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Thorens TD-125 MKII adjustment pots

John_73

John_73

pfm Member
Hi folks.

I'm just sprucing up a very nice condition Thorens TD-125 mkii for a friend.

In addition to replacing the two 1000uF caps, I want to replace the voltage adjustment pots on the main board, but the values available at Rapid Electronics of a similar physical size differ slightly to what was used originally. The 500R trimmer value is available, but for the original 47K and 22K values, I can only find 50K and 25K versions. Is it OK to use these?

uO5vzgy.jpg


Many thanks,

John.
 
+1 Yes

From Rapid the part numbers are:

51-9093 (500R)
51-9098 (25K)
51-9099 (50K)

The PCB has two sets of holes for different size pots, you need to wick the solder out of the 'other' set of holes for these Piher pots and then they fit perfectly.
 
You need 3 pairs of hands to set the pots up .... And some little clips ... and 2 volt meters ... And some contact cleaner for the adjustment wheel .... Well worth doing though.
 
I take mine out of the plinth and sit it on top of baked bean tins to give me access to the PCB, it makes life so much easier!

I agree with Killie99 having two multimeters makes it much easier but you can do it with just one, it just takes longer as you have to keep going backwards and forwards between the adjustments (altering the setting on A1 33 affects the reading on A2 33 etc....).





 
Thanks for the tips guys, and for those photos Mike - having a good read of the service manual right now whilst I wait for the parts to arrive. All looks reasonably straight forward. Have two multimeters so that makes things easier, and will use an old Target hifi rack without the bases fitted as an adjustment 'jig'.

One thing I could do with some information on, which doesn't appear to be in any manual. What is the thread size and screw length for the four screws which attach the deck to the plinth? Amazingly there were none fitted to this deck, it was a friction fit only! The holes are there in the wooden supports within the plinth, but obviously somebody forgot to fit them. Just as well this deck was never stored in the box upside down!
 
I'm positive the screws you need at 40mm M4 cheesehead but I can't check as I don't fancy taking mine to pieces to find out. Maybe someone else can confirm?
 
Nima and a Russ Collinson plinth. Yes, will post pics, though feels a bit lame since all I will have done will be to have posted some WTD threads on the forum and tightened a few screws.

Sorry to derail thread - the pics Mike posted are (I think) of the deck I'll be collecting from him next month.
 
killie99 said:
I'm positive the screws you need at 40mm M4 cheesehead but I can't check as I don't fancy taking mine to pieces to find out. Maybe someone else can confirm?
Click to expand...

Thanks - have gone and ordered a set & will see if they fit. Fingers crossed!
 
Is it worth fitting an earthed mains lead when servicing a 125, bolting an earth to the chassis, or leaving it as intended with the two core?

Cheers,

John.
 
I wouldn't, you may cause a groundloop and the only way to remove the loop would be to remove the earth you just fitted ....
 
The screws that fit the chassis to the plinth are a pig to fit. Probably explains why they were left off. The chassis is so hard it can strip the threads easily if they are misaligned.
 
You really need to loosen off the front and rear 'locating' bars to get the screw holes to line up, then tighten the locating bars and then tighten the plinth screws.

rear_view.jpg
 
Thanks for that photo & suggestion Killie - extremely helpful! Hopefully the screws will be here tomorrow. Replacing the adjustment pots and those two 1000uF caps went smoothly.

Assume the voltages can all be adjusted without the sub-platter & belt in place, with only the final speed trim stages needing it all setup?
 
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