|
Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment. |
|
Thread Tools |
12th Apr 2019, 5:51 pm | #1 |
Dekatron
Join Date: Nov 2006
Location: London, UK.
Posts: 3,496
|
Garrard AT-6 autochanger, idler wheel dia?
Hi,
I'm restoring this AT-6 autho-changer (as well as the Dansette Hi-Fi amplifier MKI that helps it realise its ambitions, for someone else. I've removed and de-greased the idler wheel, which was covered in machine oil. I'm just checking, what's the diameter of a new wheel (ie not worn), before I replace it an circlip it back. Also... Has anyone found slippage of the wheel on the spindle? What's the remedy?
__________________
Al |
12th Apr 2019, 5:52 pm | #2 |
Moderator
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,287
|
Re: Garrard AT-6 autochanger, idler wheel dia?
The diameter of an idler wheel is immaterial unless it's worn so small that it does not grip the motor shaft and turntable rim.
__________________
Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
12th Apr 2019, 6:10 pm | #3 |
Hexode
Join Date: Dec 2018
Location: Sheffield, South Yorkshire, UK.
Posts: 364
|
Re: Garrard AT-6 autochanger, idler wheel dia?
Garrard wheels are 40mm but as Graham says the diameter plays no part in speed accuracy
|
12th Apr 2019, 8:20 pm | #4 |
Dekatron
Join Date: Nov 2006
Location: London, UK.
Posts: 3,496
|
Re: Garrard AT-6 autochanger, idler wheel dia?
Thanks Graham and brassbits...
What about the wheel slipping on the spindle? It’s only push-fit, so why wouldn’t it slip?
__________________
Al |
12th Apr 2019, 8:23 pm | #5 |
Moderator
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,287
|
Re: Garrard AT-6 autochanger, idler wheel dia?
Sorry, but I don't understand the question. Is the (idler) wheel required to drive the spindle it's mounted on?
__________________
Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
12th Apr 2019, 8:43 pm | #6 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,535
|
Re: Garrard AT-6 autochanger, idler wheel dia?
Spindle = motor shaft?
__________________
....__________ ....|____||__|__\_____ .=.| _---\__|__|_---_|. .........O..Chris....O |
12th Apr 2019, 9:24 pm | #7 |
Moderator
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,287
|
Re: Garrard AT-6 autochanger, idler wheel dia?
Possibly, but that would be fitted with a pulley, not an (idler) wheel.
__________________
Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
13th Apr 2019, 9:32 am | #8 |
Heptode
Join Date: May 2015
Location: Reading, Berkshire, UK.
Posts: 692
|
Re: Garrard AT-6 autochanger, idler wheel dia?
|
13th Apr 2019, 10:34 am | #9 |
Hexode
Join Date: Dec 2018
Location: Sheffield, South Yorkshire, UK.
Posts: 364
|
Re: Garrard AT-6 autochanger, idler wheel dia?
|
13th Apr 2019, 10:45 am | #10 |
Dekatron
Join Date: Sep 2015
Location: Southwold, Suffolk, UK.
Posts: 8,327
|
Re: Garrard AT-6 autochanger, idler wheel dia?
The AT6 idler wheel should rotate freely on its own spindle mount.
__________________
Edward. |
13th Apr 2019, 12:38 pm | #11 | |
Dekatron
Join Date: Nov 2003
Location: Heckmondwike, West Yorkshire, UK.
Posts: 9,642
|
Re: Garrard AT-6 autochanger, idler wheel dia?
Quote:
Other problems relate to drag in the auto mechanism or excessive pickup tracking weight. |
|
13th Apr 2019, 12:57 pm | #12 | |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
|
Re: Garrard AT-6 autochanger, idler wheel dia?
Quote:
Check clean enough. Check lubed enough. Rough up rubber. New idler. Rebuilt idler. Replace idler with a homebrew DIY job....that's been covered on this forum somewhere, basically a stock plastic or metal wheel with a stock O ring or square section ring glued to it or the old one machined down a bit to take a square section ring glued to it. Lawrence. Last edited by ms660; 13th Apr 2019 at 1:11 pm. Reason: eplaced words re-shuffle |
|
13th Apr 2019, 1:51 pm | #13 |
Rest in Peace
Join Date: Nov 2010
Location: North Hykeham, Lincolnshire, UK.
Posts: 515
|
Re: Garrard AT-6 autochanger, idler wheel dia?
I think the OP is getting confused between the rubber idler wheel and the stepped motor drive wheel.
