I require assistance in the identification of a diode. 1

[mishomi]

Good day,

I have the following diode arrays in a rectifier assembly for a welding device. The device is no longer supported by the manufacturer but is still functional and of use to me and the company I work for.

I would very much like to know about these diodes, however several online searches have revealed almost nothing of them.

They are marked "T25-4-C9". The machine is Italian in origin. The Diodes, I believe, are what are called "T25 press fit" packaging.

The dimensions of the diodes are:

Base (Press fit portion) 12.60MM/.496IN Diameter
Diode housing 8.56MM/.337IN Diameter
Overall height minus lead 10.43MM/.410IN

The maximum output of the machine is 85 Amps DC, at roughly 18 volts, DC. Traditionally, the rectifier will be able to handle slightly more than the rated average output.

There are a total of 8 diodes, for a full wave bridge rectification effect on the output voltage of the machine.

Please, see the enclosed pictures of one of the removed diodes next to a US Dime. Current specification of the individual diode would be of much use to me.


I am grateful for any replies.



Thank you.

http://i1117.photobucket.com/albums/k595/mishomi/IMG00270-20101008-2159.jpg

http://i1117.photobucket.com/albums/k595/mishomi/IMG00269-20101008-2159.jpg

 

[Comcokid]

Can't help you on what the original spece might have been.

Press fit diodes in packages similar to what you've shown are commonly used in automotive alternators. It sounds like your voltage and current range are also similar to an automotive alternator, and if it's 50/60 Hz going through the diodes, then then the diode speed is also similar (alternators rectify up to a few thousand Hz). Is there a starter/alternator rebuild shop in your town?

I don't think there's anything special about the diodes except the press-fit package. If you intent is to replace or have spares for machine repair, it shouldn't be much of an issue.

 

[Skogsgurra]

Yes. They have been around for at least fourty years and are common as dirt. No problem finding substitutes.

But be aware that they come in two polarities. One with catode connected to stud and one with anode connected to stud. Yo will probably need 50 percent of each type to make a bridge rectifier.


Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[mishomi]

My friends,

Thank you kindly for these replies.

I made a mistake, I was not clear, please understand my intentions:

I need to know the current rating of these diodes (Voltage is less important) so that I can replace the matched pairs of T25 press-in diodes with a single DO-4 style bolt mounted package of higher rated current.

I will fabricate my own heat sink as the stock heat sink is too thin, (merely a thin plate of aluminum with no fins) and relies on stagnant air for cooling, reducing the duty cycle. I will also be cooling the entire rectifier assembly with moving air.

I understand the base anode and base cathode relationship, the switched polarity needed for proper plate polarization. I thought I had the problem solved with 2 diodes until I managed to find the schematic and realized it is a full wave bridge rectifier and not a simple rectifier.