I used a glue called liquid glue it is something similar to silicone there is also rubber glue to use, check with the car industry there are lots of products they use that I use. You do the right thing by checking the vacuum pump you can use a vacuum pump from VW from the year 2000 they have it for the central locks in their cars you will find the cheapest on a junkyard for cars.
From the looks of the newer style record seal, it appears to be nothing more than cut out of a flat sheet of rubber where the inner circle is slightly smaller than the groove where it lays in.
The stretched effect allows it flair up just enough to seal to the record . Think of a flat rubber band effect.
The type of rubber or where to get it is the 500$ question
Ebay has many small 12v vacuum pumps for peanuts
Regards
David
The stretched effect allows it flair up just enough to seal to the record . Think of a flat rubber band effect.
The type of rubber or where to get it is the 500$ question
Ebay has many small 12v vacuum pumps for peanuts
Regards
David
Yes that’s the question. Have you ever pulled-off the top layer of Sota platter? How is the rubber configured there?
Ebay has many 12v pumps, but most of them, if not all, are of rotary type, not a rubber diaphragm type. And I don’t know how much vacuum they pull. So I guess I will have to experiment. BTW, I never found any specifics on that Pyramid motor/controller... Thank you for your help!
Ebay has many 12v pumps, but most of them, if not all, are of rotary type, not a rubber diaphragm type. And I don’t know how much vacuum they pull. So I guess I will have to experiment. BTW, I never found any specifics on that Pyramid motor/controller... Thank you for your help!
Pyramid is a member here and has some excellent very well documented builds. I have built 2 of them and 1 replaced the Versa,s stepper design. One of the best threads for TT mods
I haven’t yet needed to replace the lip, but can’t imagine it goes very deep under the acrylic
layer. Maybe a small amount of lacquer thinner would be enough to get it started ?
Acetone is to aggresive and eats into acrylic so avoid.
I haven’t yet needed to replace the lip, but can’t imagine it goes very deep under the acrylic
layer. Maybe a small amount of lacquer thinner would be enough to get it started ?
Acetone is to aggresive and eats into acrylic so avoid.
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.
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Diaphram vacuum pumps are inclined to fracture be it rubber or spring type steel usually where the piston pushes up or down .
Rotary pumps vanes wear down over time , I have replaced many industrial size ones over the years and you have to watch out for cylinder scoring .
Dont buy cheap , have you looked at medical vacuum pumps , I have replaced those when working as a hospital engineer .
Rotary pumps vanes wear down over time , I have replaced many industrial size ones over the years and you have to watch out for cylinder scoring .
Dont buy cheap , have you looked at medical vacuum pumps , I have replaced those when working as a hospital engineer .
Success!!! I glued the cracks in nipples with crazy glue; used this crazy hose arrangement for now, and - 7 in of Hg vacuum with old rubber parts in pump!!! Now I only have to come up with more compact system to fit into factory enclosure. BTW, could those suspending springs be replaced by layers of sorbothane? I have to try now how this new high vacuum will affect operation of the circuit. It’s very possible now that it will operate fine.
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Excellent !
As far as suspension, don’t touch it as it works and all you would do is raise how it responds to its low frequency isolation point and everything above that frequency.
On Sotas, leave the acrylic cover off as it is a sounding board that muddies and blurs bass definition, easy to hear
You are way ahead of DD tables that sacrifice low frequency isolation for torque startup and whatever vibrating platform it sits on goes thru to the cartridge
Regards
David
As far as suspension, don’t touch it as it works and all you would do is raise how it responds to its low frequency isolation point and everything above that frequency.
On Sotas, leave the acrylic cover off as it is a sounding board that muddies and blurs bass definition, easy to hear
You are way ahead of DD tables that sacrifice low frequency isolation for torque startup and whatever vibrating platform it sits on goes thru to the cartridge
Regards
David
12V DC vacuum pumps are easy to find. The majority are all one type, selling $16-$23.
https://www.amazon.com/Karlsson-Robotics-D2028-Vacuum-Pump/dp/B00DYA21PU
https://www.amazon.com/12v-vacuum-pump/s?k=12v+vacuum+pump
Vacuum Pump - 12V - ROB-10398 - SparkFun Electronics
Vacuum Pump - 12V
There are also electric pumps for vacuum-boosted brakes in Diesel engine conversions:
$72 https://www.amazon.com/dp/B001KQF6PC
$168 https://www.amazon.com/maXpeedingrods-Electric-Vacuum-Brake-Booster/dp/B07WHS6R8V
If you can fix your leaks, I am sure you do not want the big high-buck pumps.
It IS an aquarium pump! But really small, only about 7.5 cm long. Modified from “Second Nature”’s whispers 100 or 200.
Thx
While I was working on it, I have removed the plinth completely, and used it “naked”, sitting on four 7/8” thick sorbothane picks. I liked the way it sounded, so I may continue to use it this way. I don’t need suspension, it sits on a large old Target wall shelf. Plus my Dynavector 505 arm is too heavy for this suspension anyway.
I had three Goldmund Studios before, different vintages, and they sounded pretty good to me. But I feel that this Cosmos sounds better.
I didn't mean table's suspension, I meant the PUMP's suspension. Sorry for the misunderstanding.
Rgds
Mark
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.
So now to speed control.
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.
So now to speed control.
