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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 29th Nov 2021, 3:03 pm   #1
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Default Shifting the crud?

We’ve all ‘been there’ - and I’d welcome any advice and counsel with regard to your own individual approaches and experiences!

Yesterday’s ‘patient’ was part of a Sony Mini Hi Fi system that I’m in the process of restoring - this module being the TC H500 twin ‘auto-reversing’ cassette tape deck unit. I’ve worked on many tape decks before [including another one of this particular model] - and I wasn’t looking forward to it .... given that transport access etc. necessitates major autopsy/dismantling. This unit is now some thirty/forty years old and was impregnated with nicotine and infested with dust of indeterminate composition! It was obvious that the drive belts had long since given up the will to live, but that the pinch rollers remained perfectly serviceable. So, apart from deep-cleaning [even the boards were ‘sepia toned’!] a few ‘repairs’ were necessary i.e. load-latch mechanisms, drive belt replacement, and a re-lube etc. etc.

And here’s the rub! The drive belts [an unfair description of these particular specimens!] were the worst artefacts that I’ve ever encountered! Remnants were scattered around the transport - but most had fused to the capstan flywheels, idler, and motor pulley - and thereafter assumed the properties of un-set polysulphide/silicone sealant!

I donned a pair of nitrile gloves [several in fact] and set to work armed with: a toothpick, cotton buds, scraper and a catering flagon of IPA [and some meths too]. This ‘revolting mess’ will adhere to anything that it touches, and is difficult to remove from your hands too i.e. without appropriate solvents etc. (Each ‘nasty shovel-full’ was therefore progressively smeared onto a piece of kitchen tissue and repeatedly disposed of as the mission progressed ...)

Given that this unit utilises vee rather than flat belts - I grudgingly removed the metal capstans/flywheels [+ spacers/thrust washers] and spent a long time raking-out the belt grooves and lands, mindful that any residue could pick-up on the replacement belts and impair playback and recording quality [which is usually very good on these decks]. The idler and motor pulleys are however of nylon composition and rather more difficult to disassemble - so these were done in-situ (and perhaps because of their material composition), were marginally easier to clean.

As mentioned earlier, I have always used IPA as a cleaning solvent for this ‘horrid’ job - mindful that other more aggressive solvents [e.g. lighter fluids etc.] may damage adjacent plastic-based components.

The unit has now been reassembled, and performs perfectly - but this was never a job that I wanted to throw myself at - and sincerely hope that I don’t encounter a similar challenge for some [considerable] time!

So - my question is this: what has been your own approach, method[s], tools and materials when confronted with this awful crud?
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Old 29th Nov 2021, 3:07 pm   #2
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Default Re: Shifting the crud?

Declining!

David
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Old 29th Nov 2021, 3:10 pm   #3
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Declining!

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I can't say that I blame you David - I'm still recovering from the experience!
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Old 29th Nov 2021, 4:28 pm   #4
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Default Re: Shifting the crud?

Packs of wooden ice lolly sticks are available on the internet, and probably elsewhere too. By shaping the end of a stick to match the belt groove it is possible to remove a good amount of the crud in a single sweep and with a much reduced chance of damage compared with a metal tool. These sticks cut very easily with a pair of wire cutters so once the stick is contaminated just snip off the bad bit and start again.

As well as the lolly sticks I find wooden cocktail sticks very useful for similar tasks. They are also great for plugging oversized screw holes.

Al
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Old 29th Nov 2021, 4:29 pm   #5
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Default Re: Shifting the crud?

When IPA is struggling, I sometimes try white spirit. Not sure I've used it on belt goo, but may be worth a cautious try.

B
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Old 29th Nov 2021, 4:47 pm   #6
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Default Re: Shifting the crud?

Yes can be a really difficult horrible job even on a reel to reel with better access.

When IPA/Meths struggle (often) I resort to Cellulose Thinners (at least for removing stubborn belt deposits off metalwork) but of course have to be very careful not to get on rubber/plastic parts and initially of course it just spreads the mess more quickly.

David
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Old 29th Nov 2021, 4:58 pm   #7
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Default Re: Shifting the crud?

I've recently successfully done a mid-1990s JVC microsystem, and an early 1980s Marantz cassette deck.

