Fidelity RG35 radiogram running too fast.

[Ekco-Scott]

Hi everyone.

I have a Fidelity RG35 radiogram but the turntable is running a good 15 to 20% fast making it unlistenable.


Does anyone know where the speed adjustment pot is? or how to adjust the speed?

Has me a bit stumped.

Thanks

Best Regards

[Techman]

No speed adjustment possible on these if it's the original deck.

Check the drive mechanism for the idler running on the correct step on the motor pulley.

[Ekco-Scott]

Thanks for the swift response!

It is the original deck.

Sorry to sound silly but how do you remove the platter on these there is no circlip and it doesn't seem to lift off

Regards

[Techman]

If it's the deck I think it is have a look at the centre and there should be a decorative disc that prizes out - careful not to bend or scratch it and there'll be a circlip below - careful not to break or lose it.

[Edward Huggins]

Well there would normally be a circlip on the BSR C Series autochanger. Just use 3in1 Oil or WD40 around the centre spindle base and remove the platter by easing it off lifting one side - then the other - in very, very, small movements. You will then see the idler wheel position. It might be that the motor mounts have perished/softened and the 33 rpm setting has moved to the 45 rpm.

[vinrads]

Also look for a build up of rubber on the stepped motor spindle ,Mick.

[Ekco-Scott]

For reference here is the deck.

It's a bsr

[Ekco-Scott]

Got to the circlip!

Thank you both for your help and tips

[Ekco-Scott]

Hi everyone

I have just sorted out the problem.

The motor mounts were fine there was somthing wrong with the rubber idler wheel it seems that it was slightly oversized.

After cleaning the motor spindle I then sanded the idler wheel as it spun correcting the speed

[John10b]

Glad you sorted out the problem. I am a little puzzled however, but you fixed it that’s the important thing.
Cheers
John

[Heatercathodeshort]

This is an odd one. The actual size of the idler does not effect the speed of the turntable. I can only think that the pulley was out of adjustment running between two 'steps'. Anyway you have sorted it. John.

[Ekco-Scott]

It was the only thing I could think of to try.

The motor pulley alignment seems correct as its absolutely central in each step.

Every time I removed a small amount of the rubber surface the speed improved.

Now it's dead on in every speed.

[Station X]

Inexplicable. The turntable speed depends only on the size of the step on the motor pulley and the internal diameter of the turntable. The diameter of the idler wheel is immaterial. In theory it could be the size of a dustbin lid.

[slidertogrid]

Originally Posted by vinrads

Also look for a build up of rubber on the stepped motor spindle ,Mick.

This is almost certainly what the problem was it only needs a slight build up to increase the speed. I have had this problem a few times with this type of deck.

Rich

[John10b]

In post #9 he only talks of the idler wheel curing the speed problem, that is the puzzling thing don’t you think?
Cheers
John

['LIVEWIRE?']

I'd agree with others who say that there are only two things which can cause any record player fitted with a shaded pole AC mains motor to run at the incorrect speed, one being the idler wheel engaging with the wrong step on the motor pulley, the other being a build up of rubber on the motor pulley, increasing its diameter. I clean off all rubber which has accumulated on motor pulleys, which solves the speed problem. A shaded pole motor is synchronised to the mains frequency, as most members will know, and is, to a lesser extent, dependant on the mains voltage. These motors seldom develop faults, other than binding bearings, which obviously will have the opposite effect, slowing down the motor.

[Herald1360]

Originally Posted by 'LIVEWIRE?'

A shaded pole motor is synchronised to the mains frequency, as most members will know, and is, to a lesser extent, dependant on the mains voltage. These motors seldom develop faults, other than binding bearings, which obviously will have the opposite effect, slowing down the motor.

Not quite... a shaded pole motor like any other induction motor requires a degree of "slip" from synchronous speed in order to develop any torque. The rotor is not locked to the rotating field produced by the stator as in a synchronous motor. Though the difference in speed is small (the slope of the torque-speed curve near synchronous speed is quite steep) it is finite and will vary with load as well as frequency and voltage.

True synchronous motors were fitted to posher mainly belt drive decks before fully electronic speed control types came along. Some even needed to be manually started!

Rubber build up on the inside of the turntable rim will also speed things up as it will reduce the effective diameter and hence the ratio between the driven and driving "gears".

[crackle]

The only explanation I can think of is; whilst in transport the motor became dislodged slightly so the idler was running on the wrong step of the motor pulley. It must have dropped back into position when it was disturbed.
Sanding the rim of the idler wheel will help if it is slipping and the speed is slow or varying, but it will NOT slow the speed down.

Mike

[Techman]

Originally Posted by Ekco-Scott

the turntable is running a good 15 to 20% fast making it unlistenable.

A quick reminder of the exact description of the fault as reported by the OP.

I think this description of being 'unlistenable' sounds more like an idler stuck on the wrong pulley step rather than just rubber build up on same.

I think that the OP is now happy that it's now working and probably won't come back to this thread anymore. However, the original question has opened up an interesting debate on the various possible causes, so well worth the discussion.

It's been said before that BSR record changers don't suffer from the slipping idler syndrome as much as the Garrards do. This makes me wonder whether the BSR idler wheels have a slightly different composition of rubber that doesn't harden and glaze the same as the Garrard ones do, but because of that, there's a tendency for the rubber to wear away and 'pick-up' on the surface of the pulley, increasing its diameter over time. I have to admit that I've never myself found this problem with rubber build up on a pulley step, but obviously it does happen as others have reported it a number of times, although I tend to doubt that it would make the huge difference that would seem to be reported by the OP in this instance. He says that he sanded the wheel as it spun which corrected the speed. He wouldn't have known whether the speed was correct until he'd refitted the platter, so I definitely think that the mechanism was stuck on the wrong pulley step, which was released when the platter was pulled off and the idler assembly manipulated. Obviously there's more to say to the OP about giving the deck a proper service and giving a drop of clock oil or whatever to those poor old drying up bearings, but he probably won't be back to read this now as he's happy he's cured the original fault - but we can all carry on discussing it and we may discover something about the possible differences in the rubber content between BSR and Garrard idler wheels

[Ekco-Scott]

Hello all.

I'm still stumped on this myself.

You see it wasn't playing at the next speed up. It was too fast on every setting. But only enough to be annoying to me making it unlistenable to my ear.

I checked the alignment when I first took the platter off and it was fine. I cleaned the stepped motor spindle and put the plater back on and it did not improve the speed at all.

I didn't think that sanding the rubber wheel would work either but I just did it as I have nothing to lose and it some how worked. It seems that it was a complete fluke.

I've repaired many record players and radios at this point and am not a complete novice. I still cannot figure out what has corrected the problem and it is annoying me some to be honest. I know sometimes when you fiddle with things with minor problems they work themselves out.

It just seems illogical that everytime I sanded the wheel a bit more the speed reduced slightly until it got to the correct speed.

It's left me very confused.

Regards