Rowe 130 watt amp problem

I have a rowe 130 watt amp part# 60993102. When you turn the jukebox on
all you get is a loud hum and some crackling.Can anyone give me an idea
on where to start troubleshooting the amp?...thanks

First thing to do is look on the driver boards for blown fuses (all are
5 amp fast blo). If any are blown then one or more of the output
transistors are shorted/bad on the heat sink assembly.

Is the 13 pin white jumper plug on the preamp board plugged in? It
could be missing and you'd have no sound if it were missing.

The following capacitors go bad on the preamp board due to the heat
from the voltage regulators so check/replace these:

C70 (10 uf @ 50 volt)
C63 (100 uf @ 16 volt)
C64 (100 uf @ 16 volt)
C65 (100 uf @ 16 volt)

Sometimes one or both of the two giant filter caps on the chasis can go
bad (usually they go open circuit when they fail). These two caps are
4700 uf @ 50 volt.

If all the above check out ok then here is what else to check:

With the amplifier completely removed from the machine and nothing else
plugged into it, power it up and set your volt meter to 50 VDC scale.
Connect red (+) meter lead to the metal chassis and use the black (-)
lead to probe both ends of resistor R24 on each driver board. If any DC
voltage (especially reading 30 to 35 volts DC) is present, then that
particular driver board has a problem. Check all the transistors on the
driver boards out-of-circuit (especially Q5). Look for cracked/burned
resistor R26 (0.2 ohm, 2 watt) on driver boards also.

The schematic of this amplifier is in Rowe R-90 SHOP manual # 36535512
which may still be available from Rowe. It has _not_ been reproduced.

I'm told this schematic may be in the regular R92 or R94 Field service
manuals, but I cannot confirm.