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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 1st Feb 2015, 6:45 pm   #1
derek.ireland
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Default Sony TC252.

I have had this Sony 5 years or more.

A yearly lube and clean; suddenly has started to roll the tape off the pinch roller. Cannot see anything wrong. Pelp please, gentlemen.

Thanks Derek

Last edited by Mike Phelan; 1st Feb 2015 at 8:15 pm. Reason: Readability.
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Old 1st Feb 2015, 9:30 pm   #2
ben
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Default Re: Sony TC252.

Pinch roller is hard, shiny or deformed. Had this with Akais of that period. The tape path on these sonys is fairly acute, I find that they and the Akais often give tape skew if the roller is not in tip top condition.
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Old 2nd Feb 2015, 9:06 am   #3
derek.ireland
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Default Re: Sony TC252.

Thanks ben.

I gave roller a quick boil in washing powder and a good scrub, seems to be running OK.

Hoping for a few more years from her.

I had an idea the roller shaft may have bent, putting it out of alignment. A good job I did not go in that direction.

Thanks again.

Derek.

Last edited by Mike Phelan; 2nd Feb 2015 at 9:52 am.
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Old 2nd Feb 2015, 4:55 pm   #4
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Default Re: Sony TC252.

The term, rolling off the pinch roller, might be the tape climbing and slipping off the top. That is something common to my experience with recorders .

We called it 'overhauling', and was caused by the takeup reel exerting too much pull, especially at the start when the effective build diameter was the spool hub. Higher torque at the start than at the end when the spool is full.

The cause was the take up slip clutch too tight, mostly because of felt surfaces getting gummed up.

The ratio of the 'wind', or the pull that the capstan roller can exert on a leader tape attached to spring scale, to the take up pull, measured the same way, must be fairly high.

The test was to start the machine with the tape going through loose, i.e. no take up spool. If there was no overhauling that way,the roller was correctly parallel with the capstan.
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Old 2nd Feb 2015, 8:07 pm   #5
derek.ireland
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Default Re: Sony TC252.

thanks for you suggestion re tape pickup torque.but is not the torque the same whether the spool is on leader tape or full ..derek
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Old 2nd Feb 2015, 10:30 pm   #6
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Default Re: Sony TC252.

Yes the torque is the same but the tape tension isnt. Conversely, not enough back tension can exacerbate the problem. Back tension is lowest when take up tension is highest, at the beginning of the reel of tape.
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Old 3rd Feb 2015, 8:34 am   #7
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Default Re: Sony TC252.

The use of the term leader tape might have been unclear. We used leader
tape, not in the sense of being at the start and end of some tape reels.

We used leader tape, as tape ,for these tests. It wouldn't stretch, for
example in the capstan pull of 'wind measurement, when we expected
hundreds of grams of pull. Here are the two measurements
illustrated.
Attached Thumbnails
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Name:	784 capstan pull or  WIND.jpg
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ID:	103637   Click image for larger version

Name:	784 takeup.jpg
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Size:	38.7 KB
ID:	103638  
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