Q561 is the control transistor for pin 4 of the 494. What does the signal do on the base leg? That is driven directly from u501 pin 19. You can short that transistor and the amp should turn on. Leave it on for a few seconds and feel for warm parts.
You may have another issue causing that pin to stay high.
You may have another issue causing that pin to stay high.
I know the component designations won't be the same, but the schematic should be really close to what you have.
Does the base of Q563 connect to pin 19 of U501? What does the signal do on the base of that transistor. That transistor needs to be on for the amp to see 5V on pin 4. If that isn't happening, we have troubles some place else.
If you short that transistor what does the display read? It should give you some error code.
Does the base of Q563 connect to pin 19 of U501? What does the signal do on the base of that transistor. That transistor needs to be on for the amp to see 5V on pin 4. If that isn't happening, we have troubles some place else.
If you short that transistor what does the display read? It should give you some error code.
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