Just received a few score of dead PSU using the above logo in various stages of undress. Three versions - underside fan, rear fan, and with extra input smoothing choke ('P' ). Some look clean and virtually brand new, others are rather different.
The worst have QA2 vaporised and/or the input reservoirs 470mfd/200WGV melted, yes, you read correctly. The fuse may or may not be blown; the fast switching NPN evidently is sometimes faster than an exploding wire!
In all cases, CA5, CA6, C27 (2200mfd/10V) and C25 & C26 (1000mfd/16V) will be suspect; most show bulging and leaky tops with a brown deposit - beware not all do, though. Caps generally carry the CS, (or is it SC?) logo referred to and beautifully illustrated! by Tom41:
https://www.badcaps.net/forum/showth...4&highlight=SC
Provided damage is not massive, these reasonably well designed units are capable of repair. All five caps listed should be replaced without hesitation.
QA2 (Fairchild FJP5027 - available) should be removed and tested out-of-circuit, although its integrity or otherwise will usually be evident upon inspection! Surrounding diodes, QA1, emitter current sharing resistor, etc can be tested in-circuit.
Discretion needed concerning other cap replacements - strangely, CS caps seem OK in other values and circuit locations. The fuse is easy to deal with, but if TH1 has been taken out in the melee`, best regard the entire board as a source of spares: ditto, if there are any melted components!
The basic design and other component quality seems good enough to merit consideration for resurrection. Can supply as much juice as some recent junk claiming twice the power output.
Receiving such a large number of essentially identical dud units was helpful in diagnosing the caps as primarily responsible for the awesome carnage.
The company was obviously aware of the issue, due to one or two having late mods. like the input filter and guess what? : substitution of G-Luxon caps (which, of course, also need replacing).
There are a few identical units in the field carrying different badges, eg.WTSC, but they give the game away by using the same MPT300 model number.
The worst have QA2 vaporised and/or the input reservoirs 470mfd/200WGV melted, yes, you read correctly. The fuse may or may not be blown; the fast switching NPN evidently is sometimes faster than an exploding wire!
In all cases, CA5, CA6, C27 (2200mfd/10V) and C25 & C26 (1000mfd/16V) will be suspect; most show bulging and leaky tops with a brown deposit - beware not all do, though. Caps generally carry the CS, (or is it SC?) logo referred to and beautifully illustrated! by Tom41:
https://www.badcaps.net/forum/showth...4&highlight=SC
Provided damage is not massive, these reasonably well designed units are capable of repair. All five caps listed should be replaced without hesitation.
QA2 (Fairchild FJP5027 - available) should be removed and tested out-of-circuit, although its integrity or otherwise will usually be evident upon inspection! Surrounding diodes, QA1, emitter current sharing resistor, etc can be tested in-circuit.
Discretion needed concerning other cap replacements - strangely, CS caps seem OK in other values and circuit locations. The fuse is easy to deal with, but if TH1 has been taken out in the melee`, best regard the entire board as a source of spares: ditto, if there are any melted components!
The basic design and other component quality seems good enough to merit consideration for resurrection. Can supply as much juice as some recent junk claiming twice the power output.
Receiving such a large number of essentially identical dud units was helpful in diagnosing the caps as primarily responsible for the awesome carnage.
The company was obviously aware of the issue, due to one or two having late mods. like the input filter and guess what? : substitution of G-Luxon caps (which, of course, also need replacing).
There are a few identical units in the field carrying different badges, eg.WTSC, but they give the game away by using the same MPT300 model number.
But today, I’m making an exception here. Why? No idea. Perhaps only because the repair details are still “fresh” in my head… which is ironic, given this is a 16 year old monitor that hardly anyone will care about today. It is new to me, though. 
I picked it up last November from someone on my local Craigslist. It wasn’t very close to where I live, but was close to a family friend that I had to go visit anyways. So after watching the posting on Craigslist for a few weeks and seeing it getting...
(if he is still reading BCN forums) – I got a new old stock / open box Casing Power MPT-301 PSU on eBay for $4 total. 
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