Rockola 480

I’ve just started working on this 480. It was in pieces when I got it and apparently housed nasty little creatures that liked dog food. But it cleaned up really well. Now to get it working. Several components test OK, but it still does not work. According to the manual, the magazine should revolve as soon as the unit powers up. It does not do this. It will only move if I click the home switch on the opto assembly in either scan or operate modes on the service switch. In either mode, the magazine will rotate until the home switch drops back into the notch, then stops. All this while the gripper bow is at rest over the magazine. If I rotate the knurled end on the gripper motor to simulate placing a record on the turntable with the service switch in the off position, then switch back to operate anywhere along the way, the gripper motor kicks in and returns the gripper to its home position. Leaving the service switch off until the until the tone arm is over the turntable, I then switched back to operate. Nothing, other than the turntable moving. No sound and the tonearm switch would not cancel. Turning the motor by hand until the tonearm cleared the turntable causes the gripper motor to come on, returning the record.
I have service manual and wiring diagram. The credit unit checks out OK per the manual and adds credits, but the machine will not accept selections on the keyboard. I have tried another keyboard with the same results. I’ve applied Deoxit to all connections and checked the fuses. I have tried replacing both relays on the mech power board with known good ones. I have no idea what to do with the logic board other than observe that the power L.E.D. is lit. Any guidance here would be appreciated. This mechanism appears to be the same on models 478, 480, 484, and 488.
Patrick

Hi Patrick
Are the leds for the various voltages lit up on the power supply pcb, should be three leds on it, there is a case where by the +9.6 volts vdc will stray slightly from +9.6 volts and will result in unusual things happening , one example i have come across if you input the title number it clocks up credits instead. The adjustment is listed in the manual.
On these rockolas the real weak points are the credit unit and logic board, there are a seires of troubleshooting procedures in the manual but all roads seem to lead back to the credit unit and logic board. You could try reseating all the plug connections
regards
clones

Clones: thanks for your reply. All the L.E.D.s are on and the voltage checked at 9.7. The manual did not specify tolerances and my meter is not a certified, calibrated instrument, so I left it as-is. Should I make an adjustment? The credit unit passed each test in the book. I've tried re-seating the connections. As to the logic board, what is the function of the load/memory switch and in which position should it be left? Not that either seems to make a difference. And can this board and its components be tested? It seems there should be something better than just trying to find another "untested" board and hoping it might work. I've been there / done that with the S2 controllers on the 490 / 494s and I'm getting quite the collection of junk there. Will we be able to keep these "microprocessor" units going like the older electro-mechanical ones?
Patrick

I have did the adjustment with the meter i have and it is not certified, you measure at the pink wire on the connecter using the chassis as ground, the voltage can be adjusted with one of the pots which is labelled R220. The load memory swithc should be off. There is a couple of tests for the logic board but i have seen them work in testing mode but still the machine wouldn't fuction in normal operation. The ic's on the logic board can be difficult to get which normally cause them problems, i suppose its a gamble to get a secondhand one and try it out. I prefer the older electro mechanical machines, the newer ones if they cause problems can be difficult to repair, the profit setters seem to be fairly rare, although there is a company in the Netherlands which will repair them
regards
Clones

Are the ICs generic, replaceable parts, like capacitors and resistors; or are they programmed, Rockola-specific parts?
Patrick

Not fully sure, i think three of the ic's are fairly standard, the rare one is he MM5799NAX/N chip which can be got but at the price of it, its cheaper to find a replacement logic board
regards
clones