Author Topic: Telefunken S500 Turntable Speed regulation problem  (Read 343 times)

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Offline Matthew98

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Telefunken S500 Turntable Speed regulation problem
« on: February 11, 2019, 12:28:50 pm »
Hey, guys !
I have a Telefunken 6001 hifi with S500 Turntable platform and Im really close to it being in pristine condition. There is a problem with speed regulation on the platform. After lets say ten minutes of playing or so it decides to run for it. It will keep speeding up until i stop it. That was at 33 rpm. I believe 45 worked fine even after that. Turn the turntable off for a minute, turn it on and its working great again. Any idea what could it be ? I cleaned the trimmers for the speeds, but no change. 
The turntable tends to get quite warm when playing, so it might have something to do with that. With luck its gonna be just a loose connection somewhere.
Im sorry for asking before looking myself, but this turntable is quite valuable, my opening window to audiophile experience and I would kill myself by ruining it :)

Ps. Also, the circuitry for picking up the needle when it reaches end of the record doesnt work. I believe that the optical resistor (sorry, cant remember the name)  just got old... Dont know if that is reusable or even If there is a potentiometer to set the sensitivity, but would appreciate any help on those problems. :)

Thank you guys so much !
 

Offline shakalnokturn

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Re: Telefunken S500 Turntable Speed regulation problem
« Reply #1 on: February 12, 2019, 12:19:54 am »
Looking at schematic on Elektrotanya: https://elektrotanya.com/telefunken_s_500_hifi_sch_print.png/download.html

There are 4 electrolytic capacitors. C118 is not likely to be the cause, at least check voltage and ripple at C117 and C111.
If power is clean move on, you've cleaned the speed trimmers but have you cleaned (and measured values?) of all 4, the 2 on the table and the 2 on the PCB? Also clean contacts on PCB connector.
Once you have been through this, I'd name 2 other suspects: C113 on tacho feedback and T109 on motor control. (BC338/25 I've seen plenty of these go wonky when warm...)

For the auto-stop, light dependent resistor (LDR) is the name you are after, could be bad, could be dirty. Sensitivity is on trimpot R116.
 
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Offline floobydust

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Re: Telefunken S500 Turntable Speed regulation problem
« Reply #2 on: February 12, 2019, 12:33:50 am »
+1

I would replace all electrolytic capacitors, this is 45 years old and they dry out. There are only 4.
C118 - 220uF 16V
C117 - 1,000uF 25V
C113 - 47uF 10V
C111 - 10uF 35V
 
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