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-   -   How VCR pinch rollers work! [FAQ] (http://www.digitalfaq.com/forum/vcr-repair/6518-how-vcr-pinch.html)

Quasipal 05-01-2015 06:39 AM

How VCR pinch rollers work! [FAQ]
 
On all VCR's the pinch roller does need attention quite regularly to keep the tape running across the various heads correctly. I thought I would share a few thoughts as during deck cleaning and maintenance this vital component is often not given the correct treatment.

Firstly, the roller is not what drives the tape - that is the job of the capstan - however the roller (under spring pressure) presses the tape against the driving capstan. Due to the fragility of the tape and the high pressure of the roller you can understand any mechanical problem will likely damage the tape. I have seen many tapes ruined after one play in a faulty machine because of this. What happens is due to wear on the roller (caused by no maintenance) the tape is no longer pressed squarely against the capstan so drifts up or down, pushing the edge of the tape against the metal tape guide or bottom of the audio head.

Pinch rollers are designed to absorb tape detritus such as plastic backing particles and oxide. This gives rollers a lifetime, after which they become saturated and look polished or shiny and also at this time they can deform. At this point no cleaning will save them as the contaminants go quite deep into the rubber. Also due to smoking or storage in hot places the rubber may harden even if unused (causing the same effect).

So what to do? Regular cleaning with isopropyl and a microfiber cloth at 100 hour intervals does help as it cleans off the contaminants before they have a chance to migrate into the roller material (to a certain extent) but I really do feel that it is worthwhile to replace rollers in machines that are purchased used and have an unknown history - especially when dealing with precious tapes. I have also had machines where the pinch roller bearing is faulty (be it a bearing race or nylon bushing) causing wobbly linear audio due to the roughness caused vibrating the tape. Again, a new roller works wonders.

I'm in the UK and have had great success with ordering from Donberg and 121Spares, the latter of whom have a very good array of spares. A new roller will last many hundreds of hours and is a worthwhile investment. I use Panasonic decks and their G and K decks use the same roller (with bearing) and the Z deck uses the same dimension roller but with a nylon bush instead of a bearing race.

A good way to tell if a roller is needing replacement is to clean it with isopropyl and a cloth (out of the machine is best as it prevents anything being mis-aligned by cleaning pressure) is if a discoloured or polished area remains where the tape travels after cleaning and also if the roller is not flat when held against a straight edge.

Winsordawson 05-04-2015 11:14 PM

Does it matter much if you install a roller which is not of the same exact model number or family? Because a VTR of mine is about 30-years-old, and so far I have had little luck finding many parts for it...

Quasipal 05-05-2015 04:15 AM

Quote:

Originally Posted by Winsordawson (Post 38079)
Does it matter much if you install a roller which is not of the same exact model number or family? Because a VTR of mine is about 30-years-old, and so far I have had little luck finding many parts for it...

The most important thing is that the roller is the same size (for the correct pressure onto the tape) and the centre bearing fits the spindle. I have used Sony rollers in Panasonic VCR's with no problem but when ordering online it is not easy to see what is at least similar to what you want. What VCR is it you need a roller for?

Winsordawson 05-08-2015 10:25 PM

Thanks. I would probably want to replace the one on my Panasonic Ag-1970 down the road, but the biggest priority is for my JVC CR-850U. I did find some parts here, including the $45 pinch roller, and a erase head, for those still recording U-Matic tapes....

https://www.encompassparts.com/model...50U/PRO_34_VCR

Since they also sell belts, I thought I should acquire them while I can, but if the belt is not specified, how would I determine which drive belt it is intended for? Would the VCR belt kits have the necessary belts?


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