Before I take it out does anyone know if they are repairable? It's probably 
got dodgy brushes.

Si

In article <42dcb1f1$0$13705$cc9e4d1f@news-text.dial.pipex.com>,
   Mungo \two sheds\ Toadfoot  wrote:

> Before I take it out does anyone know if they are repairable? It's
> probably got dodgy brushes.


They're usually well and truly sealed because of the hostile environment.
But I'd say it's unlikely the brushes would wear out anyway, given their
limited use.

You're certain it's the motor and not the control or wiring to it? The
switches, relays, and connectors are IMHO more likely to give trouble.

The only certain way is to apply battery volts direct to it. They're
usually a simple two wire device with no ground required. Reversing the
connections reverses the motor. If it's working but sluggish I'd first
check for voltage drop.

-- 
*Where there's a will, I want to be in it.

    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

Dave Plowman (News) (dave@davenoise.co.uk) gurgled happily, sounding much 
like they were saying :


> The only certain way is to apply battery volts direct to it. They're
> usually a simple two wire device with no ground required. Reversing the
> connections reverses the motor. If it's working but sluggish I'd first
> check for voltage drop.


It's also well worth checking the physical side - is the glass moving 
smoothly, is the cable grotty etc.

Dave Plowman (News) wrote:

> In article <42dcb1f1$0$13705$cc9e4d1f@news-text.dial.pipex.com>,
>   Mungo \two sheds\ Toadfoot  wrote:
>> Before I take it out does anyone know if they are repairable? It's
>> probably got dodgy brushes.
>
> They're usually well and truly sealed because of the hostile
> environment. But I'd say it's unlikely the brushes would wear out
> anyway, given their limited use.
>
> You're certain it's the motor and not the control or wiring to it? The
> switches, relays, and connectors are IMHO more likely to give trouble.
>
> The only certain way is to apply battery volts direct to it. They're
> usually a simple two wire device with no ground required. Reversing
> the connections reverses the motor. If it's working but sluggish I'd
> first check for voltage drop.


I *think* it's the motor; when the window works it works perfectly but it 
just stops on occasion. A good tug on the window often makes it start 
working again so I guessed it might be that when the motor stops in a 
certain position it won't restart.

I will apply the leccy to it directly, as you suggest, and test the output 
from the box of gubbins. Bugger to get to though.

Si

Adrian wrote:

> Dave Plowman (News) (dave@davenoise.co.uk) gurgled happily, sounding
> much like they were saying :
>
>> The only certain way is to apply battery volts direct to it. They're
>> usually a simple two wire device with no ground required. Reversing
>> the connections reverses the motor. If it's working but sluggish I'd
>> first check for voltage drop.
>
> It's also well worth checking the physical side - is the glass moving
> smoothly, is the cable grotty etc.


It's all fine mechanically, but I did wonder where the "stop" sensor part 
lived, and whether it just detects strain within the motor itself or 
something a bit more technical. Oh, I know; why not have a look at the 
workshop manual which arrived yesterday on cd!? Sometimes.......

It's a Nissan Terrano (the bane of my life), btw.

Si

In article <42dcd97a$0$13701$cc9e4d1f@news-text.dial.pipex.com>,
   Mungo \two sheds\ Toadfoot  wrote:

> It's all fine mechanically, but I did wonder where the "stop" sensor
> part lived, and whether it just detects strain within the motor itself
> or something a bit more technical.


I can only be general, since I don't know your car.

Older systems had no limit switches at all - the motor simply stalled.
There would usually be some form of over current protection, though,
usually in the form of a self resetting breaker, in case you kept the
switch closed. Or even on some you had to re-set it manually.

More modern types - usually with 'one shot' operation - will have a
current sensor in the motor feed which cuts the power when it reaches the
end of its travel or is stopped in any way.

