Dual 621 spinning out of control


New member
Username: Saqwerty

Post Number: 1
Registered: Jan-15
Hello everyone.

I was hoping someone would help me with a problem I have. I received a dual 621 as a birthday gift. However before I could even try to use it myself, someone accidentally plugged it into a 220v power supply instead of the 110v that it should have been in
I opened it up, found a fuse that was busted. However its a 63mA fuse...which i had been having lots of difficulty finding. Kind of giving up, I decided to just use a larger fuse instead (not sure if this is the problem).
Now when i turn it on, it lights up and everything. However, the turntable spins really fast. And by really fast, i mean really really fast, probably the max speed of the motor. It didnt do this and was apparantly working fine before being plugged into the wrong voltage.
Ive been reading up on turntables and everything to try and figure out the problem and whether i can fix it.
Im not in a country where I can find a shop that will fix a turntable, so anything I do will have to be done by myself.

Thank you very much for any info you can give me. If you require any more information, please feel free to ask. Thank you verry very much again!

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 18008
Registered: May-04

Well, I've never dealt with a Dual that was plugged into the wrong Voltage before. My guess would be the main section of the speed control board has been fried. The direct drive tables were quartz locked and synchronized for further fine control of constant speed. If the motor turns, it probably has not sustained any real damage but has no "governor", so to speak, to keep it at a rational speed.

There are a few service manuals on line for the table if you know how to use one and have the appropriate tools and test gear. If you have neither, the cost of the tools and test gear will set you back more than the table's worth. However, I'd warn you, this is not a job for someone who hunts and pecks at an electronics board. And a detailed repair is pretty difficult to direct over a forum. There's nothing particularly specific to the Dual control board but you have to have some idea what you're doing.

This isn't really the forum to get you through the repair. Try Those are the audio geeks and probably there is someone there who might take on the job of directing the servicing. My best guess would be, if you can definitely determine the speed control board is fried, just replace the entire board with one scrapped from another beyond repair table.

Good luck.


New member
Username: Saqwerty

Post Number: 2
Registered: Jan-15
Thank you very much for your reply!

Yeah. Because the turntable is actually spinning, I thought maybe theres a chance i can fix it. And usually I wouldnt really go through all the hassle, but it being a gift from someone special, it has some sort of sentimental value.

I was hoping that there might be some easy stuff that i could try to maybe fix the problem, such as checking or cleaning connections, maybe checking fuses and stuff. If anyone has any more suggestions, I would love to hear them. I will also try posting at the forum you linked me too. Thank you again for your help.
If its beyond my ability to fix it, most probably ill just leave it lying in my room (still looks nice even if it doesnt work!) and maybe sometime in the future if i can, get it to a qualified person.

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