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Asus A7V v1.02 initial power up and then automatic power off issue

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First post, by TbirdAthlon

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Hello Everyone,

I have an old Asus A7V v1.02 board that I bought new back in the day that I'm trying to resurrect after at least a decade of not being used but it was a very reliable setup for years when was using it. The original working setup is/was an Athlon 1.1Ghz, two 256MB DIMMs, Nvidia GeForce2 GTS AGP video, Adaptec 29160 PCI SCSI controller, SB Live PCI sound card, and Intel 1xGE PCI NIC. If I remember when I last tried to use the machine (>10 years ago), I think it was becoming unreliable to turn on and/or sometimes it would just power off. The current behavior tested in a simplified configuration consisting of the motherboard, CPU, RAM, video card or no video card and PCI post card setup ONLY is that the machine will 99% power up via the soft-power switch, the PCI post card will show good power LEDs, the reset LED lights up and then goes off, sequence through a few different post codes (C0 -> C1 -> 48 --> C0 -> C1 ), stopping on displaying "C1", the PC speaker will give one long beep (not super long.. lets call it medium long) and then power off. I have tried the following but nothing helped to keep it powered up and get to a BIOS post:

- inspected the board for any obvious capacitor or other component issues (burns, cold solder joints, etc)

- brushed off the motherboard of any dust, etc

- removed, cleaned and re-applied new Arctic Silver thermal compound between the CPU and the quality CPU fan. I confirmed I didn't use too little / too much and everything i evenly spread

- tried across three different ATX power supplies

- tried a different CPU fan to see if it's a "too slow" RPM issue

- tried different RAM (one and two other sticks installed at the same time)

- Sprayed contact cleaner in the DIMM slots and inserted / ejected the DIMMs a few times

- tried disabling the "Jumper free BIOS mechanism and set the various DIP switches and jumpers for a 100Mhz buss * 11x multiplier for a 1100Mhz Athlon CPU. That did speed up the initial power to single-beep time but the motherboard still powers off within say 1.5 seconds.

It might be worth noting that if I remove ALL RAM and power up the system, it will go through almost all the same steps as above but the post card will stop on code "DE" and it will just keep giving that one single medium-long beep in an endless loop. That I totally expect but when any RAM is installed, the MB powers off.

I think part of the power-on issue I was experiencing a decade ago was a failing power switch as I recently confirmed with a multi-meter that it wouldn't give me any continuity at all. I just sprayed in some Deoxit and that seems to have fixed the switch but even with manually shorting the "power on/off" soft pins on the motherboard, the MB rarely occasionally won't do anything. Sometimes it instantly reacts like you would expect but other times it does nothing! Other times (rarely), the MB will power on, go through the above sequence but not power off yet never post. Maybe there could be some power on circuit issues here?

For completeness, the various capacitors on board are:

Main board
- size: very small caps : color: black : manufacturer: teapo : common value: 100uF 16v : other identifying codes: none
- size: small caps : color: black : manufacturer: rubycon : common value: 1000uF 6.3v : other identifying codes: YXG
- size: medium caps : color: black : manufacturer: JEC : common value: 470uF 16v : other identifying codes: none
- size: tall caps : color: black : manufacturer: rubycon : common value: 1500uF 16v : other identifying codes: ZL
- size: tall caps : color: purple : manufacturer: rubycon : common value: 1500uF 16v : other identifying codes: YXG

rear / VRM like vertical board
- size: medium caps : color: yellow : manufacturer: Fujitsu ? : common value: 680uF 6.3v : other identifying codes: none
- size: short/squat caps : color: lighter purple : manufacturer: oscon : common value: cannot rear : other identifying codes: SP

I don't know if it would be worth re-cap'ing this board but I can do it if there is high confidence that would solve this issue.

Other posts here on Vogons and other places say it might be a dead CPU or dead motherboard. I suppose either of those are possible and I don't have spare CPUs or MBs to do any A/B testing with. Can anyone recommend other things to try here? I'd love to resurrect this board if possible.

