You should have about 12volts across C472. Both amps are in series, one gone = both gone.
The supply rectifier is D420. I should have AC one side and DC the other.
D420 is not the supply rectifier for the display bulbs
D415 an D417 are the rectifiers and there is only DC supplied to the display bulbs. This supply voltage is the same supply of speaker delay/protection circuit. If the amp works with sound output then this supply circuit is OK.
The problem maybe broken PCB copper trace or bad soldering pads of these display bulbs, you may try soldering the display bulbs to the nearby connected component pads directly.
D415 an D417 are the rectifiers and there is only DC supplied to the display bulbs. This supply voltage is the same supply of speaker delay/protection circuit. If the amp works with sound output then this supply circuit is OK.
The problem maybe broken PCB copper trace or bad soldering pads of these display bulbs, you may try soldering the display bulbs to the nearby connected component pads directly.
Attachments
There was no DC voltage across the capacitor feeding the lamps ... why solder them in to a dead circuit.
Your trace makes the DC feed more realistic.
Yes, as JonSnell said that the supply capacitor also need to check the connection to the circuit