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Semiconductor ID

 

Semiconductor ID

Post by GeoffB » Mon Jun 15, 2015 5:00 pm

Hi Folks,
I'm trying to fix an electric/gas welder for my local garage and I would appreciate some help identifying a semiconductor, please. I'm unable to measure any resistance across any pins.

Its in a TO-18 can and the marking on the top are as follows:
TAG
1
400
L5
There are also some faint stamped marking on the side: 7524, prefixed with a mark that could be a B or a D.
The can is very badly pitted. This may be just a date stamp !!!

Regards
Geoff

 
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Location: Worksop

Re: Semiconductor ID

Post by Refugee » Mon Jun 15, 2015 5:03 pm

That will be a little thyristor and will most likely be driving a bigger thyristor or triac on a heat sink.

 
Posts: 4092
Joined: Wed May 02, 2012 3:35 pm
Location: Worksop

Re: Semiconductor ID

Post by Refugee » Mon Jun 15, 2015 5:12 pm

The only reliable way I have found for testing them is to connect them up to 12 volts with a car dash lamp in the anode circuit and use a diode tester or resistor to trigger the gate.

 

Re: Semiconductor ID

Post by GeoffB » Tue Jun 16, 2015 1:29 pm

Hi folks,
Many thanks for the many helpful replies. Once you identified the device I was able to built a test circuit which tested Ok
Thanks to all.
Regards
Geoff


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