Pl 12D - Rubber Cushions (For Motor) - How To Get New Ones?

[clh1997]

The Rubber Cushions for my two PL 12Ds need replacement since they have gone stiff/dried out and make the motor audible through the cartridge.

The Danish Pioneer agent says they are no longer available here in Denmark. So I'll ask if some of you have been able to get new ones and maybe help me getting them. The spare part no is: E 31-605-A

Three cushions are needed for each PL 12D (but I'll like to some extras - 12 if possible).

An alternative could be to somehow "revitalize" the old rubber, so it'll regain some of it's original flexibility. I've seen - but not yet bought or tested - a “LaCross Rubber Conditioner” and I’m thinking of maybe giving the old cushions a bath in this.

Link: http://www.lacrossefootwear.com/product ... tioner.do#

Any experiences or opinions are welcome!
Thanks - Claus

[Mark E Smith's Dentist]

If they're the ones that mount the motor I'd just use something like the grommets for mounting computer fans - they're basically the same thing.


JT

[fscl]

Whoa, an exact replacement may be difficult to fabricate / substitute......

Take a look at the service manual here:

http://www.vinylengine.com/library/pioneer/pl-12d.shtml

Refer to page 8 of 11 of the pdf. This shows exactly the rubber grommets that cushion the motor.

Hmmmmm....... if you want to try to restore the existing rubber, if they aren't stiff and dried out to the point where they disintegrate with the grommets are backed out of the metal mounting plate, remove them and put them in a rubber restorer solution / bath. Hopefully, they will "drink" the plasticizers up and you'll get nice plump grommets again. If they will crumble, then do not back them out of the mounting plate, just soak the entire plate in the aforementioned plasticizer solution. This will take time?...though waiting for the rubber to reabsorb....

If I had to fabricate these from common available (putting on my MacGyver hat) products:

1. I'd try some sticky rubber / silicone feet that are squishy and come to a point, drilled in the center to the diameter of the mounting screw.
2. Fabricate a foam washer from perhaps mouse pad(s).
3. Use your imagineering and insert idea here.....

Of course tweaking to find the right materials, feet, etc... is part of it, however, VE members should be good? at that.....

Oh yeah, try partstore or one of the Inet parts suppliers for this... hopefully they MAY turn up NOS......especially if the parts manager's name is Wayne DeBack.....OK lifted from the Car Talk guys....

Good luck.

Fred

[clh1997]

Fred and Jon - thanks for your suggestions.

In the meantime I went the "Rubber Revitalization"-way - and with a very good result: The cushions are now much softer and flexible, the motor is no longer audible - and the trusty PL 12Ds are back in business.

Here is what I did:
1) Took out the cushions
2) Washed in hot water w. disc detergent
3) Rinsed and dried
4) Put the cushions in a test-tube and fully covered them w LaCross Rubber Conditioner for app. 1 hour
5) Poured the Conditioner back in the bottle (for reuse) and dried the cushions
6) Remounted the cushions

I also treated the rubber mat with the conditioner: Sprayed a thin layer all over and dried with a soft cloth after 5-10 minutes (repeat on other side).
As with the cushions the mat now looks & feels much softer and has regained its original darker color (black in stead of dark grey).

- Claus

[fscl]

CONGRATULATIONS......

Excellent outcome. Nothing like original equipment......

Those grommets were thirsty....

Thanks for the heads up on the LaCrosse Rubber Conditioner...WOW that was pretty fast Int'l shipping to Denmark....

Will have to purchase some and add to the chemical restoration arsenal...

Fred

[clh1997]

Just at few pics to illustrate the difference before/after treatment with the mentioned LaCross Rubber Conditioner.

The treated rubber looks darker and feels smoother & more flexible.
Wonder if the conditioner can save old belts as well? Not tried this yet.

- Claus

Rubber cushions: No. 1, 3 and 5 treated - No. 2, 4 and 6 not treated

Rubber disc mat: Left treated - Right not treated


PS: The re-conditioned cushions look a bit larger than the not-treated ones. This is not (as I thought in the first place) a result of the treatment - they were a bit different before.

[fscl]

Claus,

THANKS for the pictures. In fact, I tried to purchase the La Crosse restorer here in the US through local distributors, however, they were closed this weekend.

You read my mind regarding belts.

Also, I hate to retire / throwaway good equipment for lack of spare parts... as mfg are paring parts / no longer making them in this economic environment and I've got lots stuff which have thirsty rubber, ie printers, scanners, etc... etc.. which can use some refreshing.....

Thanks for the lead and "before / after" pics... and hope to make my rubber wait... not that kind of rubber....have enough right now and can't afford another....

[drdave_56]

I just overhauled my PL-12D (now 35 years old!) and have found the advice in this forum invaluable. I was unable to obtain the Lacrosse product mentioned above so I treated the rubber mounts and the platter with a different conditioner, Autoglym Vinyl and Rubber Care, which is readily available from automotive accessory shops in the UK.
http://www.autoglym.com/enGB/product-proddetail.asp?v06VQ=HE

Results were amazing, it has completely eliminated the hum I was getting due to motor drone breakthrough.

