Garrard SL95B running 8% slow

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al_roethlisberger
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Garrard SL95B running 8% slow

Post by al_roethlisberger » 09 Feb 2020 19:50

After a complete tear down, cleaning and lubrication my Garrard SL95B is still consistently running about 8% slow at all speeds (33.3,45,78).

Spec = Actual
33.3 = 30.71
45 = 41.34
78 = 71.71

1) Platter: I've cleaned and lubricated the ball thrust bearing, and main spindle sintered bearings, and the platter spins smoothly, silently, and freely. If I give the platter one full turn with my finger and release, it will spin 45-50 seconds until spinning to a complete stop.

2) Idler: I have had the idler reconditioned by Voice of Music, but this did not produce any improvement over the original idler. With the original idler wheel the table also ran 8% slow. The idler spins easily. The idler shaft and sintered bearing is clean and oiled, and the fiber washer is present under the idler.

3) Motor: I have disassembled, cleaned, and lubricated the electric motor. The spindle was very clean, shiny, and does not look scored. The single ball bearing is still present in the bottom bearing. The spindle turns easily and if spun by hand will spin several rotations with almost no effort, then stops and then "bounces" back and forth a few times in the magnetic field which indicates to me that the motor is spinning freely.

As there are no other components of the table that influence the platter speed, it seems to me that this speed discrepancy must be tied to one of these three components. But mechanically they seem fine. Or am I missing something?

If I am not missing another contributing component to platter speed, I think the motor is electrically suspect, especially given the consistent 8% slow discrepancy, which I have verified several times.

The motor is a Garrard, Synchro-Lab Synchronous Motor, 110-125V, 12W, 60Hz, Model D. This is not a series II. I have attached a photo of the motor for reference.

48394



Can the motor suffer an electrical failure that could cause this problem yet still run, like a shorted winding, or...

Any thoughts on next steps to inspect or to repair this speed issue?

Thanks.

A70BBen
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Re: Garrard SL95B running 8% slow

Post by A70BBen » 09 Feb 2020 21:41

If one of the motor's two coils were open, it would, effectively, become a two-pole motor which would run at DOUBLE speed (that was the fault in the infamous Dual 1249 and 601). If a coil were shorted, excessive heat would build up in the motor since the two coils in a 120V Garrard motor are connected in parallel and the shorted coil would draw excessive current.

The physical condition of the motor and bearings sounds good. The "bounceback" in the rotor as it slows and stops is normal and proper. Since you are in the USA using 60Hz power, the issue is not that it is running on 50Hz current, either (and that would be a 16.7% slow speed error, not 8%).

A 50Hz unit running on 60Hz would be similarly fast, but the 50Hz pulleys are nickel-coloured; yours is brass, as the 60Hz pulleys are.

The next thing to check would be the motor pulley though I have never encountered one that was 8% off. Use of a Synchro-Lab pulley on a similar-chassis nonsynchronous unit such as AP76 would result in slow operation; but an AP76 pulley on a Synchro-Lab unit would cause FAST running.

If you could measure your motor pulley with calipers or preferably a micrometer, and post the result here, perhaps some other member could do the same and cast some light on the subject (I have calipers but not a micrometer).

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Re: Garrard SL95B running 8% slow

Post by al_roethlisberger » 09 Feb 2020 23:14

Thanks, I don't have a micrometer handy, but perhaps these shots with a dial caliper will help.

The top scale of the dial caliper is millimeter, the dial is fraction of inch.


33 1/3 step

48398


45 step

48399


78 step

48400

al_roethlisberger
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Re: Garrard SL95B running 8% slow

Post by al_roethlisberger » 10 Feb 2020 14:50

I also found a used motor for next to nothing, so I'll swap that out too and see if that makes any difference. It'll be a few days before that arrives, but I'll provide an update then.

