Garrard Model 770

the jewel in the crown
jdjohn
long player
long player
United States of America
Posts: 2472
Joined: 20 Sep 2015 04:14
Location: Nashville, TN

Garrard Model 770

Post by jdjohn » 30 Dec 2018 18:33

Rescued one of these yesterday from my wife's grandparents. It was stored fairly well, and is pretty clean. The only immediate problem I have noticed is that the speed/size selector has limited movement. There are four settings: 78, 45, 33 (7 in.), & 33 (12 in.). Right now, the selector will only move between the 45 and 33/7 settings. There is strong resistance if trying to go to either 78 or 33/12. Of course I don't want to force it.

I've already removed the platter, and the floating chassis from the plinth, so have full access to the underside at this point. I see that the selector levers and mechanisms are on the bottom layer of all of the mechanicals, so before I start pulling things apart, I wondered if someone here had dealt with this selector issue before.

Thanks for any input!

DSJR
long player
long player
Wales
Posts: 2824
Joined: 01 Feb 2009 20:29
Location: Suffolk

Re: Garrard Model 770

Post by DSJR » 31 Dec 2018 10:37

These mechs are reportedly VERY FRAGILE around the plastics and also sadly, difficult to service. Garrard took a step back with this design, but if you search this Garrard 'room,' you should find plenty of advice from poster A70BBen here, as I believe he's worked on a good few of them I gather. Just tale care with removal of the selector levers prior to removing dried lubricants. there's a service manual here in the library that should help.

jdjohn
long player
long player
United States of America
Posts: 2472
Joined: 20 Sep 2015 04:14
Location: Nashville, TN

Re: Garrard Model 770

Post by jdjohn » 31 Dec 2018 17:10

Thanks for your reply. I found this thread: https://www.vinylengine.com/turntable_f ... 6c896eb495 which helps a little, but as the OP there mentioned, the service manual here in the Database is not very helpful for the 770.

This pic shows where I believe the friction/resistance is:
IMAG1413.jpg
(103.97 KiB) Downloaded 100 times
The red arrow points to a rod which travels through a multi-curved slot, and the yellow arrows show the contact area where no doubt there is old grease. You can see a blob of it.

Looks like I need to remove the entire Unimech sub-chassis in order to access and service the suspect area. Right now I'm stuck trying to figure-out how to remove the tonearm. I thought this bolt might be holding it in:
IMAG1415.jpg
(97.64 KiB) Downloaded 97 times
but not sure at this point. EDIT: No, it appears that bolt is kind of a bottom lateral bearing for the tonearm pillar...could maybe even serve to raise/lower the tonearm like a VTA adjustment. I'm wondering if I need to remove the vertical bearing topside so I can access a screw that I see going vertically through the pillar. The bearing screw has a weird little rod in the middle of the flat-head slot.

Maybe @A70BBen will see this post and chime-in [-o<

DSJR
long player
long player
Wales
Posts: 2824
Joined: 01 Feb 2009 20:29
Location: Suffolk

Re: Garrard Model 770

Post by DSJR » 31 Dec 2018 19:28

Search 'Unimech' here and see if that helps more. Also Unimech tonearm bearing?

First quick search of the latter term gave me some info kindly provided by A70BBen -

'Garrard 62 and models 42 and 6-300 with similar tonearms and pivot design should really be used with cartridges tracking no lower than 2.5 grams. This is specified on Page 5 of the service manual for the Garrard 6-300, available by free download from the Library section.'

The higher-line Unimech models such as the Model 70 and 770 had a different tonearm thrust bearing which permitted lighter tracking. It was not included on the lower priced Unimech models because it requires adjustment on the assembly line; the 62/42/6-300 design uses a thrust ball and a spring which require no adjustment but are of higher friction.'



I'd possibly get a can of solvent cleaner spray - some are not too vicious and may be fine for cleaning, diluting and softening the old lubes enough to help you. The ones I have don't leave a film of goo behind either. I'm going to get into trouble if I go too far down that road and don't wish to advise something that'll mess things up more or even cause damage.

There is a procedure for removing the arm and I gather that later models improved the lateral bearing friction a little as well (maybe top later ones without the steady-arm). The manual here covers several models (6-300 and so on) so hopefully that'll assist a little.