-- 
*Yes, I am an agent of Satan, but my duties are largely ceremonial 

    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

> I *think* it's the motor; when the window works it works perfectly but it 
> just stops on occasion. A good tug on the window often makes it start 
> working again so I guessed it might be that when the motor stops in a 
> certain position it won't restart.
>


If the window jams (or reaches the end of its travel) the motor can't turn 
any more and the current it draws goes up. With one system a sensor detects 
this and cuts the power feed. If the motor is one where the current is being 
monitored like this either the monitor is too sensitive or the glass is 
jamming on its way up. You need to be sure that neither of these factors is 
true in your case.

Rob Graham

Rob graham wrote:

>> I *think* it's the motor; when the window works it works perfectly
>> but it just stops on occasion. A good tug on the window often makes
>> it start working again so I guessed it might be that when the motor
>> stops in a certain position it won't restart.
>>
>
> If the window jams (or reaches the end of its travel) the motor can't
> turn any more and the current it draws goes up. With one system a
> sensor detects this and cuts the power feed. If the motor is one
> where the current is being monitored like this either the monitor is
> too sensitive or the glass is jamming on its way up. You need to be
> sure that neither of these factors is true in your case.
>


Righto, will do. Ta.

Si

> > If the window jams (or reaches the end of its travel) the motor can't
> > turn any more and the current it draws goes up. With one system a
> > sensor detects this and cuts the power feed. If the motor is one
> > where the current is being monitored like this either the monitor is
> > too sensitive or the glass is jamming on its way up. You need to be
> > sure that neither of these factors is true in your case.
> >
>
> Righto, will do. Ta.
>
> Si
>
>


It could also be that one of the coils in the motor has fried leading it to
run at normal speed when no load is applied but then running slowly under
load and/or refusing to start if it stops with the dead coil connected
across the brushes, just a brief helping hand is needed to startit. You can
only really check this by dismantling the motor and checking for
shorted/open circuit coils between the armature segments. If this is the
problem then just change the motor.

Chris

On Tue, 19 Jul 2005 12:45:20 +0100, "Dave Plowman (News)"
 wrote:


>More modern types - usually with 'one shot' operation - will have a
>current sensor in the motor feed which cuts the power when it reaches the
>end of its travel or is stopped in any way.


Something that surpised me was the way my Punto's service manual says
that it detects when it ought to stop.

Apparently there's a microphone and some electronics detect a change
in the pitch of the sound from the motor!

Is this unique to Fiat?
-- 
Locate your Mobile phone: <http://www.bizorg.co.uk/news.html>
Great gifts: <http://www.ThisBritain.com/ASOS_popup.html>

In article ,
   David Quinton  wrote:

> >More modern types - usually with 'one shot' operation - will have a
> >current sensor in the motor feed which cuts the power when it reaches the
> >end of its travel or is stopped in any way.

> Something that surpised me was the way my Punto's service manual says
> that it detects when it ought to stop.


I can't see why, given that modern windows use much less powerful motors
than once. The ones on my SD1 positively whizz up and down compared to my
much newer BMW.


> Apparently there's a microphone and some electronics detect a change
> in the pitch of the sound from the motor!


What a strange way of doing it. ;-)

The easiest way is simply to measure the voltage drop in a length of the
cable feeding it (or by using a very low series resistance which won't
effect performance) - easily done with modern electronics. Really a bit
like an ammeter. Once that drop exceeds a certain figure, it means the
motor is drawing too much current and gets switched off.

-- 
*In some places, C:\ is the root of all directories *

    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

The message 
from "Dave Plowman (News)"  contains these words:


> I can't see why, given that modern windows use much less powerful motors
> than once. The ones on my SD1 positively whizz up and down compared to my
> much newer BMW.


I noticed that getting back into the Montego after the Audi. Apart from
being high up, tinny and plasticky, the windows fly up and down so fast.

-- 
Skipweasel.
Ivor Cutler - "Never knowingly understood."

David Quinton wrote:


> Apparently there's a microphone and some electronics detect a change
> in the pitch of the sound from the motor!
> 
> Is this unique to Fiat?


Fiat tends to have a very unique approach to anything approaching 
elektrikery, often with amusing or dire results.