In the meantime any other theories are welcome :)

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Re: Garrard SL95B running 8% slow

Post by DSJR » 10 Feb 2020 23:00

On the lower cast Autoslim with SL motor, the 60Hz pulleys were a different 'colour' than the 50Hz ones I think. The 50Hz pulleys were a brass colour from memoru, but if a 50Hz one was used in the USA, the platter would run too fast.

Has this deck ever run at the correct speed for you? The thing is, if it's a recently obtained used one, I'm going to make some cautious observations - the 95B era decks would have come with the series 2 motor with no ball bearing at the bottom and rotor slightly less free to spin on it's own. The series 2 was labelled underneath on the screen plate and the bottom bearing housing is flat without the little 'well' the ball sat in.

Finally, the 4 pole standard motor runs at a different speed to the SL ones, so for example, if a motor PULLEY from a AP75 or 76 with 4 pole motor was substituted and fitted to the SL motor, the platter speed would be wrong quite audibly.

Forgive me if the above is a bit garbled. Apart from the added depth underneath, the original SL motor should run just fine in 'B' series decks *as long as the correct pulley is fitted!* The idler wheel plays no part in this by the way and it's interesting that yours has 'Garrard' embossed on the rubber tyre, as I've not seen that before. A70BBen here has seen loads of them so will correct me I'm sure...

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Re: Garrard SL95B running 8% slow

Post by Howard365 » 10 Feb 2020 23:29

I have restored several SL-95Bs; here are a few observations FWIW:

--Your pulley looks to me like it might be an autoslim pulley [or from some other model], not a 95B. Here is a pix of a 95B pulley, note how your 33-1/3 section is a lot longer/deeper.
IMG_6882.JPG
(27.44 KiB) Downloaded 48 times
I would compare the measurement but I can't see/decode your micrometer reading. The longer vertical 33-1/3 step that I see in your photo is similar to what I have with pulleys in my parts bin for other Garrard models.

Anyway, even if you have the correct pulley, have you measured the speed after the TT warms up for 5 minutes? I've never been able to figure this out, cause a synchronous motor is supposed to be synchronous, right? But my ''prized'' restored 95b starts off at 30.7 rpm and only slowly comes up to speed, and finally settles down at 33.6 or 33.7.

BTW, it's annoying that I can't get any of them to run at a true 33.33, but slightly fast is obviously better than audibly slow. [Indeed, 33.6 sounds just fine. I'm playing Beatles not Chopin so there's no issue with slightly off piano notes.
An old Garrard guy told me once that there were 6 slightly different pulleys for the 95b and when the TTs were coming off the line at the factory, if they were out of spec, they would get a different pulley to get them to the ''correct' speed. [Again, I never quite got why you'd have this with a synchronous motor, but it's definitely true in my experience that, in restoring Garrards, one needs to play with different combos of donor motors and pulleys to get the speed right. Get some junker decks and play around.

As to the wobbly tonearm [which is your question in the other thread], the answer is no, it shouldn't be loose, even at rest. People crap all over these old Garrards, and I don't take it personally, but it has been my experience that the SL-95B tonearm performs a lot better than it looks, or than audiophiles would tell you. It tracks very nicely at 1.75 grams and can handle 1.5 if you insist. I think the key is that you have to do a complete strip down when restoring the deck, which is very difficult, especially with the tonearm.

Hope this info is of assistance

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Re: Garrard SL95B running 8% slow

Post by aardvarkash10 » 11 Feb 2020 00:11

its is almost definitely the pulley. The synchro motors are exactly that - they sychronise with line frequency, so even if the bearings are knackered etc etc they still HAVE to spin at line frequency. If they can't, they tend to "cog" ie jump erratically as they try to sync.

The platter sure isn't changing and the idler is intermediary - it does not affect the drive ratio regardless of its diameter.

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Re: Garrard SL95B running 8% slow

Post by al_roethlisberger » 11 Feb 2020 04:23

DSJR wrote:
10 Feb 2020 23:00
On the lower cast Autoslim with SL motor, the 60Hz pulleys were a different 'colour' than the 50Hz ones I think. The 50Hz pulleys were a brass colour from memoru, but if a 50Hz one was used in the USA, the platter would run too fast.

