Tech help - Power supply issues with my turntable

[Jerjo]

I have a Dual CS-455-1 table that I bought about a decade ago. Two years ago it developed some issues with running too fast. I found a guy that could work on it and we seemed to get it back on track. Cut to Christmas 2016 and while my wife was playing holiday music we noticed it was now playing slow. @#$%!!

I stowed it downstairs because I just didn't want to deal with the issue. The power supply unit that I had was a piece of junk and I threw it away (the original was lost in a move seven years ago). It occurred to me that maybe the issue was that power supply. So I got a new one off Amazon. This one:

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

I just tried it out and now it's playing quite fast. 33 1/3 sounds like 45. Any suggestions? I posted this on the Hoffman forum as well but no answers so far. I'll eventually take it to the guy that worked on it a couple years ago but that's a two hundred mile round trip.

[markwoll]

Look at this thread for a potential answer:
https://www.vinylengine.com/turntabl...ic.php?t=36990

[Jerjo]

Thanks Mark but I saw that one while I was trying to find answers. It doesn't answer the issue of why it runs at different speeds depending on the AC adapter.

[markwoll]

If the power supply is delivering the correct voltage it should turn the motor at the right speed.
No chance it is the wrong voltage?
The speed control might be bad.

[Jerjo]

Well, I set the new adapter at 12 V BUT it's such a huge difference in speed from the old AC adapter I figure something ain't right in the power supply. One thread on Vinyl Engine says you need a 12 V 150ma adapter. I have no idea what 150ma is or what difference it makes.

[Edit] Looks like ma is milliamps (Euro) and converts to watts (American).

[rcarlberg]

150 milliamps is just the power draw. Wouldn't affect speed.

The Dual CS-455-1 turntable is "Belt drive with polished flat belt. DC motor with electronic speed control. " That DC motor wouldn't be getting its speed from the AC mains frequency. The 12v power supply should be + or - some percentage and still work within specs (wirth a voltage regulator in there somewhere.)

Best guess: defective "electronic speed control." But that's a remote diagnosis so take it with a huge grain of salt.

[Jerjo]

Well Robert at least I can eliminate the power supply as the issue. And the belt is new so that's not the issue and the motor itself got a rehab. I guess I can now research speed control and see it the speed adjustment screws in that link Mark provided can bring it down to normal.

[Jerjo]

Jebus, finding the speed adjustment screws was a pain in the ass. You have to take the actual platter assembly out of the base and they're on the bottom of the motor. I took a mini-screwdriver that we use for eyeglasses and kept making tiny adjustments on the screw for LPs/33 1/3. The one for 45 rpm had collapsed inside and there was nothing I could adjust. I must have pulled that thing apart a half dozen times. But finally I could flip back and forth between LP and CD on an old Zeppelin warhorse and Bonham's beat was identical. I call it a win.

My wife calls it a win as well. Now she can pull out all her ancient Christmas LPs that she salvaged from her parents.

[markwoll]

Good job, persistence pays off.

[rcarlberg]

My wife calls it a win as well. Now she can pull out all her ancient Christmas LPs that she salvaged from her parents.

Pyrrhic victory.

[Jerjo]

True, there's only so much lounge lizard Christmas carols a man can stomach.

[Plasmatopia]

milliamps is current, watts is power (volts multiplied by amps)

[Jerjo]

I battled the beast again yesterday. Last Monday I had put on an LP and I realized it was still too fast. So I spent a chunk of time taking out the platter assembly, making an adjustment to the little invisible screw inside the motor, putting the platter back in, playing a record, rinse and repeat. I must have spent half the morning fucking with it. But I finally achieved something close to perfection, or at least close enough for rock n' roll and lounge lizard Christmas albums. If it speeds up again I'll punt the sonovabitch back into the electronics graveyard.

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