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Mitsubishi LT-5V speed issues

GMAN1970

GMAN1970

Active Member
So when I got the turntable, everything works fine with an exception of the speed was going too fast ! much faster than 45. I open the back cleaned all of the pots including the 45 and 33 fine-tuning pots that are on the circuit board put it back together and no change. So I bought the new motor that was identical in spec and housing, it was from a Toshiba turntable. I connected it and I was amazed that the speed was now perfect, upon further inspection I noticed that it was going the wrong direction. So I thought to myself, switch the polarity and it should work perfect in the other direction. I was wrong, switching polarity did change direction but now it was going fast again, thinking that I fried the motor I switched polarity back again and the speed was fine.. This is about the extent of my technical ability, so if anybody has any suggestions on what my next step is besides taking it to a technician let me know and I greatly appreciate the assistance!
 
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Do you have the service manual? It can be downloaded from vinylengine. There is a pot for setting the speed. I would have to check my copy to tell you where. Also, what belt do you have on it?
 
Some years now since I had my LT-5V, yet another deck I wished I'd kept.

I remember the "runaway speed" issue was quite common. Apparently the motor benefits from lubing, and sometimes a motor transistor failure results in the speeding up but can be replaced with care. A quick search did not show the schematic I used years ago, it may still be out there. Otherwise a slow trawl through the service manual on VE I guess.

Good luck.
 
The belt is correct and the pots have no effect on speed in 33 or 45 and neither does the speed selector
perryinva said:
Do you have the service manual? It can be downloaded from vinylengine. There is a pot for setting the speed. I would have to check my copy to tell you where. Also, what belt do you have on it?
Click to expand...
 
Oh, so there is a defect problem with your TT electronics, not just running a bit faster than expected, which is what I thought you were talking about. Not a runaway fast. I am not intimately familiar with the motor. Some have FG electronics built inside the motor, so switching polarity to the motor does nothing. The motor leads inside the motor must be swapped to the servo electronics AND the correct DC polarity applied. I only suggest this because you said it was perfect with the new motor in reverse direction. I fix this issue in some cassette decks.
 
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