Hi Folks... New to this (or any other) audiophile forum... Typically here because I have a problem - When do folk sign up and visit just to be sociable eh..?? 
I wanted to transcribe my vinyl collection across to digital, so I can move it around on MP3, etc... So I dusted off my old MB-10 to see what was what...
1st mistake - I'd left the belt stretched around the motor spindle, for some years..!!
- Yes, a new belt was required...
Fitted new belt, reset the tracking & bias on the arm, tried some vinyl... No sound - new PP3 battery required in my old "Realistic" phono pre-amp...
New battery in pre-amp... now we have audio..!! But doesn't sound "quite right"... Seems to be "slow.."
So, since then, I've tried to check the platter speed with a strobe disc (50Hz to suit UK freq) - the strobe bands rotate anti-clockwise on both 33+1/3 and 45 rpm. Neither sits stationary...
I've taken the TT centre bearing apart and cleaned and lubricated it... I was advised that grease is used... Tried Lithium DiSulphide, LM wheel bearing and Hi Temp Silicone grease - none made any difference at all... Cleaned out the bearing again and tried 5W50 fully synthetic motor oil - slight improvement, only just noticeable, but the speed definitely increased... Cleaned the bearing/spindle again and lubed with light machine oil - slow again, so we're back to the 5W50 at the moment...
I also dropped some light machine oil into the motor lubrication point - marked "oil". No noticeable improvement in platter speed...
I was also advised that the motor spindle should be cleaned with fine emery cloth as it's spinning - I did that with 800 grade cloth - nice and bright now, but no difference to platter speed...
So... what next..? do the AC motors in these TTs simply wear out..?? I tried to check if the motor is "weak" and it takes quite a grip to get that spindle to slow to a stop... It's possible, but it ain't easy at all...
Anyone out there have any further tips to improve the platter speed on my old MB-10..?
BTW: I'm using a Nagaoka MP-11 cart with elliptical stylus... Tracking weight is set @ 2.0g so I doubt that it's this that is slowing the platter down... Tracking bias is set accordingly...
Also: If it's likely to be the motor that needs replacement... Anyone know of suitable spares and where to source them from..??
Many thanks for any info provided...
Miti
I wanted to transcribe my vinyl collection across to digital, so I can move it around on MP3, etc... So I dusted off my old MB-10 to see what was what...
1st mistake - I'd left the belt stretched around the motor spindle, for some years..!!
- Yes, a new belt was required...Fitted new belt, reset the tracking & bias on the arm, tried some vinyl... No sound - new PP3 battery required in my old "Realistic" phono pre-amp...
New battery in pre-amp... now we have audio..!!
But doesn't sound "quite right"... Seems to be "slow.." So, since then, I've tried to check the platter speed with a strobe disc (50Hz to suit UK freq) - the strobe bands rotate anti-clockwise on both 33+1/3 and 45 rpm. Neither sits stationary...
I've taken the TT centre bearing apart and cleaned and lubricated it... I was advised that grease is used... Tried Lithium DiSulphide, LM wheel bearing and Hi Temp Silicone grease - none made any difference at all... Cleaned out the bearing again and tried 5W50 fully synthetic motor oil - slight improvement, only just noticeable, but the speed definitely increased... Cleaned the bearing/spindle again and lubed with light machine oil - slow again, so we're back to the 5W50 at the moment...
I also dropped some light machine oil into the motor lubrication point - marked "oil". No noticeable improvement in platter speed...
I was also advised that the motor spindle should be cleaned with fine emery cloth as it's spinning - I did that with 800 grade cloth - nice and bright now, but no difference to platter speed...
So... what next..? do the AC motors in these TTs simply wear out..?? I tried to check if the motor is "weak" and it takes quite a grip to get that spindle to slow to a stop... It's possible, but it ain't easy at all...
Anyone out there have any further tips to improve the platter speed on my old MB-10..?
BTW: I'm using a Nagaoka MP-11 cart with elliptical stylus... Tracking weight is set @ 2.0g so I doubt that it's this that is slowing the platter down... Tracking bias is set accordingly...
Also: If it's likely to be the motor that needs replacement... Anyone know of suitable spares and where to source them from..??
Many thanks for any info provided...
Miti
Is the speed consistently slow or does it vary in pitch as well (best heard on something like a sustained piano note)?
You could try cleaning the pulleys and the belt with some white spirits, but normally that only works when you have wow. Also do you know if this deck uses an AC motor or is it a DC motor? If its DC there might be a pitch adjustment on it.