The important points were:

Lots of newspaper over the kitchen worktops,
Disposable gloves,
Old clothes,
Scrape off as much as possible with cocktail sticks and slices of old loyalty (etc.) cards,
Cif and a non-stick scourer work surprisingly well to remove what's left (thanks to whoever mentioned that on this very forum).
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Old 29th Nov 2021, 5:00 pm   #8
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Default Re: Shifting the crud?

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Originally Posted by Bazz4CQJ View Post
When IPA is struggling, I sometimes try white spirit. Not sure I've used it on belt goo, but may be worth a cautious try.
I agree, white spirit or turps substitute is cheap and dissolves oily filth quite well. It doesn't seem to attack plastics. WD40 works too, but is a lot more expensive than bog standard white spirit.
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Old 29th Nov 2021, 5:15 pm   #9
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Default Re: Shifting the crud?

Freezing can help, the majority of the offending will "ping" off. Dry ice or liquid nitrogen (LN2 available at work!) for the stubborn stuff.

As to white spirit, paraffin is cheaper but smellier.
 
Old 29th Nov 2021, 5:53 pm   #10
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Default Re: Shifting the crud?

I carefully apply dry fine powdered earth from my garden to the sticky goo and work it up into a stiff paste with a wood spill The paste can be scraped off more easily than the goo. Care needs to be taken to ensure that the powder doesn't get onto bearings etc. Our local soil is predominantly a very fine brick earth that reduces to an impalpable powder when thorougly dried. Crushing a piece of broken flower pot in a pestle and mortar is another way of making a very fine, highly absorbent powder.
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Old 29th Nov 2021, 6:21 pm   #11
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Default Re: Shifting the crud?

Pics of the aforementioned Marantz, before and after some Cif:
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Last edited by Nickthedentist; 29th Nov 2021 at 6:27 pm.
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Old 29th Nov 2021, 6:33 pm   #12
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Default Re: Shifting the crud?

Some interesting and ingenious responses to-date guys - much appreciated. I wonder ..... whether localised application of freezer spray would have a similar effect as [the somewhat extreme] liquid nitrogen and/or deep-freezing approach?

That said - I once watched a mate drop an effects pedal into a bath of liquid boron .... which emerged 'like new' (I can't recall whether it ever worked again tho') !!!
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Old 29th Nov 2021, 6:47 pm   #13
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Default Re: Shifting the crud?

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As to white spirit, paraffin is cheaper but smellier.
There's not much in it really - Poundland sell 500mL bottles of WS for a quid. You can certainly use paraffin or diesel if you have some to hand, though you obviously need to clean it off thoroughly.
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Old 29th Nov 2021, 7:52 pm   #14
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Default Re: Shifting the crud?

Interesting reading up on the liquid Boron, can't say I had heard of it before.

Used Boron a lot in a previous job, well actually Boron Ions extracted from carrier gas BF3 (Boron Trifluoride).

David
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Old 30th Nov 2021, 4:09 am   #15
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Default Re: Shifting the crud?

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As to white spirit, paraffin is cheaper but smellier.
I wonder if domestic fuel oil works - I've just had a delivery of 1000 litres of that stuff (58p/L) .

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Old 30th Nov 2021, 10:30 am   #16
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Default Re: Shifting the crud?

I can see that Paul and Bazz generally prefer the more 'aromatic' bargain basement solutions!

However - Nick's suggestion re. the use of sliced-up old credit cards etc. [which produce a thin, sharp, square, but non-damaging edge] is a great idea.
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Old 30th Nov 2021, 10:41 am   #17
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Default Re: Shifting the crud?

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Originally Posted by Tractionist View Post
Some interesting and ingenious responses to-date guys - much appreciated. I wonder ..... whether localised application of freezer spray would have a similar effect as [the somewhat extreme] liquid nitrogen and/or deep-freezing approach?

That said - I once watched a mate drop an effects pedal into a bath of liquid boron .... which emerged 'like new' (I can't recall whether it ever worked again tho') !!!
Boron has a melting point of about 2073 deg C: set the place on fire!

Borax decahydrate melting point 75 deg C. More likeley or maybe just a strong solution of the same in water
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