Hi i have a question about this old welder regarding the pcb board -- in particular the large round power transistor which sits on a heat sink . Does anyone know the details / info of this piece. The information printed on my one has long since disappeared. Thanks
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Barking Mat
Cuddler of hedgehogs.
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Photo would help.
Welcome to the forum.
Welcome to the forum.
- Photo is a good idea however i will need to enlist the help of my daughter .Hello and welcome to the Forum !
According to the hand-drawn circuit diagrams provided by @Wedg1e in this earlier Romarc thread:
that device is a PNP power transistor.
In Post #11 there is a photo showing the PCB, with a black TO-3 style power transistor on the heatsink.
According to the hand-drawn circuit diagrams provided by @Wedg1e in this earlier Romarc thread:
Romarc 200 MIG
Looking at one of these that is local. research on here shows them as old but indestructable/repairable and as my search for a used inverter MIG isn't turning anything up, I thought I might get something in the interim to practice with. Any idea what sort of current I will get on a 16A...
www.mig-welding.co.uk
In Post #11 there is a photo showing the PCB, with a black TO-3 style power transistor on the heatsink.
Thanks Eddie - its my intention to leave the PCB in its original state - no new stuff. I have had a look on fleabay and punched in your info.
This is what came up Item No 186669634436. This is the type i am looking for and my question now is this the correct one . The print on my one is gone so
no reference at all. The welder is working fine and what i am doing is gathering some items that at some stage may be difficult or impossible to get. Cheers Terry.
This is what came up Item No 186669634436. This is the type i am looking for and my question now is this the correct one . The print on my one is gone so
no reference at all. The welder is working fine and what i am doing is gathering some items that at some stage may be difficult or impossible to get. Cheers Terry.
That eBay item is an MJ15004, which is a PNP power transistor in the TO-3 case style. With a rating of 250 Watts, 140 volts and 20 Amps it will certainly do the job of driving a wirefeed motor ( which is probably a 12 or 24 volt motor drawing about 3 Amps ).
In general I would not expect the original device to be prone to failure, and if it ever did, since driving a motor is not really a critical application. then any basic PNP power transistor could be used.
In general I would not expect the original device to be prone to failure, and if it ever did, since driving a motor is not really a critical application. then any basic PNP power transistor could be used.
