So my Delta Elecronics 300V PSU arrived today. Very well made custom packing all recycled materials cut to size.
It attracted my attention bcaus the styling is very similar to a small LM317 based 15W supply I made about 30 years ago, even down to the Sifam meter.
However something "felt" loose, so I took the cover off and sure enough the transformer screws are loose. But
ther are burn marks, lifted componets and looks like missing components! (see photos) This was listed as teste
But I'm a nice person so rather than going in
and
I sent a nice message (not "not as described" because this autometically opens a case with ebay). I got a nice reply saying they did test it (the seller looks like a house clearance / pawn shop type) " to my best ability, using Ac/Dc mechanical or digital meters ." yeh, right. He did offer a refund though. Anyway got the manual from the maker
https://www.delta-elektronika.nl/en/support/discontinued-products.htmlI'd buy their kit again, just because they suppport it, had a recent case on he day job were a maker still has a bit of kit on their website, but not even a spec sheet for it never mind a manual, no kit in stock either.
So this little PSU has an SCR pre-regulator and the blown / missing components seem to be releted to that. So What the hell, I plugged it in and it works
Outpu there, varies with control andd matches a DMM on the output.
OK thinking about it the SCR left in circuit is probably shorted so no pre-regulation but the linr regulator is working. Obviously pas transistor will get very hot if unit is loaded at low voltage.
Looks like the seller did do basic checks. I've asked for a £20 partial refund and will be placing an order on Farnell. The SCRs are HS64s, long unobtanium but should be easy to subsitute, sensitive gate 600V 4A.