I can't get my large probes in there where I feel comfortable enough to not be shorting out pins to other pins and other components... I don't want to destroy the amp by doing such a thing.
Any recommendations on what to do? it's a small surface mount ka7500 tucked in behind the transformers and under capacitors on the PWM board
Any recommendations on what to do? it's a small surface mount ka7500 tucked in behind the transformers and under capacitors on the PWM board
4.91v on pin 9 and 12.53v on 11 and 12 with the black probe on pin 7.
I used some leads snipped from a resistor and alligator clamped them to my probes
according to the schematic, pins 11 and 12 are both connected to the remote input lead which should mean I should see battery voltage right?
I used some leads snipped from a resistor and alligator clamped them to my probes
according to the schematic, pins 11 and 12 are both connected to the remote input lead which should mean I should see battery voltage right?
The drive signal voltage is likely low because the DC voltage at the B+ and ground terminals is so low.
Did you have the 1k resistors (or anything close)?
I wouldn't normally want to double-check the drive circuit but I want to make sure that you don't blow out another set of FETs.
Did you have the 1k resistors (or anything close)?
I wouldn't normally want to double-check the drive circuit but I want to make sure that you don't blow out another set of FETs.
If you want to double-check the drive circuit, solder a 1k resistor to pads 1 and 2 of each of the 4 FET locations that you were previously instructed to check. The drive voltage will increase slightly but shouldn't increase by more than about 1/2v. If you move the resistor to pads 1 and 3, the drive voltage may drop a bit but shouldn't drop more than about 1/2v.
You don't have to use multiple resistors. You can do one at a time.
You don't have to use multiple resistors. You can do one at a time.
I see the rise and drop your describing.
without the resistor from pads 1 to 2 I get 8.60v
and from pads 1 to 3 I get 3.82v
with the resistor I get
7.87v from pads 1 and 2
3.63v from pads 1 and 3
edit: unless I'm checking in the wrong places? I used my probes on the same pads as the resistor leads were soldered
without the resistor from pads 1 to 2 I get 8.60v
and from pads 1 to 3 I get 3.82v
with the resistor I get
7.87v from pads 1 and 2
3.63v from pads 1 and 3
edit: unless I'm checking in the wrong places? I used my probes on the same pads as the resistor leads were soldered
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with the resistor in place from pads 1 to 2 I see the voltage go up from 3.80v to 4.71v
with the resistor in place from pads 1 to 3 I see the voltage drop back to 3.63v
voltage without resistor 3.80v
red probe on pad 1 and black probe on pad 3 for each test at each location
with the resistor in place from pads 1 to 3 I see the voltage drop back to 3.63v
voltage without resistor 3.80v
red probe on pad 1 and black probe on pad 3 for each test at each location
Will do Perry, thanks for the great diagnosis Doc! Right now, I'm off to Thanksgiving dinner, and probably the casino afterwards out of family tradition. I will get it put back together, probably within the next few hours sometime, and see what happens.
for now, Have a Great Thanksgiving, Eat, Drink and be Merry, and above all, Be Safe! and Always keep your eyes on the children! there's creepos out there everywhere.
Happy Thanksgiving Everyone!
for now, Have a Great Thanksgiving, Eat, Drink and be Merry, and above all, Be Safe! and Always keep your eyes on the children! there's creepos out there everywhere.
Happy Thanksgiving Everyone!
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