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My Model 62 table forgot how to measure platters

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My Model 62 table forgot how to measure platters

Postby efhjr » 03 Jan 2018 00:11

I'm currently working my way through a Model 62. It's pretty clean but spent decades unused in a closet.

The speed/platter size selector was stuck. It took some brute force to get it moving again, and now it's moving pretty well. The problem is that the selector correctly changes speed, but whether I've chosen the 7-, 10-, or 12-inch position, the tonearm always drops at the 10-inch position. Any ideas about how to fix this?

Also, the platter is running about 3% too fast. Any way I can slow it down?
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Re: My Model 62 table forgot how to measure platters

Postby DSJR » 03 Jan 2018 17:56

All I know of these mechs is that they're frail - so be careful - and difficult to properly service. A70BBen knows them well I think and hopefully he'll come along with some decent advice for servicing.

As for the speed, I think you should service the motor bearings first, check the idler wheel is correctly set on the motor pulley and not binding on the faster speed 'step' immediately below it. if the speed is still slightly fast, I can't suggest anything other than a fine strip of emery paper to shave a tad off the affected speed step on the motor pulley. Are you sure the strobe you're using is correct here? Maybe costly, but you can get battery operated higher frequency crystal generated strobe lights with special discs to confirm speeds away from mains frequencies. Both my Dual 701 direct drive and a Technics SL1500 I had keep perfect speed but appear to drift because the mains frequency isn't as accurate, the built-in strobe lights coming off the incoming mains frequency...
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Re: My Model 62 table forgot how to measure platters

Postby A70BBen » 04 Jan 2018 00:05

I don't know them all THAT well. In fact I don't LIKE the Unimech chassis all that well!

The Model 62 is a glorified 6-300 (the Garrard 440 is even LESS glorified) with the REVERSED pusher mechanism for the spindle, so it pushes the record toward the left front of the unit to drop it off the spindle ledge and side platform, instead of toward the right rear. This does not affect the part of the mechanism that controls where the tonearm drops.

DOWNLOAD THE GARRARD 6-300 SERVICE MANUAL FROM THE LIBRARY SECTION!

In the attached photo of the Unimech subchassis removed from the unit, the part with the broad V-shaped slot is what "tells" the tonearm where to set down. Make sure that it is free to move and that everything that is associated with it, including the pin that rides in that slot, is also free to move, and not broken. Unfortunately these parts do not have identifying callouts in the service manual; they were supplied only along with the Pickup Base Assembly. And equally unfortunately, you have to do a major teardown to get the mechanism subchassis and the tonearm base out to where you can directly service them...and that's where the instructions for doing that, in the service manual, come in handy.

CLICK on the photo, then CLICK AGAIN to enlarge.
Unimech subchassis Garrard 6-300.jpg


Note that occasionally one of the sloppy plastic control levers for speed/size will break, and will not be controlling the setdown mechanism, only the speed. This is because the setdown mechanism usually freezes up long before the speed change mechanism, and excess force was applied by the user.

After you enlarge the photo, look at all that excess grease on the subchassis/pickup base...and imagine what good cement it makes when dry and hardened!
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Re: My Model 62 table forgot how to measure platters

Postby efhjr » 04 Jan 2018 18:46

A70BBen wrote:DOWNLOAD THE GARRARD 6-300 SERVICE MANUAL FROM THE LIBRARY SECTION!


Thanks a lot for the great information, sir!

This thing isn't nearly as easy to work on as my Lab 80 and 301, but live and learn. I'll get under the hood again this weekend and see what I can loosen up.
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Re: My Model 62 table forgot how to measure platters

Postby A70BBen » 04 Jan 2018 20:19

In comparison , the Lab 80 is a walk in the park. Many Unimechs were thrown away because the cost of fixing them was so excessive, for a turntable costing half as much, or less.
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Re: My Model 62 table forgot how to measure platters

Postby efhjr » 08 Jan 2018 22:45

A70BBen wrote:Many Unimechs were thrown away because the cost of fixing them was so excessive, for a turntable costing half as much, or less.


Pity, that. The one I'm working on is going to a friend, and I know he'll get a lot of joy out of it. Gotta keep these old machines making music.
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Re: My Model 62 table forgot how to measure platters

Postby DSJR » 08 Jan 2018 23:24

You should get a real sense of achievement in sorting it as well, especially as they're so awkward to work on - that mech looks far more complicated than the famous Autoslim design which preceded it and I think all but outlasted it as well (on the last SP25/125SB derived models)...
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Re: My Model 62 table forgot how to measure platters

Postby A70BBen » 09 Jan 2018 03:42

I fixed a Unimech that I got for $2 and donated it to a school, which is still using it years later.

Using modern synthetic grease makes a difference! It was rumored that Plessey, when they acquired Garrard, made changes in suppliers and this may have included Plessey's preferred (read: CHEAP) grease vendor. I have noted that the Garrard grease issue more severely affects units built in the Plessey era than earlier ones. The Unimech itself was a cost-cutting exercise too, adapting the cheap Garrard minichanger's mechanism to full-size record changers including some with hi-fi pretensions.

The Autoslim chassis did indeed outlive the Unimech. The Garrard 125SB, SP25 Mk VI and the various units labelled "Belt Drive" were Autoslim chassis modified to belt drive but with the same basic auto mechanism dating from pre-Plessey days.
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Re: My Model 62 table forgot how to measure platters

Postby KentT » 09 Jan 2018 04:13

efhjr wrote:
A70BBen wrote:DOWNLOAD THE GARRARD 6-300 SERVICE MANUAL FROM THE LIBRARY SECTION!


Thanks a lot for the great information, sir!

This thing isn't nearly as easy to work on as my Lab 80 and 301, but live and learn. I'll get under the hood again this weekend and see what I can loosen up.


And also, your 301 and Lab 80 weren't cheapened either, they represented, along with the 401, Garrard when it was Garrard and engineering and build prowess. Unimechs were so cheaply made, and such inferior performers to even the cheapest AutoSlim based mechanisms that many when they died didn't get repaired. Now for a basic changer, I love the AT6 a lot, that was a nice changer.
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