"T i m" wrote in message
...
On Sat, 29 Jul 2017 13:17:05 -0500, "Dave M"
wrote:

Replace the shorted recctifiers!!!! As a precaution, replace all 4 of
them;
they're cheap. Even in circuit, they should not test as a short corcuit.

snip

Thanks Robert / Dave,

I haven't played much with SMPS (for obvious (safety) reasons) so
assumed there might be some strange 'appears short but isn't in use'
type thing going on. I should have pulled those diodes before asking
here. ;-(

However, I just desoldered one end of both and one appears to be dead
short but the other was ok (but I've pulled them all).

Problem is, while I probably have 1,000 IN4004's, I don't have any
1N4007's and I'm guessing we need the 1000V peak reverse
/ DC blocking voltage (rather than just 400) and 700 over 280V RMS?
;-(

So, I can pick some of those up next week (eBay) or it looks like
Maplin have 1N4007S's in stock but are they an acceptable equivalent?
(Peak forward surge current, 30 not 50A)?

http://pdf1.alldatasheet.com/datashe...YI/IN4004.html

http://www.mouser.com/ds/2/395/1N400...15-1082941.pdf

Cheers, T i m

p.s. How long is a piece of string question but ... Is it 'likely'
that diode just went (the charger is a good few years old now and has
been used quite a bit), or is it more likely something further down
the line took it out?

It is likely that the off line switch regulator is also failed. Grab a copy
of the TOP223Y datasheet to see the reference design for your supply.

Here is a source for those chips:

http://www.ebay.com/itm/5PCS-TOP223Y...AOSwnLdWrEJ R