emachine T3092 appears to be dead - going to try to recap

[ap42]

emachine t3092 (FIC AU31 MB)
AMD AthlonXP 3000+
Bestec ATX-300-12E Rev. D power supply

My pc had no video this morning, but appeared to be running. I held down the power button for a few seconds to shut it down, let it sit for a few seconds, and then rebooted it. Nothing happened - it did not POST and no info popped up on the screen. I tried this a few times & once it started to display info on the screen, but then went dead again (all fans were still running, so some juice was flowing).

I took the case cover off & blew out the huge amount of dust that had built up inside, hooked my monitor to the built-in graphics (I had it on an AGP graphics card) and still nothing. I've had the machine reboot mysteriously before in the past, but it would always come up fine & run like normal afterwards.

So I did some searching, and found a posting here that sounds like my problem:
https://www.badcaps.net/forum/showthread.php?t=7611

I checked the caps around my CPU and they appear to be hosed. They are all bulging to some extent & 3 of them have gunk oozing out the top. Doh!

The power supply appears to have valid voltage to all the pins, but I tested it out of the system with pins 14&15 shorted so it wasn't under load. Those caps look like the culprit though.

I had an old good MB that had some nice Rubycon MBZ caps on it, and my plan is to recap my board with those. I took the Rubycons off the old board and am going to attempt to put them on my board tonight. Has anyone had any success doing this - using harvested caps to fix a dead board? They're all the same rating of caps: 2200uF 6.3V caps & appear to be the same size.

If anyone has any advice for me I'd appreciate it - this is the first time I've recapped anything, but at least I have some soldering experience. I figure it's worth a shot!

On a side note - my wife finally got me a Blue ESR Meter for Christmas, which of course has not been put together yet. Doh! It would have been useful for checking the harvested Rubycons, but I need to try to get the PC up & running before I play with that.

I'm going to attach some pics I took. (Hmmm I keep getting "upload of file failed" messages. I'll try posting them in a response to this post)

Thanks!

[ap42]

Re: emachine T3092 appears to be dead - going to try to recap

I guess I had to resize the pics down to be smaller before they could be uploaded.

The CPU caps are the only ones that are bulging/leaking.

[retiredcaps]

Re: emachine T3092 appears to be dead - going to try to recap

I took the case cover off & blew out the huge amount of dust

I checked the caps around my CPU and they appear to be hosed. They are all bulging to some extent & 3 of them have gunk oozing out the top.

1) Nichicon HM(M) caps made between 2001-2004 are problematic.

https://www.badcaps.net/forum/showpo...53&postcount=4

2) If your PC was so dusty, you may want to take apart your power supply, vacuum it out, and also look for bad caps inside.

[ap42]

Re: emachine T3092 appears to be dead - going to try to recap

Thanks for the info - the Nichicon HM's I have are the problematic ones. They have the code H0343, so they fall right in the faulty year range.

I opened the power supply to look for any bulging caps inside, but saw nothing out of the ordinary (it was pretty tight in there) so I closed it back up and did the voltage tests on the power connector. I'll blow it out again when I get home to make sure I got most of the dust out.

[yyonline]

Re: emachine T3092 appears to be dead - going to try to recap

I've redone a few of those boards. A few of the ones I recapped were unstable even after recapping. All the unstable ones had a really hot southbridge chip. To me this indicates something in the southbridge shorted internally.

Isn't the -12E the infamous motherboard killer Bestec? Or are only the 250 watt ones prone to failure in that way? If it is, it may be worth replacing with a good power supply.

Edit: Be careful reusing caps. The general recommendation is to use new caps and not reuse old caps. If they came off the same area of a similar motherboard you are probably okay. If you got them from all over the parts board, it may not be good to reuse them. See, as caps are used they reform to whatever voltage line they're on. The caps are rated for 6.3, which means they can handle up to 6.3V. If you put them on a line with 1.5V, after awhile the caps will reform into 1.5V capacitors. If you then remove them from the 1.5V line, and put them on a 5V line, they will not last very long. That's an Athlon XP board, so if you pulled them off of the VRM circuit of another Athlon XP board, you're likely OK as they'd run at similar voltages. If you pulled them from other areas on the parts board, you don't know what voltage they were originally used at. That said, the Athlon XP is in the lower range of the 6.3V cap...1.6-1.75V I believe...so you're probably ok, but no guarantees.

