If I put the 7915 in circuit R41 burns instantly
If I remove it and put the 7815 in R40 will burn instantly.
If I remove it and put the 7815 in R40 will burn instantly.
Install it in place of the 10 ohm resistors for one of the regulators. Leave the other 10 ohm resistor open.
Use the two terminals on the bottom of the lamp to connect the wires. Nothing will be connected to the base housing.
Does the lamp light up?
What is the input and output voltage of the regulator?
Use the two terminals on the bottom of the lamp to connect the wires. Nothing will be connected to the base housing.
Does the lamp light up?
What is the input and output voltage of the regulator?
Before I go any further with this amp I noticed something .
With the 10 ohm resistors removed and the regulators removed I bet 16 ohm measured between the output leg of the 7815 to the output leg of the 7915.
Also on the opamps (TL074) I get 16 ohms between pins 4 and 8
Is this normal or do I have a short a bad opamp or diode ?
With the 10 ohm resistors removed and the regulators removed I bet 16 ohm measured between the output leg of the 7815 to the output leg of the 7915.
Also on the opamps (TL074) I get 16 ohms between pins 4 and 8
Is this normal or do I have a short a bad opamp or diode ?
A TL074 would have a short between 4 and 11.
Yes, it appears to be a loading problem. That's why I wanted you to use something that wouldn't burn but would use current pass.
The 1157 is incandescent. I'm assuming that you mean a 120v incandescent. That will work but I don't know if the current will be enough. Try it.
Yes, it appears to be a loading problem. That's why I wanted you to use something that wouldn't burn but would use current pass.
The 1157 is incandescent. I'm assuming that you mean a 120v incandescent. That will work but I don't know if the current will be enough. Try it.
With the 120 volt bulb in place I get
3.77 volts on the input pin 7815
1.53 volts on the output pin
Input pin on the 7915 -3.84
Output pin -1.96
3.77 volts on the input pin 7815
1.53 volts on the output pin
Input pin on the 7915 -3.84
Output pin -1.96
Is your meter ground on the ground pad for each regulator when measuring in and out voltages?
Are you using 2 lamps?
Are you using 2 lamps?
My probe is on the ground terminal of the regulator when measuring .
I put the bulb in place of 1 10 ohm resistor and left the other location blank nothing installed in the location .
When I measured the voltage on the 7815 I moved the bulb to the other resistors location and left the first location blank
I put the bulb in place of 1 10 ohm resistor and left the other location blank nothing installed in the location .
When I measured the voltage on the 7815 I moved the bulb to the other resistors location and left the first location blank
Are all transformers being driven?
Do you have the same waveform on both terminals of C53 when the lamp is in place of R40?
...on C54 when the lamp is in place of R41?
What is the DC voltage on the output of the 7915 when the lamp is in place of R40?
Do you have the same waveform on both terminals of C53 when the lamp is in place of R40?
...on C54 when the lamp is in place of R41?
What is the DC voltage on the output of the 7915 when the lamp is in place of R40?
Do you have FETs in all PS transformer banks?
Do you have a 24v amplitude square wave on all FET tabs?
Do you have a 24v amplitude square wave on all FET tabs?
I found the issue .
I removed 1 of the opamps closet to the regulators and it took care of the issue .
I have +- 15 volts on the remaining opamps now .
I will solder in new 10’ohm resistors since I’m using leased ones for testing
And replace the opamp
Will post back with results
I removed 1 of the opamps closet to the regulators and it took care of the issue .
I have +- 15 volts on the remaining opamps now .
I will solder in new 10’ohm resistors since I’m using leased ones for testing
And replace the opamp
Will post back with results
It's good that you found it but replacing random op-amps when there is something loading the regulated supply will result in replacing a lot of good components for no reason.
I was trying to get enough current flowing to try to find one that was heating up.
I was trying to get enough current flowing to try to find one that was heating up.