Tweaking: Bypassing spindle motor with caps: Yay or Nay?

[Scorpio(DDMF)!]

In one of the older threads about cd-player tweaking, someone suggested this as a method for filtering RF “junk” wich “toy motors” seem to produce. Tweak consisted of using 3 1 nF ceramics caps: one from + to – terminals on the motor, others from + and – terminals to the ground.

I’ve used it on a good ol’ Mabuchi in KSS-151a transport recently. As a result I ended up keeping only the on the motor terminals, since the motor wouldn’t spin at all when other two were used.

The fact that there was an empty space for a non-polarised capacitor right between the + and – motor terminals on the motor board of my player (no reference to it in the service manual) got me thinking

What would be the teorethycal benefits and/or problems (excluding the obvius ) of such tweak?

Cheers

[I_Forgot]

If a cap was needed, the engineers who designed the thing would have put one there.

I_F

[Rambi]

Originally posted by I_Forgot
If a cap was needed, the engineers who designed the thing would have put one there.

I_F

For a commercial product the question wouldn't be: 'do we need it there?', but rather: 'can we do without?'.
Apparently the answer to the last question was 'yes'
A cap may filter out some of the garbage coming from a motor, but a separate small power supply would be better.
If there's already a space for a capacitor just try it and see (hear) what happens, if anything.

Remco

[siezien]

For a commercial product the question wouldn't be: 'do we need it there?', but rather: 'can we do without?'.

exactly or HOW MUCH ??

Scorpio, do you have somme pics please, I don't undestand very well.

ceramic caps = COG or NDO caps ?, can I use silver mica ?

thanks a lot.

[Scorpio(DDMF)!]

Originally posted by Rambi


If there's already a space for a capacitor just try it and see (hear) what happens, if anything.

Remco

I've already bypassed the motor's + and – terminals with a regular 1 nF ceramics cap, I think I percieved a suble increase in overall clarity and resolution. My question would be if this is the correct implementation, or there is a better (more effective) way?

Originally posted by siezien


Exactly or HOW MUCH ??

Scorpio, do you have somme pics please, I don't undestand very well.

ceramic caps = COG or NDO caps ?, can I use silver mica ?

thanks a lot.

Unfortunatly, I don't have any pics, but the modification is rather easy to implement. I've soldered the 1 nF ceramics cap from + to – terminal on the spindle motor. The cap is regular of the shelf ceramics, nothing special or out-the-ordinary. I don't know if it would be beneficial and/or cost effective to use something different. I did plan to find out by starting this thread, but that isn't working out as expected until now...

OK, here are the threads that contain the references to the tweak by multiple people:

Which Philips is the best ?

Originally posted by Bernhard

Motors with brushes make a lot of noise.

Acoustical and electrical (RF).

Radio controled cars ( toys ) have ceramic caps across the Mabuchi motor terminals and to ground from each terminal.

The transports do not.

http://www.diyaudio.com/forums/showt...t=#post1033626
Hi Guido, in decoupling the +&- to ground, what type cap and value do you recommend?

Cheers George

Originally posted by Guido Tent



Hi george

I never went that far. If the machine runs OK let them in, I achieved major reduction in radiated RF by using 10nF, so 100nF will work as well

best

My primary concern would be the effective suppresion of RF without getting in the way of the motor controller (like it was the case with bypassing the motor with 100 nF MKT cap )...

I would like to invite people to share their opinions about the subject (especially the authors of the quotes mentioned!)...

The last quote offers somewhat a different solution, using the caps from + and – terminals to ground only (without using the one directly on the motor terminals).

Which of these two examples would be best?

Thanks in advance

[Scorpio(DDMF)!]

Anyone?