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Any Yamaha GT-750 owners out there? Noise problem from platter.

Psimonics

Psimonics

Active Member
I posted previously that the noise issue had disappeared but I was wrong. It's still audible.
I've cleaned and re-oiled the bearing and run it overnight and it hasn't made any more difference.

There seem to be scratch marks on the motor pcb surface right below the outer rim of the sub platter, which would suggest that could be the source of the scraping sound I'm hearing. I've no idea how to resolve this.

The bearing appears to be bronze or brass, and has no ball bearing in the bottom. I read that the Yamaha GT-2000 bearing does. I know that unit is a different design, but could it be that somehow a ball bearing is missing on my tt causing the platter to ride low?

I'd be interested to hear from any other owners of this unit and grateful for any guidance.

Cheers,
Simon
 
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Psimonics said:
There seem to be scratch marks on the motor pcb surface right below the outer rim of the sub platter, which would suggest that could be the source of the scraping sound I'm hearing.

Cheers,
Simon
Click to expand...

I'm surprised that you mention a "sub platter". I've never heard of any direct drive with a sub platter and I assure you that the GT 2000 doesn't have a sub platter. On the '2000 the platter has a tapered hole which fits onto a similar taper on the motor bearing spindle.

Do you have access to a camera?

Even if you are able to access a camera I will apologise in advance that I won't be able to assist with a fix for the problem. I'm not savvy with the knowledge required to repair components. I suggest that you post a photo to simplify the process for those who might be able to assist you. I'm sorry to hear that you are faced with this problem. Just a question: Was there any evidence on the box that it was shipped within, that the box had been dropped/damaged?
 
theophile said:
I'm surprised that you mention a "sub platter". I've never heard of any direct drive with a sub platter and I assure you that the GT 2000 doesn't have a sub platter. On the '2000 the platter has a tapered hole which fits onto a similar taper on the motor bearing spindle.
Click to expand...

Thank you for your reply.

I must be using the wrong terminology. It must be the motor bearing spindle.
There are photos on this japanese webpage here:
http://blogs.yahoo.co.jp/doraemondayo4518/GALLERY/show_image.html?id=46448793&no=1

The bottom rim of the motor bearing spindle is I think scraping the pcb just visible in the photo.

And no, no sign that the box was damaged. The delivery companies here in Japan are meticulous.
 
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Have you contacted the person you purchased it from? Because if there was no damage to the box, they have sold you a faulty turntable.
 
I have on experience with that table, but have seen other DD motors where the drive magnet has slid down the spindle.
A few well placed taps put it back in position.
 
theophile said:
Have you contacted the person you purchased it from? Because if there was no damage to the box, they have sold you a faulty turntable.
Click to expand...

I'm considering that, but I'd like to make sure it's not something that's easily rectified first. I would really like to know if there is a ball bearing missing, but I don't think that's the case. I'm pretty sure the bearing hadn't been opened up for years until I did and there was certainly no ball in there then.

But if I have no luck this weekend I'm going to contact them. They gave me a 6 month gaurantee.
 
Psimonics said:
I'm considering that, but I'd like to make sure it's not something that's easily rectified first. I would really like to know if there is a ball bearing missing, but I don't think that's the case. I'm pretty sure the bearing hadn't been opened up for years until I did and there was certainly no ball in there then.

But if I have no luck this weekend I'm going to contact them. They gave me a 6 month gaurantee.
Click to expand...
If you paid via Credit Card it might be worth investigating whether they can retrieve your money if the seller doesn't honour their warranty.
 
On my Akai AP-206 (I know - this is no GT-750....but maybe this can help, it's also a DD) the bottom of the motor spindle sits in a big plastic retaining nut accessible from the bottom (thats where the thrust plate is). This nut is threaded and screwing it in lifts the rotor and platter, unscrewing it lowers them. It was factory "glued" but I dismantled it for cleaning and thats when I discovered this.
 
Bert 1100 said:
On my Akai AP-206 (I know - this is no GT-750....but maybe this can help, it's also a DD) the bottom of the motor spindle sits in a big plastic retaining nut accessible from the bottom (thats where the thrust plate is). This nut is threaded and screwing it in lifts the rotor and platter, unscrewing it lowers them. It was factory "glued" but I dismantled it for cleaning and thats when I discovered this.
Click to expand...

On the underside of the bearing, the GT-750 also has a plastic plate with ridge that positions it in the bearing and an o-ring seal around that. Then a steel cover over that with screws / spring washers. No way to adjust the height.
 
Success!

I discovered that the the magnet on the base of the motor bearing spindle had become loose, just as in the photographs in the link I pasted before. I just hadn't noticed it. I tried to prise the magnet off and it cracked and broke which dismayed me, but I cleaned off the old glue and put it back into place using epoxy resin. When I put the spindle back in the tt it was scraping less, but still there, so I followed the advice from Number13 and tapped the top of the spindle with a hammer. It now spins with no noise whatsoever! The quartz lock indicator lamps come on and the sound is fantastic!

Great thanks to you all for your advice.
Simon
 
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