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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 10th Feb 2021, 10:38 pm   #1
Linnovice
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Default PR99 transport problems

Good evening all. I have a couple of problems with my Revox PR99 MkII.

The first is getting the thinner range of tape to run (Maxell 18-180). It wonít play, fast forward or reverse. The relevant button will not hold engaged. Itís fine on thicker tapes so Iím guessing the problem lies with the EOT light. It must be going through the tape so my question is, is there any adjustment that can be made. I canít find anything n the manual but Iím hoping for suggestions (polite please).

Second is a fast forward problem. When in the ff mode towards the end of the tape it looses power, especially on 7.5Ē spools. The tape path is clean and itís on any tape, itís not sticky shed. The brakes are releasing fine and Iíve changed the motor run caps. I canít think what else to check. Itís good in play and fast rewind, it only happens in fast forward.

All suggestions would gratefully received.
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Old 11th Feb 2021, 5:12 am   #2
TIMTAPE
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Default Re: PR99 transport problems

18 micron is a thin tape on a machine not known for gentlest tape handling. I'd be checking that braking as well as pinch roller and capstan are in good working order. I think the B77 on which the PR99 is based was optimised for 35 u tapes.

With the EOT sensor, maybe a quick, easy workaround would be placing a semi opaque piece of material in front of the sensor until you find something which works for the thin tape as well as thicker types.


FF problem: motor bearings? Check tensions with a spring gauge and string.
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Old 11th Feb 2021, 12:30 pm   #3
Linnovice
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Default Re: PR99 transport problems

I’ve just checked the torque on the reels as per the manual. Three of the stated measurements are well within tolerance the four (left spool pulled down at 8:00) is 0.5N over the stated. Could this be the problem.

Daft question perhaps. These are static measurements, ie. reels not powered? Just measuring brake drag?
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Old 11th Feb 2021, 5:22 pm   #4
Tim
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Default Re: PR99 transport problems

Does your PR99 have a special button to press when you are using large( NAB) spools? If so is it in the appropriate position for your chosen take up reel?
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Old 14th Feb 2021, 5:54 am   #5
Linnovice
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Default Re: PR99 transport problems

I think I’ve corrected my ff/fr problem. The supply side tape guide consists of a ball race with in a pair of stainless guides. The ball race has a shim either side of the central race to lock it and set the 1/4”+ spacing between them. I found that by increasing the shims the dragging on the tape was alleviated and all speeds run fine now. The give away was that I realised it was only happening on on Agfa PER368 tape. When I used a Maxell (any) or other Agfa (PE36) it wasn’t happening. I’ve only increased the shims by .004” and it’s now fine on all tapes. I can only think that PER is just slightly wider and being a backcoated tape, stiffer, it was binding on the sides of the guide. It may well be the other tapes were tight in there too but were a bit narrower and smoother so the dragging wasn’t so apparent.

As far as the EOT and thinner tapes is concerned. I’ve taken the advice of TIMTAPE, I now have a piece of masking tape, cut to size and blacked out at one end whic I stick over the EOT. Works a treat, thank you ��
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Old 14th Feb 2021, 9:12 am   #6
Ted Kendall
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Default Re: PR99 transport problems

PER368 has a very rough back coating - it could be that there is excess friction on the moving guide pins, especially if these are worn. Usually two shims on the roller are all that is needed.
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Old 14th Feb 2021, 10:13 am   #7
Linnovice
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Default Re: PR99 transport problems

Yes Ted, that is correct. I still only have two shims, just slightly thicker ones. I do think I’ll avoid using the PER368 on my A77 all the same.
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