I don't know a lot about Wurlitzers of this era. I'll start this off
with, on the bench, applying 14vdc on the bench power supply to pins 3
ground and the plus to pin 4 of X5, in about 1/2 second, the leds K and
Z light up and stay on. Then in another 1/2 second relay 2 energizes and
stays on. I don't know if that is a normal power up routine? The SCC
is a 2500 CD.
Now the really weird part. Inside the jukebox, with no cables plugged
into the board, from pins 3 and 4 of the plug for X5, it measures about
14 volts DC, no AC, this is normal. But, when that plug is in the SCC
on power up, the 14 volts jumps up to 30 volts! Thankfully the 7805 has
over-voltage protection, in addition to a zener on the board so the
+5vdc goes to zero.
I have tried this with all of the plugs in the SCC and with only plug X5
in. Either way the 14vdc jumps up to 30vdc and the +5vdc goes to zero.
On the SCC, it has a history of R3 running hot and turning the board
very dark. Also someone cut into the plasic cover in what looks like an
attempt to cool the area at and above the 7805 and R3.
Also, I don't know if it's common, the interface board top third is very
dark from heat. This machine has been on 24-7 for most of its life.
Any help greatly appreciated.
--
Tony Miklos
Tony's Jukebox Repair