I can't help more as my 'expertise' is more on the Autoslim and larger format models. Good luck..

jdjohn
long player
long player
United States of America
Posts: 2472
Joined: 20 Sep 2015 04:14
Location: Nashville, TN

Re: Garrard Model 770

Post by jdjohn » 31 Dec 2018 20:56

Update: I got the Unimech off =D> I'm taking a few pics along the way, so will post them later. I'm afraid the manual is not much very help with the 770, but the other thread was, especially about the tiny c-clip beneath the cueing platform.

The stiff bit is the Selector Index Plate, I will call it. Lots of grease slathered on the bottom side of it, but I have no idea why since the bottom of the plate doesn't appear to be in contact with anything. The top side slides against another plate, and that's where old grease has stiffened and dried. I'll be stripping it of grease, and then deciding what the best replacement lubricant is. I think grease is too thick for this spot, and maybe a lighter oil or spray lube would be better. Maybe a PFTE spray.

Thanks for the information about the tonearms. Good thing this one is the Model 770 since I plan to use lighter tracking cartridges with it. It came with a Shure M93E

jdjohn
long player
long player
United States of America
Posts: 2472
Joined: 20 Sep 2015 04:14
Location: Nashville, TN

Re: Garrard Model 770

Post by jdjohn » 31 Dec 2018 22:47

Here's that Selector Index Plate in it's heavily-lubed state, and I've added text boxes to show where the speed/size settings land.
IMAG1423.jpg
(120.52 KiB) Downloaded 94 times
Again, this side of the plate doesn't contact any other pieces, so no need for all this gunk. IMO this is not the best design with the rod supposedly tracking through the slot...it doesn't want to move easily between certain settings. Fancy a guess which ones? It moves easily between the two middle settings of 33/7 and 45/7, but when you try to go to either end of the track for 33/12 or 78/10, it is rather difficult. Best I can tell, it's simply the friction of the rod against the sides of the slot or the changing of direction that causes the heavy resistance.

DSJR
long player
long player
Wales
Posts: 2824
Joined: 01 Feb 2009 20:29
Location: Suffolk

Re: Garrard Model 770

Post by DSJR » 01 Jan 2019 11:59

I'd try using a solvent here to clean (isopropyl alcohol?)

Not much around and about concerning these decks, as I suspect many seized ones were junked along with the complete players/music centres many came fitted to. ANY pics would be a huge help if you don't mind sharing - thanks :D

Some of these parts run happily 'dry.' if you can get all the old goo off (there'll be more inside the mech I promise you ;) ), in this case, SPARING use of 'Superlube' - as recommended by Spinner here - should sort it for many more years. You MUST try to get all the old stuff off first though, as mixing greases is not a good idea.

A70BBen
senior member
senior member
Posts: 796
Joined: 16 Feb 2014 21:56

Re: Garrard Model 770

Post by A70BBen » 03 Jan 2019 22:13

A70BBen just now checked in on this thread, and thinks you did fine. The only reason why that much grease may have been used was that if they'd used any less it would have dried out faster, perhaps during the warranty period, which they especially would not want.

ONLY PARTLY KIDDING!

The part involved in this mess is not called out by part number because it was supplied only in the subassembly to which it is riveted.

I have fixed these without dropping the subchassis. On a Model 440 I grasped the frozen part witb needle nosed pliers and forced it loose after a soak in
solvent. On a 775, I left the unit in a closed car on a hot, sunny day. The heat was sufficient to soften the grease so it could be budged. To anyone who tries this: do not attempt to force this mechanism with the plastic control levers. You will, most assuredly, break them.

DSJR
long player
long player
Wales
Posts: 2824
Joined: 01 Feb 2009 20:29
Location: Suffolk

Re: Garrard Model 770

Post by DSJR » 04 Jan 2019 00:26

P.S. the Shure 93E was a sibling of the M75-EJ (they're basically the same thing inside and track at 2g safely - usually). A bit 'dull' sounding today but stable secure trackers. If the arm and trip assembly is free enough to track down to 2g or slightly less, you could try an AT95E which will run in almost anything and give a little more high frequencies - it's never an 'edgy' listen. The Ortofon OM5e tracks at 2g ok as well but is rather more 'toppy' than the Shure and may sound rough if you match it wrongly...

jdjohn
long player
long player
United States of America
Posts: 2472
Joined: 20 Sep 2015 04:14
Location: Nashville, TN

Re: Garrard Model 770

Post by jdjohn » 04 Jan 2019 18:01

Thanks guys! I still plan on posting some pics to maybe help others out in the future. The only casualty was one of the prongs on the plastic Forked Control Link. I inquired about a replacement from two different places, but no luck. I tried gluing, but it didn't hold during re-installation. I've got the link re-installed now, and the switch control works fine as-is, but I went ahead and glued the broken fork on again as installed, so should be fine.

