Sip feed problem

[Whackman]

Was welding a bike part yesterday as normal, placed the gun down and stepped outside to try the part for size, noticed a funny smell, on turning around i saw that the wire was feeding through non stop...probably lost about 3m of wire before i got to switch it off...now the only way tto stop the wire feeding is to switch it on and off at the switch...i havent used it since...the trigger is ok, i tested it...wondering what else it might be....pic of the PCB ...what should i be looking for, theres a burnt smell from the board..

Tanx

Its a Sip Autoplus 196

 

[rtbcomp]

Welcome to the forum.

The most likely cause will be the transistor on the heatsink has gone short circuit. Have a close look at the PCB for burnt tracks/components.

 

[Dunk_c]

When I blew my SIP wire feed controller board, the power transister went short circuit and this drew a lot of current through a small reisiter, this burnt and smoked. Easy to find the rsuster and when it happened a second time I checked the transistor. Replaced both. (BTW I was mucking ariund with the SIP feed motor capacitor mod).

 

[Whackman]

Tanx for the welcome and replies...tbh i may as well be looking at a load of electronic components..!!!!!

Cant see anything obvious (to me anyway)...i've no problem fixing it if i know whats gone..can you point out the bits you mentioned maybe..???

 

[rtbcomp]

The heatsink is the aluminium plate in the centre of the board and the power transistor is the thing riveted to it.

 

[Whackman]

I assume this is the fella.....is there any way of testing it..or do i just get a new one...

 

[rtbcomp]

That's the fella, TIP35C it's a common enough power transistor, get a couple they do fail.

 

[Whackman]

That's the fella, TIP35C it's a common enough power transistor, get a couple they do fail.

Tanx pal..i'll get a couple next week...€1.50 each...cheaper than chips..!!!