Commonwealth 12/D3 capstan confusion

[kaputt]

Hi everyone, especially the usual suspects from the Commonwealth crew.
I finally have my 12/D3 rebuilt and running but the platter speeds seem wrong. First of all the idler wheel seemed awfully low in respect to the capstan and now that it's mounted the platter spins at 33 when switched to 45 and 45 when switched to 78. When in 33 gear it does 16.
Could it be that the capstan on the D3 and the D4 are the same and the uppermost step on the D3 is unused?

I hope so, otherwise I don't know what else to do as i've disassembled, cleaned and relubed the motor a couple of times now with various lubricants and was wondering that the speed is exactly one step off but otherwise rocksolid.

[cafe latte]

I think your rubber gromets have gone soft that the motor hangs lower than it should making the idler be one step out, the top step is not used it is for another model. This problem is an easy fix by fitting rubber washers under the gromets to raise the motor. There is an adjustement on the base of the motor which you should try first, but dont adjust too much, if the motor gets noisy back it off again you need a little vertical play on the bearing. There is a locknut and screw slot which will allows you to raise and lower the spindle, but if if you run out of adjustement washers are the way to go. If you add rubber wahers check also that the motor is hanging square as mine was not causing the idler and the spindle to meet at and angle making the turntable run slow and the idler to scrub. Also check that the idler arm is not bent, again mine was as if the platter is fitted when the turntable is not in neutral the platter comes down on the idler and bends the bracket. I dont think this is your problem but it something to be aware of.
I am sure this will sort you out, but if you need any other help dont hesitate to ask.
Regards
CL

[kaputt]

the top step is not used it is for another model.

Thank you very much, that was what I needed.
I heightened the idler assembly to get the idler wheel to the upper step of the capstan as I was sure this was the 33rpm section. I changed it back and now everythings fine. I'm still fiddling with solenoid pressure which has quite some effect on rumble.

Best regards,
Daniel

[cafe latte]

the top step is not used it is for another model.

Thank you very much, that was what I needed.
I heightened the idler assembly to get the idler wheel to the upper step of the capstan as I was sure this was the 33rpm section. I changed it back and now everythings fine. I'm still fiddling with solenoid pressure which has quite some effect on rumble.

Best regards,
Daniel

You should not have ANY rumble at all so if you have i would be looking at the idler or idler bearing first and the lube of the spindle bearing. The idler wheel will be hard by now as this is an old turntable, but the surface of the wheel will be the problem and couple of mm in the rubber will be fine. Spend the money and ask a machine shop to do this and lathe the idler wheel down to soft rubber, do not attempt to try to sand it by hand as you will make the rumble worse as the idler must be PERFECTLY ROUND. The idler bearing is sintered bronze and mine was worn out. It is a commmon size so is easy to get and should be lubed with iso 46 compressor oil as should the spindle bearing and the motor oil tubes and the idler will take a few days with the new bearing to become completely quiet.
Regards
CL

[kaputt]

I had the idler refurbished by Svalander in Sweden. What bothers me is, when I start the turntable without platter and push the idler to the capstan by the idler spindle so it lightly touches and turns, I feel the spindle move back and forth quite a bit. That movement corresponds with the sound I hear when the table is spinning with platter on.

[Alec124c41]

If you hold the point of a pencil to the side of the capstan, you will know immediately if it is off center.

Cheers,
Alec

[cafe latte]

I had the idler refurbished by Svalander in Sweden. What bothers me is, when I start the turntable without platter and push the idler to the capstan by the idler spindle so it lightly touches and turns, I feel the spindle move back and forth quite a bit. That movement corresponds with the sound I hear when the table is spinning with platter on.

Do you mean the idler spindle has play?
The sintered bronze bush in the idler wheel is available as an off the shelf size as I ordered mine from my local parts shop were I get all my car parts and bearings. Under the idler whell on th spindle there should be a little ptfe plastic washer, if it is missing the idler will be noisy. You should also have a little circlip on the top of the idler spindle to prevent the idler from 'walking' up and down the spindle. Also lube the idler spindle with iso 46 compressor oil which you should also use for the main TT bearing and the motor oil tubes too. When I fitted the new sintered bronze bush to the idler wheel it took several oilings and cleaning each re oil until it ran quiet, now i just add a tiny drop of oil when I reoil the rest of the turntable, but make sure you dont get any oil on the idler wheel rubber.
Another source of noise is if the height is not set correctly or if the idler wheel is a bit out of shape (easily fixed as you manipulate it by had if it is)and the side of the idler wheel is touching the steps on the capsian. If it is adjust the height of the motor a touch lower so the idler is clear of the flat steps by a mm or 2.
Hope this helps
Regards
CL

[kaputt]

If you hold the point of a pencil to the side of the capstan, you will know immediately if it is off center.

