Sota Cosmos restoration, or...

[marknoir]

Hello fellow AKs
Recently I made a rather bad acquisition. I always wanted a Sota Cosmos, and this looked like a decent table. Turned out not so much. It’s an early unit, and would cost too much (for me) to upgrade it to current status by Sota. So my choices are: 1. Selling it as is; 2. Parting it out. 3. Trying to fix it, and to do this I need technical help, because not much info is available. It has three major problems:
1. Speed inconsistency, which can be fixed in two ways: rebuilding motor-associated electronics and hoping it will work, or buying new Eclipse motor/controller from Sota, $750;
2. Lip on platter does not seem to hold the vacuum too well. “Seem”, because when I do recommended by Sota test - sucking on the vacuum line - record does get sucked to platter and I don’t feel any leaks. This has to be done by Sota, another $500;
3. Vacuum pump is acting strange, and I actually don’t know if it’s because the lip is not sealing, our electronics are at fault, or the pump is not pulling enough vacuum. I know that pump is supposed to pull maximum at the start, and then slow down. Well mine doesn’t do it. It stays on all the time. The records seem to stick to platter pretty well, afterI help them by tapping my finger on the edge to overcome that stiff lip. If I knock on record’s surface I can tell it’s snug against the platter. I news help with electronics, since no schematic is available for the vacuum control. I could just stupidly replace everything, but the pump itself I couldn’t find. The fittings at the pump are rather ugly and not sealing right.
I have to say that when it’s speed instability is at its minimum, this things sounds really great. But if I can’t solve the problems, I will have to get rid of it one way or another. I have a ton of pictures of some guru is willing to help me. Thanks in advance.

 

[polypetalous]

I can't help with any specifics of the inner workings of a SOTA, never owned one but sure would like to someday...

Its almost pointless, IMO, to buy something "vintage/used" you can't reasonably afford to restore or maintain (one of many reasons I have yet to own a Porsche 911)... I assume the hope was that this table would work fine upon purchase, unfortunately didn't work out.

So I guess the question I'D ask myself:
Did I get it at a cost that I could easily recoup selling as is?
IF no... I'd personally try and fix it enough to run and use it, while saving up for a proper SOTA rebuild/upgrade.
IF yes ... I'd proabbly unload it and hold out (be patient) for a better unit

Honestly, this sounds like something I would do, jump into a basket case because the price is right on something I couldn't typically afford. Therefore, I'd almost feel that "the money is spent" what have I got to lose, trying to fix 'er up.

Again though, take it as a grain of salt from a never-SOTA owner here
Good luck, hope you end up with the SOTA of your dreams!

Ben

 

[Blue Shadow]

Had one here recently. I'm sure it would have failed the upgradeable test by SOTA as what they make today has lots of improvements compared to old units. Like a few high end companies that repair back to like new is their property available at their price.

The unit I worked on had a number of issues and I just went through the table to make it usable, not like new. I don't have access to the parts among other issues that keeps the home hobbyist from diving into do the repairs needed.

Knowing what the table sell for the repairs are in line with high end gear and it is one of the impediments to ownership of the second hand gear that is not treated well.

I would make the table as good as you can and move it on as you probably want the vacuum system and other performance qualities of a fully working nice condition SOTA.

 

[captouch]

While you're deciding, you may want to post it for sale and see what you can recover with no additional effort.

If someone who already knows Sota tables has some confidence they can fix the issues, you may be able to move it on and not lose a lot.

On the other hand, if you invest a bunch of time and possibly make things worse or break something, you'll have invested a lot of time and possibly have something that's harder to fix.

One thing with Sota is that while I'm sure they do a great job in their restorations to like-new operating condition, the costs seem really high and if there's a chance that it's not your long-term/endgame table, the chance of recovering what you invested in a later sale is basically none.

So, sometimes, it's best just to take a loss and move on with a lesson learned. If your lucky enough to find someone local with Sota knowledge to help you out, of course all this changes. But I would be cautious of a general purpose tinkerer who offers to try and fix your issues without any Sota specific knowledge.

 

[ghamilton]

Call sota and talk to Donna.