Is this what it looks like:
http://www.vinylengine.com/library/micro-seiki/bl-10x.shtml
Fran
You could try cleaning the pulleys and the belt with some white spirits, but normally that only works when you have wow. Also do you know if this deck uses an AC motor or is it a DC motor? If its DC there might be a pitch adjustment on it.
Is this what it looks like:
http://www.vinylengine.com/library/micro-seiki/bl-10x.shtml
Fran
Hi Fran
The speed is consistently slow. Nothing appears to be "slipping" and I cleaned the motor spindle and the platter pulley with de-greaser when I fitted the new belt - didn't seem to have any effect...
The MB-10 has an AC motor and looks like this:
Cosmetically, mine is in really good nick and it'd be a real shame to have to scrap the old girl... Think there's any mileage in pulling the motor out and getting a part number off it..?
Miti
The speed is consistently slow. Nothing appears to be "slipping" and I cleaned the motor spindle and the platter pulley with de-greaser when I fitted the new belt - didn't seem to have any effect...
The MB-10 has an AC motor and looks like this:
An externally hosted image should be here but it was not working when we last tested it.
Cosmetically, mine is in really good nick and it'd be a real shame to have to scrap the old girl... Think there's any mileage in pulling the motor out and getting a part number off it..?
Miti
How do you change speeds? Is it by moving a belt onto a different step on the pulley?
Slow speed on an AC motor is caused by a few things:
1. Bearing somehow causing the drag. Usually more evident as "wow" rather than consistently slow speed.
2. Belt worn out - again more evident as wow.
3. A 50Hz/60Hz problem. the motor runs at a constant speed determined by the frequency on the mains, in the UK its 50Hz. In the US its 60Hz. The manufacturers made 2 pulleys to compensate for this.
4. Motor problems and PS problems usually mean that the motor is slow to start or won't start - platter needs a push to get it going.
So just for pig iron:
This is a UK TT, not one that you bought/brought home from the USA?
You replaced the belt with the correct cross section one, cleaned it with some white spirits and where it runs on the platter and motor? (just wet a rag with the spirits and pull the belt through it.)
When you cleaned the bearing, you didn't allow a ball bearing at the tip of the bearing shaft to fall out? (if there was one)
If you remove the belt does the platter spin freely if you give it a spin?
Does the motor spindle turn freely? It might "cog" but it shouldn't feel rough or like its grinding/scraping.
You have to try and work through it methodically.
Another question: by how much is it slow. To measure you need a stopwatch. Stick a little bit of tape to the platter so it sticks out over the edge. Hold your finger on the deck so that the tape hits your finger as the platter turns. Start the watch as the tape hits your finger and then count to 100 revolutions. At 100 stop the watch. If the speed is perfect it will read 3 mins. Either side of that and you can work out the % speed slow or fast.
Fran
Slow speed on an AC motor is caused by a few things:
1. Bearing somehow causing the drag. Usually more evident as "wow" rather than consistently slow speed.
2. Belt worn out - again more evident as wow.
3. A 50Hz/60Hz problem. the motor runs at a constant speed determined by the frequency on the mains, in the UK its 50Hz. In the US its 60Hz. The manufacturers made 2 pulleys to compensate for this.
4. Motor problems and PS problems usually mean that the motor is slow to start or won't start - platter needs a push to get it going.
So just for pig iron:
This is a UK TT, not one that you bought/brought home from the USA?
You replaced the belt with the correct cross section one, cleaned it with some white spirits and where it runs on the platter and motor? (just wet a rag with the spirits and pull the belt through it.)
When you cleaned the bearing, you didn't allow a ball bearing at the tip of the bearing shaft to fall out? (if there was one)
If you remove the belt does the platter spin freely if you give it a spin?
Does the motor spindle turn freely? It might "cog" but it shouldn't feel rough or like its grinding/scraping.
You have to try and work through it methodically.
Another question: by how much is it slow. To measure you need a stopwatch. Stick a little bit of tape to the platter so it sticks out over the edge. Hold your finger on the deck so that the tape hits your finger as the platter turns. Start the watch as the tape hits your finger and then count to 100 revolutions. At 100 stop the watch. If the speed is perfect it will read 3 mins. Either side of that and you can work out the % speed slow or fast.
Fran
Fran
UK Model - I've owned it since about 1985...
Hmmm... I bought the belt as a model-specific replacement for the MB-10... I did do a quick check between old & new to see how "stretched" the old one was, but didn't think to check cross-section...
