Hi Im trying to identify a replacement Diode for a old cutting machine . The machine stopped working and it was found that the power supply had burnt out . The transformer has now been replaced but the operating panel is still not working . The component in the picture is getting very hot and has burnt the pcb . I am guessing this is the cause of the problem and am looking to replace it . The numbers on it are 334X 18129 . This is from a CMC Burny 2.5 . Now the power supply has been changed the display flickers on for a few seconds and is then permanently off . Placing a meter on the component show a short in both directions .

 

hi Sheppey,
Welcome to AAC,
The part number is on the diagram, the arrow points at has the part type along side is, MRB21 or MR821, hard to see on the posted image.
E

 

hi Sheppey,
Welcome to AAC,
The part number is on the diagram, the arrow points at has the part type along side is, MRB21 or MR821, hard to see on the posted image.
E

I thought this but when looking at the image of the MR821 on ebay it shows a silver ring not a brown one like the image on this post

 

hi,
The silver polarising ring has probably changed colour with the heat , they often do.
E

 

https://www.tme.eu/gb/details/mr821-dio/tht-universal-diodes/diotec-semiconductor/mr821/

 

Thanks for your help . Will source one and give it a go

 

Just removed the rectifier from the board and I can ow read the numbers on it properly , Cant get a good photo of it but it says V334X 8129 with a symbol , V with a circle around it before the 8 and the brown ring on it is definatly brown not burnt silver . Does any one know if the MR821 I have ordered is suitable . Dont want to mess these up the parts for this machine are virtually unobtainable .

 

hi,
As the circuit diagram shows a MR821 , which is a 60V min 5Amp fast recovery diode, that is the type I would use.
Bear in mind the fact the diode has failed, it is likely to have been caused by a failure/fault elsewhere on the board, so a new diode may not fix the overall problem.

E

 

Seems to be working now . Gonna use it for a couple of hours to test it . Thanks for your help every one .