Rock-ola 477 Max random play, no play, etc.

[Ron Rich]

Hi Pete,
I just had a thought-- by any chance, is this a phono, that uses the black, flat A-MP, 18 to 25 position plugs ? If so, or if not-- have you "serviced" all of the plugs-- sounds as if the contacts are making erratically ? Ron Rich

[prime]

Ive decided to replace all of the power caps regulator board, rectifier etc. I feel i need to make sure this is not a faulty cap so the big ones need to be replaced to confirm. I had a friend of mine that used to service arcade games help me check all connections, after looking at all connectors i think they are ok, as i mentioned i checked resistors and all transistors in logic and profit setter and all voltages but did not replace caps, i think you mentioned them in first posts, my bad. If that turns out to be the problem i deserve what has transpired. pete

[prime]

Hi guys, i changed all power caps no change, I would like to go over what the unit does one more time to see if some idea pops out. When i turn the unit on, all power lights that should come on are lit, fluorescents come on, carriage does not move. at this moment if i want i can press selection buttons and screen will show numbers pressed, they will light but as the third number is pressed , it lights then all three go off. After this selection buttons do not work unless i press clear button on Profit setter which allows me to select numbers again, this process i can repeat over and over. If i move the operate switch to scan, carriage will start, then as it starts if i move switch back to operate carriage will keep rotating then stop at usually 134 and select record, then if i press cancel record will return, carriage spins and returns to proper resting place, at this moment scan will not work anymore, if i turn unit off and on i can repeat the process immediately. Does this still sound like a bad connection or a defective chip. Seems strange the i can repeat the same thing over and over by just turning off and restarting unit,

[Ron Rich]

Hi Pete,

My GUESS, would be a "contaminated" chip-- is there a default reset proceedure  for it ? If so try it-- I did not ever see your reply to my earlier question--Did they use a black colored A-MP card edge, connector, or two, in that phono ?  Ron Rich

[prime]

I dont think they used the A-MP i see only pins and white connectors. Hopefully that was what you were asking. I have checked all connectors for loose or broken wires, i have also been able to check all plug wires going from Profit setter to display and all have continuity. I will be trying to follow all wires from logic board and all of the other wires from profit setter to see if they have continuity this weekend, this will not be easy as the wires go every where. In your opinion can this be any wire or just power, logic and profit setter. Also for testing purposes i have an issue , my number credit display is not working, i have ordered a retrofit including chip to replace, then hopefully i can go through the testing listed in the service manual.

[jukenorman]

Hi Pete,
If I remember correctly, this is basically how you machine operates - feel free to correct any errors.

When you turn the jukebox on, the carriage make one rotation back to the home position - this is not happening on yours.

Making a selection is as you have described. After you press the third digit, I believe it's normal that the selection digits go out. What then happens is the carriage rotates and the digits then increment from the opto disc. After the selection is made, the operation is handed off from the profit setter to the logic board. It's my guess (and it is a guess), that's the area where your problem lies. I think this may have already been suggested along with procuring schematics and a logic probe (there are six pages on this thread!).

If you shift the operate switch to scan, the carriage ought to scan and if you then return it to operate, you might expect it to return to the home position under the action of the home switch. It wouldn't be a surprise if these actions were causing the system to hang up.

I believe that you are at the stage of schematics and checks with a logic probe!

Norman.

[prime]

We are definitely at that stage, we have tested all power supplies as per schematics, we have tested all transistors on logic and profit setter, all resistors and diodes, I tried to use the manual to test profit setter board but my credit display is shot, i tried the chip from the popularity board no change, i have ordered retrofit displays with matching chip. We looked at opto board all seems well, with power on i can manually trip switch and engage magazine to spin, opto board light flashes as it should. Sometimes while sitting at the jukebox the now playing box randomly shows a record playing but this is not the case. Im thinking logic board. pete

[jukenorman]

Pete,
I should have also added that the operating sequences in the manual give very specific details of what should happen at each step so working through these in conjunction with the schematics should help your fault finding.

Norman.

[prime]

Problem solved, after going to hell and back it was a chip. I decided today that the issue must be the logic board and ordered a NOS from Victory glass, although i have solved the issue i am still going ahead with the board, this will give me options if anything like this happens in the future. I also decided while waiting for the board i would see if it was possible to purchase the controller chip for the logic board. In my search for a chip i came upon an old post of someone who was trying to repair a 477 with no luck, they had purchased a used board on ebay and still no success, later in the post someone had mentioned in the past they had a similar issue and solved it by replacing the Hex Inverter chip, they also mentioned the hit tracker board had the same Hex as the logic. I removed my Hex and replaced it with the one from the hit tracker board, problem solved the unit works perfectly again, the carriage spun at start up and when i selected a song it played that selection. I still dont have the credit screen working but im sure when i replace it all will be right as rain.

[jukenorman]

Hi Pete,
As a matter of interest, I took a look at the schematics to see where the failure was. The problem was with the home switch circuit. If you had gone checking with your logic probe you would have seen that after the third digit was pressed that the logic board run line would have been high but the failure of the hex inverter was preventing confirmation of the mech. being in the home position so the play control relay was prevented from energising. See sequence 10 for reference.

Norman.

[prime]

I think that may be a valid point, but the number pressing did not always produce a reaction, sometimes the play screen would show a record playing and the number selections buttons would not work, sometimes when turning on the power the gripper would grab air and start the turntable, it would take 1-6 ejects to get it to stop. Unfortunately either the faulty Hex chip or whatever may have damaged the chip caused different actions on different startups. It was very difficult to ascertain if it was a faulty part or a loose connection. I think if my credit display did not go blank at the same time i could of used the test procedures to try and isolate the problem area.

[prime]

Hi Norman and Ron, thanks for all of your help and advice, i am starting to realize these units can be quite a challenge and in the future i will try harder to be more concise and maybe follow directions a little better.

[sock]

hi all im having similar problems with my 478 could you tell me this chip you swapped from the hit tracker to the logic board regards keith