rails +/- 48 V (Class D) , +/- 24 V (Class AB), Regulated Voltage +/- 12 and 15 as well as 32V from the voltage doubler that feeds into the output driver stage.
Just to mention, the DC across the speaker terminals are Class AB: (35, 30, 24, 2.5)mV and the Class D: 30 mV.
I have found from the J108 gate a 10k resistor which goes to another 10k resistor that connects to the J108s gate in the opposite channel. Between these two 10K resistors there is 350 ohms to secondary ground. That is all I can find at the moment.
Any fresh ideas or guidance as how to find why the muting transistors gates are not getting proper voltage would be very much appreciated.
The Class D section has clean audio.
The AB section has no audio output. Protection light is green/good.
I have audio to the muting transistor but no negative voltage at its gate to turn it off. This amp uses 1 ea J108 for each channel.
I removed the J108 in one channel and I get clean audio on the speaker terminal for that channel. So I know I need to find out why the correct voltage is not being supplied to turn off the muting transistor, but I am having trouble finding where it should be supplied from.
I have both sets of rails +/- 48 V (Class D) , +/- 24 V (Class AB), Regulated Voltage +/- 12 and 15 as well as 32V from the voltage doubler that feeds into the output driver stage.
Just to mention, the DC across the speaker terminals are Class AB: (35, 30, 24, 2.5)mV and the Class D: 30 mV.
I have found from the J108 gate a 10k resistor which goes to another 10k resistor that connects to the J108s gate in the opposite channel. Between these two 10K resistors there is 350 ohms to secondary ground. That is all I can find at the moment.
Any fresh ideas or guidance as how to find why the muting transistors gates are not getting proper voltage would be very much appreciated.
This amp is fixed. Thank you Perry!
A short recap of what was wrong for somebody else with similar issues:
C148, a 0.1uF ceramic disk, was shorted causing excessive current through R797, a 1W 22R resistor, to burn open.
After taking care of this the amp idled fine and the excessive dc was gone from across the speaker terminals, but there was no audio from any of the channels.
After Perry pointing me towards the KX700.5 schematic I found D770 was shorted, a 1SS133. I replaced it with a 1n4148 and all was good.
FWIW the muting part of the circuit in this amp is the same as KX700.5 with the only exception, originally the switching diodes this amp used were 1ss133s and the Kicker shows 1n4148s.
All of the components I replaced and their locations can be seen in the original images posted in the 1st post.
A short recap of what was wrong for somebody else with similar issues:
C148, a 0.1uF ceramic disk, was shorted causing excessive current through R797, a 1W 22R resistor, to burn open.
After taking care of this the amp idled fine and the excessive dc was gone from across the speaker terminals, but there was no audio from any of the channels.
After Perry pointing me towards the KX700.5 schematic I found D770 was shorted, a 1SS133. I replaced it with a 1n4148 and all was good.
FWIW the muting part of the circuit in this amp is the same as KX700.5 with the only exception, originally the switching diodes this amp used were 1ss133s and the Kicker shows 1n4148s.
All of the components I replaced and their locations can be seen in the original images posted in the 1st post.