Gateway with no Capacitors at all!

[washu]

My wife asked me to take a look at her friend's computer as it had what sounded like a usual spyware infestation. It was pretty badly infected, but the USB ports were dead and would reboot at random, even in the BIOS screen. I took the drive out to backup her data and noticed that there are NO electrolytic caps on the MB at all. No apparent solder pads for them either. None of the surface mount parts stood out as caps either.

The PC is a Gateway with a Slot-A athlon 650. Looks like a standard ATX board. PS is weird as it's an SFX size in a rather large case, but the mounting hole is SFX size too. Haven't had a chance to crack the PS, but the PC behaved the same with a known good PS.

Now it barely does anything. It has about a 50% chance of getting to the gateway logo and hanging or just displaying nothing at all. Swapped everything except the MB/CPU and it still does the same.

Am I missing something? Does this board really have no caps and just rely on the PS regulation? At this point I'm going to have to tell her it's dead after thinking it was going to be a simple nuke and pave.

Don't have the exact model right now, I'll post that and a pic after I get off work.

[370forlife]

Usually these use proprietary psu's and connectors, I think because the power supply is able to control ripple enough to not need extensive filtering on the motherboard. I have a dell slimline like this as well as a dell precision 420mt and poweredge 4400 like this.

May also be a different type of VRM that can withstand more ripple.

[washu]

Originally Posted by 370forlife

Usually these use proprietary psu's and connectors, I think because the power supply is able to control ripple enough to not need extensive filtering on the motherboard. I have a dell slimline like this as well as a dell precision 420mt and poweredge 4400 like this.

May also be a different type of VRM that can withstand more ripple.

I've seen those, but this board seems to be standard ATX. Standard 20 pin power connector. Other power supplies work, at least no worse than the stock one.

VRMs are a bit interesting, there's a bunch with little heatsinks along the rear of the CPU slot.

[hardwareguy]

OK this thread is worthless without pics!

I gotta see this strange beast.....crack open the PSU too.

[kc8adu]

it has caps...sm tantalums!
and the soic8 mosfets with little heatsinks soldered on.
power supply is top suspect as these boards are very reliable.

[washu]

kc8adu wins here, it has SM caps.

I must have had a brain fart last night or just been really tired to not notice what they were. It was pretty late before I cracked the case and got a look at it.

It also has one solder pad for a normal cap which was hidden under the drive cables.

The model on the back is "LP Mini Tower KAD Select 650"

PS has no obvious faults other than being filthy. Board doesn't post anymore even with a couple of known good PSes. Swapped everything except the CPU again, no go.

The small heatsinks seem to come out of the board directly and are not touching the VRMs.

[gdement]

I have a dual slot-2 HP with a similar setup. I can't take a decent picture because it's too difficult to remove from the case. But the board is loaded with tantalums. There are some electrolytic caps on the removable VRM cards though.

Boards built without electrolytics implies it wasn't cheap and should be very well made, so it's surprising if it died. But stuff happens.

[washu]

It does seem pretty well built. The case is a tank and the video card is a quadro workstation board.

Found a possible cause of failure. The board has an unusual (for it's age) USB config of three ports stacked instead of the usual two. I took a look at them and the top one is bashed to hell. The plastic pin support is gone and all the pins are pushed back and shorted to the shell. Theoretically this could have killed something in the chipset. The owner has a few young kids so the damage is understandable.

[hardwareguy]

SOIC8 FETs and all tantalum and MLCC caps...that had to be an EXPENSIVE box!

Why use SOIC8 FETs with heatsinks...why not use TO220 or D2PAK TO263?

[gg1978]

Yup, the Gateway "Kadoka" motherboard is the benchmark for having good caps, as the SMT caps are very reliable.. It's a Quad phase VRM, with two top and two bottom MOSFETs per phase.. The SOIC MOSFET's are basically dumping the heat into the board itself, and the heatsinks are soldered to the board only, and conduct heat into the air, as the solder mask would definatly reduce heat transfer to the air..

[Wizard]

THese what gg1978 and hardwareguy mentioned. The biggest ISSUE is tantalum is not best choice for high ripple and high current that is used with P4 and C2D, AM2 AM3 systems. Second, tantalum fails by short circuit and in many cases burn out in big way cratering the board like shotgun shot thru a board. For this reason, engineering have been told to do not allow list for tantalum for any new designs at all.

Cheers, Wizard

[japlytic]

Some boards are badly designed and in this instance, this problem is compounded by the use of poor quality power supplies.

[phoenixlament]

Originally Posted by washu

Am I missing something? Does this board really have no caps and just rely on the PS regulation? At this point I'm going to have to tell her it's dead after thinking it was going to be a simple nuke and pave.

The caps ARE present, but unlike regular motherboard caps, the caps on this board are solid state, rectangular, and yellow. I've seen these before on a few older Seanix boards.

If you look carefully, Voltage and Capacitance ratings are written in tiny brown letters on these yellow caps.

I've re-uploaded your image with red circles indicating their location.

----------

EDIT: "it has caps...sm tantalums!" ... sorry, I must be blind..

[severach]

The yellow caps are just filter caps. The power supply caps are just above the CPU connector. There are rows of them lined up. Old motherboards don't need as much capacitance so it doesn't take many SMD caps in parallel to get what is needed.