Emachine Mess

[zerologik]

Ok so i work in a computer store. we have a pandemic of emachines comming in. common boards are fic am37 and au31. i have tested the capacitors and the fets. forgive me for being a noobie. both the caps and the fets test ok... i tested both according to posts i read on this website... hehe. what else could be a common factor between these boards. Most of the people that we buy our boards from know about this and charge a fortune for them. im sure that its just a vrm or something... any help from you guys would be great... thanks..

[willawake]

Re: Emachine Mess

please give more info about the issues with the boards and the guys will help. the more details the better.

[zerologik]

Re: Emachine Mess

ok the customer describes the problem like this. "I was working on the internet an it just cut off" or "i went to fix something to drink and when i got back, the computer was turned off". I know basically that they have bad motherboard. We have a company that sells us these boards for alot of $$$. we also have to send the bad ones back and they fix them... the board symptoms are ;all the fans will power and the led's but no video. i have tried with the board out of the case, new power supply, different memory, different processor, and agp video card. same thing power but no video. usualy this happens after a power supply failure. a visual inspection of the board reveals no burnt chips, resistors, caps, no signs of physical damage at all. which makes the trouble shooting tough. i have tested the caps and the fets so far, both pass. my guess is that they use cheap power supplies and when it blows it takes out something on the motherboard. im fairly new at the component side of this but am very willing to learn. any help would be greatly appreciated. if you need more info let me know what you need to know and i will post it.

thanks.

[tiresias]

Re: Emachine Mess

my guess is that they use cheap power supplies and when it blows it takes out something on the motherboard.

Welcome Zerologik

Sounds like a good guess to me - could you tell us a little more about the power supplies that are normally used by these systems? If it's a "mysterious" brand you haven't heard before, perhaps you could even take a picture of the insides of one, to allow us to, at least roughly, gauge the PSU's quality, or lack of it!

A quality PSU is absolutely vital to a machine's reliability. Badcaps may be bad, but a bad PSU can devastate a system's parts like little else.

Only a few months ago, in the Christmas vacation, my cousin asked me to troubleshoot his two-year-old machine that had "just died with a funny smell". The PSU, a Codegen "350W", had failed (never had a chance to find out why), with black burn marks all over on the secondary (output) side of the PCB. Also dead were: motherboard, hard drive, an attached USB stick (!), and even an internal modem that was sitting in a PCI slot. What did the PSU send down the +5v rail as it failed, I wonder?

[zerologik]

Re: Emachine Mess

the power supply is a bestec 250 watt

[Chris1992]

Re: Emachine Mess

yuk. Bestec are shit. And loud too. I'd not consider running a Bestec in a system I cared even remotely about.

[tiresias]

Re: Emachine Mess

I assume this is the PSU we're dealing with: (thanks to "dood")

https://www.badcaps.net/forum/showpo...0&postcount=82

On seeing that picture, I'd agree with Chris92 with regard to Bestec PSUs' quality - although I'd probably word it slightly more diplomatically myself.

[willawake]

Re: Emachine Mess

i have tested the caps and the fets so far, both pass.

what method are you using to check the caps?

[zerologik]

Re: Emachine Mess

im using a method i found on this site. vom. starts meter bumps to the right and then gradualy moves up until it reaches infinity

i also used the method on this site for checking the fets.

i hope this helps


and yes that is a picture of the power supply... but its blown so it will not be going back... hehehehe

[Rainbow]

Re: Emachine Mess

im using a method i found on this site. vom. starts meter bumps to the right and then gradualy moves up until it reaches infinity

This is not a good method. Almost all bad, bulged and leaked caps can pass this "test".

[zerologik]

Re: Emachine Mess

wow im open for suggestions on a better way to test the caps and or the fets. im sure that im doing it the wrong way. so far all i have for test equipment is analog volt meter, and a digital multi-meter. again any suggestions would be appreciated. thanks

[larrymoencurly]

Re: Emachine Mess

The Fuhjyyu caps that bulged in my Antec not only tested fine with the ohmmeter test but also measured correctly for capacitance. It seems that an ESR meter is far more likely to detect bad caps.

[scarfman]

Re: Emachine Mess

I could use help with this too. Our church had an Emachines system with an AM37 board and the power supply's cap blew. I put in a replacement power supply from Antec that's ATX12V compatible but I can't get the system to boot. I tested the RAM & it's fine in another system. I've tested the CPU (an Athlon XP 2200+) and it works on an ECS board that I borrowed. I found a replacement AM37 board on Ebay & it won't boot either.

Any ideas how to get this to work? Either that or a good recommendatation for a replacement board?

[PeteS in CA]

Re: Emachine Mess

lmc, in my torture testing, I have had (and currently have) caps whose C is in spec (though greatly reduced from the pre-test value), but the ESR is triple or quadruple the initial ESR. OTOH, I've also had caps vent but with an ESR that was close to the initial ESR. So if the caps are bulging, vented, or high ESR, well ... you know what to do.

[Chris1992]

Re: Emachine Mess

Is it possible that a cap be bulged and have in-spec capacitance and ESR?

[willawake]

Re: Emachine Mess

in my experience no.

- it will have high esr
- it will have ok esr but the capacitance will have become very high.
- it will be open
- it will be shorted

[PeteS in CA]

Re: Emachine Mess

I've seen that in my tests, but I measure the C and ESR daily of the caps I'm testing. In real life I wouldn't expect it other than a total coincidence in timing.