Install roller guides on Pioneer RT 707 tension arms - diyAudio
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Old 12th March 2014, 01:36 AM   #1
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Question Install roller guides on Pioneer RT 707 tension arms

I would like to find roller guides to attach to the tension arms of my Pioneer RT 707. I went to the Action Bearing site but couldn't find any that are sized or shaped right. I would like beveled flanges at both sides of the flat surface but the only bearing with that shape was much too large. I may take the arms to the store to see if they can come up with a bearing that could do the job.
Playing old dried out tapes through the non-roller guides on the tension arms makes the tape vibrate and chatter. On my last transfer job, I had to apply silicone lubricant with a pipe cleaner as it ran. Has anyone put roller bearing guides on this machine?
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Old 13th March 2014, 11:42 PM   #2
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How old are your tapes?

As tape gets older they absorb moisture and become gummy and sticky, and sometimes start to shed profusely because of it.

It is always good to have guides that are on rollers but I have the same problems with some of my tapes on my MSR-16 and everything is roller except for the guides right next to the heads.

My older Teac's have the same issues as your machine as well, I used to have one of those RT-707's, I loved that thing.

My 1/2" test tape is sticky like that as well.

It will sometimes stick to the heads causing the machine to not go into a rewind or fast forward mode is the tape is locked up and stuck to the surface of the heads.

I understand the only way to alleviate this problem is to bake the tapes to dry them out, But I have not tried this yet.

jer
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Old 14th March 2014, 12:47 AM   #3
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Baking from my very limited experience is a one shot deal, had best transfer them to another medium immediately after baking. Watch out with acetate based tape, it is quite flammable.
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Old 14th March 2014, 12:57 AM   #4
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Thanks for the tip on that, all of may tapes are Mylar based but I am still wary about trying it.

Especially with my $200 test tape!!

I have read about cleaning them with alcohol and have done this with a few spots, and, I have done this dry with some tapes before and it seems to help.

I have thought about maybe using a Graphite powder to coat the tape as well, as this seems a lot safer than using any oils that can later collect more dirt and dust.


jer

Last edited by geraldfryjr; 14th March 2014 at 01:04 AM.
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Old 14th March 2014, 11:25 PM   #5
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Thanks geraldfryjr for your reply. I operated the recording studios at Berklee College of Music for 31 years. In the late 1970s many of the tape manufacturers changed their binder formulation and later we found that it absorbed moisture and became gummy as you experienced. Before transferring a recording to digital, we would put it in a convection oven and monitor the temp for around 130 degrees for around 3 to 6 hours and then let it cool. The tape I recently was asked to backup was a Gene Krupa concert from 1970. The tape was likely a copy and it was on a Concert brand tape made for and sold by Radio Shack. I couldn't tell if it was acetate or mylar but I think it was acetate. The lubricant, which I think was mixed in the binder when manufactured, was completely dried out. I applied silicone lubricant via a pipe cleaner as I stated before. I should have applied the silicone to several pipe cleaners so I wouldn't have any time gaps when having to change applicator. Because of the application gaps in time, I did get some scraping sounds. I should have stopped, backed up, prepare an applicator and start from there but I would have had to do edits of the digital file. Once I applied too much lubricant and lost traction between the capstan and pinch roller so I did have to restart and edit that spot. I did buy some talc but didn't try it until I was done with the transfer. I did then give it a brief try and it seemed to work. I did go to Action Bearing with the tension arm and they said they don't know of any bearing made that would do the job.

Last edited by Reel To Reel Joe; 14th March 2014 at 11:50 PM.
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Old 15th March 2014, 11:41 PM   #6
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You can try contacting Terry's Rubber Rollers & Wheels,

Terry's Rubber Pinch Rollers & Wheels

I know he makes Roller bearing Pinch rollers for my Tascam's and other machines maybe he can custom make you the Idler's.

I need to get a hold of him myself as my pinch roolers on my MSR16 & 38 have gone soft and gummy!

jer
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Old 4th April 2014, 11:29 PM   #7
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Default Pioneer RT-707 roller guides

I did it!
I sourced some miniature ball bearings that had dimensions that I could make work. It was a compromise from my ideal but it works. My ideal would have been a quarter inch diameter flat area one quarter inch wide with outward beveled flanges. I did find the shape I wanted but it was in a series of bearings that were much too large. I ended up using two miniature bearings for each arm which had extended inner rings at both ends. The width of the inner rings are one eighth inch, so two on the same shaft added up to a width of one quarter inch. I used revet washers with an ID of 1/8" all on a #5-40 machine bolt. I had to put all 4 washers on the bolt with a nut and mount the bolt in a Dremel machine to grind the washers down to a little less than 9 mm in diameter so that they would give me enough room between the washers and the roller or capstan roller. One nut plus one washer added up to 4 mm, which is the original spacing between the arm and the edge of the original Pioneer guide. I did have to do a bit of grinding on the thickness of the washers to meet this goal.
So I have roller gudes with a small space in the middle between the two bearings and I have guides with a 1/4" width even though the guides are fixed (not rotating).
If enough of you would like to try this, I could work on an information sheet listing parts, sources and instructions.
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