Micro-Seiki MB-10 TT - Too Slow..! - diyAudio
Go Back   Home > Forums > Source & Line > Analogue Source

Analogue Source Turntables, Tonearms, Cartridges, Phono Stages, Tuners, Tape Recorders, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 6th April 2008, 08:57 PM   #1
Miti is offline Miti  Scotland
diyAudio Member
 
Join Date: Apr 2008
Question Micro-Seiki MB-10 TT - Too Slow..!

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
  Reply With Quote
Old 6th April 2008, 09:06 PM   #2
diyAudio Member
 
Join Date: Jan 2006
Location: Ireland
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/m...i/bl-10x.shtml

Fran
  Reply With Quote
Old 7th April 2008, 02:13 AM   #3
Miti is offline Miti  Scotland
diyAudio Member
 
Join Date: Apr 2008
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:

Click the image to open in full size.

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
  Reply With Quote
Old 7th April 2008, 11:41 PM   #4
diyAudio Member
 
Join Date: Jan 2006
Location: Ireland
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
  Reply With Quote
Old 8th April 2008, 02:21 PM   #5
Miti is offline Miti  Scotland
diyAudio Member
 
Join Date: Apr 2008
Fran

Quote:
This is a UK TT, not one that you bought/brought home from the USA?
UK Model - I've owned it since about 1985...

Quote:
You replaced the belt with the correct cross section one?
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...

Quote:
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.)
I cleaned the platter belt run and the motor spindle... Didn't think to clean the belt, so I'll do that tonight...

Quote:
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)
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...

Quote:
If you remove the belt does the platter spin freely if you give it a spin?
Oh yes... it's almost a perpetual motion machine... I don't think the centre bearing is the culprit here...

Quote:
Does the motor spindle turn freely? It might "cog" but it shouldn't feel rough or like its grinding/scraping?
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
  Reply With Quote
Old 8th April 2008, 03:33 PM   #6
h_a is offline h_a  Europe
diyAudio Member
 
h_a's Avatar
 
Join Date: Sep 2006
Location: Graz, Austria
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
  Reply With Quote
Old 8th April 2008, 04:15 PM   #7
diyAudio Member
 
Join Date: Jan 2006
Location: Ireland
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
  Reply With Quote
Old 8th April 2008, 09:50 PM   #8
diyAudio Member
 
makinson1's Avatar
 
Join Date: Aug 2004
Location: Tallahassee, FL
If the AC motor speed control is anything like a Thorens, you're in for a real ordeal. Parts aging can make the adjustments really sensitive. Are there some adjustment pots inside or underneith to tweek?
  Reply With Quote
Old 8th April 2008, 11:19 PM   #9
Miti is offline Miti  Scotland
diyAudio Member
 
Join Date: Apr 2008
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
  Reply With Quote
Old 8th April 2008, 11:39 PM   #10
diyAudio Member
 
Join Date: Jan 2006
Location: Ireland
I know a bunch of those TTs (linn ariston and more) use a 110V 4 pole synchronous motor. You end up with 4 wires to the motor, 2 are neutral and 2 are live. One of the lives will have a capacitor which throws it out of phase - is your like that?


Fran
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Micro Seiki Tonearm. MiiB Analogue Source 2 28th May 2007 03:14 PM
Micro-seiki DQX-500 gotster Analogue Source 0 11th January 2005 07:44 PM
Micro Seiki 1500 Cobra2 Analogue Source 18 15th November 2003 09:33 PM
Micro Seiki MC ktigerb Analogue Source 0 27th May 2003 09:16 AM


New To Site? Need Help?

All times are GMT. The time now is 12:48 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2