[ap42]

Re: emachine T3092 appears to be dead - going to try to recap

From what I've been reading on here it's the bestec 250W supplies that are the killers. Mine might be okay.

The harvested caps are from a working (at least it was when it was given to me) MB of about the same age that had a pentium cpu on it. The old board had 9 of the rubycons in the same general location as on my board around the cpu. I wasn't aware that caps can mold themselves to the circuit they were used in - thanks for the tip! If this doesn't work I can order some new caps & try again in a week or so.

I'm not sure where the southbridge chip is on my board - is it the heatsinked chip in the center of the board just below the cpu?

The hope is that this will get things up & running again for the short term. Then I can order a decent pc as a replacement & have some time to transfer what I need from the old one to the new. Then the old recapped board can become the kids' pc that they can run their Jumpstart learning games on.

If this fixes it I still plan on getting a new power supply rated at 400W or so. If it fixes it but I still get random reboots, then I'll recap it again with new caps.

[yyonline]

Re: emachine T3092 appears to be dead - going to try to recap

Pentium 4 CPUs use slightly lower voltages, though not so much lower that it should cause any issues.

The southbridge chip is the large square chip on the motherboard that says "NVidia nForce 2" on it. It has no heatsink. This chip will get very warm during intense I/O usage, but it should not be burning hot all the time.

The chip with the black heatsink is the northbridge chip.

[ap42]

Re: emachine T3092 appears to be dead - going to try to recap

A quick update: I am writing this from my recapped machine that appears to be working. Apparently I didn't completely F it up. It booted up fine & has been running for about an hour. Windows did some updates & I need to reboot, so we'll see how that goes - I'm a little nervous to shut it off.

I did take some pics of the power supply (which is probably fine) that I'll up tomorrow. It might be hard to find a replacement that fits into the exact dimensions of the emachines case, so any suggestions would be welcome.

I was surprised at how different soldering on/off these caps is from doing my normal pcb project work. I'm not used to having the iron turned up all the way to 450C just to get something in or out. Usually I'm at a low 250C to solder ICs/leds/LCDs/passives to a SS/DS pc board. I also found out that some needles are not stainless steel, and are quite happy to have solder stick to them. I had a panicky 20 minutes using desoldering braid to get the first needle I tried out of the damn hole. Try soldering a wire to the needle first - if it doesn't stick, you're good to go.

I'll up some pics of the finished results tomorrow. I think the soldering job I did was complete crap, but these through-holes must be very forgiving. I did not get the nice pretty connections I am used to on small projects. There were a few scary moments when the iron slipped and I almost knocked off a tiny SMD cap, but apparently I didn't do any real damage.

Thanks for the help. Without these forums I doubt I'd have had the cahones to try something like this. Now I can go build a decent PC to replace this one instead of just grabbing a quick replacement.

[ap42]

Re: emachine T3092 appears to be dead - going to try to recap

Some pics of the power supply & of my recapping process.

[POM_MJ]

Re: emachine T3092 appears to be dead - going to try to recap

I saw one cap inside your PSU locate near small transformer look like bulged.
just guess it is JAMICON 2200/10V for 5VSB.

[bigbeark]

Re: emachine T3092 appears to be dead - going to try to recap

Yes, the pear-shaped solder blobbing - very familiar.

The heat is staying in the leads and not flowing into the holes.

Possible causes:

The old solder (on the pads) is dirty or has a higher melting point than the replacement solder.

The base of the cap is not flush with the board, leaving too much "leg" exposed.

Too much heat in the iron tip or iron tip is dirty.

New solder/flux is crappy.

Some joints flow beautifully, others not so much.

More likely to blob on the heavier ground planes or where theres a lot of
caps concentrated together

The heat is wicked off by the surrounding components. I imagine that pre-heating the board with hot air would help.

But it works, that's the main thing. Congratulations!