It's too late now, the old one is well binned... The Ebay belt vendor had V/Good feedback over a LOT of sales... I'm assuming it's the correct belt...
I cleaned the platter belt run and the motor spindle... Didn't think to clean the belt, so I'll do that tonight...
Actually... I did... But I spotted that it had escaped, caught it, cleaned and lubed it... It's definitely in there... If it wasn't I don't think the spindle would turn at all...
Oh yes... it's almost a perpetual motion machine... I don't think the centre bearing is the culprit here...
Can't remember checking for this... Is "cogging" that feeling of alternating magnetic repulsion/attraction that some motors have when you spin them over, or is it a more "mechanical" feeling like brushed motors sometimes have? Another check I'll do tonight...
I'll also dig out my stopwatch and do the 100 turns = how many mins/secs calculation... Stand by for news of how I was hypnotised by the rotating tape, fell headlong onto the deck and now a slow motor is the least of my worries...!
Miti
UK Model - I've owned it since about 1985...
Hmmm... I bought the belt as a model-specific replacement for the MB-10... I did do a quick check between old & new to see how "stretched" the old one was, but didn't think to check cross-section...
It's too late now, the old one is well binned... The Ebay belt vendor had V/Good feedback over a LOT of sales... I'm assuming it's the correct belt...I cleaned the platter belt run and the motor spindle... Didn't think to clean the belt, so I'll do that tonight...
Actually... I did...
But I spotted that it had escaped, caught it, cleaned and lubed it... It's definitely in there... If it wasn't I don't think the spindle would turn at all...Oh yes... it's almost a perpetual motion machine... I don't think the centre bearing is the culprit here...
Can't remember checking for this...
Is "cogging" that feeling of alternating magnetic repulsion/attraction that some motors have when you spin them over, or is it a more "mechanical" feeling like brushed motors sometimes have? Another check I'll do tonight... I'll also dig out my stopwatch and do the 100 turns = how many mins/secs calculation... Stand by for news of how I was hypnotised by the rotating tape, fell headlong onto the deck and now a slow motor is the least of my worries...!
Miti
Most probably the electronics controlling the motor are no longer correctly adjusted. Sometimes this happens with cheap potentiometers. I could not find your reply regarding how you switch the rotation speed (electronically or by moving the belt onto a different diameter area on the pulley).
Since it's a Micro, I assume it's done electronically and in this case you should be easily able to find the adjustment pot on the pcb.
I cannot imagine a motor fault; a synchronous motor runs synchronous or it does not run at all.
Have fun, Hannes
Since it's a Micro, I assume it's done electronically and in this case you should be easily able to find the adjustment pot on the pcb.
I cannot imagine a motor fault; a synchronous motor runs synchronous or it does not run at all.
Have fun, Hannes
H_A is indeed correct.
From your experiments so far, you have ruled out the bearing, platter and most likely the motor too - and yes it is that feeling of repulsion/attraction you were talking about.
You are going to have to have another look under the bonnet. Is there anywhere you can see an adjustment for pitch? Have a look under, if its a DC motor there will be significant circuitry in there. AC there might well be less, especially if there are 2 steps on the pulley for different speeds.
Fran
From your experiments so far, you have ruled out the bearing, platter and most likely the motor too - and yes it is that feeling of repulsion/attraction you were talking about.
You are going to have to have another look under the bonnet. Is there anywhere you can see an adjustment for pitch? Have a look under, if its a DC motor there will be significant circuitry in there. AC there might well be less, especially if there are 2 steps on the pulley for different speeds.
Fran
Hi Folks...
Sorry... I missed an answer out - The speed control moves the belt up/down to 2 different diameter areas on the motor spindle... The motor is 230V 50Hz AC and is connected direct to the mains supply (via a 2-pole switch)
There is no speed control PCB, just a couple of spike-suppression capacitors between the switch terminals and the earth connection, and a solder-tag strip where the switch wires connect to the motor wires...
So, no pcb, no motor control, no potentiometers...
Side-tracked by loving spouse tonight, so speed experiments will continue tomorrow... Watch this space for more...
And thanks for the input guys, much appreciated...
Miti
Sorry... I missed an answer out - The speed control moves the belt up/down to 2 different diameter areas on the motor spindle... The motor is 230V 50Hz AC and is connected direct to the mains supply (via a 2-pole switch)
There is no speed control PCB, just a couple of spike-suppression capacitors between the switch terminals and the earth connection, and a solder-tag strip where the switch wires connect to the motor wires...
