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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc.

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Old 27th Sep 2020, 9:56 pm   #41
Ewasterecycling
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Default Re: Cleaning video heads etc

Hope this helps on head cleaning too?...

I found yesterday that ebay had some stocks of Chemtronic cleaners, so if you don't have an Amazon account, these are also available:

https://www.ebay.co.uk/itm/Chemtroni...0/283597680940

Soak a pad certainly with IPA Isopropyl Alcohol (99.9%) and very gently press to the side of the entire head block azimuth unit. Hold it there, then gently turn the upper drum part to where the tiny head slot is located (usually 2, but some can have 4) so that then contacts with the wet pad and slowly turn the drum back and forth about 3 times.
Once done remove the pad and you should see a blackish line if any dirt was removed.
Never then reuse the pad, even if you can't see anything on it. Get a fresh one and repeat for the other head(s).

Retain the plastic sticks though as then you can reuse them again, with a new bit of Chamois strip cut from a large cloth that's widely available from most suppliers

It's true also (certainly for the VCR's I get in) many have dirty tape paths so it will be best to clean up everything before running a tape.

Most faults incidentally are just: worn pinch-roller, reel idler, broken and/or bad belts.
Being mechanical, it's a joy to work with as you'll be able to easily see which parts need replacing!

Getting the bits sadly is now the only real problem.

Also lastly, once/if you do get the machine to play, if the picture displayed is bad and looks like the heads could be worn out... just try a fastforward playback (if the machine has that function) as I've found in the past what looks like a sad tale of a dud head, actually it CAN be just a stubborn bit of gunk (possibly from a mouldy old tape!) that gentle cleaning didn't shift but a highspeed rip-through playback actually can clear!

This 'trick' also works well on Umatic machines too, as experience has shown their heads can clog-up badly certainly if bad tapes are used, and often machines are scrapped as it was assumed the heads were gone, but again it's just dirt.
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Old 11th Jan 2021, 9:20 pm   #42
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Default Re: Cleaning video heads etc

I used to use my thumb nail, whilst attached of course, I never broke a head tip and thinking about it now it appears crazy. I managed to judge the pressure needed to achieve good results, you see people pussy footing around on successful methods but mine worked.
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Old 10th May 2021, 6:51 am   #43
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Default Re: Cleaning video heads etc

Metho on a clean handkerchief, pulled tightly over the index finger. Pure Alcohol is better, with metho you must wait for it to evaporate or the drum can stick to the tape and make a terrible tangle. Same with pure alcohol, but it evaporates more quickly. Move the drum while holding the finger still, and turn it in the direction away from the finger. Then clean the lower drum trouble spots with the same covered finger, only, obviously this time you have to move the finger. The complete tape path must be cleaned, if it's a modern machine, you may find that the pinch roller is made from something other than rubber, which DISSOLVES in metho. You can clean it all day and still get a black finger. Also they go hard before they should. If you have an early roller that's OK, keep it in service. If the tape guides have nylon rollers, make sure they're free to turn. The audio/sync head is an important clean, the audio portion is at the top, I use a strip of kangaroo thonging, which is about 5mm wide, and work it like a shoeshine boy cleans a shoe with a rag, keeping it near the top of the head. The audio track is only something like 0.3mm wide so clean is essential. It doesn't need to be wet. If the machine is a 6-head type, because there are six heads on the spinning drum, the tape is slightly pushed away from the drum by each head that hits it, so the tape to head contact is never as good. This usually means that the performance drops off earlier with these machines. Clean the drive belts and the pulleys they run on. Re cleaning rollers, the foam rubber ones we used over here in recent times, were perished when we bought them into stock, so we had to stop using them and remove the cleaning assembly altogether. Creases in the tape is the main cause of dirty heads. Good tapes and you get a long time between problems.
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Old 28th Sep 2021, 5:33 pm   #44
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Default Re: Cleaning video heads etc

I wonder if anyone can offer me advice on my Toshiba RDXV59DT VCR player which has suddenly started to reject the tapes. Yesterday, after cleanng the opto sensor, I was able to get the machine to accept the tape, and advance the rollers to wrap it around the drum but then it would switch off. Switching it on again, it rejected the tape without rewinding it. Today, I am back to square one, the tape goes in and is immediatly rejected, and ejected again.

The player is 6 years old and this is the first problem it has thrown up. I am more famiar with radio sevicing than VCR recorders so any advice on where to start trouble shooting this problem would be much appreciated.

