It is indeed! Is that from the HK?
Dead Sota Sapphire Motor
- Thread starter fmjunkie
- Start date
It is indeed! Is that from the HK?
restorer-john
Addicted Member
Yours will have a 24volt regulator next to the filter cap (7824)- check. There's a diode hanging off underneath too- what's the deal with that?
Feed in 27volts or more (3 volts above the regulator voltage if it has it) to test it.
The motor can be repaired- there's not much to it. Could be caps, dead transistor/s etc.
Feed in 27volts or more (3 volts above the regulator voltage if it has it) to test it.
The motor can be repaired- there's not much to it. Could be caps, dead transistor/s etc.
You don't think it's important to know if it was running prior to any work done on it? It hasn't been stated clearly in this thread so I'm asking.
Ok non factory, new PS, are you sure it's working correctly?
Where they able to plug together like the factory unit with the jack?
In the 4 years I'v had numerous SOTAs and been online I have only heard rumors of motor speed issues, the only motor speed issue I have had where due to the belts.
I have never heard of a motor failure, thats why I'm asking questions as to what's going on. There was just a parts deck being sold in parts on the bay but the complete motor assembly is now gone. I did see another non working deck posted and they are saying the motors dead, so now in one night I have seen two first I have never heard of with this motor.
So I'm a bit skeptical as to what might be happening, I would also check that power supply and it's contacts.
The non factory PS seems good, but I'll have another look and up its output to 27VDC as John suggested.
This is actually third Sapphire I've rebuilt. For what the go for on the used market, they just can't be beat and I am always taken back by how well they are built...The last SOTA I worked on had some speed issues too. It's been a while, but I think the 220uF cap was off and one or two resistors had drifted out of tolerance. I replaced them, Deoxit the pots, and it kept speed like a champ.
This board has no signs of burns from some kind of surge and the components check out o.k. (Most are dead on in fact, after 30+ years.) Since I went to the trouble to pull the motor and had parts on hand, I tested everything and replaced any resistors whose tolerance had drifted with matching values at 1% tolerance. Went ahead and replaced the voltage regulator and 220uF cap too. Still nothing...If the motor has failed, the only thing I can think of is somebody lost the original PS, then tried to run it off of a wall wart that killed the motor.
I have a hard time believing the motor completely failed, too, so I'll keep testing to see what I can find out. (I also noticed those SOTA parts units on the bay. A shame.)
This is actually third Sapphire I've rebuilt. For what the go for on the used market, they just can't be beat and I am always taken back by how well they are built...The last SOTA I worked on had some speed issues too. It's been a while, but I think the 220uF cap was off and one or two resistors had drifted out of tolerance. I replaced them, Deoxit the pots, and it kept speed like a champ.
This board has no signs of burns from some kind of surge and the components check out o.k. (Most are dead on in fact, after 30+ years.) Since I went to the trouble to pull the motor and had parts on hand, I tested everything and replaced any resistors whose tolerance had drifted with matching values at 1% tolerance. Went ahead and replaced the voltage regulator and 220uF cap too. Still nothing...If the motor has failed, the only thing I can think of is somebody lost the original PS, then tried to run it off of a wall wart that killed the motor.
I have a hard time believing the motor completely failed, too, so I'll keep testing to see what I can find out. (I also noticed those SOTA parts units on the bay. A shame.)
restorer-john
Addicted Member
OP's original post- always helps to read that...
He has 24v on the pcb for the motor. As long as the switches, pots and associated wiring are correct and functional- the finger is well and truly pointed at the motor itself. Schematic for motor.
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Well maybe English is different down under, there is nothing in his post saying he tried running it prior to any work.
And we are spinning. I overlooked the simplest of things: I was in a hurry to put power to the board and wired up the stupid little connector to the PS incorrectly. 
Dumb and embarrassing. I guess it happens. Luckily I wasn't playing with power tools or I would have lost a finger.
Thank you all for the help. The advice was valuable. When I get the table back together, I'll report back.
Dumb and embarrassing. I guess it happens. Luckily I wasn't playing with power tools or I would have lost a finger. Thank you all for the help. The advice was valuable. When I get the table back together, I'll report back.
captouch
Addicted Member
And we are spinning. I overlooked the simplest of things: I was in a hurry to put power to the board and wired up the stupid little connector to the PS incorrectly.
Thank you all for the help. The advice was valuable. When I get the table back together, I'll report back.
That's the best kind of resolution. Any momentary embarrassment should be outweighed by the fact that you don't need to spend any more time or $ to get going again.
