They almost always fail with a dead short, couldn't miss that with a diode check ( 0.2 to 0.8V is a typical good-rectifier reading forward, and no conduction in reverse).
Since the capacitors on output were replaced, are you sure they're low-ESR types? The ripple current ratings have to add up to about the output (20A) of the unit. Correct capacitance but low ripple current ratings (aka high ESR) on the replacements could explain bad output with good rectifier.
Agreed. I think I read .2xxV on my DMM diode test in the forward (x2) and as you say nothing in the reverse (x2 + 2 (between the two outers)).
I believe they were:
"Panasonic 1000uf 16v Electrolytic Capacitor 105 LOW ESR FR Series EEUFR1C102L" ?
(Interesting, thanks) From that spec the only value I can see related to ripple is:
"Rated ripple current-1 (mA) 1560.0"
So the 4 would give 6.24A but would that still impact the off load voltage?
I might see if I can rig up my USB scope and actually 'see' what the output is doing.
Cheers, T i m
p.s. Because I need the 3D printer running I've since bought 2 x Mean Well (SP-200-12) 12V x 16.5A PSUs and have tacked them in to be able to get going (and need to design and print some new mounting brackets ). However, whilst it looks like I could end up spending ~10 GBP (more if you count to total cost when it's more sensible to buy 10 off something when I only need one) to get this old PSU running (assuming I ever do etc) and could buy another cheap one new for just a few pounds more, I am interested to see if I can get it going (with the guidance of some good folk here etc ), firstly, because I would find it satisfying, second because I then have a spare PSU and third I wouldn't them have to throw the rest away. ;-)
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