With pin 5 lower than pin 6, I'd expect pin 7 to be very near ground. The IC could be defective. Do you have a replacement?
No, i've trying to locate a replacement, unable to find one. can i bypass it? for testing purposes
2904 voltages again
Pin 1: 0.1
Pin 2: 7.8v
Pin 3: 2.12v
Pin 4: 0.1v
Pin 5: 9.85v
Pin 6: 4.96v
Pin 7: 10.5v
Pin 8: 12.08v
Pin 1: 0.1
Pin 2: 7.8v
Pin 3: 2.12v
Pin 4: 0.1v
Pin 5: 9.85v
Pin 6: 4.96v
Pin 7: 10.5v
Pin 8: 12.08v
second set from underneath the pcb directly on pins of the ic, first set is not correct (for 2904l only)
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this the led connector, i assume:
PT - Protection
GD - Ground
RE - ?
PT - Protection
GD - Ground
RE - ?
An externally hosted image should be here but it was not working when we last tested it.
RE? Maybe remote? I don't know.
Is there a diode connecting pin 7 of the 2904 to pin 1 of the 494? If so, desolder one lead and lift it.
This may disable the protection where the amp could be damaged if you're not careful. If the amp draws excessive current, be prepared to immediately disconnect it from the power supply.
Is there a diode connecting pin 7 of the 2904 to pin 1 of the 494? If so, desolder one lead and lift it.
This may disable the protection where the amp could be damaged if you're not careful. If the amp draws excessive current, be prepared to immediately disconnect it from the power supply.
22 ohms is what I see in photos of a similar amp.
How much current does the amp draw when powered up (after the initial surge, charging the rail caps)?
Did you check the gate drive before installing the PS FETs?
Did you replace the driver transistors for the PS FETs?
Did you confirm that all gate resistors were within tolerance?
Clamp the FETs to help protect them from overheating during testing.
How much current does the amp draw when powered up (after the initial surge, charging the rail caps)?
Did you check the gate drive before installing the PS FETs?
Did you replace the driver transistors for the PS FETs?
Did you confirm that all gate resistors were within tolerance?
Clamp the FETs to help protect them from overheating during testing.
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