Even after cleaning, loosening, and lubricating the speed/size index plate, I don't feel comfortable changing the setting (still too much resistance), so it will stay on 33RPM/12inch! :D It holds speed pretty well - only a tiny dip in speed at the same spot on each revolution. I cleaned the inside track of the under-platter, cleaned the idler wheel, added a few drops of light machine oil to the top of the motor bearing, and added a little chainsaw chain oil to the spindle bearing. I don't think I can get all the spindle bearing layers totally out without removing the main cam...which I'm not inclined to do at this point since I've re-attached the Unimech to the chassis.

The stylus on this M93 was destroyed (by me) while trying to straighten the cantilever, but it seems an M91 stylus I have fits it, at least for testing purposes. I have several other cartridges available to try, but I noticed there is absolutely no alignment adjustment with the headshell sled. After balancing and setting VTF, it measures quite accurate according to my digital scale, so I think I can safely go below 2g if I want.

Is there any tweaking of cue lift damping for this deck? It drops pretty fast. Also, was I correct before about that one bolt possibly controlling tonearm height for VTA adjustment?

This will never be my primary turntable, but really just a sentimental piece for my wife since it was her grandfather's. I just wanted to get it working, and clean it up a bit, so I'm almost there. It had a powdery mold on the platter mat, but I've been able to scrub it off. I've only applied power so far for testing the mechanics, but should be able to do a sound check soon!

DSJR
long player
long player
Wales
Posts: 2824
Joined: 01 Feb 2009 20:29
Location: Suffolk

Re: Garrard Model 770

Post by DSJR » 04 Jan 2019 18:27

The M91 plays at 1.25g, which is borderline for the decks above this one (86SB, 100SB and so on) and trying to play it at 1.75g may well cause the cantilever to all but collapse. The 'compliance' of the 93E was lower to accommodate a higher downforce. The body was the 'universal' M75 model that we in the UK saw mostly as an M75-6S. Not having the plastic mounts of various shapes and sizes meant we could use any of the M70/75/91 styli in it to great effect.

If not for main duties, then, rather than a pattern Shure stylus (or a rare as hens teeth original), an AT91 (or the posher looking Rega Carbon) or evergreen AT95E would be my choice. despite their cheap-as-chips pricing, they really do perform very well and the conical tipped AT91 especially will be happy in a tonearm that's not quite 'level' when playing a single record and tracking at 2g or slightly less...

jdjohn
long player
long player
United States of America
Posts: 2472
Joined: 20 Sep 2015 04:14
Location: Nashville, TN

Re: Garrard Model 770

Post by jdjohn » 09 Jan 2019 03:15

Good point on the M91E/93E difference in compliance, although I suspect the difference is in their stock OEM styluses. Looks like they both now take the same replacement stylus. Regardless, I actually had an M91E 'clip-in' cartridge and stylus in my stable already, so I swapped that in. Interesting to note now that the M91E is a clip-in, and the M91ED has a mountable cartridge body. The bodies of the M91E and M93E are indistinguishable, and DC resistance is very close comparing the two.

jdjohn
long player
long player
United States of America
Posts: 2472
Joined: 20 Sep 2015 04:14
Location: Nashville, TN

Re: Garrard Model 770

Post by jdjohn » 09 Jan 2019 03:32

Finally adding some more pics for this project. Here it is with the instruction sheet still on the spindle. Note the dusty mold on the platter mat.
G770.jpg
(121.51 KiB) Downloaded 67 times
Idler assembly, which has a nylon washer and c-clip on top of the wheel, and a metal washer under the wheel.
G770idler.jpg
(61.64 KiB) Downloaded 64 times
The inner/outer needle-drop indexing screw is here at the base of the tonearm:
G770tonearmcuescrew.jpg
(40.01 KiB) Downloaded 63 times
Turn clockwise to move the drop-point in, and counter-clockwise to move it out more towards the edge.

After removing the tonearm, here are the removal parts:
G770parts.jpg
(119.86 KiB) Downloaded 64 times
More about how to remove them in my next post.