--David

Reply 1 of 6, by aaronkatrini

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Do you have an ESR meter? Some multimeters will measure Capacitance. Also there are those cheap cinese LCR-T4 testers that are quite good for testing capacitors.
Maybe you could pull out 3-4 capacitors at random, especially those near the CPU are and see if they still are good. The board is from the plague era. Even though ASUS wasn't particularly affected it might just be. I've starting seen more and more Rubicon caps that are going bad, even though in good aesthetical condition.

About being a dead CPU or Motherboard, doesn't seem to be, if you're getting codes it means something is running. CPUs at least are 99,999% either working or not working. BIOS also seems good, maybe you could take the chip out and put a little deoxit in the socket as well. Deoxit on the CPU socket doesn't hurt either. Also measure the Resistor packs that are on top of the CPU socket that lead to the Ram slots.

Reply 3 of 6, by TbirdAthlon

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Ok, back from traveling and time to focus on this board again. I do have an old "Blue ESR tester" and that was probably going to be my logical next step. I sure wish that checking for ESR values would reliably work w/o having to pull the component though. This means I'm going to have to resurrect my old solder sucking station or buy a new one to reliably pull components. As I was reading other threads here on Vogons, there used to be some re-cap kit vendors where I could get everything in one pack. Are you aware of any people still doing that or at least a place that has a BOM of all the caps I might need to order for an A7V?

Thanks for the other link which mentions a7vtroubleshooting.com. I'll have to go do a deep dive on that site as well.

Reply 4 of 6, by TbirdAthlon

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@aaronkatrini , Everyone, Ok.. I now have a quality Hakko desoldering station and am ready to dig into this A7V v1.02 board. You mentioned doing random checks on caps around the CPU. Do you mean the caps between say the parallel port connector and the VRM, the caps on the VRM itself, or the caps between the VRM and the CPU socket? There is also a bunch of caps around the ATX connector too. Would you suspect any specific vendors be it Fujitsu or OSCON (the ones on the VRM board), Rubycon, JEC, or TEAPO? You mentioned Rubycon before so I have to assume to start with those. I've also recently learned that the physical size of caps matters. I *really* don't want to have to research what caps are the right size for the right capacitance value, voltage, temperature range, etc. so I'm hoping someone has a recap kit BOM I could just buy from say Digikey but I've been unable to find one. If I have to go all manual here, I've read that Panasonic FM-series caps are good. Any specific recommendations here?

Reply 5 of 6, by Minutemanqvs

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I had a similar behaviour than yours on an A7V8X. The (most) dead capacitors were the ones in the path of the direct CPU-cooler airflow, other similar capacitors just outside of the airflow seemed fine. But in my case they had visible leaks to point me to the right direction. Other than the random shutdowns, my symptoms were that I could boot mostly reliably at a low clock speed, but as soon as I went up in frequency the system shut down.

Searching a Nexgen Nx586 with FPU, PM me if you have one. I have some Athlon MP systems and cookies.

Reply 6 of 6, by TbirdAthlon

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Ok, I did a full inventory of the caps on my A7V v1.02 board here: https://www.trinityos.com/SCRATCH/Recap/ASUS-A7V/ See the tabs for pictures, etc. I found Ebay vendor LF Components ( https://www.ebay.com/sch/i.html?_ssn=lfcompon … lfcomponentsinc ) where they seem to make a lot of ASUS Recap kits using SUNCON capacitors. Does anyone have experience with them, SUNCON caps, etc? I'm willing to pay a little more to get a complete PROPER kit with the right capacities AND the correct physical sizes but I also don't want crap. All thoughts are helpful here.

@Minutemangvs: If you look at the above spreadsheet, I have pictures on one tab. I looked and my CPU fan vents it's hot air in the directions of the chipset heatsink so there really aren't any caps really close other than the one yellow cap just next to the vertical VRM. Is that were you would recommend to start?

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