The -15v reg could be defective. If you have a 1 ohm resistor, connect it between the 3rd leg of the regulator and the board. Connect a meter directly across the 1 ohm resistor. If the voltage across the resistor never gets near 1v, the regulator is very likely defective. If the voltage across the 1 ohm resistor is 1v or more, the current draw from the regulator could be shutting it down.
There is about .2V across the 1 ohm resistor.
I've been looking for the LM7915CT and have found it in a TO-220 and TO-220AB.
What's the difference in those packages?
I've been looking for the LM7915CT and have found it in a TO-220 and TO-220AB.
What's the difference in those packages?
With the new regulator installed I have a steady +15 and -15. It is still in protect, one channel has no DC and the other shows -.4v and climbing (toward the negatives) at the emitter resistors.
Which channel has the DC?
Did you replace the power supply FETs?
What work have you done to the channel with DC?
Did you replace the power supply FETs?
What work have you done to the channel with DC?
The channel I did not repair has DC in the negatives and slowly going negative.
Replaced PS fets with 75344G3.
None.
Replaced PS fets with 75344G3.
None.
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U5:
Pin 1: -15
Pin 2: -.5v and climbing beyond -1v
Pin 3: -.5v and climbing beyond -1v
Pin 4: -15
Pin 5: 0v
Pin 6: 0v
Pin 7: -10 and climbing
Pin 8: -15
Pin 1: -15
Pin 2: -.5v and climbing beyond -1v
Pin 3: -.5v and climbing beyond -1v
Pin 4: -15
Pin 5: 0v
Pin 6: 0v
Pin 7: -10 and climbing
Pin 8: -15
With the black probe on the secondary center tap and the red probe on the emitter resistors, does the DC voltage go positive while these are going negative?
Is one end or R46 directly connected to the secondary center tap?
Is one end or R46 directly connected to the secondary center tap?
Pin 7 should be steady. It's the 15v input to the IC. Are you sure it's climbing (or otherwise changing)?
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