Where can I get large diodes for my Butters ?

[classic2cv]

Where can I get large diodes for my Butters Autoweld 140 ?

2 of the diodes have gone short circuit and I need to replace them

Would weldequip have any parts like this ?

 

[Wozzaaah]

deja vu? No luck last time you asked then? Did you try Butters? The problem is that the machine you have is nothing like the 'new' Butters ones, I wouldn't imagine they'd keep any parts for the older ones but it's got to be worth a phonecall if you haven't tried already.

 

[shenion]

What's the part # on the diodes? I can see if there is a cross.

They are getting hard to get these days; used to be in stock at my suppliers. Now the major semiconductor co's are selling off their diode lines. Seems most are no longer stocked.

 

[Highway_Star]

The numbers on it are everything, pay particular attention to it being forward or reverse (F or R on the markings)

That's not a particularly big diode, I use similar ones on cinema arc lamp rectifers.
RS stock a good range. www.rswww.com

We often use a wee firm called Caspian Semiconductors on 01565 634000 for obscure diodes, triacs etc. Forget the blokes name but they are very knowledgeable and helpful.

 

[classic2cv]

Did you try Butters? The problem is that the machine you have is nothing like the 'new' Butters ones

i tried RS but they were not sure if they could get them and if they could it would a few weeks so i left it there

i'll try Caspian Semiconductors they might have the bits i need

funny thing is that i always thought that diodes went open circuit when they failed ?

 

[Highway_Star]

Not necessarily they can fail in either direction.

 

[classic2cv]

Not necessarily they can fail in either direction.

oh i see

many thanks

 

[shenion]

Actually they normally short. Then that causes huge currents and that opens them. Depends on the diode size vs the current capacity of the transformer.

 

[HasBean]

They appear to be the large ones!!!!
Try CPC ( http://cpc.farnell.com/ )

 

[bill_gj]

Have a look at this:
http://cgi.ebay.co.uk/2-Pcs-IR-1N37...oryZ7287QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
I bought some diodes for a bridge to add onto my old arc welder from the same seller.
Victoria is her name and she runs a business selling on older high current stuff.

 

[Gasman]

Might have an option, will PM you

 

[Highway_Star]

I'm not understanding why he's having such a hard time sourcing these. We supply and fit diodes like this to cinema arc lamp rectifiers day in day out.

 

[classic2cv]

i tried Caspian Semiconductors and after a good look through their books they gave me a price, £25 each + vat

thats a lot for a single diode ?

and i might need 4

 

[Highway_Star]

No that's not a lot for single diode! I've seen some of the big ones (and yours isn't) for large arc lamp rectifiers weigh in at well over a ton each.

Best practice IS to replace them as a complete set. They will all have gone through the same heat/cool cycles, done the same hours and the remaining 'good' diodes may have been damaged by the duff ones.

 

[Welsupplies.co.uk]

What thread is it on the diode?

 

[scarecrow]

Would it make a difference if you put a bigger diode in once it is rated to handle the current involved or even build a new bridge

 

[Robotstar5]

Probably sorted by now, thread is nearly 18months old!

 

[scarecrow]

aaaaaaaaaaaa

 

[Wozzaaah]

Probably sorted by now, thread is nearly 18months old!

Welsupplies hadn't noticed the thread date on this and the other threads he'd replied to as the pound signs in front of his eyes had blurred his vision