 

[Vintagear]

Hello fellow AKs
Recently I made a rather bad acquisition. I always wanted a Sota Cosmos, and this looked like a decent table. Turned out not so much. It’s an early unit, and would cost too much (for me) to upgrade it to current status by Sota. So my choices are: 1. Selling it as is; 2. Parting it out. 3. Trying to fix it, and to do this I need technical help, because not much info is available. It has three major problems:
1. Speed inconsistency, which can be fixed in two ways: rebuilding motor-associated electronics and hoping it will work, or buying new Eclipse motor/controller from Sota, $750;
2. Lip on platter does not seem to hold the vacuum too well. “Seem”, because when I do recommended by Sota test - sucking on the vacuum line - record does get sucked to platter and I don’t feel any leaks. This has to be done by Sota, another $500;
3. Vacuum pump is acting strange, and I actually don’t know if it’s because the lip is not sealing, our electronics are at fault, or the pump is not pulling enough vacuum. I know that pump is supposed to pull maximum at the start, and then slow down. Well mine doesn’t do it. It stays on all the time. The records seem to stick to platter pretty well, afterI help them by tapping my finger on the edge to overcome that stiff lip. If I knock on record’s surface I can tell it’s snug against the platter. I news help with electronics, since no schematic is available for the vacuum control. I could just stupidly replace everything, but the pump itself I couldn’t find. The fittings at the pump are rather ugly and not sealing right.
I have to say that when it’s speed instability is at its minimum, this things sounds really great. But if I can’t solve the problems, I will have to get rid of it one way or another. I have a ton of pictures of some guru is willing to help me. Thanks in advance.

I assume the new belt didn't solve the speed problem. I forgot to ask you if you had an external PS on your bench. If so, did you try feeding the motor with it? Or have you measured the voltage coming from the existing PS?

I think that trying to get this table to hold speed would be the first step before you look at anything else. The new Eclipse motor will ultimately be costlier than $750 because it will require a plinth cut-out (modifications and installation that would start at $475 if done by SOTA) and it would also require a new pump/power supply to drive these electronics ($1300, internals only or keeping your cabinetry). So hopefully the Papst motor in you unit is not shot (probably unlikely since it seems to hold speed at times) and it's just a faulty resistor, cap or diode somewhere that is screwing up the voltage regulation. Using a different external PS may help you narrow down the issue.

It's also curious that the pump is staying on possibly drawing more constant power than the PS is designed for, while also running the motor. Maybe the external unit (PS/Pump) is where your faulty component(s) lie.

 

[marknoir]

While you're deciding, you may want to post it for sale and see what you can recover with no additional effort.

If someone who already knows Sota tables has some confidence they can fix the issues, you may be able to move it on and not lose a lot.

On the other hand, if you invest a bunch of time and possibly make things worse or break something, you'll have invested a lot of time and possibly have something that's harder to fix.

One thing with Sota is that while I'm sure they do a great job in their restorations to like-new operating condition, the costs seem really high and if there's a chance that it's not your long-term/endgame table, the chance of recovering what you invested in a later sale is basically none.

So, sometimes, it's best just to take a loss and move on with a lesson learned. If your lucky enough to find someone local with Sota knowledge to help you out, of course all this changes. But I would be cautious of a general purpose tinkerer who offers to try and fix your issues without any Sota specific knowledge.

I am that tinkerer myself ))). I will lose a few hundred.

 

[marknoir]

Call sota and talk to Donna.

I did. Many times. It’s become clear that I can not afford Sota’s refurbishing. And it’s so old that they don’t have that vintage parts for it.

 

[marknoir]

I assume the new belt didn't solve the speed problem. I forgot to ask you if you had an external PS on your bench. If so, did you try feeding the motor with it? Or have you measured the voltage coming from the existing PS?

I think that trying to get this table to hold speed would be the first step before you look at anything else. The new Eclipse motor will ultimately be costlier than $750 because it will require a plinth cut-out (modifications and installation that would start at $475 if done by SOTA) and it would also require a new pump/power supply to drive these electronics ($1300, internals only or keeping your cabinetry). So hopefully the Papst motor in you unit is not shot (probably unlikely since it seems to hold speed at times) and it's just a faulty resistor, cap or diode somewhere that is screwing up the voltage regulation. Using a different external PS may help you narrow down the issue.

It's also curious that the pump is staying on possibly drawing more constant power than the PS is designed for, while also running the motor. Maybe the external unit (PS/Pump) is where your faulty component(s) lie.

