Replaced R22 and lifted D16 ..
Audio still cuts in and out..
Replaced C40,41,42 and the problem still remains audio cuts in and out ..
The amp is outside the sink so the audio cuts in and out still ..
The problem remains if the board is in the sink or out of the sink..
Audio still cuts in and out..
Replaced C40,41,42 and the problem still remains audio cuts in and out ..
The amp is outside the sink so the audio cuts in and out still ..
The problem remains if the board is in the sink or out of the sink..
Check L212(Toroid) & L213 for discoloration,burnt windings,cracked core etc.
Recheck the Vdc on the preamp board's 5 pins and reference to power ground,black probe on pwr gnd terminal. It's possible the pwr transformer is passing the battery terminal voltage through partial shorted windings or the transformer is rubbing the main board.
With your scope, check the drive signal (square wave) to the gate's of outputs,both with and w/o signal.
Also, this amp has 3 banks, 1 bank of 3 IFR640's, 2 banks of 3 IRF940's. Make sure that all three banks are getting rail voltage(approx -/+60 volts),Drive voltages (the Vdc between the outside leads of mosfets( I realize I had you check this before, but at the time I neglected to mention there are three banks) If one of the IFR9640's is not firing this will cause the problem you describe.
Recheck the Vdc on the preamp board's 5 pins and reference to power ground,black probe on pwr gnd terminal. It's possible the pwr transformer is passing the battery terminal voltage through partial shorted windings or the transformer is rubbing the main board.
With your scope, check the drive signal (square wave) to the gate's of outputs,both with and w/o signal.
Also, this amp has 3 banks, 1 bank of 3 IFR640's, 2 banks of 3 IRF940's. Make sure that all three banks are getting rail voltage(approx -/+60 volts),Drive voltages (the Vdc between the outside leads of mosfets( I realize I had you check this before, but at the time I neglected to mention there are three banks) If one of the IFR9640's is not firing this will cause the problem you describe.
With the black probe on main ground terminal i get the following voltages
+12 :11.99
GND :0.04
-12 :-12.24
V.C :-10.95
GND:0.04
On all 640's i get -3.66
On all 9640's i get -3.94
This is with red probe on gate leg and black probe on leg 3
The square wave on all outputs looks good..
L212,213 look good no signs of damage..
I noticed when looking at the output on the scope once i increase gain to a lil half past way so gain control is in about the 2 oclock posistion the output becomes a square wave like the output is clipped..
+12 :11.99
GND :0.04
-12 :-12.24
V.C :-10.95
GND:0.04
On all 640's i get -3.66
On all 9640's i get -3.94
This is with red probe on gate leg and black probe on leg 3
The square wave on all outputs looks good..
L212,213 look good no signs of damage..
I noticed when looking at the output on the scope once i increase gain to a lil half past way so gain control is in about the 2 oclock posistion the output becomes a square wave like the output is clipped..
So, outside of the sink and no load, when you turn up gain to the 2 o'clock position, you see clipping,correct?
What are you using to test with? Test tone(40hz is what I use on this amp), or audio?
What are you using to test with? Test tone(40hz is what I use on this amp), or audio?
Yes outside of the sink with no load and no RCA's plugged in i see clipping a square wave on the output positive terminal..
I also get this with a 100hz sine wave
I also get this with a 100hz sine wave
Anyone have any ideas on what to look at next since amp is still doing the same thing ..
See post above
See post above
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