Rock-ola 432 will not scan or read-out

[nateg]

Hello all. First post. I’ve been working on a 432 for a month or so now, i believe i have sorted out all the mechanical problems. It will write-in, but no read-out, and the scan switch will not rotate the carousel motor. I have removed the gripper arm, and the cam switches are in the right position. I swapped out control boxes with a working unit, and tested the motor. I have a manual, but not complete schematics. With the info i have i suspect the scan switch itself, the play control relay or a bad micro switch. Any suggestions?

[jukenorman]

If you operate the play control relay manually (push it with your finger), does the motor run? If not, probably micro switches. If it does, something associated with the scan/operate switch.

Your manual surely must have some schematics - schem-a-grams?


Norman.

[nateg]

As i stated in the OP the scan service switch does not operate the motor. I checked the micro switches, they seem fine (circuit is closed at rest, open when button is depressed).

[jukenorman]

Apr 18, 2024 15:39:47 GMT nateg said:

As i stated in the OP the scan service switch does not operate the motor.

Yes I knew that because I read the post!  If you had done what I suggested in my reply, we might be in a position to make some progress.

Norman.

[nateg]

I misunderstood your response, i apologize. Manually depressing the play control relay, holding micro switches 2 &3, scan switch still does not move motor.

[jukenorman]

The scan switch energises the play control relay and the play control relay then sends current to the magazine motor provided that the switches in circuit are in the correct position and serviceable. So if depressing the relay does nothing, there is an issue with the switches (or something in the switches circuit). Of course, it could be possible that there's also an issue with the scan switch but that would mean a second fault (less likely especially since you manually operated the relay). I will have to refer to the service manual and I will add the schem-a-gram to you to follow.

I don't have a pdf of the 432 (although I think I may have a print copy in my workshop files) but I'm fairly sure the 433 is the same electrically.  The schem-a-gram on page 38 of the manual shows the circuit through the magazine motor when the play control relay is energised (or held in).  So 28VDC goes through the play control relay contact, the No. 2 micro switch, the interlock relaese relay contact and No.1 micro switch to the magazine motor.

Can you see that and understand it?  Are you able to check the voltage through these contacts with the play control relay in the "made" condition?  The wire colours are shown on the diagram to help you.

Norman.

[nateg]

the manual i have is for the 431, i would imagine all 3 are the same in this respect. pg38 is "seq 2, sel reg". i am able to follow the schem, now that you have narrowed it down for me. i will check for 28v at the relay and follow it from there. is bad ground a possibility as well, if the write-in circuit operates? appreciate your help!

[jukenorman]

Yes, the same diagram in the 431 manual. A bad ground is a possibility but fairly unlikely because the magazine motor is directly connected to ground and not switched on the ground side.

Norman.

[nateg]

alright. we're blowing fuses. with a fresh fuse i was getting over 30v to the purple wire feeding the play control relay and continuity with the red/blue wire when depressed. getting 36v to the red/white wire off the rectifier feeding the mech fuse.

[jukenorman]

Unfortunately you need to find what's blowing the fuse and there is no magic cure! It could either be something shorting to ground or something broken (or burned out) causing a short to ground for example. You could use a resettable fuse while fault finding. When exactly is the fuse blowing?

Norman.

[nateg]

forgive me for obvious questions, my electronics training was very limited and long ago. with the tester across the fuse it started out under 35 and slowly climbed to 36.30V over abt a minute. not sure if thats normal voltage, or if it should increase. the fuse went immediately when i plugged the power wire from the credit unit into the control box. i heard a faint pop that sounded like it came from the control box. looking at the schem, the interlock relay seemed the most likely component to me as it was the only one with a ground. i have a working 425 and have removed the control box on it. i swapped it before and it made no difference, but i probably had a blown fuse then too. i will try again.

**UPDATE**

My man!!!!!! swapped control boxes and fuse did not blow immediately. depressed #2 microswitch, pressed the scan switch, and MOTOR TURNS!!!!

second update. 

pulled the old control box apart, and one of the components has been crudely replaced. will see if i can salvage it. thank you so much for your help! been fumbling around on this for 2 months, and you were able get me through it in 2 days.

[jukenorman]

Good news! But all we were doing was a bit of logical fault finding. Why do you have to depress micro switch #2; if the gripper arm is over the magazine, #2 switch should be in the correct position?

Norman.

[nateg]

mechanism is completely disassembled. i pulled all the motors, the turntable and the gripper arm mechanism off for cleaning. had hoped to begin with that it was a mechanical issue, box was in really bad shape. wanted to sort out the electrical problem before reassembly in case i needed access for testing. turned out pretty much everything needed attention. now i start putting it all back together and hope there are no other issues (spoiler: there will be).

[nateg]

...also, i was under the impression that the #2 switch needed to be depressed. now that i have the motor installed i see that as long as #1 is not depressed i have power. next issue is the read-out carriage is not finding or resetting the selector switch. ive seen that addressed before, so i will do my research.