AMS DMX 15-80s part II -12vac fan?

Archived from groups: rec.audio.pro (More info?)

cs@guavatone.com wrote:

> in this box there was a fan rattling away and recently died. It was
> runing off its own secondary 12.7 VAC/measured drom the toroid. I
> don't see any such AC fans other than 120/220. Did they used to make
> AC fans for this small voltage?
>
> Should I...
>
> A. Try a 120VAC fan with the toroid?

AC fans tend to take rather more power IME and are somewhat rare these
days.

> or
>
> B. Bake a tiny DC regulator or bridge rectifier and a 12VDC fan.

Bridge rectifier and small storage cap would be my choice. You'll end up
with rather more than 12V DC though but it should run a 24V fan ok at
reduced speed.

Graham

Archived from groups: rec.audio.pro (More info?)

Scott Dorsey wrote:

> Pooh Bear <rabbitsfriendsandrelations@hotmail.com> wrote:
> >cs@guavatone.com wrote:
> >
> >> in this box there was a fan rattling away and recently died. It was
> >> runing off its own secondary 12.7 VAC/measured drom the toroid. I
> >> don't see any such AC fans other than 120/220. Did they used to make
> >> AC fans for this small voltage?
> >>
> >> Should I...
> >>
> >> A. Try a 120VAC fan with the toroid?
> >
> >AC fans tend to take rather more power IME and are somewhat rare these
> >days.
>
> Comair/Rotron still makes them for the military market. You don't want
> to know what they charge.
>
> If the fan is shot, you may well just be able to rebuild it and put new
> bearings in. That will almost certainly be easier and cheaper than
> finding a direct replacement. It will, however, be harder and more money
> than it would have been if you'd have relubed it when it started rattling.

That's assuming you can get to the bearings these days !

Graham

Archived from groups: rec.audio.pro (More info?)

In article <1116660812.579756.90600@o13g2000cwo.googlegroups.com>,
<cs@guavatone.com> wrote:
>Thanks scott and pooh.
>
>I nrelubed and epoxy'd the fan to the axle and alll is quiet. I think
>the fan came undone from the axle which made thumping sounds. all is
>good now. from what i can see is that the fan has 2 elcaps -I don't
>see any diodes. Can elcaps "trick" ac to DC?

Are you sure they are electrolytics? They could be motor run caps.
Is it really a three-phase fan in disguise?

> How would one renove
>bearings that small? I've knocked out motorcycle bearing but I don't
>know if I would knock out bearings on a small 1/8" size scale the same
>way.

Same sort of concept. Take the U-clip off so that you can remove the shaft
and the fan blades; you will usually find that the motor armature is part
of the blade assembly. There might be additional expansion clips holding
the bearings on either side in place, or they might just be press-fit in
and putting a metal punch in from the other side and applying a little hand
pressure will knock them out. A small hammer _might_ be required but be
careful.

If the bearings have New Departure numbers on them, you can usually get a
cross-reference from Applied Industrial Technology in the US over the phone,
otherwise you might have to measure them.

SOME fans have sleeve bearings which aren't replaceable, but you'll know
that as soon as you get the shaft out. Most older fans, before they started
making them as cheaply as possible, were ball bearing.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."