[tiptonamps]

I have recently been laid up with a duff knee cartilage. Bored out of my mind, I decided to scratch a very old itch. My late wife badgered me into selling my old hifi separates years ago (Yes, I know, I know! Give me a break). Over the last few weeks, I've scoured eBay and picked up a mint Sony STR-6055 receiver that I serviced and restored. This week, I got a Pioneer PL12D II turntable in fairly reasonable cosmetic condition.

The fitted cartridge, a Shure M75EJ Type 2, was, as I recall, a pretty respectable low end cartridge back then (mid 70s). I sourced a replacement stylus from a local branch of Maplin and set about breathing life into the turntable. Did the basic arm adjustments. Mmmm, those bearings feel a tad rattly, more on this later. The drive belt, that looks and feels new (ish) was good to go, so I fired her up.

Huuuummm! Oh. Dear.

Not an earth loop or bad wiring (I'm an audio technician). Must be motor vibration. I scoured the 'net and found you guys. This thread proved most invaluable.

I bought some 'AutoGlym' Rubber and Vinyl care solution from Halfords and soaked the motor support cushions.

This helped *a lot*, but the hum was still clearly audible. albeit much less loud.

I replaced the foam damping material inside the platter suspension springs and this lowered the hum still further. But it was still there. By now, you've pretty much discovered that I am like unto a dog with a big juicy bone about stuff. I have issues

There was mention in this thread of mousemat material coming into play. I use a 7/8" 'Qmax' punch to cut a number of pads from a sacrificial 1/4" thick mousemat that I inserted into the spring locating holes on the plinth to physically isolate the springs from the plinth ledges. Quieter still.

But. Still. There. Aaaargh!

I removed, cleaned and re-tensioned the tone arm bearings. Fiddly and not for the faint hearted but this was *not* going to beat me. This helped with isolating the tonearm and eliminated most of the tracking rattles I was hearing.

I removed, cleaned and lubricated the central spindle that was, as it turned out, drier than a kangaroo's dry bits. The bearing surfaces were still good. As witnessed by the time it took to get the air out from the cylinder meaning that bearing was still a good interference fit; the spindle took a long time to slide fully home. This augered well. At least the platter runs true.

I cleaned and lubricated the motor bearings with EP90 (Gear box oil) and... voila! Silence! Beautiful silence!

I'd almost forgotten just how good vinyl sounds.

Hello from a newbie and many thanks for pointing me in the right direction.

This turntable will do until I buy a modern replacement. Which may be a while since I restored this Pioneer. Clearly, it was popular back in the 70s for a good reason other than price

regards

Trev

[spitfiresun]

Good post Trev.

I am just going through the same processes with my recently acquired PL-12D.

First of all are the grommets easy to remove/replace?
I will be soaking them in 'Autoglym', this should hopefully help with the motor hum problem.

Also what is the process to clean, lube and tighten up the arm bearings?...as I can't seem to find much information on this as yet. (The arm seems ok, but there seems to be a little 'rotational' movement when I place my forefinger and thumb either side of the collar and apply a little pressure alternately to each finger.)

After that is complete I will applying some damping material, something like 'Silent Coat' to the platter, plinth and chassis to improve things further.

Cheers,
Ian

[Alec124c41]

Be very careful with the arm bearings. A barely perceptible amount of play is good. Too tight will damage the bearings.

Cheers,
Alec

[spitfiresun]

Having removed, (soaked the grommets in Autoglym) and then replaced the 3 rubber grommets I seemed to have caused more problems than I have solved!.

Firstly after tightening up (but not over tightening) the three retaining screws to their capacity, there seems to be some lateral movement in the motor unit....is this right?

Also. the motor unit can be lifted vertically (by a few mm)....is this to allow the motor to drop down on to the grommets when it is not inverted?

I don't remember any movement at all prior to removing the grommets!

Finally after turning the deck the right way up again, and trying it out I now have audible motor hum without even connecting it to the amplifier!

I would be grateful for any advice/help here, as I just seem to have made things worse!

Cheers,
Ian

[kesh]

The lateral and vertical movements of the motor are normal : the motor effectively "floats" on the grommets which permits a degree of movement.

It's a long shot, but try re-lubricating both the motor bearing and spindle bearing. Some of the oil may have drained out while the turntable was inverted.

(You don't need to invert a PL12D and remove the base to work on it. Under the platter at 6 and 12 o'clock are two silver-head screws in slots. Loosening them and sliding them in the slots towards the spindle re-positions retaining plates under the metal plinth, which enables it to be lifted away from the wooden base.)

Otherwise, check that the earth (ground) lead connections haven't been disturbed while you were working on the motor.

[spitfiresun]

Thanks for the reassurance Kesh, I'm kinda new to this, so just wanted to make sure I hadn't messed it up already!

I think I have found the cause of the motor hum!...It appears the motor support plate was rubbing against a protruding section of the plinth adjacent to the motor.

(The plinth of my deck was 'custom-made' in wood, not plywood, by the previous owner, which looks good, but is probably not the best material to use as it seemed 'resonant' from the start...but that's another issue!)

Anyway, what I was probaby hearing was the whole plinth vibrating and amplfiying the hum!...as soon as I made sure the plate was not rubbing the hum disappeared!

After removing that 'annoying' part of the plinth, I shall turn the deck up the right way, and try to access the suspension springs from the top to check that the damping foam is in place. (I take it I would have to temporarily remove the cable restraint bracket from the back to allow me to do this).

What would be the best type of foam to use for this purpose?

Cheers,

Ian