Cheers,
Alec

Hi Alec, I already did this and the wheel is perfectly centered.

[kaputt]

I did check the spindle for play and the bushing is perfect, no play at all. I meant when I take the platter off, switch on the motor and move the idler spindle towards the capstan so the idler starts turning it feels as if the idler was a hexagon.
I used some slim washers (don't know the english term, very thin washers used to set play) on the idler wheel spindle and the spindle of the idler arm and noise is much less.

Do you mean the idler spindle has play?
The sintered bronze bush in the idler wheel is available as an off the shelf size as I ordered mine from my local parts shop were I get all my car parts and bearings. Under the idler whell on th spindle there should be a little ptfe plastic washer, if it is missing the idler will be noisy. You should also have a little circlip on the top of the idler spindle to prevent the idler from 'walking' up and down the spindle. Also lube the idler spindle with iso 46 compressor oil which you should also use for the main TT bearing and the motor oil tubes too. When I fitted the new sintered bronze bush to the idler wheel it took several oilings and cleaning each re oil until it ran quiet, now i just add a tiny drop of oil when I reoil the rest of the turntable, but make sure you dont get any oil on the idler wheel rubber.
Another source of noise is if the height is not set correctly or if the idler wheel is a bit out of shape (easily fixed as you manipulate it by had if it is)and the side of the idler wheel is touching the steps on the capsian. If it is adjust the height of the motor a touch lower so the idler is clear of the flat steps by a mm or 2.
Hope this helps
Regards
CL

[Alec124c41]

If the capstan is centered and the idler is round, that leaves motor cogging. I'm guessing, now, that the phasing capacitor(s) may be out of spec. Anybody?

Cheers,
Alec

[kaputt]

I checked the capacitor after disassembly. Supposed value 0.5uF, actual value 0.55uF.
I saw the idler wheel "wobbles" a bit. The edge moves up and down on the capstan a bit.

If the capstan is centered and the idler is round, that leaves motor cogging. I'm guessing, now, that the phasing capacitor(s) may be out of spec. Anybody?

Cheers,
Alec

[cafe latte]

I checked the capacitor after disassembly. Supposed value 0.5uF, actual value 0.55uF.
I saw the idler wheel "wobbles" a bit. The edge moves up and down on the capstan a bit.

If the capstan is centered and the idler is round, that leaves motor cogging. I'm guessing, now, that the phasing capacitor(s) may be out of spec. Anybody?

Cheers,
Alec

You say it feels like the idler wheel is a hexagon means it may not be perfectly round. It may have been refurbed, but did they do a good job? With my idler I clamped it in a friends lathe and clamped a deremel cut off wheel in place of a cutting tool. I slowly brought the cutter forward and the dremel cut of wheel basically sanded the idler wheel perfectly round. Dont attempt it though without a lathe as you wont get it round. If you have put a metal thin washer under the idler it will help noise but you really need a plastic washer or even a felt washer would also do.
If the idler rubber is bent a bit so it wobbles side ways as it rotates as it did also on mine I found that gently bending it by hand you can bend the warps out. It took me a few attempts of bending the rubber, and restarting the ider and watching it spin, and retrying until it spun without wobble.
It is worth replacing the caps too as Alec said even if the measure correct they can still leak and cause problems.
Regards
CL

[kaputt]

I put in a spare cap with no change. I ordered a fresh oilite bushing for the idler and I have a lathe at my disposal and will check the idler roundness with a dial indicator and if necessary rework the edge.
I'll keep you posted.

[cafe latte]

I put in a spare cap with no change. I ordered a fresh oilite bushing for the idler and I have a lathe at my disposal and will check the idler roundness with a dial indicator and if necessary rework the edge.
I'll keep you posted.

If the edge if the idler wheel rubber is cast and not lathe finished (you said your idler had been refurbished) then it might be round but not perfectly smooth and even. If you have a lathe at your disposal I would however it measures take maybe even just a mm or rubber so then you are sure everything is perfect. I mounted the dremel cutting disc in its spindle (the one you use if you were going to mount it in the dremel). I then clamped the spindle in the lathe instead of the lathe cutting tool. I slowely moved the cutter up to just touch the idler wheel and cleaned it up.
Look forward to your update.
Regards
CL