The stepped wheel slipping is a common fault and for the best long term method of fixing it, copy the way that tyres are fitted on railway wheels. What happens is that the motor is somewhat inefficient and runs very hot. In manufacture, everything is assembled at room temperature and relies on a pointed grub screw being tightened so much that the point makes a slight indentation in the motor spindle. In use, the motor spindle and drive wheel get very hot, which loosens the screws grip but, for some time, the small indentation and the point remain engaged and all is well. I assume that the repeated expansion and contraction eventually blunts the screw point slight;y until one day, when everything gets nice and hot, it is able to escape from the indentation and the turntable stops. Switch off, wait for it to cool, and it will work normally - for a time ... For a permanent cure (I fixed no end of these and never had one bounce) my method is as follows. Use the transit screws to clamp the changer so that it doesn't wobble around. Check, whilst cold, that the drive wheel height is correct by checking that the idler sits in the middle of each step as the speed is changed, then set the speed selector mid-way between two speeds so that the idler is retracted away from the drive wheel. Switch the motor on and leave running for at least half an hour. In the meantime, modify a pair of pliers by wrapping something insulating, such as a strip of cloth round the jaws. This serves two purposes: it avoids damage to the wheel and stops the wheel being cooled down while it is fastened in place - it is vital that it stays hot. Don't touch the hot drive wheel with bare fingers!! Switch off the motor and, with a bit of cloth round a finger, rotate the drive wheel - if necessary - so that the grub screw is in a suitable position. To help avoid moving the vertical position of the wheel, keep the finger in place whilst starting to tighten the grub screw. However, don't apply any undue pressure, as you are certain to end up with the blade embedded in your finger! Use the insulated pliers now to hold the wheel firmly in place while you finish tightening the screw as tight as you possibly can. You can, of course, tighten the screw without heating the motor/drive wheel combination but it won't be such a permanent fix. |
13th Apr 2019, 5:47 pm | #14 |
Dekatron
Join Date: Sep 2015
Location: Southwold, Suffolk, UK.
Posts: 8,327
|
Re: Garrard AT-6 autochanger, idler wheel dia?
This now confuses me, surely on a Garrard AT6, they are the same thing?
__________________
Edward. Last edited by Station X; 13th Apr 2019 at 6:15 pm. Reason: Quote fixed. |
13th Apr 2019, 7:36 pm | #15 |
Hexode
Join Date: Dec 2018
Location: Sheffield, South Yorkshire, UK.
Posts: 364
|
Re: Garrard AT-6 autochanger, idler wheel dia?
I think / assume he is calling the stepped pulley on the motor shaft a motor drive wheel
|
13th Apr 2019, 8:13 pm | #16 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,535
|
Re: Garrard AT-6 autochanger, idler wheel dia?
Isn't a pulley a wheel with a rim profile suitable for driving a belt? Otherwise it's just a wheel.
Whatever..... there's a motor with a shaft, axle or spindle which may itself be stepped or it may have a stepped wheel attached. This drives the idler wheel which spins freely on its spindle or axle which in turn drives the platter either directly or via a secondary rim attached to the platter. A decent annotated picture showing all the bits in question would save all the confusion over terms and probably another thousand words discussing them. Unfortunately, I don't have one to attach!
__________________
....__________ ....|____||__|__\_____ .=.| _---\__|__|_---_|. .........O..Chris....O |
13th Apr 2019, 8:33 pm | #17 |
Moderator
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,287
|
Re: Garrard AT-6 autochanger, idler wheel dia?
I'd always assumed that a pulley was something which drove, or was driven by, a belt. The belt itself could take many forms. However, as far as turntable drives are concerned, the term pulley is also used to refer to the stepped portion of the motor shaft. Whether this is correct terminolgy I don't know, but it's certainly in common use.
We need an update from the OP which will hopefully put an end to our speculating.
__________________
Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
13th Apr 2019, 8:34 pm | #18 | |
Hexode
Join Date: Dec 2018
Location: Sheffield, South Yorkshire, UK.
Posts: 364
|
Re: Garrard AT-6 autochanger, idler wheel dia?
Quote:
|
|
13th Apr 2019, 9:48 pm | #19 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,535
|
Re: Garrard AT-6 autochanger, idler wheel dia?
Errrr........ where?
Missing attachment?
__________________
....__________ ....|____||__|__\_____ .=.| _---\__|__|_---_|. .........O..Chris....O |
13th Apr 2019, 10:12 pm | #20 |
Hexode
Join Date: Dec 2018
Location: Sheffield, South Yorkshire, UK.
Posts: 364
|
Re: Garrard AT-6 autochanger, idler wheel dia?
|