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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 21st Apr 2022, 1:30 am   #21
nickdoofah
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Default Re: Removing Technics Rollers

To me your rollers have had it although we have all seen far worse! - It's funny with cassette machines, sometimes the roller looks completely knackered but the deck performs amazingly well! There must be a huge variation between makes & models as I noticed this more then you would perhaps expect whilst servicing cassette decks through the 1980's & 90's!
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Old 21st Apr 2022, 9:50 am   #22
knobtwiddler
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Default Re: Removing Technics Rollers

If you look at the rebuild link in post 11, his rollers are looking a lot worse and he's getting 0.02 W+F (!!). The photos I provided are from my spare machine - I suspect that my main machine (the one that's started crinkling tapes) has far more of a glazed look to its rollers. But I'm not 100% sure that's what's crinkling the tape... If I'm going to get the lid off it, I might as well change the rollers for peace of mind. Terry comes highly recommended, from all quarters of the audio fraternity.

I checked out 2 of my Sony machines yesterday (both TC-K666ES) and the rollers look almost new. I suspect they've been changed in one of them, along with the heads (sloppy soldering, scratched nuts and perfect looking heads on a 40-yr old machine make me think this).

The big question in my mind is what's stopping me from replacing the lock washer with a c-clip, assuming the groove fits one? And if there's sufficient groove in the spindle, why did Technics put a c-clip on one side of roller, but a plastic washer on the other?

If you look at the link in post 11, you'll notice that the Technics has a motor the size of a bowling ball. Methinks it'll have decent W+F even in mediocre condition. I don't think replacing washer with circlip will affect W+F. Figuring out why it's skewing tapes could be the harder part of the task...
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Old 22nd Apr 2022, 8:57 pm   #23
DMcMahon
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Default Re: Removing Technics Rollers

I cannot really see the purpose of the plastic lock washer over a conventional circlip/e clip in that position.

David
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Old 23rd Apr 2022, 12:51 pm   #24
Analogue man
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Default Re: Removing Technics Rollers

Quote:
Originally Posted by DMcMahon View Post
I cannot really see the purpose of the plastic lock washer over a conventional circlip/e clip in that position.

David
Cheaper and much quicker to install on the production line.
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Old 24th Apr 2022, 9:10 am   #25
BGPDenmark
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Default Re: Removing Technics Rollers

You have to be very careful with the arms for the rollers. Due to the size of the rollers, there is almost no space for the cassette. Therefore, an edge is also ground on the upper side of the arm. If the cassette does not lie exactly in the holder, it lies and tilts, with the result that the tape makes a curl when it falls into place.
The tolerances are very small about 1 mm on each side from the arm to the cassette.
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Old 24th Apr 2022, 1:27 pm   #26
knobtwiddler
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Default Re: Removing Technics Rollers

This is superb advice- thank you!

As I wrote before, the rollers I am getting refurbished are from a spare machine. My 'working' machine started curling tape and I presumed it was due to shiny rollers, so I simply took ones off spare for purpose of sending to.Terry. Maybe the actual problem is arm alignment, as you describe? But why would it change overnight? In late Jan I checked W+F before transcribing a tape and got 0.03 RMS / 0.05 Peak. It had less than 10 hrs use after this before it started curling.

Maybe I ought to start a dedicated RS9900 thread. It is a special machine and there is very little info on the web pertaining to its maintenance.
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Old 24th Apr 2022, 2:42 pm   #27
BGPDenmark
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Default Re: Removing Technics Rollers

Yes you are right there is not much about the machine on the net. Funny enough because there must still be a lot of machines today. It must be simple because no one writes anything about their experiences and issues.
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Old 3rd Jun 2022, 12:59 am   #28
knobtwiddler
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Default Re: Removing Technics Rollers

Update: it looks like I might have been over-eager to get my rollers to Terry. I didn't give the bearings much of an inspection beyond a quick spin before they went off. I finally got around to fitting the re-rubbered rollers back on spindles (not in machine) today, only to find that one of them has such a worn bearing that you can feel visble play... How much play is too much play?

I realised that I'd put the worn bearing on the right arm, with the tight one on the left, so I've swapped them around...

These bearings are off my spare machine, not the one I plan to fit them to. Am now wondering if I might have to send one or two rollers off the main machine to Terry in order to find 2 good ones... Which will leave me with a spare machine that has shot rollers... (and a very collectable machine that I'd like to have working at some point).

I've looked at various sites that sell rollers, but never seen anything that fits the RS-9900 spec (very small, bronze bearing).

I might try them as-is, with the slack bearing as left roller and tight one as right. I worry that, if it works ok, it'll only be a matter of time before the worn roller causes skewing. Am kicking self that I didn't give a more thorough inspection before I sent them to Terry.

edit - at a guess I'd estimate play at somewhere around 0.5mm...
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