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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

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Old 29th Sep 2019, 3:11 pm   #1
Michael Maurice
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Default Sony TC377 running slow.

I've been servicing this machine, cleaned and lubricated the parts that needed doing.

Replaced motor run capacitor 2uF 450V~

But motor runs slow, it seems alright on FF or REW but definately slow on play.

Any ideas?
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Old 30th Sep 2019, 12:24 am   #2
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Default Re: Sony TC377 running slow.

Your problem is a puzzle Michael, is the motor pulley the right one for 50Hz? If nothings dragging it should run right, is the speed change mechanism lining up the idler wheel properly?

I have two of these, one I hope to get finished and a donor, If you want a motor or anything else to try let me know.

BTW I need an idler pulley for mine, rubbers gone hard and has tiny surface cracks, you wouldn't happen to have a spare?
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Old 30th Sep 2019, 4:17 am   #3
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Default Re: Sony TC377 running slow.

In the service manual the motor cap is listed as 1.5uF with a switchable parallel cap plus resistor (values not stated) which I assume compensates for 50/60Hz.
Hope that helps.

Tim.

https://www.hifiengine.com/manual_li...y/tc-377.shtml

Ed: Looking at the photo of the back of the machine, yes for 50 Hz it's 1.5 + 0.5 so not the cap it seems.
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Old 30th Sep 2019, 7:11 am   #4
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Default Re: Sony TC377 running slow.

The switchable cap arrangement corrects the motor running conditions for 50/60 Hz but it cannot alter the speed which will be 1500rpm at 50Hz for a 4 pole synchronous motor or 1800rpm for the same motor at 60Hz.

You either need a 50Hz pulley or in some cases the machine may have a stepped pulley in which case the belt needs to be on the larger diameter.
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Old 1st Oct 2019, 1:22 am   #5
Michael Maurice
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Default Re: Sony TC377 running slow.

As far as I know, the tape recorder is original. When I first looked at it the motor was partially seized. I manage to free it off, oil it with sewing machine oil and it ran freely. The capacitor was changed as I’ve had problems in the past with the originals.

Barry, the only belt that is connected to the motor is for rewind. The capstan flywheel is driven by a pulley which in turn is driven by a stepped pulley. At all three speeds the pulley contacts the correct step on the motor pulley.

Andrew, may I take you up on your kind offer.
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Old 1st Oct 2019, 10:53 am   #6
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Default Re: Sony TC377 running slow.

No problem, I'll extract it Michael and PM you.
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Old 1st Oct 2019, 11:50 am   #7
barrymagrec
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Default Re: Sony TC377 running slow.

Quote:
Originally Posted by Michael Maurice View Post
Barry, the only belt that is connected to the motor is for rewind. The capstan flywheel is driven by a pulley which in turn is driven by a stepped pulley. At all three speeds the pulley contacts the correct step on the motor pulley.
In which case presumably the stepped pulley would be changed for 50 / 60 Hz operation? Or the pulley which is driven by the stepped pulley?
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Old 1st Oct 2019, 12:14 pm   #8
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Default Re: Sony TC377 running slow.

The capstan flywheel is idler driven.

Lawrence.
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Old 5th Oct 2019, 4:12 pm   #9
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Default Re: Sony TC377 running slow.

So I've now fixed it! And it wasn't the motor!



The problem was two fold, Under the flywheel is a piece of something called a thrust bearing, this had gone missing at some stage. The flywheel has two two steps, the upper one for 1⅞ and 3¾ the lower with a smaller diameter for 7½. The pulley was contacting the upper part on 7½.


I made up a thrust bearing from a couple of washers, I did try some paxolin but it was too thick. The idler wheels bracket was slightly bent, so I bent it back.


It still runs slightly slow but there's nought I can do about it. Maybe even my thrust washer was too thick.
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Old 5th Oct 2019, 11:24 pm   #10
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Default Re: Sony TC377 running slow.

Congratulations on the repair Michael. I did wonder about the idler wheel position, see post #2

If you wish to return the motor I sent I will refund its cost, not the postage I'm afraid though.
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