sqlsavior
Lunatic Member
I've had a Teac TN-400 Magnefloat turntable since '79 or so.
It went into the closet for a speed-control problem after a few years. Dug it out a couple years ago and got it going, sort of, but it still has speed issues. The adjustment knobs are all the way in one direction, but that is not enough to get the strobe steady. There is a slow drift, and a pulsing to it as well, at maybe 1 Hz or so. So, I've finally dug into it, and hope to get it fixed...
The Teac has a DC motor, and old-fashioned, discrete components, so it should be fixable, I hope.
I cleaned the two pots at the top of the picture ^^^^, which seemed to help - no more wild variations in speed while adjusting, and it settles and stays anywhere in the range now, but still runs a fraction too slow, and still has the pulsing to it as well. There are 3 capacitors on this board - 820 uF, 220 uF, and 10 uF.
The two pots are actually wired to this board with two smaller caps on it, 1 uF and 4.7 uF.
The capacitance meter I got won't measure the bigger two, but the smaller three are all off:
1 uF -> 1.7 uF
4.7 uF -> 6.7 uF
10 uF -> 14.1 uF
It went into the closet for a speed-control problem after a few years. Dug it out a couple years ago and got it going, sort of, but it still has speed issues. The adjustment knobs are all the way in one direction, but that is not enough to get the strobe steady. There is a slow drift, and a pulsing to it as well, at maybe 1 Hz or so. So, I've finally dug into it, and hope to get it fixed...
The Teac has a DC motor, and old-fashioned, discrete components, so it should be fixable, I hope.
I cleaned the two pots at the top of the picture ^^^^, which seemed to help - no more wild variations in speed while adjusting, and it settles and stays anywhere in the range now, but still runs a fraction too slow, and still has the pulsing to it as well. There are 3 capacitors on this board - 820 uF, 220 uF, and 10 uF.
The two pots are actually wired to this board with two smaller caps on it, 1 uF and 4.7 uF.
The capacitance meter I got won't measure the bigger two, but the smaller three are all off:
1 uF -> 1.7 uF
4.7 uF -> 6.7 uF
10 uF -> 14.1 uF
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