Has anyone here worked on early Betamax VCRs? - Videokarma.org TV - Video

ChrisW6ATV · #1 01-17-2012, 09:26 PM

Hello-

I am working on an early Sony Beta VCR (SL-8200) for a friend, and I have hit a potentially tough problem. The symptom is, the tape will not move when Play is pressed, but FF and Rewind are OK (or should be fine once I replace their idlers/tires). Play uses a part called a Forward Idler that includes a plastic multi-section cylinder with a spring in the top section and a rubber tire around the middle section. The idler is driven by a belt from below; all of the belts are new. The rubber tire contacts the take-up reel. Between the middle and top/bottom sections of the cylinder are pieces of material that seem to act as a clutch with the pressure from the spring in the top. The Sony test/repair procedure (from my original Sony service manual) is "test the torque in Play mode; below a certain number, replace the Forward Idler". The part is no longer available (no surprise there!). Its tire looks good as opposed to the FF/Rew ones, but I will probably replace it anyway if possible.

My questions are: Have you seen and repaired this problem in any SL-6200/6300/7200/7300/8200 Sony VCRs, and if so, how? Lacking a new idler, do you have a suggestion about maybe replacing or improving the clutch material if in fact it is bad? Thanks.

tvtimeisfun · #2 01-18-2012, 07:08 AM

Hello that machine is a boat anchor I have a couple of top loaders setting on my front porch I am not sure if they would have the parts you need.. I believe you could find those parts somewhere maybe somebody has nos parts good luck...

maxhifi · #3 01-18-2012, 09:16 AM

there is a product called rubber re-nu i think by MG chemicals. I bought a tin of it 20 years ago and have plenty left. If the idler isn't too far gone that'll get it going.

Retrovert · #4 03-05-2012, 12:37 AM

Quote:

Originally Posted by maxhifi

there is a product called rubber re-nu i think by MG chemicals. I bought a tin of it 20 years ago and have plenty left. If the idler isn't too far gone that'll get it going.

Not to reactive a dormant thread, but I found this posting and dug out some information on the product. The product is indeed from MG Chemicals but it is called Rubber Renue. It is described as:

Quote:

Rejuvinates and conditions rubber. Apply with a cloth, brush, or swab to bring belts, platens, rollers, and rubber parts back to life.

Zero residue
Fast dry
Removes oxidation film
100% Ozone safe

The MSDS says it contains: Xylenes 70-90% and Methyl salicyate 10-30%. Xylene is a common solvent; it's like toluene. Methyl salicyate is Oil of Wintergreen, and is the active ingredient in the electric shaving cleaner/lubricants sold in an aerosol can.

Another product that I dug out is called Fedron from Federal Mining & Manufacturing Company. It is described as:

Quote:

FEDRON is a clear liquid, blended of highly refined pure chemicals, specially formulated for cleaning rubber, metal, Teflon, silicon, and similar materials. FEDRON cleans and revitalizes, making your investment last longer.

The MSDS lists: Xylol 40-50%, Ethyl Acetate 5-10%, Methanol 1-3%, Ethanol 40-50%, Methyl isobutyl ketone 1-5%. Ethyl Acetate and Methyl isobutyl ketone are used as solvents as in nail polish remover.

I have no direct experience with either one.

ChrisW6ATV · #5 01-22-2012, 01:57 AM

Thank you both for the notes. TVtime, if I do not have success with replacing the tires on these idlers, I may get in contact with you for a possible part from one of your units if they are otherwise not going to be used/restored.

ChrisW6ATV · #6 02-11-2012, 04:27 PM

I have replaced all of the tires and FF/rewind are fine. Play is still bad, for a different reason: The capstan motor does not turn. My service manual is actually for the SL-7200 (one-hour-only version of this machine), so I am ordering a Photofact manual for this model.

ChrisW6ATV · #7 02-15-2012, 10:32 PM

I got the manual and looked online for the motor. Other owners have had the same motor freeze, so I took this one apart and added a drop of oil, then exercised it, now it turns nicely. I am going to put it back in and see what I get.

ChrisW6ATV · #8 02-16-2012, 12:01 AM

I reinstalled the motor, and the machine plays and records well in both speeds.

tvtimeisfun · #9 02-16-2012, 06:37 AM

Hello congrats on fixxing your machine hope it last awhile good luck..Timothy

ChrisW6ATV · #10 02-19-2012, 06:21 PM

Thanks, Timothy. The machine has some trouble locking onto signals recorded on older tapes (the motor/servo system "hunts"), but it seems fine with its own recordings, so I am doing a few more tests.

ChrisW6ATV · #11 02-19-2012, 07:16 PM

Well, it is not a new/old issue, or this VCR/other VCRs issue, but an X1/X2 (Beta I/Beta II speeds) problem. It locks onto the BI one-hour recordings perfectly every time but has problems with BII recordings, even the ones it just made itself. Now, I need to start figuring out the motor servo control system, apparently. Anyone here have any hints or tips? Thanks.

Electronic M · #12 02-19-2012, 09:13 PM

look at the speed switch and what parts it connects into circuit exclusively for the beta II speed odds are it is one of the parts that is only used for beta II.

ChrisW6ATV · #13 02-19-2012, 10:54 PM

Thanks for the suggestion, Tom. There is a speed switch but it is only for recording; the play speed is set automatically (as with all VCRs I know of). The servo circuits do possibly have sections that are dedicated to each speed that I will look at. Also, a few things I have found online point to bad tantalum capacitors in those circuits. I already checked the electrolytics and tantalums in some of the circuits and replaced one bad tantalum (with no improvement), but now I will check them again more closely and also look for more servo circuits I may have not yet checked. (They are spread over at least two boards that I have checked so far.)

ChrisW6ATV · #14 02-22-2012, 11:50 PM

I checked the boards again and found several tantalum caps that have high ESR. I am going to replace them and see if it helps.

ChrisW6ATV · #15 03-05-2012, 10:31 PM

Thanks, Retrovert. I am still working on this VCR, but I did buy replacements for all of the rubber components except the pinch roller. I also got a second of the same model VCR, and I am going to replace all of its rubber parts and relubricate it before I work further on the first one. The second machine worked OK in both speeds when I got it (except for standard symptoms of old belts and tires), so I hope to use it to help troubleshoot the first one.