Sharp gf 525

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andyt2256

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Nov 12, 2010
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Hi all, today I found myself a sharp gf525 laying in a factory cellar in reasonable condition. But I powered it up but have now sound either on radio or tape , LEDs all light up, I have no idea how long it's been down there for.I am going to take the back off and spray some switch cleaner about but I'm sure it's prob more serious than dust etc,Any help would be great.
Regards Andy.image.jpg
 

Northerner

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Apr 16, 2012
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I've got a 525, its a quality box :)

Clean all the switches and chances are it'll likely come back to life.

The decks will likely need the capstan tyre that turns to goo replacing as it always does on GF's.

How are you at dismantling?
 

Beosystem10

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Feb 21, 2013
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At least these aren't too difficult to take apart, here's a picture of the decks after reassembly following those tubes being replaced, the bits that usually dissovle first are visible here as I had to replace them with pink fuel pipe - it was cheaper than the black stuff and fits perfectly:


And the source of suitable tyres, their round profile is fine with silicon sleeves and the o/d won't affect speed as they're idlers so play no part in the gearing, simply being there to maintain direction:



And check the plight of these capstan bushes and their holders, the black goo-fadge is the remains of what came before thae pink sleeves seen in the first picture:



Clean the goo off the bearings with contact spray, a carbon tetrachloride-based one such as that from Halfords which comes in a can with a green label. DO NOT use IPA-based cleaning products around Oillite bushes as that stuff will be absorbed by the bushes and dry them out. Once the bushes and the carriers are clean, soak the bushes in non-EP gear oil overnight to replenish their ability to self lubricate, they will start to squeal if that step is missed.
 

andyt2256

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Nov 12, 2010
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Thanks for your reply, dismantling mmm ! I can take things apart but to tell you what stuff is inside not good,may need some help! Gonna start tomorrow evening with my switch cleaner. Will see how that goes then I will stuck if that don't work, you mention capstan tyre whats that?
Regards Andy.
 

andyt2256

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Nov 12, 2010
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Sorry John , me again the pink thing I must be colour blind , the round black thing is the third in the row of pick ups meaning play and second record, I'm I making any sense. The heads I mean but don't understand the pink thing.sorry
 

baddboybill

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Jul 14, 2009
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Sorry John , me again the pink thing I must be colour blind , the round black thing is the third in the row of pick ups meaning play and second record, I'm I making any sense. The heads I mean but don't understand the pink thing.sorry


He is talking about fuel line that is used as tire over capstan shaft. This tire deteriorates over years and becomes goo. It has to be fully cleaned with Isopropyl alcohol then replaced with a small diameter gas fuel line made for gas powered radio control vehicles.

ImageUploadedByTapatalk1372801140.478082.jpg
ImageUploadedByTapatalk1372801154.332715.jpg
 

Beosystem10

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It would want to be! ;-) (Please don't use IPA in the vacinity of Oillite bushes as it is absorbed by the bushes and can make it difficult for them to absorb the fresh oil that you'd be marinating the bushes in as the two liquids aren't easily miscible. Carbon Tetrachloride-based cleaning products such as Halfords Contact spray are fine, just make sure to crack a window open while you work...)
 

baddboybill

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You mean bearings :hmmm: never had issue and the alcohol evaporates. I have never heard of alcohol absorbing into metal only rubber and plastic.
 

Beosystem10

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Bearings in terms of their rôle here, yes, but these are Oillite bushes as used in - for example - spigot bushes in flywheels on engines to carry the end of the 1st motion shaft where it passed through the clutch driven plate. They're porous and are designed to absorb gear oil which is what allows them to lubricate the capstan without making a mess of oil all over the place since they hold the oil but don't drip or leak it. Admittedly the load on a cassette transport mechanism is much lighter than that on a gearbox, clutch and flywheel assembly but when these things were built they would have been assembled with bushes that were marinated prior to assembly in a non-extreme pressure gear oil of around 90-140 weight.
A GF-555 - yet another one, I've had four boxes that use the same deck assemblies in parts this past couple of months from eBay buyers who wanted their "perfect, working" examples sorted - that I fixed recently had been stored in a very dry but also very hot attic right by a hot water tank. While this undoubtedly had helped to preserve many aspects of the set in great condition, its capstan bushes were completely dried out and when they were loaded by the pinch rollers in play mode, they screamed like an extra from a horror movie. Even a good soak didn't get enough oil into those to cure their noise completely since they'd been running dry for long enough to cause some brinelling so I spun up four fresh ones on the lathe from a chunk of suitable phosphor-bronze, marinated those in straight 90 weight oil overnight, pressed them back into the blocks, reassembled the set and sent it back to its owner. Working without the sound effects.
:-)
 

baddboybill

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I don't disagree with it being a porous bearing but the lubricant can only be applied once during manufacturing and usually dries up causing swelling, friction and noise. But after 30 plus years its most likely lubricant is gone already and because its a low speed with very little torque it shouldn't cause issues. So therefore using alcohol which evaporates shouldn't hurt. I have a fan that I've been working on with same issue with the lubricant having already dried up after only 5 years. But the fan motor builds up more heat from speed/torque causing issues. Now because of no lubricant the shaft and bearings heat up causing it to swell and then eventually lock up.

But again with the low speed of the capstan and little amount of use it gets it shouldn't heat up enough causing the swelling. So therefore using rubbing alcohol should not hurt anything ;-)
 
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