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-   -   Thorens TD 125 speed problems (http://www.diyaudio.com/forums/analogue-source/103885-thorens-td-125-speed-problems.html)

singinghairdo 20th June 2007 11:04 AM

Thorens TD 125 speed problems
 
Hello.

I realize the Thorens TD 125 mkII is known for having a pitch control that wears out. Mine has and I'm desperate to fix. 33 rpm is fine, but 45 runs consistently too fast. Does anyone know how I can fix this problem please. I imagine a change of the electronics controlling the pitch?

Mark Kelly 20th June 2007 12:14 PM

Check R22

singinghairdo 20th June 2007 12:17 PM

R22
 
Sorry, new here, what's R22, or is that a component?

Mark Kelly 20th June 2007 10:33 PM

R22 is the variable resistor controlling the frequency of the Wien bridge in the motor controller for 45 RPM. It is the most likely cause of the symptoms you describe.

singinghairdo 21st June 2007 07:28 AM

Cool thanks. So a replacement resistor should do it?

John Caswell 21st June 2007 01:59 PM

TD125 speed
 
Hi singing
What I suggest you do is initially mark the positions on to the PCB of all the variable resistor wipers with something indelible, then give them all a squirt of IPA and wind the controls back and forth to clean the tracks and wipers or scrub them with a small stencil brush. Let them dry off, then set all the wipers to their marked positions and you should be very near to the original settings and speeds.

John Caswell

singinghairdo 21st June 2007 06:34 PM

Thanks
 
Thanks John,

That's most useful - I'll let you know how this goes...

Ed.

singinghairdo 25th June 2007 11:24 AM

Thanks
 
Hi John,

As promised some feed back on your advice. The IPA spray, plus some action with a tooth brush worked a treat. 1st time it didn't work so well, so I did it again and re-cleaned. Speed goyt much more stable. I then fine tuned the position of the wipers by moving them very slightly (clock wise and anti clockwise) from underneath the deck and checking to see what affect this had on the speed and pitch control. Some crazy results if you over-do it...

Very happy with the results, thanks for you advice.

Ed.

John Caswell 25th June 2007 01:07 PM

Thorens TD125
 
Hi Ed,
Well done! Ideally you need a scope and DMM to sort it properly but if it is just dirty controls then this quick and dirty fix often works very well

John

singinghairdo 25th June 2007 01:24 PM

Learning as I go... I realise the tooth brush was a little bit crude!

I have heard rumours that the 16 rpm setting can be tweaked to run at 78 RPM, is this true, or ill advised?


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