Well, actually I had two Antecs that died on me. The SP300 is now alive after replacing a bunch of caps and the toroid filter inductor. Now it's time for the SP400 to live once more.
I see a lot of postings about replacing the +5VSB circuitry. Well it's dead on this unit, but is there a particular reason why? I don't mind any inefficiency but if it just is impossible to fix, then I'll understand.
I found it weird that though the 5VSB uses the same 2-transistor topology (as far as I can tell) it actually uses an IGBT to pull down on the primary - this would be the first PSU I've seen an IGBT.
Also it's weird, this PSU uses the TL494/KA7500 controller + TPS3510 monitor instead of the UC3842 the SP300 used, though I think both supplies were made by Channel Well Tech. And both are full of Fuhjyyu's. Surprisingly they aren't exploded or leaking just yet for the most part...except for the two 1mF +5VSB output caps whose ESR are off the chart as well as some small caps here and there.
One unfortunate thing I did notice is that one resistor (R54, close to the +5VSB transformer, closer to the "tickler" (in the middle) and main transformers) is heating up and smoking when I plug it in. I'm not exactly sure why, anyone seen this resistor heat up? I measured 1.5K in-circuit (with caveats of course since it was measured in circuit) which means something is really wrong, if it's dissapating 1 watt (utter guess, because it's a 1/4W resistor and it'd take at least 1 watt or so to smoke) across a 1.5K resistor, there would be almost 40 volts across it.... Since it's across the mason-dixon line from the mains input this should be low voltage but I don't quite get why it's heating up... Anyone seen this failure mode before?
(I'm in process attempting to get a photo without removing the heat sinks...)
I see a lot of postings about replacing the +5VSB circuitry. Well it's dead on this unit, but is there a particular reason why? I don't mind any inefficiency but if it just is impossible to fix, then I'll understand.
I found it weird that though the 5VSB uses the same 2-transistor topology (as far as I can tell) it actually uses an IGBT to pull down on the primary - this would be the first PSU I've seen an IGBT.
Also it's weird, this PSU uses the TL494/KA7500 controller + TPS3510 monitor instead of the UC3842 the SP300 used, though I think both supplies were made by Channel Well Tech. And both are full of Fuhjyyu's. Surprisingly they aren't exploded or leaking just yet for the most part...except for the two 1mF +5VSB output caps whose ESR are off the chart as well as some small caps here and there.
One unfortunate thing I did notice is that one resistor (R54, close to the +5VSB transformer, closer to the "tickler" (in the middle) and main transformers) is heating up and smoking when I plug it in. I'm not exactly sure why, anyone seen this resistor heat up? I measured 1.5K in-circuit (with caveats of course since it was measured in circuit) which means something is really wrong, if it's dissapating 1 watt (utter guess, because it's a 1/4W resistor and it'd take at least 1 watt or so to smoke) across a 1.5K resistor, there would be almost 40 volts across it.... Since it's across the mason-dixon line from the mains input this should be low voltage but I don't quite get why it's heating up... Anyone seen this failure mode before?
(I'm in process attempting to get a photo without removing the heat sinks...)
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