STD 305M main bearing question

snap, crackle and pop
Trio KD1033
senior member
senior member
England
Posts: 342
Joined: 20 Oct 2015 00:18

Re: STD 305M main bearing question

Post by Trio KD1033 » 29 Dec 2016 14:02

Just raising this old thread from the dead with a conclusion of sorts.

I figured out by experimentation that this bearing did not have a ball at the bottom, rather a domed thrust base. I think that it may, when new, have had a dome of something like ptfe. This had worn away leaving the rest of the dome. I bought a 7mm ptfe thrust pad from SRM Tech and dropped it in. This immediately reduced a lot of the noise. It was while I was doing this that I realised that in order to get any oil to the upper sleeve of the bearing, you would need to put a considerable amount of oil in. This is because the gap between the upper and lower sleeves would need to be filled as well. I put enough oil in and cleaned away any overfill. Since then it has got quieter every day to the point that even in a totally silent room with my ear on top of the spindle, I can hear nothing!

The amazing thing is, because of the extensive damping and thick mat used, I could never hear any noise even with the quietest of silent rumble test tracks, and that was when the bearing was making a distinct "swishing" sound.

So to sum up it needed:

Cleaning out
Refilling with enough oil to fill the void between the bearing sleeves
A replacement thrust pad from SRM Tech.

Just thought I would post this for anyone doing a search in future on the STD 305m bearing.

Andy

Armbored
member
member
Great Britain
Posts: 106
Joined: 19 Jan 2015 18:14
Location: Aberdeen, Scotland

Re: STD 305M main bearing question

Post by Armbored » 22 Apr 2019 22:33

Most interesting Andy. I have recently acquired one and the bearing was noisy. Independent of this thread, I have purchased a PTFE thrust pad from SRM along with their turntable oil. Initial results are promising, buoyed by your message that it will get better over time. Incidentally, mine has the ball but the spindle is flat at the bottom. There is a dimple on it, slightly off centre strangely, could it be the deck was ran for a long time while not being perfectly level? Not sure what would cause this.


Mike
Attachments
WP_20190316_22_45_29_Pro.jpg
(173.13 KiB) Downloaded 65 times

Trio KD1033
senior member
senior member
England
Posts: 342
Joined: 20 Oct 2015 00:18

Re: STD 305M main bearing question

Post by Trio KD1033 » 23 Apr 2019 11:31

Armbored wrote:
22 Apr 2019 22:33
Most interesting Andy. I have recently acquired one and the bearing was noisy. Independent of this thread, I have purchased a PTFE thrust pad from SRM along with their turntable oil. Initial results are promising, buoyed by your message that it will get better over time. Incidentally, mine has the ball but the spindle is flat at the bottom. There is a dimple on it, slightly off centre strangely, could it be the deck was ran for a long time while not being perfectly level? Not sure what would cause this.


Mike
You obviously have a different bearing, as there was no room for a ball in mine, plus there was this odd structure at the bottom which suggested that it performed the function of the ball.
Does the ball fit fairly snugly? I can't imagine being off level would cause the dimple to be off centre, they tend to take up their position naturally. Someone else may have some ideas on that one. Mine has remained absolutely silent since which is great!

Good luck

Andy

Edit: Lots of oil appears to help

Armbored
member
member
Great Britain
Posts: 106
Joined: 19 Jan 2015 18:14
Location: Aberdeen, Scotland

Re: STD 305M main bearing question

Post by Armbored » 23 Apr 2019 22:30

Andy,

The ball in the bearing housing is captive, placed in from underneath and then sealed with the epoxy type. It's too big to come out the spindle hole. Great to hear the tt is quiet and giving you pleasure!

Cheers
Mike

Trio KD1033
senior member
senior member
England
Posts: 342
Joined: 20 Oct 2015 00:18

Re: STD 305M main bearing question

Post by Trio KD1033 » 23 Apr 2019 22:47

Armbored wrote:
23 Apr 2019 22:30
Andy,

The ball in the bearing housing is captive, placed in from underneath and then sealed with the epoxy type. It's too big to come out the spindle hole. Great to hear the tt is quiet and giving you pleasure!

Cheers
Mike
Hope you sort the noise out Mike, they are things of beauty aren't they? I can only imagine how much something built so heavily would cost today!

Andy

Armbored
member
member
Great Britain
Posts: 106
Joined: 19 Jan 2015 18:14
Location: Aberdeen, Scotland

Re: STD 305M main bearing question

Post by Armbored » 23 Apr 2019 23:00

Yes, it's a sturdy beast for sure and so retro it's really cool. Mine is actually a 305D and I have not mounted an arm yet. I'm surprised the bearing spindle is so narrow though, there will be a reason for it, I guess.

Best
Mike

Trio KD1033
senior member
senior member
England
Posts: 342
Joined: 20 Oct 2015 00:18

Re: STD 305M main bearing question

Post by Trio KD1033 » 23 Apr 2019 23:14

Armbored wrote:
23 Apr 2019 23:00
Yes, it's a sturdy beast for sure and so retro it's really cool. Mine is actually a 305D and I have not mounted an arm yet. I'm surprised the bearing spindle is so narrow though, there will be a reason for it, I guess.

