Matsonic MS7177C (ECS P6VXA) - does not work after replacing caps

[Rainbow]

I've replaced bulging caps on Matsonic MS7177C board (relabelled ECS P6VXA) rev. 1.0 but it still does not work.
I replaced all 1500uF and 1000uF. When I power it up, the CPU starts but hangs almost immediately at POST code C0h (sometimes even before - at FFh).
There are some smaller caps that don't look bad. G-Luxons 470uF/6.3V, 100uF/25V, 10uF/25V and one Canicon 33uF/25V. I suspect that some of these are bad too?
This is the only board that refuses to work after replacing caps (I've done that on many other boards).

[kc8adu]

Re: Matsonic MS7177C (ECS P6VXA) - does not work after replacing caps

did it work before the recap?if so recheck your work.solder shorts,cap in backwards,ect.

[Rainbow]

Re: Matsonic MS7177C (ECS P6VXA) - does not work after replacing caps

I got it because it didn't work. The bulging 1500uF caps seemed obviously to be the problem. So I replaced them but it still didn't work. Then it was sitting somewhere for some time and when I saw it again, some of the 1000uF were bulging (there looked OK before). So I replaced them all too and it still does not work.
I've checked my work and found no problems.
I wonder if it's worth trying to replace the smaller caps? I don't have ESR meter, only a multimeter that can measure only up to 20uF. I've removed one 10uF/25V and it seemed fine (more than 9uF, IIRC).

[Chris1992]

Re: Matsonic MS7177C (ECS P6VXA) - does not work after replacing caps

did you replace caps with non-low-esr as mentioned in other post? if so, read my post there.

[kc8adu]

Re: Matsonic MS7177C (ECS P6VXA) - does not work after replacing caps

if you didnt use low esr caps you may still have noisy vrm's which will cause all sorts of trouble.

[Rainbow]

Re: Matsonic MS7177C (ECS P6VXA) - does not work after replacing caps

Yes, that might be possible (this board might be more sensitive to cap quality) but I doubt it. I don't think that it will help, but I'll try - I'll replace them with low-ESR ones from dead board (caps OK, chipset dead).

[Rainbow]

Re: Matsonic MS7177C (ECS P6VXA) - does not work after replacing caps

Recapped again with low-ESR G-Luxons, absolutely no change

[bushytails]

Re: Matsonic MS7177C (ECS P6VXA) - does not work after replacing caps

ugh!!!! you're recapping with g-luxons?!

[Rainbow]

Re: Matsonic MS7177C (ECS P6VXA) - does not work after replacing caps

I took these for test from dead board (and no, that board did not die because of them going bad). I don't have anything better here in sufficient amount (two Panasonics from dead QDI board is not enough, three Nichicons on dead Asus too).
I usually use NA and KOME (can't find anything online about these "brands").

[Rainbow]

Re: Matsonic MS7177C (ECS P6VXA) - does not work after replacing caps

Found KOME - http://www.proan.com.hk/enkome.htm

[OldeCrow]

Re: Matsonic MS7177C (ECS P6VXA) - does not work after replacing caps

@Rainbow

If the motherboard uses the "large can" (10mm wide) 470's and or 330's you might try changing them out too, Ive seen them bad frequently on motherboards and have taken to just replacing them automaticly now.

[Rainbow]

Re: Matsonic MS7177C (ECS P6VXA) - does not work after replacing caps

So the board had a rest in the pile of weird boards. I flashed this into a flash ROM:

0001FFF0: B0AA             mov    al,0AA
0001FFF2: E680             out    080,al
0001FFF4: FA              cli
0001FFF5: F4              hlt

and watched what POST card displays - "A2"! So there is a problem with data bit 3 somewhere.
I traced the D3 from the CPU to north bridge - seems OK. Also traced AD3 from PCI slots to south and north bridge and it seems OK too. So probably either there is a bad joint under the north bridge or it's bad.

[arneson]

Re: Matsonic MS7177C (ECS P6VXA) - does not work after replacing caps

It may be difficult to tunnel under a bridge.

[gg1978]

Re: Matsonic MS7177C (ECS P6VXA) - does not work after replacing caps

I don't think you can do exactly what you're doing with the 4 ASM instructions, and expect to get the proper data out. Don't you have to initialize the northbridge and southbridge in order to do so?? Not to mention that modern systems don't have discrete data lines for stuff like that. Sounds like the P6VXA is a Via chipset board, is this a P3 system?? I suppose if you have a "real" ISA slot, the 4 instruction code could work, but like i said before, your code doesn't initialize the hardware at all. Try changing the value to 00 or something like that, and see what happens.

[Rainbow]

Re: Matsonic MS7177C (ECS P6VXA) - does not work after replacing caps

It's VIA Apollo Pro 133A chipset (694X north bridge). There's no ISA slot, so I use MSI TL46 POST/service PCI card. It has a very useful BIOS override function - there are sockets for flash ROM chips on it, you put BIOS in the socket, flip a DIP switch and the board boots from it instead of onboard BIOS Very useful if you have a board with soldered flash ROM and bad BIOS (it does not work on all boards but better than nothing).
That simple code should work fine (the chipset should allow this simple thing always) - and also works on other boards.
This seems to be a dumb luck - the opcodes for "mov al,xx" and "out 080,al" have the 3rd bit zero. Otherwise, it wouldn't show anything.

[Neo2_000]

Re: Matsonic MS7177C (ECS P6VXA) - does not work after replacing caps

@OldeCrow

If the motherboard uses the "large can" (10mm wide) 470's and or 330's you might try changing them out too, Ive seen them bad frequently

These would have to be G-Luxons - right?

Bad with physical signs or bad tested with ESR meter?

I have a gigabyte board with these but given their size versus capacitance naturally assumed that they would be OK.