NTE is OK. If the 50 watt isn't significantly more buy it instead.
Resolder all components in the board and clamp it to the heatsink. Confirm that no tab or center leg of any output or power supply transistor reads near 0 ohms to the heatsink.
REMEMBER, if it has the M displayed, it's millions of ohms. If it has a K displayed, it's thousands of ohms. If neither is displayed, it's ohms. This is very critical and has cost a couple of days of work.
When you get the resistor, you'll install it in place of the inline fuse. You'll power up the amp (including remote voltage) and measure the voltage across each of the green emitter resistors. They should all read 0.000 volts. Let me know if any read more than 0.000v.
Only power up the amp for a minute or so at a time. The resistor will likely get very hot and could fail if you leave the amp on too long.
Resolder all components in the board and clamp it to the heatsink. Confirm that no tab or center leg of any output or power supply transistor reads near 0 ohms to the heatsink.
REMEMBER, if it has the M displayed, it's millions of ohms. If it has a K displayed, it's thousands of ohms. If neither is displayed, it's ohms. This is very critical and has cost a couple of days of work.
When you get the resistor, you'll install it in place of the inline fuse. You'll power up the amp (including remote voltage) and measure the voltage across each of the green emitter resistors. They should all read 0.000 volts. Let me know if any read more than 0.000v.
Only power up the amp for a minute or so at a time. The resistor will likely get very hot and could fail if you leave the amp on too long.
Perry,
Sorry about miss reading my meter. I am not an electrical guy. I will make sure that it will not happen again.
I got a 25 watt 2 ohms resistor.
I soldered everything back together.
Confirmed that no tab or center leg of any output or power supply transistor reads near 0 ohms to the heatsink.
I will power my amp up per your instructions.
I have do one question before I power up. How do I measure voltage across each green emitter resistor? Can you please tell me if I should have both probes touching the resistor? One on each side of the resistor or should one be on the neg. power terminal and the other on one end of the resistor? I think I should put both on the resistor but I just want to make sure.
Thanks,
Sean
Sorry about miss reading my meter. I am not an electrical guy. I will make sure that it will not happen again.
I got a 25 watt 2 ohms resistor.
I soldered everything back together.
Confirmed that no tab or center leg of any output or power supply transistor reads near 0 ohms to the heatsink.
I will power my amp up per your instructions.
I have do one question before I power up. How do I measure voltage across each green emitter resistor? Can you please tell me if I should have both probes touching the resistor? One on each side of the resistor or should one be on the neg. power terminal and the other on one end of the resistor? I think I should put both on the resistor but I just want to make sure.
Thanks,
Sean
Did the fuse blow before or only after you applied voltage to the remote wire?
With the resistor in series with the B+ terminal again, power up the amp and measure the DC voltage on leg 3 of the output transistors. You should get positive and a negative voltage. What is the voltage?
Place the black meter probe on the RCA shield. Place the red meter probe on the point where you need to measure the voltage.
With the resistor in series with the B+ terminal again, power up the amp and measure the DC voltage on leg 3 of the output transistors. You should get positive and a negative voltage. What is the voltage?
Place the black meter probe on the RCA shield. Place the red meter probe on the point where you need to measure the voltage.
Did the fuse blow before or only after you applied voltage to the remote wire?
With the resistor in series with the B+ terminal again, power up the amp and measure the DC voltage on leg 3 of the output transistors. You should get positive and a negative voltage. What is the voltage?
Place the black meter probe on the RCA shield. Place the red meter probe on the point where you need to measure the voltage.
With the resistor in series with the B+ terminal again, power up the amp and measure the DC voltage on leg 3 of the output transistors. You should get positive and a negative voltage. What is the voltage?
Place the black meter probe on the RCA shield. Place the red meter probe on the point where you need to measure the voltage.
When you powered it up with the secondary windings out of the circuit and it didn't blow the fuse, did you have remote voltage applied?
Sorry for all of the questions but I don't want to take anything for granted.
This is strange. There is excessive current draw but it doesn't appear to be through the outputs and the power supply alone didn't draw excessive current. The rail caps don't appear to be shorted (probably wouldn't have ±6.5v if they were). It's unlikely anything on the regulated ±15v circuit could cause the excessive current draw. You've checked and none of the heatsink mounted components are shorted to the heatsink.
I'd like to be able to check the amp with lower voltage to see if it still draws excessive current but that's not possible if you're using a battery. If the rail voltage regulator is defective, it could be producing too much rail voltage which could cause the caps to begin leaking (electrically) and cause excessive current draw when the amp isn't powered up through a resistor.
Sorry for all of the questions but I don't want to take anything for granted.
This is strange. There is excessive current draw but it doesn't appear to be through the outputs and the power supply alone didn't draw excessive current. The rail caps don't appear to be shorted (probably wouldn't have ±6.5v if they were). It's unlikely anything on the regulated ±15v circuit could cause the excessive current draw. You've checked and none of the heatsink mounted components are shorted to the heatsink.
I'd like to be able to check the amp with lower voltage to see if it still draws excessive current but that's not possible if you're using a battery. If the rail voltage regulator is defective, it could be producing too much rail voltage which could cause the caps to begin leaking (electrically) and cause excessive current draw when the amp isn't powered up through a resistor.
Perry,
I would bet no that when I powered it up with the secondary windings out of the circuit and it didn't blow the fuse, I didn't you have remote voltage applied. Do you want me to unsolder those 4 wires and power it up correctly?
Yes, checked and none of the heatsink mounted components are shorted to the heatsink.
Thanks,
Sean
I would bet no that when I powered it up with the secondary windings out of the circuit and it didn't blow the fuse, I didn't you have remote voltage applied. Do you want me to unsolder those 4 wires and power it up correctly?
Yes, checked and none of the heatsink mounted components are shorted to the heatsink.
Thanks,
Sean
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