Thomas.
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Old 19th Oct 2021, 10:12 am   #45
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Default Re: Cleaning video heads etc

When I had a Grundig V2000 2x4 Super, I found that using my BASF tapes would always clear the video heads. If the heads had become badly clogged it may take a minute or so but always seemed to work. Of course the formulation for their VHS tape may be different and also the head structure.
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Old 19th Oct 2021, 10:41 am   #46
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Default Re: Cleaning video heads etc

Nail polish remover pads work well too with IPA on them.
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Old 16th Nov 2021, 6:41 am   #47
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Default Re: Cleaning video heads etc

Sometimes if the loading takes too long the computer may bail out, make sure the guide path is not gummy. If there is no sign of tape movement the capstan motor may not be providing the next step. Or if it IS, maybe no takeup owing to a dodgy takeup clutch. The later design of these used a coil spring over a plastic shaft, which chewed away the shaft until it was too small for the spring to have friction with it anymore. But there are MANY other possible causes.
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Old 25th Nov 2021, 9:38 pm   #48
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Default Re: Cleaning video heads etc

In broadcast we used to use Xylene. It evaporates very quick and is a better solvent than alcohol. Unfortunately it's nasty stuff and got banned from use a couple of decades ago. Nevertheless you could often still find a small bottle hidden at the back of the the cupboard for those stubborn head clogs.
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Old 27th Nov 2021, 4:37 pm   #49
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Default Re: Cleaning video heads etc

Quote:
Originally Posted by Sundog- View Post
In broadcast we used to use Xylene. It evaporates very quick and is a better solvent than alcohol. Unfortunately it's nasty stuff and got banned from use a couple of decades ago. Nevertheless you could often still find a small bottle hidden at the back of the the cupboard for those stubborn head clogs.
Blimey. Xylene -- That stuff will melt some plastics ! almost as nasty as trike. I stick with IPA (not the beer).
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Old 27th Nov 2021, 4:52 pm   #50
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Default Re: Cleaning video heads etc

Not sure what's in it, but back in the days when I occasionally needed to cklean heads I used 'brake cleaner' spray available from car-parts shops.

Squirt a bit onto a Q-tip and dab away the accumunated cruft and oxide-particles.
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Old 28th Jan 2023, 10:23 am   #51
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Default Re: Cleaning video heads etc

IPA is preferred because some heads use lacquers that can be dissolved by meths - it was an essential consumable for computer industry maintenance (for both fixed heads amd helical scan).

It's really sensible to do the tape guides too, very cautiously (both audiovisual and comuter drives), as crud can cause edge damage to the tape, which in turn can cause misalignment going round the drum, and/or affect control and audio tracks.

Speaking of head drums, don't neglect the 'shelf' on the static part of the drum, that helps the tape conform to the helix. Also, particularly on smaller mechanisms, take extreme care not to disturb the movable tape height guides either side of the drum assembly. They were adjusted on test (AoT) in the factory, to get the correct waveform off the replay heads - depending on the overall system can cause a significant drop in output if they are wrongly adjusted. It was a common form of 'read failures' in the computer industry, until it discovered stronger Loctite!

I am more familiar with the design of digital systems than analogue: most computer industry drives had separate read heads (two read and two write in most instances), to optimise for reading and writing. I'd expect two head (i.e. one head does both functions) systems' performance to drop off rapidly with wear, as the head gap opens up.

The idea of an IPA-soaked business card isn't a bad one. HP's DAT/DDS drives started off with a foam wheel that was briefly moved into contact with the head drum for a few seconds during tape load, to clean detritus off it and the heads, DDS-3 and later drives had this replaced with a slightly abrasive flap wheel ("the flapper", which looked similar to those used in a drill for DIY sanding/shaping applications, but miniaturized). That said, heads are pretty tough and will probably collect the surface of the card if allowed to spin at normal RPM. I think I'd only do this turning the drum manually.

Personally I do use cotton buds to clean helical heads. The original reason this was deprecated was the idea that loops of cotton fibre could catch and pull the head out of alignment, but in my experience they're not that fragile, and I use extreme care and gentleness. Point being that cotton buds can contain more IPA than other things, so you stand a better chance of removing the crud, and you can easily see if you "caught" anything.

On our head drums (DAT-DDS), there were usually "W" and "R" letters screened on the printed circuit board, corresponding to the radius of the write and read heads. Read heads are slightly smaller and more fragile, so it was easy to tell which one you were addressing.

On DAT drives, the written tracks overlap slightly (it's in the original standard for the system, which uses slightly slanted azimuth to help separate them out)), which is another reason why misaligned guides can be a real nuisance - the read heads pick up too much crosstalk. I think this is also true of some helical video formats.

Cleaning tape cartridges also existed for many of the helical formats, which use slightly more abrasive tape. In the case of computer drives, these were detected as such by the drive when the cartridge was loaded (For DAT by a hole pattern at the back of the cartridge, for others by reading a chip in the cartridge rear corner). The drive had a cleaning algorithm, and only used a section of the tape without rewinding it. In my experience cleaning tape work well, but should never be rewound for re-use, as they retain the carp off the heads and guides.

PS: I think Colclene (ubiquitous in the BBC) had a small amount of Xylene in it, judging by the smell. Even though Xylene is an excellent degreaser (and you can still get it), I wouldn't go near a tape head of any sort with it! (did anyone else modify Colclene nozzles to get a 10ft jet from the can for use as a Star Wars weapon? It's amazing I haven't died of something nasty... ).

Last edited by Simondm; 28th Jan 2023 at 10:37 am.
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