EDIT: I should note that the platter and floating chassis need to be removed at this point. Please refer to the service manual on how to do that step.

jdjohn
long player
long player
United States of America
Posts: 2472
Joined: 20 Sep 2015 04:14
Location: Nashville, TN

Re: Garrard Model 770

Post by jdjohn » 09 Jan 2019 04:24

Step one is to remove the headshell-cartridge adapter 'sled' from the front of the tonearm, and then unscrew the counter-weight from the rear of the tonearm. Next step is to remove the protective bracket above the tonearm bearing assembly. These two screws need to be removed from behind the tonearm post:
G770tonearmscrews.jpg
(33.28 KiB) Downloaded 63 times
Carefully tilt and lift the bracket out after the screws have been removed. The plastic piece has little notched slots at the base where it slides into slits in the chassis, so be careful.

It's about to get real, so now is the time to pull the tonearm wire clips from the terminal under the chassis. There are five: red, green, white, blue, and yellow. Gently pull the slide-on clips from the tabs, and then go ahead and gently pull the wires and harnesses from their very fragile brackets; this is necessary for removal of the tonearm in the next steps.

Next, the vertical and lateral bearing screws/nuts need to be removed, labeled 1 and 2 in this pic.
G770tonearmrear12.jpg
(47.13 KiB) Downloaded 65 times
Special bits with notches are needed for removing the screws. Here is the vertical bearing screw after removal:
G770vertbearings.jpg
(92.79000000000001 KiB) Downloaded 64 times
Here is the lateral bearing nut after removal (note that the little domed cap pops-out easily with a poke from underneath):
G770vertbearings2.jpg
(137.29 KiB) Downloaded 65 times
Clearly from the pics, the tonearm had already been removed, so this was after removing the bearing the screw and nut. There is some gentle persuasion involved with the tonearm itself, and the wires going under the chassis, so be patient and careful; I highly recommend a pair of fine tweezers for guiding the wires out from underneath the chassis.

Next steps will be to remove the Unimech assembly from the chassis.

jdjohn
long player
long player
United States of America
Posts: 2472
Joined: 20 Sep 2015 04:14
Location: Nashville, TN

Re: Garrard Model 770

Post by jdjohn » 12 Jan 2019 03:37

In removing the Unimech from the chassis, I found it best to start underneath. First, remove all the wiring and harnesses. It's best to go ahead and get those out-of-the-way. Next, the switch lever needs to be detached from the Unimech at two points.
G770Unimech.jpg
(148.04 KiB) Downloaded 55 times
The red 1 in the pic is the Forked Control Link. I broke one of the forks on mine when first taking it off. Luckily, I was able to glue it back on, but only AFTER reassembly...just glued it back in place. Learn from my mistake, and leave the forked-end alone when removing the link. Instead, detach the other end of the link by prying the metal lever up near the 1, and then gently slide the plastic post out. The c-clip at the red 2 needs to be removed as well so that the bearing can be lifted off the post. In fact, I would recommend removing the clip from 2 before attempting to remove the link from 1. Might need to slide the lever bearing off the post at 2 first, and work the other end at the same time. After detaching the switch lever, to keep it out-of-the-way, use a twist-tie to secure the end of the lever to the suspension spring in the lower right part of the picture.

With the wiring removed, and the switch lever detached underneath, attention can now be directed topside to continue removing the Unimech.

Before removing the three brass nuts topside on the chassis - underneath where the platter sits - a screw and a clip need to be removed first. In this pic, the screw at the red 3 needs to be removed. The tonearm bearing assembly should already be removed at this point, so it should be easy to access the screw at 3.
G770tonearmrear12.jpg
(47.23 KiB) Downloaded 54 times
Also, the clip under the cue platform needs to be removed; best to remove it with a pick.
G770cuelift.jpg
(28.62 KiB) Downloaded 55 times
Next quick step is to remove the anti-skate/bias knob, AND the tiny little indicator piece. Gently lift the cover plate behind the tonearm to access and remove the anti-skate bits - a fine pair of tweezers comes in handy.
G770antiskate.jpg
(94.64 KiB) Downloaded 54 times
Now the chassis can be turned on its side, and the three brass nuts removed...don't forget about the star washers underneath the nuts. The cue arm lever should be put in the up position, and then carefully pull the Unimech assembly away from the chassis. One of the levers attached to a main post is spring-loaded a bit, so it will jump when freed.

Post Reply