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

[prime]

Hi guys still waiting for clear set of schematics but i have a question if you dont mind, if i read my manual correctly at start up Q703 turns on causing relay K701 and Q701 to operate, Q701 scan enable is used for self test. I looked at the transistors and find readings that seem ok but i have no idea how to test K701, is there a way i can check this with my meter, i see it looks like it has stained the board just below it, maybe from heat.

[Ron Rich]

Hi Pete,
Mostly guessing here- if it's a relay, and soldered to a board-- it must be removed and the coil resistance read. Then powered with the correct type/value power. Ron Rich

[prime]

Hi ive been thinking i have a power issue but now wonder if it could be a processor issue, my unit gets power to the carriage because the scan works at start up, the selection buttons work at start up but they do not activate anything, when i use the scan and switch back to play the gripper grabs a record at random, places it on the turntable, table spins and amp starts. I am getting the impression that the processor may be the culprit. Is this reasoning sound or does this sound like a faulty connection or part. Any thoughts appreciated. pete

[jukenorman]

Hi Pete,
I'm losing the thread here a bit. You say the buttons don't do anything and you mention a possible processor problem. Isn't there a procedure in the manual to test the profit setter - have you carried that out?

Norman.

[Ron Rich]

Guyz,
"processors" HATE power that is not perfect ! Always, check that the power supplies are perfect before, you test anything else -- Ron Rich

[prime]

Hi Norman i stated when selecting a record the screen shows the selection but the unit stays at idle, if i push clear i can reselect, sometimes the play screen will display a song playing but nothing is on the turntable. I did the test that the manual recommended for the profit setter but unit does not go through sequence as test shows it does nothing , but i also did the logic board test and using the method listed it states the logic board is defective. Should my focus only be on the profit setter first. I tested the power value at the 9.6 light per manual and got 9.5777 so i thought power was ok, also all units work such as carriage, turntable, gripper but not in the sequence they should.

[jukenorman]

Hi Pete,
The voltage for the profit setter will be fine. Most of the tests for the profit setter (as I remember) involve resposes to pushbuttons. If you can input a selection via the pushbuttons and it displays and clears, that would indicate to me that the profit setter is basically OK (it might not be totally OK but it's doing more or less what it should!) The selection you have entered is passed from the profit setter to the logic board for execution. The opto board interfaces to the logic board. I suspect that you should be concentrating initially on the logic board.

Norman.

[prime]

I agree, that is why i was asking if processor could be the culprit, or do you guys feel its a wire or part issue.

[Ron Rich]

Pete,
As I wrote earlier-- I am not familiar with that model--however "processors" generally, do not run on 9.6 volts. They usually require either 5 or 12 dc. Are there other power supplies in that model ?? If so, I'd check all of them-- Ron Rich

[Ron Rich]

ANYthing "can be" the culprit ! Attza why I check all power supplies first-- "plug connectors" next -- Ron Rich

[prime]

Ok i guess i was hoping that the info provided would lead to just one area, being a little lazy. I will slowly follow and test all power supply to confirm they match specs and that power is getting to where it needs to go. Hopefully my schematics will get here in a few weeks.

[jukenorman]

Hi Pete,
As I said earlier, I am somewhat losing the thread here - is it the "processor" on the logic board that concerns you?

Norman.

[prime]

Yes Norman, i was thinking if the processor was defective it may affect the information flow to the profit setter, that would explain why at startup it does not go through the test stage.

[jukenorman]

Hi Pete,
I suppose that is possible but I think it much more likely that the problem would be in the chips that interface to that processor. The schema-a-grams in the manual are quite detailed. Do you have a logic probe that would help you fault find?

Norman.

[prime]

I hate to admit i do not know what a logic probe is, i do have a multimeter that can read caps, resistors diodes out of the board to be precise.