Thank you for the upbeat post ))). I don’t have to open up the cut-out, on my Cosmos the new motor will fit right in the same housing as the old, with very minor mods. It will be run by the new power supply, so the current PS will only provide and control the vacuum pump. I have no problems opening up the cut-ot as my friend has cmc machine and it would literally take 15 minutes, as the cut-out is sort of milled-ot on the inside of the body, thickness of Corian there is less than 1/4”. I don’t want to do it, I like motor on subchassis.
I do have external PS. I tried it with the pump - no changes - but not the motor. I will, just for the hell of it. I get a steady 30.5v dc coming from Sota PS going into the secondary PB in the main chassis, and then it’s 24v into the motor board. Funny thing about the belt: since Sota and dealers are out of stock, and LPGear’s one didn’t work out, I bought $10 set of different size belts off Amazon. Came two days ago. The largest was slightly longer than factory, 4.8 mm wide instead of flimsy 3, and 1 mm think instead of puny 0.4 mm. Guess what? Runs the same, with same W/F, but requires less effort from motor, has to adjust speed control setting in the back (linger belt - less sidevpressure on pulley)

 

[Vintagear]

Thank you for the upbeat post ))). I don’t have to open up the cut-out, on my Cosmos the new motor will fit right in the same housing as the old, with very minor mods. It will be run by the new power supply, so the current PS will only provide and control the vacuum pump. I have no problems opening up the cut-ot as my friend has cmc machine and it would literally take 15 minutes, as the cut-out is sort of milled-ot on the inside of the body, thickness of Corian there is less than 1/4”. I don’t want to do it, I like motor on subchassis.
I do have external PS. I tried it with the pump - no changes - but not the motor. I will, just for the hell of it. I get a steady 30.5v dc coming from Sota PS going into the secondary PB in the main chassis, and then it’s 24v into the motor board. Funny thing about the belt: since Sota and dealers are out of stock, and LPGear’s one didn’t work out, I bought $10 set of different size belts off Amazon. Came two days ago. The largest was slightly longer than factory, 4.8 mm wide instead of flimsy 3, and 1 mm think instead of puny 0.4 mm. Guess what? Runs the same, with same W/F, but requires less effort from motor, has to adjust speed control setting in the back (linger belt - less sidevpressure on pulley)

I didn't think the eclipse motor would fit in the covered plinth. Donna told me that the eclipse package would require cutting out the cabinetry to accommodate the motor in the "fountainhead" plinth. Maybe I misunderstood what she meant.

That's good news about the PS & motor voltages. Is there an easy way to measure them while it's spinning to see if there's a drop in voltage that coincides when you see the speed deviations?

Otherwise, at this point you may have to wait for an original SOTA belt just to be sure it's not that. If it's not the belt, I hope a member with experience electronically refurbishing the boards in old SOTAs will chimes in and save the day.

Good luck, I hope you can get it going.

 

[marknoir]

I didn't think the eclipse motor would fit in the covered plinth. Donna told me that the eclipse package would require cutting out the cabinetry to accommodate the motor in the "fountainhead" plinth. Maybe I misunderstood what she meant.

That's good news about the PS & motor voltages. Is there an easy way to measure them while it's spinning to see if there's a drop in voltage that coincides when you see the speed deviations?

Otherwise, at this point you may have to wait for an original SOTA belt just to be sure it's not that.

Perhaps (on the belt)
There’s a tech drawing of the Eclipse motor and it’s actually smaller than Papat. The height is nearly identical. She’s right if you want to go full eclipse spec and mount the motor on the bracket attached to the plynth. Because they went back to this style again. If you leave the motor on subchassis, like mine, then mods are minimal.

 

[Vintagear]

Perhaps (on the belt)
There’s a tech drawing of the Eclipse motor and it’s actually smaller than Papat. The height is nearly identical. She’s right if you want to go full eclipse spec and mount the motor on the bracket attached to the plynth. Because they went back to this style again. If you leave the motor on subchassis, like mine, then mods are minimal.

One more quick thought, did you try Deoxit on the speed adjust pot?

 

[marknoir]

One more quick thought, did you try Deoxit on the speed adjust pot?

On Cosmos, that pot is removed from the motor board, and is relocated to the back of the table, and you control speed from there. It's a small 10K SEALED pot. I don't know how to get inside of it... Everything on this table is in excellent shape, I don't think it's oxidation or anything related to that...

 

[marknoir]

Well, thank god the bearing is fine!

 

[Vintagear]

Well, thank god the bearing is fine!

I see that you removed the zirconium ball. If you ran your finger on the top of the BB were you able to feel a ridge on that circular dot in the picture or was it perfectly smooth? Is the BB fixed or is it intended to rotate on the shaft? Unless I'm missing something it seems like an inverted bearing so I'm surprised these tables do not require periodic lubing of the bearing.

