BSR deck running fast

[Growlerman]

Hi guys
Can anybody point me in the right direction to fixing this? I have just restored a Fidelity UA10 stereo record player fitted with a three speed BSR autochanger. I cannot find any model number but it has a plastic platter and the speed change in the bottom LH corner. I have removed all the old grease and re-lubricated where needed. I have also cleaned and aligned the idler wheel with the motor spindle. The mechanism runs very smoothly but a touch too fast!
Is there any other adjustment?

[Nuvistor]

Any build up of dirt on tbe motor spindle where it contacts the idler wheel, not need a lot to make it it run slightly fast, used to be a common fault.
Frank

[Growlerman]

Thanks
I thought I'd cleaned the motor shaft but will check again.
What is best to clean the shaft with? Fine wet and dry paper?

[Nuvistor]

The dirt should easily clean off with isopropyl or something similar, you will be able to see the build up if it's there. These decks very often were not that accurate on the speed though.

[Growlerman]

Maybe then I'm trying to cure an issue that I can't cure!
It's not the highest quality deck (or record player come to that!) that I've worked on.
Would I be right in my guess of it being made 1978 ish?
Never had any dealings before with Fidelity stuff but this one was bought cheaply from a trader and sounds reasonable(apart from running fast!) played through some better bookshelf speakers.

[Nuvistor]

How fast? Just don't expect them to be spot on. The speed should not be that far out.
Don't know the date but "sounds reasonable" is about right. Made for the inexpensive part of the market but I never knock that, I am sure whoever used it when new had plenty enjoyment from it.
Frank

[julie_m]

Frank's right, it doesn't take a lot of dirt to increase the diameter of the spindle enough to make a noticeable difference. If the circumference of the inside driven surface of the turntable platter is 700 mm. (about 225 mm. diameter) and the motor speed is 2800 rpm (about right for a 2-pole induction motor at 50 Hz), then in one minute, 33.33 turns, the distance travelled is 23333.33 mm. The spindle made 2800 turns in this time, so its circumference must be 8.33 mm., giving it a diameter of 2.65 mm. So it only needs an extra 26.5 µm. to give a 1% error.

[Grubhead]

The idler is either slipping up the pole or going down it. I can't remember which for the fast one. Is there a spring on it that keeps it tight to the pole? If there is the spring might be weak.
As others say grease or dirt on the pole will cause it to off position. The speed might not be as good as proper turntable, but it should not be noticeable to most people

[julie_m]

It is the number of metres travelled that is the same for both driving and driven elements. A fatter step on the motor spindle will result in more RPM of the turntable, for the same RPM of the motor.

['LIVEWIRE?']

I usually clean motor pulleys with Isopryl Alcohol or similar, but have occasionally used fine glasspaper to remove rubbery deposits. However, as I understand it, there is/was an allowable tolerance +/- the nominal playing speed of maybe 2%, and of course no adjustment is possible with shaded pole motors. I've never done the maths, Julie, thanks for explaning the relationship between inner diameter and motor spindle diameter.

[Growlerman]

Thank you to all that responded.

I have cleaned the motor spindle again but there doesn't seem any gradual stepping on the shaft apart from the obvious steps for 33, 45 and 78.

I have checked the speed with a strobe and 33 and 45 appear to run slightly fast with 78 about spot on. Perhaps this is the best I can get?

The tension spring is there and when the platter is in place there is quite some force driving the platter.

['LIVEWIRE?']

You're probably correct in thinking that 'slightly fast' is the best you can get. That deck, BTW, is a BSR C123R. There should be a red label on the underside of the deck plate cofirming this.

[Nuvistor]

Appears to be as good as it can be, it's in nice condition.

Frank

[kirstyd]

i have had these where the idler wheel sometimes touches two steps on the motor capstan at the same time.There is an adjustment screw that will move the idler either up or down. Took me ages to work out what was going on though.

[Grubhead]

I think that is precisely what is happening. It's why it doesn't effect the 78 speed. It fits on that right.

[Growlerman]

I have checked that the idler wheel doesn't rub on both the 33 and 45rpm steps on the motor pulley. There is a brass adjustment screw which looks like it moves the idler wheel up the motor shaft. I have had a tweak with it but it doesn't make any difference.

[Grubhead]

My only other thought then is the tyre is too worn and that it only get the right speed when it hits the thicker 78 part of the spindle.

[dinker11]

Hi.
I thought the same thing as kirstyd has posted.

I have a small ITT stereo with a compact BSR deck and it has the "brass screw" idler adjustment which makes a small difference when winding up or down a half turn or so.

It's time consuming to keep lifting the platter on and off but it might be the only way to get the accuracy you're after.

Also as the motor is directly mains voltage fed, your house supply may be a tad higher than average which might have an effect of slightly higher speed.

You can download a printable strobe for free which works very well.

[Grubhead]

But wouldn't the mains affect the 78 speed also?

['LIVEWIRE?']

My thoughts are still 'how fast is it at 33 & 45RPM?. As I noted in post #10, a tolerance of maybe +/- 2% of the nominal speed was no doubt permitted from new in this and other similar decks - i.e between 32.666 & 34 RPM, and between 44 & 46RPM respectively.