HELP!! SOTA TT melt down!

thunderbrick · « **on:** 4 Aug 2010, 03:35 am »

You know the drill. Multi-year DIY home renovation and I finally put the big system back together. Pull out my mid-80s SOTA table, tweak it up and it sounds GLORIOUS.

Get my wife to listen to it, and I detect a slight ticking in the TT motor.

Invited some audio guys over for an analog vs digital listening session and one channel drops out. Replaced IC.

Out of curiosity I rapped my knuckle on the plinth and all hell broke loose. Motor got very noisy and started slowing down. Sounds like someone put a bunch of walnuts in a car's hubcaps.

So far SOTA hasn't responded to my email. Anyone have a manual that might give any suggestions on how to solve this? Can an owner pull and lube the motor?

Thanks, all!

jsaliga · « **Reply #1 on:** 4 Aug 2010, 03:48 am »

SOTA can take a few days to respond to email. I needed set up information about my Series III Star Sapphire. I called them and spoke to someone. Ten minutes later I had the set up guide.

I suggest you give SOTA a call.

--Jerome

Norman Tracy · « **Reply #2 on:** 4 Aug 2010, 04:23 am »

Are you sure the transport screws that hold the jewel main bearing are backed out? They are two screws on either side of the main platter bearing, perhaps they were not quite pulled out far enough.

Russtafarian · « **Reply #3 on:** 4 Aug 2010, 06:35 am »

Sounds like maybe the motor mount broke loose. If you're mechanically inclined enough to take it apart and reassemble the chassis, it could be an easy fix.

Where are you located? Is there a TT guru in a local audio club that can take a look at it?

thunderbrick · « **Reply #4 on:** 4 Aug 2010, 02:57 pm »

Thanks, Guys!

Yeah the transport screws are correct, and yes, I am mechanically inclined, so I'll pull out the platter/bearing out and see what I can do! Anybody know if SOTA has a parts/assembly diagram? I'll call 'em later.

'brick

Scott F. · « **Reply #5 on:** 4 Aug 2010, 04:24 pm »

Bob,

Just for sh*ts and giggles, try putting the old belt back on. That likely isn't it but if it is....

If not, it sounds like cogging of the motor which means new motor time.

thunderbrick · « **Reply #6 on:** 4 Aug 2010, 04:28 pm »

Damn! That's around $600!

Wayner · « **Reply #7 on:** 4 Aug 2010, 06:08 pm »

Is it safe to ass/u/me that the motor is of the synchronous type? If so, it's a 12 or 24 pole. The first thing to do is remove the platter and belt from the motor. Without any power to the motor, see if the shaft turns rather freely. You will feel the pull of each pole position, which makes the motor feel as if it has power to it, even if it does not.

Next, because you rapped on the plinth and something started to happen, I suspect the pulley has slipped on the shaft. Most pulleys are attached in two different methods. The first one is by a .0005" interference fit. The other method is with the more conventional set-screw. In either case, the pulley may have slipped from it's normal position downward and it is now hitting the plinth or something else, which would also explain why it has also slowed down.

Wayner

thunderbrick · « **Reply #8 on:** 4 Aug 2010, 07:37 pm »

Wayner, I checked that, thanks.

The pulley seemed a little low, and since it was press-fit on the shaft I could simply pull it up 1/8". Didn't help.

I even unhooked the belt and that didn't stop the noise. I even had to push start the motor. It was like it was dying in front of my eyes. I have pulled the platter/bearing assembly out years ago, so that's easy. I am hoping that once i do that I'll see how to pull the motor out and check the mounts.

Anybody have an exploded parts diagram they can send me?

Thanks, all!

kenreau · « **Reply #9 on:** 4 Aug 2010, 07:41 pm »

I had a similar odd experience shortly after receiving & setting up my TT. My Cosmos platter started dragging / running slow so I put on a new belt. Seemed to help a little, but still not ideal. As I was trouble shooting, poking around, I bumped the dust cover lid and it slammed down on the plinth and out popped a maching screw on to the shelf. Bingo. Apparently it had dropped in the chassis by previous owner, or maybe from something inside(?) during shipping and was caught against the turning platter. From that point on it started running properly and I forgot about it.

You might disconnect the belt and spin the platter backwards to see if it is obviosly dragging and confirm it spins freely in both directions to narrow the problem down to the motor.

Fwiw, I recall reading SOTA uses Pabst motors. Also, I've read it can be difficult to disassemble the chassis suspension to get inside and it is easy to damage the bearing/thrust/spindle platter assembly.

Good luck
Kenreau

Quote from: thunderbrick on 4 Aug 2010, 02:57 pm

Thanks, Guys!

