Cordless Makita Jigsaw Model 4334D: have I fried it?

Calahonda52

Rather than keep buying 18V batteries I have got an 18V DC traffo with fly leads and all my cordless screw drivers work no problem.

I connected up the jigsaw and the blade moved about a thou and then stopped.
It now won't work even with a battery.
Assuming I connected it the right way around i.e. plus to plus etc, any thoughts on what is wrong?
Thanks as always

dingding

Is the blade jammed ?????

Steve

How sure are you that you got the polarity right?

Batteries can only go in one way so the appliance is unlikely to have protection against that.

Calahonda52

Steve wrote: »

How sure are you that you got the polarity right?

I don't think I did but the evidence and your comments would suggest I did.:)

Batteries can only go in one way so the appliance is unlikely to have protection against that.

Thanks, so have I fried some PCB or something in it, I suppose the question is it it worth repairing.
I suspect its the variable speed controller that got cooked

Blade not stuck.
Thanks

Tuco88

Surly there is a diode to stop incorrect polarity.

Bruthal

Tuco88 wrote: »

Surly there is a diode to stop incorrect polarity.

It's simple enough to have polarity protection. And the method likely used on this device is that the battery can't be reverse polarity connected. Mistakes made connecting in an external supply are not catered for probably.

Calahonda52

Thanks guys, will bring it for an estimate for getting it repaired

Calahonda52

I opened this up and my uneducated guess is that I cooked the variable speed controller. [VSC]
Am wondering what the three wires, light purple, blue and yellow do, they go, from the VSC to something at the top of what I assume is the gearbox.
In addition, if I put 18v across the red and black going to the motor I expect it to run at full speed.
Am I mistaken.
Thanks as always

Calahonda52

Calahonda52 wrote: »

Assuming I connected it the right way around i.e. plus to plus etc, any thoughts on what is wrong?

Polarity with DC ought to always be respected and ascertained before powering circuits. It's a pretty unforgiving lesson, I used to run laptop PSUs off croc clips...:rolleyes:
At least you don't need the jigsaw for internet advice. :pac:

Calahonda52 wrote: »

if I put 18v across the red and black going to the motor I expect it to run at full speed.
Am I mistaken.
Thanks as always

I expect it probably would. A current limited PSU would be the best way to see.

You could make a crude 2 speed switch with a 2 position rocker switch and a current limiting resistor. Like a truck cab heater fan switch (and sometimes relay). If you isolate parts one by one you might figure out what you need to replace. Switch or that potted gubbins would be my first two suspects.

gctest50

Calahonda52 wrote: »

...........Am wondering what the three wires, light purple, blue and yellow do, they go, from the VSC to something at the top of what I assume is the gearbox.
...........

Maybe they go to a FET , it's bolted onto the aluminium to get rid of heat

Maybe it was just that you fried ?

If you dismantle the whole thing a little more, you might be able to see a number on that part.

http://www.toolpartsdirect.com/manuals/pdf/repair/makita/4334d.pdf

eeguy

Calahonda52 wrote: »

I opened this up and my uneducated guess is that I cooked the variable speed controller. [VSC]
Am wondering what the three wires, light purple, blue and yellow do, they go, from the VSC to something at the top of what I assume is the gearbox.
In addition, if I put 18v across the red and black going to the motor I expect it to run at full speed.
Am I mistaken.
Thanks as always

Just buy a new speed controller.

15 quid on ebay: http://www.ebay.co.uk/itm/MAKITA-SWITCH-DSS611-BSS611-18V-CIRCULAR-SAW-TG73BD-4331D-4333D-4334-spare-part-/282237292449

Calahonda52

Thanks for all the ideas, will explore further.
Fitting a new speed controller is probably beyond me but if I get one its a start!

dathi

http://www.adverts.ie/tool-parts-accessories/brand-new-ni-cd-sub-c-battery-cells-1-2-v-diy-repair-fix-rebuild-your-drill-battery/11884208
or you could have a go at rebuilding battries:)

Calahonda52

dathi wrote: »

http://www.adverts.ie/tool-parts-accessories/brand-new-ni-cd-sub-c-battery-cells-1-2-v-diy-repair-fix-rebuild-your-drill-battery/11884208
or you could have a go at rebuilding battries:)

Thanks, went down that road before, did not appreciate that, like in all walks of like, there are crap replacement batteries and then super-crap, and then beyond super-crap:D Pais big mula for garbage

eeguy

eeguy wrote: »

Just buy a new speed controller.

Better diagnose the issue first.
Could be switch, FET, speed controller....

It's good practice to put a snubber diode in parallel with the drill motor to prevent inductive spikes killing the PSU.
Batteries are primitive they don't mind such things.

My 14.4v runs all day on a single charge from a house alarm 12V. It's the king of portable hole saws.

3 x 6v series = jigsaw power.
2 x 6v parallel = motorbike charger compatible.

If you recell yourself you have quality control on what cells to fit. Except good cells are only marginally cheaper than a new battery when you factor what your time is worth.

Calahonda52

Thanks, will take it apart further and do some testing

Sir Liamalot wrote: »

It's good practice to put a snubber diode in parallel with the drill motor to prevent inductive spikes killing the PSU.
.

may be one in the PSU already as I had it made and I told them what is was for.

Maybe you might throw up a sketch..:)

Calahonda52

Calahonda52 wrote: »

may be one in the PSU already as I had it made and I told them what is was for.

A salesman doesn't sell you what you need he sells you what he has.
The diode is to absorb inductive spikes when you break the motor coil power.

Steve

Sir Liamalot wrote: »

A salesman doesn't sell you what you need he sells you what he has.

So true.

Calahonda52

Just to wrap this thread up, it is the speed controller that is fried but it works at full speed so I will just post it on adverts and get shut of it as it is €80 for a new speed controller.

Thanks for all the insights