The xmas cut-50 - think I know what's wrong...

[skotl]

Following on from this thread; http://www.mig-welding.co.uk/forum/threads/cut-50-busticated-yes-the-xmas-one.51675/

I got bored waiting for the replacement to show up so I decided I may as well take it apart and see if I can find what's wrong!

(I took many pictures, plus a video as I dismantled it so that I have some hope of being able to rebuild it afterwards )


This is what looks like the high-voltage / high-frequency board; can you spot what's up yet?

The resistor is clearly well and truly fubar'd but I also didn't like the look of the pair of diodes closest to it...

Yep - a quick check with the multimeter shows that one of the diodes has gone full short circuit.

I had a look at the other nearby components and they don't seem to be in bad shape.

 

[skotl]

Aye - they're knackered...

The resistor seems pretty straightforward; 1Kohm / 5W. I don't recognise the diode marking though - RP1H? Will Google...

 

[mr migwire]

should be a relatively simple fix then mate,
good news....

 

[skotl]

One question for other plasma cutter owners - you see the two contacts, centre/top in the previous photo?

Here's a closeup;

I reckon the arc is generated across these, and that's what causes the blue light in my youtube video (when it was still working).

But they don't seem very scientifically adjusted - does anyone else have a similar cutter and can you give me an idea of the gap across the two contacts?

 

[skotl]

should be a relatively simple fix then mate,
good news....

Here's hoping - I didn't have the enthusiasm to fix it when I thought they would just send me another unit by 3-day courier but, for the sake of a few hours and £1.50 it's got to be worth a try, right?

 

[Norm]

Nice one, if you fix that and the other turns up I can see a cut 50 for sale thread in the making

 

[skotl]

should be a relatively simple fix then mate,
good news....

Oh, and thumbs up for the manufacturers for at least clearly marking the component specs on the PCBs

 

[Parm]

The ferrite core (green thing with red windings on it) looks like it's toast and possibly the transformer too.

Unless you know what your doing I would leave it to an expert as risk of electrical mis hap is quite high

 

[Norm]

Unless you know what your doing I would leave it to an expert as risk of electrical mis hap is quite high[/QUOTE


I'd get that off the Kitchen worktop before Mrs Skotl comes home or the risk of a mishap will be very high

 

[Parm]

Yes I did notice that too!!!

 

[lotus 30]

Its already busted so you have nothing to loose you can't make it any worse

 

[Norm]

http://www.mig-welding.co.uk/forum/threads/cut-50-spark-gap-setting.45116/

see this re the contact gap seems like this has been an issue before

 

[skotl]

I'd get that off the Kitchen worktop before Mrs Skotl comes home or the risk of a mishap will be very high

Yes I did notice that too!!!

Waaaaaaaaaaaaaaaay ahead of you

 

[skotl]

The ferrite core (green thing with red windings on it) looks like it's toast and possibly the transformer too.

Unless you know what your doing I would leave it to an expert as risk of electrical mis hap is quite high

I had a look at the core and it seems fine - charred, but fine. The winding is, as expected, 0 ohms and apart from that there's not really much to go wrong with a ferrite core, is there?

The transformer showed no visible signs of physical failure but I'll check the windings with the meter.

 

[skotl]

http://www.mig-welding.co.uk/forum/threads/cut-50-spark-gap-setting.45116/

see this re the contact gap seems like this has been an issue before

Cool - thanks - if that's accurate then the ~3mm gap on mine doesn't seem wildly out.

 

[eSCHEn]

SUPER DUPER BEST LUCK FINGER CROSS!

Seriously though, really hope it works for you mate.

 

[Parm]

Waaaaaaaaaaaaaaaay ahead of you

Forget the machine, kitchen looks quite cool

 

[skotl]

Forget the machine, kitchen looks quite cool

Cheers - it's only a year old (and the roof leaks, but the builders are coming back )

I wanted a steel worktop - imagine what a great workshop and welding table all that space would have made

 

[Wendelspanswick]

Cheers - it's only a year old (and the roof leaks, but the builders are coming back )

I wanted a steel worktop - imagine what a great workshop and welding table all that space would have made

Don't forget the Proctologists appointment, I can see the reminder for your appointment stuck to your fridge!

 

[roofman]

Roofman likes this thread goodluck mate.