One thing I personally like that they did on the early Cosmos was that the motor was mounted on the suspended part of the chassis unlike the rest of the line (and later Cosmos). As long as it's vibrations are well dampened I prefer this approach because the motor, belt and platter are always on the same plane. I have seen demos of the SOTA suspension in action (where the motor is on the fixed part) and the audible wow when the suspension moves drives me crazy. It seems to me that the approach on this Cosmos makes more sense but for whatever reason SOTA went back to the other approach. If it were me I would have further dampened the motor from vibrations and kept it on the same plane like it is in your unit.

Watching this thread with interest...

 

[marknoir]

I see that you removed the zirconium ball. If you ran your finger on the top of the BB were you able to feel a ridge on that circular dot in the picture or was it perfectly smooth?

Is the BB fixed or is it intended to rotate on the shaft? Unless I'm missing something it seems like an inverted bearing so I'm surprised these tables do not require periodic lubing of the bearing.

Hi. It's perfectly smooth. Is it zirconium? I thought it's ceramic. It does not turn, it sits in one position. My bearing was well lubed, some heavy grease around the ball and lighter stuff on shaft. I can not see how, as some people claim, this bearing can be "oil-free". I have to find out which lube to use. Some say white lythium will work on ball, and synthetic motor oil on shaft. It was mentioned that "Tufoil" should be used, but, they have many versions.

 

[Vintagear]

Hi. It's perfectly smooth. Is it zirconium? I thought it's ceramic. It does not turn, it sits in one position. My bearing was well lubed, some heavy grease around the ball and lighter stuff on shaft. I can not see how, as some people claim, this bearing can be "oil-free". I have to find out which lube to use. Some say white lythium will work on ball, and synthetic motor oil on shaft. It was mentioned that "Tufoil" should be used, but, they have many versions.

I use this stuff on my VPI inverted bearing. Works beautifully. Only a dab on the ball bearing tip and nothing at all on the shaft or sleeve.

https://www.amazon.com/Super-Lube-P...ywords=super+lube+ptfe&qid=1604087959&sr=8-12

Super Lube #82340

 

[marknoir]

So here’s what I found: all parts on the motor board check out fine, except the two small 2.2uf caps. Values were fine, but esr was rather high at 4.5 ohms, so I replaced them. As I mentioned before, the board was modified, probably by Sota. Looks like they have moved regulation from the motor board to an outboard regulator (ML317, you can see it in a separate board in picture), there are also same regulators in PS. All parts in PS also check out fine, with the exception of a missing something, that has obviously burned-up. I wish I had a picture of another power supply of the same model. So I can see nothing wrong with electronics so far. So speed variation is something that is probably inherent to this vintage or this particular table, and should then be attributed to gremlins. Now to the pump. I don’t think it’s working right, but please correct me if Im wrong. I have removed the stupid cracked fittings and connected it with some ingenuity to an automotive vacuum gauge. At just over 12v it’s pulling only 2 in Hg. May be the gauge is not accurate, I don’t know. Even if it’s pulling 3 in, I think it’s still low. Vacuum switch on board works fine, and it’s rated at 13 in H2O, which equals roughly 1 in Hg. So may be pump should pull about 4, and then go to about 2, and if vacuum drops below 1 the switch turns it in again? I’m not sure how it works. So I think I should start by either fixing this pump, or getting another one. I wish I knew exactly how much vacuum it should pull.

 

[Nashou66]

The belt circumference , width and thickness all matter for proper speed. If too thick it will affect the speed. sometimes thicker and beefier isn't a good thing.

Id wait for the proper belt before chalking it up as something with the power supply or motor.

Athanasios

 

[marknoir]

Success with vacuum!
I'm happy to report that I have acheived full success with the vacuum unit. After I've fixed the connections, even with old rubber parts (which felt surprisingly good after 32 years, unless somebody replaced them recently. I bought new set on ebay just in case) everything started to work as prescribed: when you first turn-on the vacuum, it goes to just under 12v, and pumps near full volume at about 7; when vacuum is achieved (with my experiments with the vacuum gauge in a couple of seconds. With a leaking lip it will not work), voltage on pump drops to 10.2v and vacuum goes down to about 3, and pump becomes very quiet. I have replaced all electrolytic caps everywhere I could see them. There are two things I have to figure out:

1. what are the correct values for vacuum on start and "maintenance" cycle? and -
2. there is a trace of a burned resistor that is situated across both filter caps. They are 2200uF @ 35v each, wired in series. Voltage across both of them is about 39v. So this was probably a draining resistor? I don't have the diagram, so don't know it's value. My friend suggested soldering two 20K 2w resistors, one on each cap. Need an opinion of electronics gurus.