Yeah the transport screws are correct, and yes, I am mechanically inclined, so I'll pull out the platter/bearing out and see what I can do! Anybody know if SOTA has a parts/assembly diagram? I'll call 'em later.

'brick

Wayner · « **Reply #10 on:** 4 Aug 2010, 07:50 pm »

I make another assumption that the motor is 300 RPM. That means every second, it goes 5 RPM. If it was a pole piece, that would be some very fast tic-tic-tic. There is also a press bushing on the shaft of the motor, to keep the motor shaft in position, relative to the pole pieces. I am wondering if the bushing is rubbing against the motor jacket and creating noise, and friction. Every motor I've seen has this little press on bushing and it rides on the motor assembly somewhere. I would try a drop of sewing machine oil on this bearing, hoping that some of it gets in between the press bushing and the motor assembly.

Please tell me if the tic-tic-tic is 5 times a second.

Wayner

Wayner · « **Reply #11 on:** 4 Aug 2010, 07:59 pm »

I just read Kenreau's post. If it's a Pabst motor, then it is likely a hysteresis type, running at a much higher RPM. My Empire is a motor like this and I think it clocks out at 1800 RPM. The pulleys are very small compared to other TTs, because of the high RPM. These motors are very durable and your problem does seem odd.

Wayner

thunderbrick · « **Reply #12 on:** 4 Aug 2010, 08:20 pm »

OK, tonight I'll tell (ask?) my wife to clean off the kitchen table so I can tear it apart.

Removing the platter assembly isn't bad. One big honkin' bolt underneath.

Bob

thunderbrick · « **Reply #13 on:** 4 Aug 2010, 08:22 pm »

Quote from: Wayner on 4 Aug 2010, 07:59 pm

I just read Kenreau's post. If it's a Pabst motor, then it is likely a hysteresis type, running at a much higher RPM. My Empire is a motor like this and I think it clocks out at 1800 RPM. The pulleys are very small compared to other TTs, because of the high RPM. These motors are very durable and your problem does seem odd.

Wayner

Nah, runs slower than that. I'll check on the 5 tics-per-second.

JakeJ · « **Reply #14 on:** 4 Aug 2010, 11:12 pm »

Hi TB,

Another SOTA owner here. I bought my Sapphire new and it did not come with any service information or exploded parts type drawing. Also, I reiterate an earlier post in that you need to call SOTA directly, they aren't so good at keeping up with email. Once contacted they are good about support and helping in field repairs...by phone.

Sorry to hear about your woes. I, too, had to replace my motor.

Best of luck,
Jake

robinje · « **Reply #15 on:** 5 Aug 2010, 12:29 am »

I had a slight problem setting up my brand new SOTA Nova vacuum table a couple of years ago. I called and spoke with Kirk and Donna, the owners. They were extremely helpful and walked me through my issue while I was on the phone. All in all, SOTA offers excellent customer support and will surely be of assistance to you. Ask for Kirk, as he knows these tables inside and out. I am very, very happy with my SOTA Nova. After initial setup, it has been completely trouble-free. Good luck!

thunderbrick · « **Reply #16 on:** 5 Aug 2010, 01:33 am »

Got a great email from Donna at SOTA with a suggestion how to re-align the motor. That didn't work so I asked for plan B.

Wayner, the tapping or clicking does sound like five times a second. I removed the belt and the sound didn't change. I turned the motor off, then on again, and I had to kick-start it to get it to move.

I'll wait to see what I hear from Donna.

Thanks, guys!

Wayner · « **Reply #17 on:** 5 Aug 2010, 12:00 pm »

Now it does sound like internal stator/rotor damage to the motor. The tap may have jared a piece loose. So I'm thinking the only cure will be a new motor. If you do go this route, get a new capacitor, too.

Wayner

thunderbrick · « **Reply #18 on:** 6 Aug 2010, 04:04 pm »

Guys, SOTA's service is superb!

Kirk, one of their techs, called me and spent 25 minutes helping me diagnose the problem and work up some solutions, ranging from motor replacement all the way up to a trade in. EXTREMELY helpful! I wrote down as many options as I could but Kirk is going to email me with an organized list of my options.

Can't ask for better than that, especially for a 25 y/o TT.

Thanks, Kirk!

Bob

Wayner · « **Reply #19 on:** 6 Aug 2010, 05:48 pm »

Bob,

If he's offering to trade up, I'd do it in a flash (provided I had the cash). The 25 year old table V. a brand new one, with (assumed) improved technologies, build, etc., sounds good to me. Also keep in mind that the on/off switch is getting old (along with the switch capacitor). Replacing the motor should be fairly easy if it can be easily gotten to, not buried.

Wayner