Best
Mike
Ah the 305D with the digital display and press button speed change, they really are cool. I think the bearing spindle is 7mm if I recall, pretty small as you say.

Andy

Armbored
member
member
Great Britain
Posts: 106
Joined: 19 Jan 2015 18:14
Location: Aberdeen, Scotland

Re: STD 305M main bearing question

Post by Armbored » 25 Apr 2019 01:13

I've stuck a Rega 300 on it and fired it up but there is terrible hum. At first I thought it was the arm, but now I think it's the power supply or transformer, I can hear it from the turntable when I select a different input on the preamp. As I'm using moving coil, the hum is being boosted, and audible through the speakers... I mean really bad! Will check the PS tomorrow.

Bearing seems good though!


Mike

Trio KD1033
senior member
senior member
England
Posts: 342
Joined: 20 Oct 2015 00:18

Re: STD 305M main bearing question

Post by Trio KD1033 » 25 Apr 2019 07:51

Armbored wrote:
25 Apr 2019 01:13
I've stuck a Rega 300 on it and fired it up but there is terrible hum. At first I thought it was the arm, but now I think it's the power supply or transformer, I can hear it from the turntable when I select a different input on the preamp. As I'm using moving coil, the hum is being boosted, and audible through the speakers... I mean really bad! Will check the PS tomorrow.

Bearing seems good though!


Mike
The RB300 doesn't have a separate earth does it? Might be worth experimenting with a wire from the chassis to the earthing point on your amplifier. I know mine is different, as it just has a very simple synchronous motor and basic power supply setup, but it's hum levels are exceptionally low, I think because of the sheilding properties of the metal plinth. Even the base has it's own earth wire!

Andy

Edit: Glad to hear the bearing's okay though!

Trio KD1033
senior member
senior member
England
Posts: 342
Joined: 20 Oct 2015 00:18

Re: STD 305M main bearing question

Post by Trio KD1033 » 17 Jun 2019 22:19

Well, anyone who has followed this thread from the start, will know that a few years ago I purchased an STD 305M that had a noisy centre bearing. Upon looking at the bottom of the bearing assembly, it appeared to be missing a ball bearing, but if you put one of seemingly suitable size in it lifted the spindle out of the lower bronze sleeve making it useless. All other 305M owners had a captive ball bearing that was about the width of the spindle, 7mm. In mine there was an unusual structure at the bottom of the well that looked as though it was there to support a smaller ball of some sort.

Fast forward a couple of years and a good friend of mine has just bought a 305M and it has exactly the same bearing as mine. His, though has a small ball bearing at the centre! Now all I've got to work out what size it is.

This is what the base of my bearing looks like, the bit In the middle is like a tiny volcano with a hole at the very centre. Just got to figure out now what size will stay put! Looks to be somewhere around 2mm.
Andy
image.jpeg
(234.42 KiB) Downloaded 19 times

Armbored
member
member
Great Britain
Posts: 106
Joined: 19 Jan 2015 18:14
Location: Aberdeen, Scotland

Re: STD 305M main bearing question

Post by Armbored » 17 Jun 2019 23:16

Hi Andy,

How interesting, I've never seen anything like that before. Have you been using it like this? I would estimate the diameter of the little 'cup' to be about 1.5mm, so some smart maths might be required to work out the perfect size ball to fit. However, the cup does not looked concave but rather just a lip to retain the ball in the correct position.

I've not been using mine, I gave up on it a bit and found another tt I am optimising at the moment. I'll come back to it when I have more time on my hands. Good luck with the ball.

Regards
Mike

Trio KD1033
senior member
senior member
England
Posts: 342
Joined: 20 Oct 2015 00:18

Re: STD 305M main bearing question

Post by Trio KD1033 » 17 Jun 2019 23:28

Armbored wrote:
17 Jun 2019 23:16
Hi Andy,

How interesting, I've never seen anything like that before. Have you been using it like this? I would estimate the diameter of the little 'cup' to be about 1.5mm, so some smart maths might be required to work out the perfect size ball to fit. However, the cup does not looked concave but rather just a lip to retain the ball in the correct position.

I've not been using mine, I gave up on it a bit and found another tt I am optimising at the moment. I'll come back to it when I have more time on my hands. Good luck with the ball.

Regards
Mike
Hi Mike,

I had been using it with a ptfe disc inbetween the spindle and "volcano". This allowed it to spin quite freely and silently.

I reckoned with a bit of working out it was about what you said, 1.5mm. I'm guessing the ball must be around 3mm. It can't be much bigger, because the spindle is then lifted out of the lower bearing sleeve.

Andy

Armbored
member
member
Great Britain
Posts: 106
Joined: 19 Jan 2015 18:14
Location: Aberdeen, Scotland

Re: STD 305M main bearing question

Post by Armbored » 18 Jun 2019 00:08

Yeah, that's what I put in mine, the PTFE disc. Seemed to work and was pretty quiet mechanically but I think the motor hum was being picked up by the cartridge (Denon 304). I will try a MM some day instead of an MC.

Cheers
Mike

Post Reply