Premier DR-B300ATX keeps blowing fuses

[Dan81]

It's me,with another Deer. (I have a few of these - a JNC,this and a Modecom,the last being really well built,which just needs new 13009 transistors and a new 12v rectifier - not shorted or anything,just crappy)


Anyways,this one I've got along with a case,made by just the same company - Deer (just for the record,I use the case right now and the PSU I installed in it is a CWT ISO PSU).

The problem with it is that it repeatedly blew almost 3 or 4 fuses (and it actually came with a cracked,blown fuse.) and I still can't find what is wrong with it.

Here's what I did so far:

-replaced fuse - blew again,just installed a new one now
-replaced primary transistors (C5706 iirc) with 13007s and original standby transistor with new 2N60 transistor
-replaced primary caps (tiny 330uF Saturn caps) with 470uF Fuhjyyu MK caps
-replaced 5vSB caps (G-Luxon) with 1000uF 16v Panasonic FJ caps.
-even replaced the diodes in the bridge rectifier,but wouldn't bad diodes cause the PSU not to show any signs of life instead of popping fuses?

I don't know what to do now. I don't have any lightbulb to test with either.

[Th3_uN1Qu3]

Re: Premier DR-B300ATX keeps blowing fuses

Well make one. A lightbulb tester only requires a bulb, a bulb holder and a spare ATX power cord to splice (in case you don't have a spare socket or extension cord lying around).

But yes the diode bridge can SHORT and also cause it to blow fuses. Maybe there is another fault which causes primary transistors to blow and they went short again after you replaced them.

[stj]

Re: Premier DR-B300ATX keeps blowing fuses

check other diodes for shorts.

[Dan81]

Re: Premier DR-B300ATX keeps blowing fuses

Well make one. A lightbulb tester only requires a bulb, a bulb holder and a spare ATX power cord to splice (in case you don't have a spare socket or extension cord lying around).

But yes the diode bridge can SHORT and also cause it to blow fuses. Maybe there is another fault which causes primary transistors to blow and they went short again after you replaced them.

I don't have any bulb holder lying around. And as far as I remember,wasn't the bulb be supposed to be put in the place of the fuse?

As for the diode bridge,I replaced the diodes with working ones from another known working Deer,along with the main transistors. I am quite reluctant to turn it on now,but somehow as opposed to shattering,last fuse I installed and popped was actually brownish-black. Any ideas why did it not shatter?

stj - I checked the secondary side and found nothing out of the ordinary,all rectifiers were fine. I also replaced the two 2.2uF 50v caps in the snubber circuit (I think) with two 10uF 50v caps.

[stj]

Re: Premier DR-B300ATX keeps blowing fuses

primary side - you often find some diodes related to the switching transistors.

[Th3_uN1Qu3]

Re: Premier DR-B300ATX keeps blowing fuses

Yes there are 2 1A diodes, you will find them alongside the primary caps. They look like 1N4007s but they are actually fast recovery rectifiers so be careful when you replace them, you want fast or ultrafast there.

The bulb comes in series anyway, it does not matter if it is used to replace the fuse, or if the fuse is still there... and you can solder directly to lightbulbs.

[Dan81]

Re: Premier DR-B300ATX keeps blowing fuses

Yes there are 2 1A diodes, you will find them alongside the primary caps. They look like 1N4007s but they are actually fast recovery rectifiers so be careful when you replace them, you want fast or ultrafast there.

The bulb comes in series anyway, it does not matter if it is used to replace the fuse, or if the fuse is still there... and you can solder directly to lightbulbs.

Just wanted to thank you about your idea of using a lightbulb. I just found one,wired it up in the place of the glass fuse and I got a positive result - light flashes when on standby,and stays dim when running. Apparently it was the rectifying diodes that were bad,causing in turn to fry the original 2SC5763 transistors,but somehow the 13007s didn't fry

While at it,I replaced the 2SC5763s that were shorted (and crappy to top it) along with the 2N60 standby transistor with a new CET 02N60 transistor and the two main transistors with 8A 13007s. I didn't replace the diodes on bracket on the secondary yet,because my only 12v transistor was shorted (16A 60V).

One thing I didn't expect to find though,was a Power Logic PL80S12M-1 fan. I heard Power Logic fans are good,is that true?

[stj]

Re: Premier DR-B300ATX keeps blowing fuses

if it passed AC to the transistors then the mains smoothing caps may be damaged too.

[Dan81]

Re: Premier DR-B300ATX keeps blowing fuses

if it passed AC to the transistors then the mains smoothing caps may be damaged too.

I think it didn't. One thing that tells me that is the fact that if that would have happened,the fuse would shatter to pieces. Instead,the fuse popped and its insides were splattered with something of a very very dark brown (near black,but not 100% black). This tells me the fuse may have sacrificed itself to save the main transistors (if it didn't,it would blow the fuse even if I replaced the rectifying diodes. And are you talking about the two 10uF 50v caps that I replaced (original ones being 2.2uF) just between one of the transformers and the primary heatsink?If so,those are fine. And if it's about the main 470uF caps,those are fine too.

Anyways,the main caps are Fuhjyyu LP 470uF 200V (or 250V?). Are those good? Here are some pics of the PSU,after the repair. It does power up now,without blowing anything.

[stj]

Re: Premier DR-B300ATX keeps blowing fuses

i am talking about the 200/250v ones.
and that make is probably the worst ever.

i would desolder them, discharge them (carefully) a couple of times - then test them on a meter.
dont be too surprised if they are only 330uf anyway - i have seen big caps miss-labelled before.

[Dan81]

Re: Premier DR-B300ATX keeps blowing fuses

i am talking about the 200/250v ones.
and that make is probably the worst ever.

i would desolder them, discharge them (carefully) a couple of times - then test them on a meter.
dont be too surprised if they are only 330uf anyway - i have seen big caps miss-labelled before.

First of all,I don't have a ESR meter,or any meter that can measure capacitance.

Now,one (possibly) normal thing that the PSU would do in that case,wouldn't it be blowing one of the primary caps,if they would be damaged (damaged as in domed tops,I guess?). This isn't the case here,the caps are still flat.

And being primary caps,should I expect Fuhjyyu to nail it even in this case? I have some 470uF 250V UCC KMQ that claim to be from 1995,according to their datecodes,if the Fuhjyyus ever decide to quit.

[stj]

Re: Premier DR-B300ATX keeps blowing fuses

if you lack capacitance then you wont see any problems until you run a heavy load.
then it could get electrically noisy and cause the computer to crash.

[Dan81]

Re: Premier DR-B300ATX keeps blowing fuses

if you lack capacitance then you wont see any problems until you run a heavy load.
then it could get electrically noisy and cause the computer to crash.

This PSU won't see a heavy load,since it would power the bare minimum for a PC to run. And also I never had a PSU crash a computer. Are you sure it isn't the line filtering (which is fully present on this psu) and the PI coils (which are present as well) that take care of the noise?

[stj]

Re: Premier DR-B300ATX keeps blowing fuses

not if the power is not stable into your switching transistors.

[Dan81]

Re: Premier DR-B300ATX keeps blowing fuses

not if the power is not stable into your switching transistors.

It is stable