This amp is using F12C20C and F12C20A as the rectifiers ..
The legs broke at the body of them ..
Would the U1620 and 1620R be good replacements or does anyone have suggestions?
When they broke it also took out the power supply which the amp is using Z44's ..
Would the 3205'S be a better choice when rebuilding this supply or isn't there much difference from using the Z44'S vs 3205'S
The legs broke at the body of them ..
Would the U1620 and 1620R be good replacements or does anyone have suggestions?
When they broke it also took out the power supply which the amp is using Z44's ..
Would the 3205'S be a better choice when rebuilding this supply or isn't there much difference from using the Z44'S vs 3205'S
Those rectifiers should be OK.
Use the 3205s. The PRZI has a good enough drive circuit. I don't know what the PRZA has.
Use the 3205s. The PRZI has a good enough drive circuit. I don't know what the PRZA has.
I thought the drivers were defective but they test fine ..
I replaced them with BD140'S and still have a problem..
With just power and ground hooked up the amp draws excessive current .
Is it most likely 1 of the transformers?
I replaced them with BD140'S and still have a problem..
With just power and ground hooked up the amp draws excessive current .
Is it most likely 1 of the transformers?
Do you see DC on the secondary ground?
Do the FETs get hot?
If so, which ones?
How much current is it drawing without remote?
Confirm that there is no drive to the FETs (no square wave an no DC more than about 1v).
Do the FETs get hot?
If so, which ones?
How much current is it drawing without remote?
Confirm that there is no drive to the FETs (no square wave an no DC more than about 1v).
With just power and ground the amp draws 60 amps of current..
I pulled the rectifiers and also pulled the power supply drivers amp still draws 60 amps of current with just power and ground ..
I can't tell if there is DC on the secondary ground since my current limiter gets hot and the voltage drops to 3 volts when trying to power the amp
Up since it draws a lot of current
The fets get hot within 3 secs M1,4,5,7,9,11
I pulled the rectifiers and also pulled the power supply drivers amp still draws 60 amps of current with just power and ground ..
I can't tell if there is DC on the secondary ground since my current limiter gets hot and the voltage drops to 3 volts when trying to power the amp
Up since it draws a lot of current
The fets get hot within 3 secs M1,4,5,7,9,11
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Without the PNP driver transistors in the circuit, you can expect the amp to draw excessive current unless there is a pulldown resistor for each group of PS FETs. Does this amp have pulldown resistors?
What's the resistance to the RCA shields from the B+ terminal (no RCAs plugged in)?
What's the resistance to the RCA shields from the B+ terminal (no RCAs plugged in)?
i checked the fets again and put the drivers back in the amp..
i still get excessive currennt draw with just power and ground..
i get 1.073M ohms from rca shields to B+
i still get excessive currennt draw with just power and ground..
i get 1.073M ohms from rca shields to B+
What is the resistance between the collector of the PNP driver transistors and the amp's ground terminal? All should read 0 ohms.
Resistance between pin 7 of the 494 and ground?
Resistance between pin 7 of the 494 and ground?
I would suspect the 494. It could be shorted internally driving all of the FETs on at once.
In the PRZI version, there are emitter follower pairs for the drivers. Does this amp have both NPN and PNP driver transistors or does it have diodes with PNP driver transistors?
In the PRZI version, there are emitter follower pairs for the drivers. Does this amp have both NPN and PNP driver transistors or does it have diodes with PNP driver transistors?
Pull any power supply FETs that are getting hot. Pull all of them if just pulling the hot ones doesn't eliminate the current draw.
With all driver components in the circuit, measure the gate-source voltage for all FETs (no remote applied). Do any read more than a fraction of a volt?
With all driver components in the circuit, measure the gate-source voltage for all FETs (no remote applied). Do any read more than a fraction of a volt?
For all 12 of the fets from gate to source I get 4.06 volts ..
All of the fets are removed right now ..
All of the fets are removed right now ..
Is that straight DC or a normal square wave drive signal?
Post the DC voltage on all pins of the 494.
Post the DC voltage on all pins of the 494.
It's straight DC
Pin 1:1.23
Pin 2:3.63
Pin 3:0.07
Pin 4:0.37
Pin 5:1.45
Pin 6:3.65
Pin 7:0.00
Pin 8:13.89
Pin 9:4.42
Pin 10:4.42
Pin 11:13.86
Pin 12:13.04
Pin 13:4.98
Pin 14:4.99
Pin 15:4.99
Pin 16:0.00
Pin 1:1.23
Pin 2:3.63
Pin 3:0.07
Pin 4:0.37
Pin 5:1.45
Pin 6:3.65
Pin 7:0.00
Pin 8:13.89
Pin 9:4.42
Pin 10:4.42
Pin 11:13.86
Pin 12:13.04
Pin 13:4.98
Pin 14:4.99
Pin 15:4.99
Pin 16:0.00
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