Just a quick update: I got the table running and, man, I've forgotten how great Sotas sound. Initially, it ran fast but I did found something interesting when I was testing the resistors that's worthy of a post. Resistor 31 (the last resistor on the motor board before voltage goes to the speed adjustment pots) was a combo of three resistors soldered in series. The resistance of the three measured at 128.8K. It was pretty ugly and my notes from previous rebuilds suggest that R31 should be 55K. I replaced the 3 in series with the 55K, but it ran extremely fast. Did a check on the board and everything seemed fine. Replaced the 55K with two resistors in series totaling approximately 130K, adjusted the 10K pot, and it keeps speed perfectly. I'm not sure if that resistance at R31 was a factory mod, but it works for now and the platter spins up nicely.
On to a bigger question. So the suspension springs are shot. I'm getting a good 1/4" drop of the sub-chassis below the outer plinth and the springs have about as much tension on them as they can bear. Sota charges $200 for springs. Uhhh...Say what?...Ace Hardware carries something similar for 50 cents. $200 isn't a lot to spend on the turntable, but what the heck? I can't in good conscience spend that much for springs.
I would imagine Sota has carefully selected these springs for their tension, but I don't know. They don't look like anything special to my untrained eye. Any DIY suggestions or sources for springs that will do the job? For example, McMaster-Carr carries 36" extension spring stock: https://www.mcmaster.com/#springs/=1bzvdw8. I would need to weigh the sub-chassis, select appropriately, and possibly do some slight modifications but can probably get them to work once cut to the right length. Thoughts?
On to a bigger question. So the suspension springs are shot. I'm getting a good 1/4" drop of the sub-chassis below the outer plinth and the springs have about as much tension on them as they can bear. Sota charges $200 for springs. Uhhh...Say what?...Ace Hardware carries something similar for 50 cents. $200 isn't a lot to spend on the turntable, but what the heck? I can't in good conscience spend that much for springs.
I would imagine Sota has carefully selected these springs for their tension, but I don't know. They don't look like anything special to my untrained eye. Any DIY suggestions or sources for springs that will do the job? For example, McMaster-Carr carries 36" extension spring stock: https://www.mcmaster.com/#springs/=1bzvdw8. I would need to weigh the sub-chassis, select appropriately, and possibly do some slight modifications but can probably get them to work once cut to the right length. Thoughts?
BarryWAudio
New Member
I am starting to use my SOTA sapphire again and have a few problems. First, the springs are shot and I am replacing those. I have spent the $220 on the SOTA spring kit and reading the instructions - but the instructions are vague; maybe on purpose. Any youtube videos or pictures on the process?
Also, my motor is weak - I need to physically turn the plattern to get the motor turning. Any advice on this will be highly appreciated!
Also, my motor is weak - I need to physically turn the plattern to get the motor turning. Any advice on this will be highly appreciated!
BarryWAudio
New Member
I read the schematic but there are no values on it - do you have a listing of the values?
Look around page 14, and really the whole thread, welcome to AK
The Official SOTA Turntable Thread
http://audiokarma.org/forums/index.php?threads/the-official-sota-turntable-thread.762110/
most likely you need a new belt.
It's suppose to hang lower. You might want to read the SOTA thread I linked here and learn about the table before working on it.
xbart
Super Member
I replaced my spring awhile back. I thought the instructions supplied were adequate, this post shows the way I extended the springs to get them reattached to the sub-base, maybe it will help you http://www.audiokarma.org/forums/in...turntable-thread.762110/page-16#post-11152557
The new springs were shorter than the old springs on my SOTA and the sub-base doesn't hang down as far as it once did.
BarryWAudio
New Member
Just replaced all the spring she on my sota sapphire and all I see much better now. The process didn't take me two days, but I was taking my time. It also gave me the opportunity to re-weight the lead shot ( note I added more than the total of 2lbs, 15 oz minus the arm board weight to get the floating chassis to sit mid range given the springs were new. Also fixed the motor which was having start up problems. I remembered there is a set screw a thing the bottom of the motor that changes motor bearing alignment. Once very minor adjustment to the bearing screw were made the motor started fine. Very good rebuild experience . It eliminated my suspected issues so now I am convinced I need a new cartridge!
BarryWAudio
New Member
Bought a new cartridge - much nicer mids came alive. Bought a 9TT IKEDA. expensive and great sounding. Now I have to set through my system to continue the enhancements . I do have the old springs - I see some people wanted them. also, a word of caution, its a bit easy to cross threat a new spring - be careful.
That's the best kind of resolution. Any momentary embarrassment should be outweighed by the fact that you don't need to spend any more time or $ to get going again.
Eric I went looking for this thread and found it, read post #31, this could be the problem with your friends table.
I left a comment for him here that maybe should be tried before any tech work.
http://audiokarma.org/forums/index....turntable-thread.762110/page-29#post-12042676