So, no pcb, no motor control, no potentiometers...
Side-tracked by loving spouse tonight, so speed experiments will continue tomorrow... Watch this space for more...
And thanks for the input guys, much appreciated...
Miti
makinson1 said:
Hi,
The chances of a strobe disk being stationary are near nil ......
A "solution" is to use spray paint on your turning motor spindle .....
Typical turntables of the MB10 ilk use a 4 pole shaded pole motor.
It is synchronous and only has two wires, i.e. the 240VAC power.
/sreten.Hi Fran
Yes. I completed the speed tests, cleaning and motor checks...
I did the speed test 6 times...
1st pair: TT revolving @ 33+1/3, "free-wheeling", no vinyl:
Both tests = 95.5 revolutions in 3 mins (digital timer).
2nd Pair: TT revolving @ 33+1/3, vinyl on TT, stylus applied:
Both tests = 95.5 revolutions in 3 mins (digital timer).
3rd Pair - Belt, platter & motor spindle cleaned with White Spirits. All dried (kitchen towel) and refitted. TT revolving @ 33+1/3, "free-wheeling", no vinyl:
Both tests = 96 revolutions in 3 mins (digital timer).
So, a slight improvement after cleaning with spirits, but still 4% slow...
I also checked the motor for "cogging" - There's no sign of this, the motor spins freely and smoothly... BUT, there is a LOT of end play in the motor spindle.. Is this normal..? It moves up/down about 4 mm - I only discovered this when spinning the motor twixt thumb & finger, it doesn't seem to move when in operation...
And, Sreten, your're right... It's a 4-pole, shaded pole motor... Just 2 wires going to it, 1 live, 1 neutral...
So... Do I "accidentally" drop the refrigerator onto it and phone my insurance company,
or is there still hope for the old girl..??
Miti
Yes. I completed the speed tests, cleaning and motor checks...
I did the speed test 6 times...
1st pair: TT revolving @ 33+1/3, "free-wheeling", no vinyl:
Both tests = 95.5 revolutions in 3 mins (digital timer).
2nd Pair: TT revolving @ 33+1/3, vinyl on TT, stylus applied:
Both tests = 95.5 revolutions in 3 mins (digital timer).
3rd Pair - Belt, platter & motor spindle cleaned with White Spirits. All dried (kitchen towel) and refitted. TT revolving @ 33+1/3, "free-wheeling", no vinyl:
Both tests = 96 revolutions in 3 mins (digital timer).
So, a slight improvement after cleaning with spirits, but still 4% slow...
I also checked the motor for "cogging" - There's no sign of this, the motor spins freely and smoothly... BUT, there is a LOT of end play in the motor spindle.. Is this normal..? It moves up/down about 4 mm - I only discovered this when spinning the motor twixt thumb & finger, it doesn't seem to move when in operation...
And, Sreten, your're right... It's a 4-pole, shaded pole motor... Just 2 wires going to it, 1 live, 1 neutral...
So... Do I "accidentally" drop the refrigerator onto it and phone my insurance company,
or is there still hope for the old girl..?? Miti
What baffles me is that you say the motor has lots of torque and doesn't seem to be cogging.
Wait a second. Who cares if it's slow? Just dump the analog output into your computer and fix the slow temp in the software!
Sell one of us the Micro Seiki and get yourself one of the Scotish turntables
Wait a second. Who cares if it's slow? Just dump the analog output into your computer and fix the slow temp in the software!
Sell one of us the Micro Seiki and get yourself one of the Scotish turntables
Now I wish I was at home with the software manual and not here at work... I hadn't even considered that..
Might be a viable option... For the A-D transcription anyway...
I would still like my turntable working though... Even with the 4% slownessosity I still prefer the sound... I've always felt that CD's sound like you're listening to them with a slight case of tinitus... Know what I mean...? (Is that AAA snobbery..?)
I'm wondering if the speed problem could be supply voltage related..?? My limited understanding of AC motors tells me that the speed of rotation is supply frequency related though...
I think the application of paint or lacquer to the spindle may be worth exploring and I may take the motor out for a close-up inspection, pending identity of available spares... (Ha!, who am I kidding..??)
Miti
Can't understand what would be wrong here. Yes, the speed is frequency dependent, and that will be better than the 4% you see.