Has this deck ever run at the correct speed for you? The thing is, if it's a recently obtained used one, I'm going to make some cautious observations - the 95B era decks would have come with the series 2 motor with no ball bearing at the bottom and rotor slightly less free to spin on it's own. The series 2 was labelled underneath on the screen plate and the bottom bearing housing is flat without the little 'well' the ball sat in.

Finally, the 4 pole standard motor runs at a different speed to the SL ones, so for example, if a motor PULLEY from a AP75 or 76 with 4 pole motor was substituted and fitted to the SL motor, the platter speed would be wrong quite audibly.

Forgive me if the above is a bit garbled. Apart from the added depth underneath, the original SL motor should run just fine in 'B' series decks *as long as the correct pulley is fitted!* The idler wheel plays no part in this by the way and it's interesting that yours has 'Garrard' embossed on the rubber tyre, as I've not seen that before. A70BBen here has seen loads of them so will correct me I'm sure...

I bought the SL95B from an estate sale several years ago, and based upon the condition of the deck and environment it came from, I don't think the original owners would have ever serviced the deck so I think it is most likely that the non Series II motor is original to this SL95B.

But I can't say if the deck ever ran the correct speed, as it came to me in such poor shape that I didn't bother to measure the speed until after I serviced the deck and noticed the slow speed audibly.

The refurbished idler came from "The Voice of Music". The old original one I sent in as a "core" was not embossed.

I have another non Series II motor on the way to test with that was pulled from an SL65B according to the auction.

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Re: Garrard SL95B running 8% slow

Post by al_roethlisberger » 11 Feb 2020 04:38

Howard365 wrote:
10 Feb 2020 23:29
I have restored several SL-95Bs; here are a few observations FWIW:

--Your pulley looks to me like it might be an autoslim pulley [or from some other model], not a 95B. Here is a pix of a 95B pulley, note how your 33-1/3 section is a lot longer/deeper.

IMG_6882.JPG

I would compare the measurement but I can't see/decode your micrometer reading. The longer vertical 33-1/3 step that I see in your photo is similar to what I have with pulleys in my parts bin for other Garrard models.

Anyway, even if you have the correct pulley, have you measured the speed after the TT warms up for 5 minutes? I've never been able to figure this out, cause a synchronous motor is supposed to be synchronous, right? But my ''prized'' restored 95b starts off at 30.7 rpm and only slowly comes up to speed, and finally settles down at 33.6 or 33.7.

BTW, it's annoying that I can't get any of them to run at a true 33.33, but slightly fast is obviously better than audibly slow. [Indeed, 33.6 sounds just fine. I'm playing Beatles not Chopin so there's no issue with slightly off piano notes.
An old Garrard guy told me once that there were 6 slightly different pulleys for the 95b and when the TTs were coming off the line at the factory, if they were out of spec, they would get a different pulley to get them to the ''correct' speed. [Again, I never quite got why you'd have this with a synchronous motor, but it's definitely true in my experience that, in restoring Garrards, one needs to play with different combos of donor motors and pulleys to get the speed right. Get some junker decks and play around.

As to the wobbly tonearm [which is your question in the other thread], the answer is no, it shouldn't be loose, even at rest. People crap all over these old Garrards, and I don't take it personally, but it has been my experience that the SL-95B tonearm performs a lot better than it looks, or than audiophiles would tell you. It tracks very nicely at 1.75 grams and can handle 1.5 if you insist. I think the key is that you have to do a complete strip down when restoring the deck, which is very difficult, especially with the tonearm.

Hope this info is of assistance

This is a lot of very helpful information!