[retiredcaps]

Re: emachine T3092 appears to be dead - going to try to recap

I saw one cap inside your PSU locate near small transformer look like bulged.

I agree that it looks bulged.

[everell]

Re: emachine T3092 appears to be dead - going to try to recap

Capacitor C36 is bulged - a common problem on Bestec power supplies. See my thread

https://www.badcaps.net/forum/showth...hlight=everell

This is one way to fix the problem. The capacitor is wedged between a hot diode and the heat sink.....and gets cooked. Not hard to simply move it to the other side of the heat sink.

[ap42]

Re: emachine T3092 appears to be dead - going to try to recap

But it works, that's the main thing. Congratulations!

Thanks! It's been going for over 24 hours so I take that as a good sign!
I was pretty careful about keeping my tip clean & keeping the temp around 450C, but I didn't completely clean out the old holes so maybe that hurt me. And maybe I didn't heat the holes up good enough (had my flat tip in the iron, maybe should have used the chisel). I was using some radio shack 60/40 solder, which has always worked great on small 1/2 sided board. Still, as you said, it works so I'm happy.

[ap42]

Re: emachine T3092 appears to be dead - going to try to recap

Capacitor C36 is bulged - a common problem on Bestec power supplies. See my thread

https://www.badcaps.net/forum/showth...hlight=everell

This is one way to fix the problem. The capacitor is wedged between a hot diode and the heat sink.....and gets cooked. Not hard to simply move it to the other side of the heat sink.

You all have good eyes! I thought it looked okay when I gave a quick scan of the power supply. I'm headed off to tiger direct today to pick up a replacement power supply (400-450W) & my plan is to turn the Bestec into a variable bench supply. I'll have to see if I have a salvaged 2200/10V lying around. I know I have one 2200/6.3 rubycon left, but I don't want to put that on a 5v rail. I'll have to see what the ones are on some CFL boards.

If I can't move the placement of the cap to the other side of the heatsink, I wonder if it would work if I just used an inch or two of heavy guage wire and used the same holes, but used the wire to move the cap out of the hotspot? Heavy guage solid core copper wire should keep the R way down I would think. Has anyone done this for a power supply fix? It seems like that's what they do on some CFL bulb boards.

[ap42]

Re: emachine T3092 appears to be dead - going to try to recap

Everything is up & running with the new power supply. I picked up a Thermaltake TR2 430W power supply (with 2 80mm fans). Model TR2-430NL1NH. It was one of the better-reviewed 400+ watt ones they had in stock. Looks pretty, and the only complaint I have is that it has a ton of cables that I had to try and tie out of the way.

I picked up a new 80mm case fan as well to replace my stock one. This one is 14-32 CFM with a thermistor to control fan speed based on heat. Plus it's wicked quiet (6-14 dba). Threw in a cheapo USB card as well so I won't have to unplug the camera when I want to plug in the portable drive. I was tempted to grab some thermal paste & redo my CPU heatsink, but I decided it wasn't worth the trouble.

Assuming my recap is doing well, I should be all set for quite a while. Thanks to badcaps.net of course.

[yyonline]

Re: emachine T3092 appears to be dead - going to try to recap

It looks like you used a twist tie in there to hold some of the wires together. I'd recommend using a proper cable tie (zip tie, tie wrap, whatever else they're called) as I've seen the twist ties fall off and short things or get caught in fans, etc.

[ap42]

Re: emachine T3092 appears to be dead - going to try to recap

Yes, I used the twist ties that came with the new power supply. I'll use a proper zip-tie to secure them out of the way tomorrow. Thanks for the advice.

[ap42]

Re: emachine T3092 appears to be dead - going to try to recap

I thought I'd post an update. My recapped board has being going strong since my last post. I think I've only powered it down twice since then (for storms) and it's been running 24/7 otherwise. Not one lockup or phantom reboot.

I did put together a new system that will eventually replace this one, but it's nice to still have the old machine so I can transition over to the new box at my own pace.

I still haven't addressed the bad cap on the power supply (which is sitting in a box). I'll fix it eventually and turn it into a bench supply.

I'm glad I found this forum! Thanks!