Please Help 1210 problem! :(

[Robmorris]

Hi there,
I was just wondering if you could help me find the problem with my 1210mk2. The platter speeds up fine (33-45 and -8 to +8) however when i try to slow the platter down the platter does it's own thing and goes whatever speed it wants and a strange grinding like noise occurs? The tt will not stop either. Could this be something to do with the brake? I recently tried to repair the target bulb but i realised it was a bulb not an LED (silly me) so i taped over the wires to prevent shorting. However if it has shorted out could this cause this problem? - or would it cause any other problems.
Thanks for any advice and sorry for the inconvenience!

 

[DonH50]

If speed is controlled by a potentiometer you might try getting a can of spray cleaner from Radio Shack and cleaning it. Spray in the little holes at back and around the shaft while spinning the knob (with the TT OFF and unplugged).

The noise is worrisome; mechanical? Can you isolate where it is coming from?

I do not know about the target bulb; if there is an optical link that could cause issues, but I think that would cause problems no matter what, not just one direction (unless the speed is maxed out?)

 

[Robmorris]

i noticed the strobe was flickering slightly and i did some research and found that this (combined with varying platter speeds) is often due to 3 components blowing when the target lamp shorts out - transistors Q2 and Q3 and Zenner Diode D3.
I am going to try replacing these and hopefully this should solve the problem - im having some trouble sourcing the parts atm though! Without paying £10 for a transistor on ebay
Thanks!