KFC25A20
Black probe on leg 3 red probe on ground : 0.02 ohms
Black probe on leg 1 red probe on leg 3 : 0.02 ohms
C25P20FR
Black probe on leg 3 red on ground terminal : 0.01
Black probe on leg 1 red on leg 3 :0.02
Black probe on leg 3 red probe on ground : 0.02 ohms
Black probe on leg 1 red probe on leg 3 : 0.02 ohms
C25P20FR
Black probe on leg 3 red on ground terminal : 0.01
Black probe on leg 1 red on leg 3 :0.02
Do you read 0 ohms from main ground to all of the locations where a board hold-down/support has contact points for the screw to ground?
You were having trouble with the regulators failing as soon as you applied power. What's different now that allowed you to measure voltage?
Replaced all the IC'S again replaced Q4901 and ZD4901 and ever since I replaced them again it hasent burnt the regulator..
I don't know why I'm not getting any voltage on pin 7 of the driver IC's everything tests good ..
I don't know why I'm not getting any voltage on pin 7 of the driver IC's everything tests good ..
Does the voltage appear correct or should i have something different?
Just trying to figure this thing out
Just trying to figure this thing out
I found a problem ..
According to the service manual on Q9301 i should have -15.69 volts on the center leg..
Im getting 47 volts
On Q9302 on the center leg i should have 15 volts im getting -47 volts
and on Q4901 on leg 1 i should have -34 volts im getting -47 volts
Any ideas why the voltages are way off?
I cannot seem to track the problem down
According to the service manual on Q9301 i should have -15.69 volts on the center leg..
Im getting 47 volts
On Q9302 on the center leg i should have 15 volts im getting -47 volts
and on Q4901 on leg 1 i should have -34 volts im getting -47 volts
Any ideas why the voltages are way off?
I cannot seem to track the problem down
Ok think im on the right track to finding out a few things..
But i heard a pop and now the amp doesnt power up at all...
I have 0.00 volts on pins 8,11,12 of the 494
Does the 7809 control these voltages or is there something else since in not getting 12 volts?
But i heard a pop and now the amp doesnt power up at all...
I have 0.00 volts on pins 8,11,12 of the 494
Does the 7809 control these voltages or is there something else since in not getting 12 volts?
The voltage regulator ICs are nearly bulletproof. They have multiple protection circuits to shut their output down in case of a fault. Are you sure that nothing connected to the regulator is shorted?
I have an amp like this in the shop now. A few notes...
The service manual voltages are wrong because they have the wrong pin configuration. The collector is at ground. The base is about 12v above the negative rail. The emitter is about 11.5v above the negative rail. You can place the black probe on the center leg of the negative rail rectifier adjacent to Q4901 to check these voltages.
The Zener should have 12v when the voltage is measured directly across it. The anode should be directly connected to the negative rail. The cathode is directly connected to the base of Q4901 (3rd leg).
The collector of Q4901 is directly connected to ground (primary and secondary grounds are tied together).
The emitter of Q4901 is directly connected to pin 3 of the IR2010S ICs.
You should read approximately 11.5v between pin 15 (black probe) and pin 3 (red probe) on the IR2010S ICs.The same voltage can be read across C9801 and C9802.
The service manual voltages are wrong because they have the wrong pin configuration. The collector is at ground. The base is about 12v above the negative rail. The emitter is about 11.5v above the negative rail. You can place the black probe on the center leg of the negative rail rectifier adjacent to Q4901 to check these voltages.
The Zener should have 12v when the voltage is measured directly across it. The anode should be directly connected to the negative rail. The cathode is directly connected to the base of Q4901 (3rd leg).
The collector of Q4901 is directly connected to ground (primary and secondary grounds are tied together).
The emitter of Q4901 is directly connected to pin 3 of the IR2010S ICs.
You should read approximately 11.5v between pin 15 (black probe) and pin 3 (red probe) on the IR2010S ICs.The same voltage can be read across C9801 and C9802.
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Do you happen to know what the value is of these 2 diodes?
ZD9301
ZD9302
These appear to be shorted
Also the value of R9303 and R9304 they sit directly behind the diodes
ZD9301
ZD9302
These appear to be shorted
Also the value of R9303 and R9304 they sit directly behind the diodes
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