Have another look at the motor pulley. Is it a flat pulley with a "domed" centre? If thats the case then you will need to adjust the motor mounting to get the belt to ride on the high bit of the pulley rather than down in the gully on either side. Usually there is one bolt that can be screwed in or out a bit to adjust the angle that the motor is at relative to the platter.
If its running the low bit all the time then that would be a source of your problem.
Fran
Have another look at the motor pulley. Is it a flat pulley with a "domed" centre? If thats the case then you will need to adjust the motor mounting to get the belt to ride on the high bit of the pulley rather than down in the gully on either side. Usually there is one bolt that can be screwed in or out a bit to adjust the angle that the motor is at relative to the platter.
If its running the low bit all the time then that would be a source of your problem.
Fran
Fran
Hmm.. Not 100% sure what you mean here... The motor has stepped "spindle" rather than a "pulley"... It has 4 well-defined diameters:
The bottom of the spindle is the widest part - it has a hollow centre that is a very close fit on the motor shaft and a single gub-screw that secures it to the motor shaft. It's NOT loose...
The next section (45 rpm drive) is slightly narrower. It steps down in dia by about 4 mm from the lower section (90 deg edge on the step). This section is a "parallel cylinder", no "high or low spots"
The next section (33+1/3 rpm drive) is slightly narrower again. It steps down in dia by about 4 mm from the lower section (45 deg edge on the step to facilitate a smooth belt transition between the two drive areas). This section narrows slightly at the top & bottom, giving the spindle a slightly rounded appearance here... But the overall length of this section isn't enough to allow the belt to ride away from the widest point..."
The topmost section of the spindle steps up in dia again - looks to be the same as the 45 rpm section... This also has a 90 deg step edge and forms a kind of "cap" to prevent the belt leaping off the top of the spindle...
So... There aren't any low areas where the belt could be lazily biding it's time... the two drive sections are parallel... The belt seems to be transitioning from one to the other quite nicely, there doesn't feel like there is any "slip" in the drive-train...
What is the significance of "cogging"...? I can't feel any problems with the motor armature - it spins quite freely and my test of the motor's torque is a very subjective one, 'cos I've notheing whatever to compare it to... Would a "good" motor spin me around the room a la Tom & Jerry? or is it about right that a firm pinch will stop it cold..??
I've tried playing with the motor spindle when it's running - lifting the shaft up seems to induce a "cogging" effect and it's quite easy to stall the motor, but when it's in it's normal position, it runs very smoothly with considerable torque...
I'm considering the application of some thin heat-shrink sleeving to the 33+1/3 section (I play my 45's on a 1964 Wurlitzer Jukebox, so that's not a problem at the moment...)
Miti
Hmm.. Not 100% sure what you mean here...
The motor has stepped "spindle" rather than a "pulley"... It has 4 well-defined diameters:The bottom of the spindle is the widest part - it has a hollow centre that is a very close fit on the motor shaft and a single gub-screw that secures it to the motor shaft. It's NOT loose...
The next section (45 rpm drive) is slightly narrower. It steps down in dia by about 4 mm from the lower section (90 deg edge on the step). This section is a "parallel cylinder", no "high or low spots"
The next section (33+1/3 rpm drive) is slightly narrower again. It steps down in dia by about 4 mm from the lower section (45 deg edge on the step to facilitate a smooth belt transition between the two drive areas). This section narrows slightly at the top & bottom, giving the spindle a slightly rounded appearance here... But the overall length of this section isn't enough to allow the belt to ride away from the widest point..."
The topmost section of the spindle steps up in dia again - looks to be the same as the 45 rpm section... This also has a 90 deg step edge and forms a kind of "cap" to prevent the belt leaping off the top of the spindle...
So... There aren't any low areas where the belt could be lazily biding it's time... the two drive sections are parallel... The belt seems to be transitioning from one to the other quite nicely, there doesn't feel like there is any "slip" in the drive-train...
What is the significance of "cogging"...? I can't feel any problems with the motor armature - it spins quite freely and my test of the motor's torque is a very subjective one, 'cos I've notheing whatever to compare it to... Would a "good" motor spin me around the room a la Tom & Jerry? or is it about right that a firm pinch will stop it cold..??
I've tried playing with the motor spindle when it's running - lifting the shaft up seems to induce a "cogging" effect and it's quite easy to stall the motor, but when it's in it's normal position, it runs very smoothly with considerable torque...
I'm considering the application of some thin heat-shrink sleeving to the 33+1/3 section (I play my 45's on a 1964 Wurlitzer Jukebox, so that's not a problem at the moment...)
Miti
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