Variable speed function on my PPPro (GMC) angle drill has just died - it
still goes from zero to top speed instantaneously but controlling speed
according to trigger pressure is no longer possible, so no use for
screwdriving.

I spoke to B&Q who pointed me to GMC who referred me back to B&Q - so
getting a spare through official channels isn't going to happen.

Anyone know how these switches work (or fail) and whether it's possible
to get/construct a generic replacement from Maplin/RS parts?

It seems a shame to landfill it just because the switch has failed.

mike wrote:

Variable speed function on my PPPro (GMC) angle drill has just died - it
still goes from zero to top speed instantaneously but controlling speed
according to trigger pressure is no longer possible, so no use for
screwdriving.

I spoke to B&Q who pointed me to GMC who referred me back to B&Q - so
getting a spare through official channels isn't going to happen.

Anyone know how these switches work (or fail)

if youre asking that you wont be able to repair the electronics

and whether it's possible
to get/construct a generic replacement from Maplin/RS parts?

I'd look out for a faulty tool with a similar speed control and see if
it
can fit. Freecycle would be a fair place to ask, or the local tip.
Why
pay if a freeb is on the go.


It seems a shame to landfill it just because the switch has failed.

yes, if you've got the time.


NT

HI Mike

On Thu, 13 Mar 2008 18:30:24 -0700 (PDT), wrote:

mike wrote:

Variable speed function on my PPPro (GMC) angle drill has just died - it
still goes from zero to top speed instantaneously but controlling speed
according to trigger pressure is no longer possible, so no use for
screwdriving.

Had exactly the same problem with my 24V drill-driver.
It's a no-name Chinese design - but it does have two 24V batteries and
a reasonable charger, so I was hoping to keep it going.
Also - it was given to me by a biulder friend who was given it as a
freebie from the Builders' Merchants (buy 3000 concrete blocks and get
a drill-driver free - that type of thing).

Given that it didn't cost anything - it might have been wiser to dump
it - but - hey - we're DIY-ers g


I spoke to B&Q who pointed me to GMC who referred me back to B&Q - so
getting a spare through official channels isn't going to happen.

No - they'll be totally useless unless you want to buy a new one.


Anyone know how these switches work (or fail)

Having taken my unit apart - it's something like this.
The trigger mechanism works a switch and a variable resistor.
The switch puts power on the control electronics, and, when released,
shorts out the motor - providing 'braking' when driving screws.

In the same plastic trigger assembly there's the necessary control
electronics - and, external to this assembly is a power-fet which does
the actual switching of the motor. The powerfets are reasonably cheap
to replace - but if the motor works at all (even at full-pelt!) then
the powerfet's probably OK. I bought some replacements, fitted them,
no change !
The mechanical part of the trigger assembly is full of 'ping****its' -
so open it over newspaper or something similar - not a deep pile
carpet g


if youre asking that you wont be able to repair the electronics

and whether it's possible
to get/construct a generic replacement from Maplin/RS parts?

I lookeed into this. It's _theoretically_ easy to do - but the
ergonomics of it are a pest - getting it all to fit inside the
existing mechanism. If all you wanted was a variable speed controller
- that's easy - but getting one that's mechanically usable when you're
20ft up a latter screwing up guttering brackers - that's another
problem !

I'd look out for a faulty tool with a similar speed control and see if
it
can fit. Freecycle would be a fair place to ask, or the local tip.
Why
pay if a freeb is on the go.


It seems a shame to landfill it just because the switch has failed.

yes, if you've got the time.


In the end I cannibalised another drill (batteries u/s). As luck would
have it, the other drill (only 12v) had the electrical rating of the
controller printed on it - and it claimed to be good to 24V / 8A.

Half an hour or so with and assortment of files and knives, and the
replacement controller was persuaded to fit in the space previously
occupied by the broken controller - and - hey presto - it's been
working fine for the last 18 months....

Now if I can only think of something to do with the motor off the
donor drill then I can claim my 'green' Blue Peter badge !

In all honesty the time & effort expended far outweighed the cost of
buying a decent driver new - but we don't so it for the money, do we ?

Adrian

"..... is full of 'ping****its' -"

LOL !!

Rob

In article ,
Adrian wrote:

HI Mike

Having taken my unit apart - it's something like this.
The trigger mechanism works a switch and a variable resistor.
The switch puts power on the control electronics, and, when released,
shorts out the motor - providing 'braking' when driving screws.

In the same plastic trigger assembly there's the necessary control
electronics - and, external to this assembly is a power-fet which does
the actual switching of the motor. The powerfets are reasonably cheap
to replace - but if the motor works at all (even at full-pelt!) then
the powerfet's probably OK. I bought some replacements, fitted them,
no change !
The mechanical part of the trigger assembly is full of 'ping****its' -
so open it over newspaper or something similar - not a deep pile
carpet g

In the end I cannibalised another drill (batteries u/s). As luck would
have it, the other drill (only 12v) had the electrical rating of the
controller printed on it - and it claimed to be good to 24V / 8A.


In all honesty the time & effort expended far outweighed the cost of
buying a decent driver new - but we don't so it for the money, do we ?

Adrian


Hi Adrian,

Thanks for the detailed answer. That's really helpful.

Now as well as repairing the switch, I'm going to have drop the word
"ping****it" into conversation!

Mike

HI Mike

On Fri, 14 Mar 2008 15:59:16 GMT, mike wrote:

In article ,
Adrian wrote:

HI Mike

Having taken my unit apart - it's something like this.
The trigger mechanism works a switch and a variable resistor.
The switch puts power on the control electronics, and, when released,
shorts out the motor - providing 'braking' when driving screws.

In the same plastic trigger assembly there's the necessary control
electronics - and, external to this assembly is a power-fet which does
the actual switching of the motor. The powerfets are reasonably cheap
to replace - but if the motor works at all (even at full-pelt!) then
the powerfet's probably OK. I bought some replacements, fitted them,
no change !
The mechanical part of the trigger assembly is full of 'ping****its' -
so open it over newspaper or something similar - not a deep pile
carpet g

In the end I cannibalised another drill (batteries u/s). As luck would
have it, the other drill (only 12v) had the electrical rating of the
controller printed on it - and it claimed to be good to 24V / 8A.


In all honesty the time & effort expended far outweighed the cost of
buying a decent driver new - but we don't so it for the money, do we ?

Adrian


Hi Adrian,

Thanks for the detailed answer. That's really helpful.

Now as well as repairing the switch, I'm going to have drop the word
"ping****it" into conversation!

I'm afraid the ping****it isn't original - think it came from a
dicsussion about motorcycling...?

The odd thing is - once you know that's what they're called then you
find them in all sorts of bits of kit g

The problem I had was that you couldn't see what was going on with the
trigger unless you had it dismantled - but when it was dismantled the
ping****its weren't in the right place so it didn't do what it should
anyway... catch 22....

Good luck!
Adrian

robgraham wrote:
"..... is full of 'ping****its' -"

LOL !!

Lovely description innit?


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk
01634 717930
07850 597257