Turntable servo motor spinning at full 12v ONLY.  - Page 1
Forum section: electronics / repair

author: WhatsICC
author_rank: Contributor
timestamp: May 12, 2023, 05:22:13 am
content: Needing some help with this Onkyo CP-1010a.This turntable spins at a constant 90-100rpm, with no speed controls. The speed selector switch does not switch between speeds (be it faster or slower than 100rpm lol,) the pots don't have any effect on the speed, nor do the internal trim pots.I have sprayed the pots, speed selector switch and onboard VRs with deoxitI have checked for continuity between the switch open and closed, between the switch open and closed to the pots, and the speed control board. There do not seem to be any shorts. I have also checked for continuity between the speed board and the motor via the white and yellow wires and there is continuity there as well.I have checked for resistances at the 33/45 potentiometers and 33/45 VRs and all line up with the 1010a manual. I also checked that the 6.2k and 22k resistor were in spec.I replaced the 1000uf capacitor, as well..The motor seems to just spin at full power with no adjustments. Initially, I thought there was a short but now I'm not so sure.Could this be the x2 film cap between the switch or a bad transformer?Any help and insight would be greatly appreciated.

author: floobydust
author_rank: Super Contributor
timestamp: May 12, 2023, 05:33:41 am
content: The motor has an internal speed regulator that appears to have failed. Under the piece of tape is usually a trimpot you can see , but here the speed setpoint seems to be switched and on the external board trimpots, so it might not have an adjustment there.Pop the back cover off of the motor and see what you have got. There is typically a power transistor that controls the motor power and it could have shorted, or the tachogenerator has no signal.

author: WhatsICC
author_rank: Contributor
timestamp: May 12, 2023, 05:44:00 am
content: From what I could see there was no trimpot visible on the motor, however there was a hole with an arrow that i covered with the piece of green painter's tape so its not visible in the photo. But there was no internal access from that hole as there was foam in the way.Just to confirm, the inner stainless portion of the motor "pops" out. Revealing the inner motor pcb?Thanks for your help!

author: floobydust
author_rank: Super Contributor
timestamp: May 12, 2023, 05:54:42 am
content: I would carefully pry off the back alumium end cover, and that should reveal the PC board under it.But do check for any tiny screws on the motor's outside case holding the cover on- but it's usually a press-fit. Don't stab inside the hole you'll hit the parts on the spped controller PC board.

author: WhatsICC
author_rank: Contributor
timestamp: May 12, 2023, 06:03:54 am
content: Perfect, thank you!! I intend to use extreme caution hahaIll do this in the morning and get back with any issues. Glad I've learned something new about these motors and another failure point!

author: darkspr1te
author_rank: Frequent Contributor
timestamp: May 12, 2023, 06:18:25 am
content: You will find its a standard 4/5 wire spindle motor as used in technics, pioneer and others.see attached diagramfor replacement search for EG530SD-3F DC5-12V 3-Speed 33/45/78 RPM ,it can be wired to single, dual and triple speed players as per the wiring in the image.3 wires-/+ , speed compensator variable resistor (pin 10,11 and VR1 as per diagram )is all thats need to drive the motorone thing to note is it does come in two models, tall and thin or short and fat , technics/kenwood favored the short fat models but they are interchangeable in most chassisalso there is a transistor onboard that fails short and often comes with the saying "it was working fine, turned it off to swap records and then it went fast" , you must check that, easy cheap part found in many psu'sdarkspr1te

author: WhatsICC
author_rank: Contributor
timestamp: May 12, 2023, 04:12:26 pm
content: awesome, ill first open the original motor and see if I can replace whatever went bad in there first.If not I'm glad to know a decent motor replacement product # to replace it with/other future projects.