I agree that my pulley looks different from yours, and that's now several observations from others in this thread that my pulley may be wrong. And that is very interesting, as I struggled to adjust the idler tire to sit centered properly on pulley sections, and in the end I could not quite get it to sit on the pulley for all three speeds. 78 specifically had to suffer with the least ideal idler placement. If I have the wrong pulley, that may explain those adjustment struggles.

I have run the deck for 5, 10 and 60+ minutes and measured with the same exact slow results. So in my case warming up the motor doesn't help to get the deck up to speed.

The SL65B non Series II motor that is on the way has a pulley more like the one in your photo.

Wouldn't that be interesting if this deck had the wrong pulley as new and that is all the problem is and ever was with this table?! :cry: It makes ones wonder if the original owner just didn't notice, or was so disgusted with the sound that they never used it after taking it home? 30 rpm is quite audibly noticeable. Who knows #-o

Regarding the tonearm, thanks for the feedback and confirming my suspicions. The looseness is the entire tonearm assembly, not in the pseudo gimbals so I don't think the tonearm needs a rebuild itself. During my refurb I accidentally loosened the main set-screw/nut on the vertical "axle" under the deck that holds the entire tonearm assembly, so I suspect I just need to loosen it again and tighten it with the tonearm properly seated.

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Re: Garrard SL95B running 8% slow

Post by al_roethlisberger » 11 Feb 2020 04:49

The used motor I have on the way from the SL65B should be here by Thursday. I'll provide an update immediately after.

Here is a closeup of the SL65B motor's pulley, which incidentally looks different from both mine AND the SL95B motor & pulley in howard365's photo above.

48409

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Re: Garrard SL95B running 8% slow

Post by al_roethlisberger » 11 Feb 2020 04:59

I also found a Series II from a parted out SL95B that seems to have the same pulley as shown in howard365's photo. This is on the way too, so I can test this pulley and motor as well.

48410


BTW, is there any advantage to the Garrard Series II Synchro-Lab motor over the earlier non Series II?

A70BBen
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Re: Garrard SL95B running 8% slow

Post by A70BBen » 11 Feb 2020 07:10

I see no advantage to Series II or original...but I don't think the motor pulleys interchange. Different shaft diameters.

That SL65B motor has a FOUR speed Autoslim pulley on it, although the SL65B only had three speeds.

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Re: Garrard SL95B running 8% slow

Post by al_roethlisberger » 13 Feb 2020 02:39

A70BBen wrote:
11 Feb 2020 07:10

That SL65B motor has a FOUR speed Autoslim pulley on it, although the SL65B only had three speeds.

Yep, confirmed the pulley that was sold as coming from an SL65B, or maybe was actually from an Autoslim, will not work. The diameters of the steps on this pulley are smaller than my original pulley, so the speeds were even slower with this replacement pulley installed.

So I'll wait for the other motor & pulley from the SL95B to show up that looks more like what the others have posted. I'll post the results.

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Re: Garrard SL95B running 8% slow

Post by al_roethlisberger » 15 Feb 2020 03:54

OK, I received the Series II motor from an SL95B with the different pulley. And an initial install of the Series II motor and pulley improved the speed to 32.7

Then I cleaned and lubricated the motor, and now I have the 33.3 speed running at 33 even, and 45 is now at 44.6

So that's a dramatic improvement, as I think one would expect with the correct pulley ;)

But I'm still a little disappointed it is running about 1% slow. However I'm going to let the "new" Series II motor break-in for a while and see if it continues to improve as it has slowly been gaining .1 RPM as it runs.


BTW, I'm using Turntabulator to check the RPM.

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Re: Garrard SL95B running 8% slow

Post by al_roethlisberger » 15 Feb 2020 03:58

A70BBen wrote:
11 Feb 2020 07:10
I see no advantage to Series II or original...but I don't think the motor pulleys interchange. Different shaft diameters.

That SL65B motor has a FOUR speed Autoslim pulley on it, although the SL65B only had three speeds.

Thanks, and you are correct. The Series I and Series II pulleys do not interchange. The Series II shaft is smaller.

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