Idler wheel on 301

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emlt
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Idler wheel on 301

Post by emlt » 29 Dec 2017 14:48

I’ve been having an unusual problem of a ‘melting’ idler wheel leaving a black residue on the motor spindle, on the inside of the platter, reducing friction to the point where the platter slows down to a trickle. The only solution so far has been to remove the platter, clean everything, and start again. After a few spins, the problem recurs. Even mild sand papering the idler wheel at 78rpm has not helped. Also, the rubber looks perfectly OK, round, smooth with the right degree of firmness. Now this is on a NOS 301 that had sat unopened for 53 years. Finally had to bite the bullet and ordered an expensive new idler wheel from Perfectsound UK(costing more than what I paid for my entire 301), which arrived yesterday. The instructions say to keep it running for 48 hours for the rubber to get evenly heated. Which brings me to my question. Would it have helped to have done the same with my NOS idler wheel? Would the long hibernation have caused the rubber to weaken? To the point where it needs to be ‘broken in’ again? The original manual does not address the issue at all, but maybe you guys have had similar experiences, and found solutions that you might share. Thanks in advance.

A70BBen
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Re: Idler wheel on 301

Post by A70BBen » 29 Dec 2017 22:53

My 301, which I have owned since 1970 or a little before, is on its original idler wheel and exhibits none of the symptoms you describe. But its whole life has been in a dry and temperate climate. If yours has spent its [-o< life in Bombay, the climate could account for a big difference.

emlt
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Re: Idler wheel on 301

Post by emlt » 30 Dec 2017 12:23

Thanks, A70BBen!
I also have a 401 ( from 1965) that has spent all Its life in a tropical climate, with an original idler wheel that runs on perfect speed. Never even had the need to clean that wheel even once. So it must be something else.

A70BBen
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Re: Idler wheel on 301

Post by A70BBen » 30 Dec 2017 21:02

DSJR has noted a change in the rubber in the Garrard 53883 idler wheel, which was used from the RC121 and Model T to the Lab 80. It could be that the change affected the 301/401 idler, too. The timeframe includes ghe acquisition of Garrard by Plessey, who had its own 6⅝ "pet" vendors.

dave999
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Re: Idler wheel on 301

Post by dave999 » 02 Mar 2018 14:52

sounds like water or oil contamination of the rubber.
oil contamination
oil contamination of bike brake blocks results in similar transference of rubber to the wheel rim. usually fixed by a good clean in clothes washing detergent dishwashing detergent...i'd suggest a quick wash with soap and water might fix that soap being the least aggressive of the 3.

Water contamination and general pershing issues due to it....

you could try sitting it in organic brake fluid, UK standard DOT 3. for a week

keep in mind this stuff is poisonous so do this in a place where children and animals can't reach

clean it with detergent.
dry it
put it in a pot of brake fluid with a lid on to keep the air and humidity out
leave it to stand for a week
remove it and leave it to dry
excess brake fluid will migrate out carrying water and black residue
keep wiping it off
when no more comes out
dust it with talcum powder
clean the rim with a dry cloth and have another go.
use neat dish washing liquid to clean the inner wall of the paltter. rinse it all off and dry it
Help the turntable start up to avoid flat spotting it and after a few minutes it should be back to normal

the old style brake fluid is designed to make the natural rubber seals in a car braking system swell so they seal well and do not break up, the swelling action also closes surface voids and cracks, brake fluid is very hygroscopic so will attach itself to any water (from humid environment) that has migrated into the rubber.
water UV light and oxygen result in perished rubber which is potentially responsible for the transfer of black stuff to the inside of your turntable platter. swelling the rubber removing the water vapour with the brake fluid might be all you need.

The result should be a more supple wheel and its surface will look many years younger.
this also works with seals and rubbers for car restoration.

it is a risk but as you already have a wheel that doesn't work, it might be worth taking,
i have used this method to great effect when restoring a garrard 4hf which suffered a similar issue, although hard to see if i had the rubber transfer that you have as the 4hf platter is black. the deck is worth way less so i was perfectly willing to take a chance and just scrub the lot in hot soapy water in the sink before re assembly.

Dave

dave999
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Re: Idler wheel on 301

Post by dave999 » 02 Mar 2018 14:58

PS total mis alignment due to a bent idler wheel carrier can also produce similar effects..break out the sprit level
totally level the deck
then check that the top of the idler wheel carrier is level as well.
Dave

DSJR
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Re: Idler wheel on 301

Post by DSJR » 03 Mar 2018 12:11

The 401 idlers I remember (we sold them fleetingly until 1975 or so when the 401's were quietly retired from production - they were awful rumble boxes by this time as we didn't have the dedicated setup and plinths available now and could be bought for £36 at discount) were hard compound I recall and nothing like the softer idlers as fitted to the 'lower' models including the Lab 80's, let alone the finely radiused ones as fitted to Duals, which I still think are amongst the finest idler decks ever made and with surprisingly good tonearms too. Maybe its the not used storage over decades but can't comment further on how the rubbery compound would react. I've never seen this myself on a Garrard, but again, I've never seen a terminally slipping 'Autoslim' idler that can't be dressed either, so maybe climate?

Rubber breaking down isn't a new thing. I had a section of a rubber drive belt (CD player loading belt) which was trapped between the clear plastic bags components come in. In ten years it had turned almost to liquid and it's a beggar to remove from carpets :(

One thing I'd say. The new-old 301 MUST have the motor bearings soaked in suitable lubricant before use and MUCH CONSIDERATION should be made of the main bearing spindle and how that is lubricated as sintered steel bushings need regular oiling apparently if the shaft isn't to get running marks quickly and if it's a grease bearing, the grease may be a tacky glue now - I'd recommend light lube on the thrust assembly as both 401s disliked flooding with oil as they rotated in sympathy if over oiled all over. These decks were designed for years of 24/7 running but please, only run the new idler in for 48 hours once fettled and not before.

They're silly-money expensive for well heeled audiophiles, but Loricraft is your friend here as at least they have the background knowledge and documents to make precise recommendations. If anyone out there wants to modify the main bearing, I'd say DON'T, but perhaps if the itch is there and the money is burning a hole in one's pocket, a total replacement could be considered - why, I don't know as it's the drive which causes the most noise, but I digress...

Good luck.

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