[Amps] L4B HV diodes

[Ian White, G3SEK]

Will M wrote:
>Not necessarily, you may get by with replacing the one diode with the 
>1N5408. I think the 1N5406 is the 600 V, 3 amp. They should all have a 
>drop of about 0.7 volts a piece. I only found one data sheet for this 
>on the web and it was a pay site. It's a wonder they didn't all fail 
>from the domino effect. But, if you want to replace them all, get some 
>good solder wick and go at it. To find an original M4G5, you'd probably 
>to search about all the surplus houses. A Google search didn't find any 
>for sale anywhere. I still don't think it would cause too much of a 
>problem just replacing that one, if it's the only bad one in the 
>string. About the only way to tell for sure if they're good or not is 
>run a hi-pot test for leakage on each.
>
As Will implies, it's not good practice to replace part of a diode 
string with one of a completely different kind. It is almost guaranteed 
to cause unequal division of reverse voltages, and will be fighting 
against any equalizing Rs and Cs that are provided on the board.

The hardest part of the whole job is removing the rectifier board so you 
can work on it. You don't want to have to repeat that, so why not 
replace all the rectifiers with 1N5408s (new, branded and supplied on a 
bandolier). They are reliable, readily available and excellent value, 
which makes them the industry standard for this type of application.


-- 
73 from Ian G3SEK         'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek