The lottery of making a motherboard POST \ VOGONS

The lottery of making a motherboard POST

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First post, by Pabloz

Posted on 2017-11-13, 16:45

Pabloz Offline

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This is kind of weird and im not sure whats going on. Maybe its the power supply but i doubt. I have 3 PSUs, two AT and one ATX
i have been testing different motherboards brands and models.

Some motherboards not listed here posted at first try, no mattery what, they always posted and machine booted.
By post i mean the monitor received a signal displayed the boot.

But on others....for example:

pcchips m919
pcchips m912
pcchips m915i
pcchips m520
fic pa-2013
Soyo 6vba 133u

The m919 is a casino jackpot, posts when it wants to post, else black screen and no signal on the monitor. its a 50% chance it wont post and you need to turn off and turn on again.

But i noticed that on the rest, there was a high percentage chance that it wont post, and that you need to turn off and turn on again for it to post and boot.
So im wondering if you experienced this with old hardware, there is no chance that im the only one that experienced this. Because there were NO changes done and nothing touched, it just needed to turn off and turn on again.

besides one of the reasons for it to not post is the memory for example, but memory was not changed at all and posted on the second try.

Any thoughts? could be capacitors even if they are not bulky they die after 20 years? or could be the voltage regulators?

Reply 1 of 8, by Ozzuneoj

Posted on 2017-11-13, 19:52

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Could be bad caps. I've seen those symptoms caused by caps before.

Now for some blitting from the back buffer.

Reply 2 of 8, by verysaving

Posted on 2017-11-14, 01:48

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Bad caps for sure. most of that motherboards used crap caps when new so after 20+ years they
should be replaced.
Can you post some pictures of them to see what brand they used?

Reply 3 of 8, by SW-SSG

Posted on 2017-11-14, 02:27

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Pabloz wrote:
could be capacitors even if they are not bulky they die after 20 years?

They don't have to look dead to be dead.

Reply 4 of 8, by ODwilly

Posted on 2017-11-14, 04:45

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My old Soyo 478 motherboard is like that. All the primary caps were blown and replaced with fresh Rubycons. However all the secondaries are the same junk brand. When I can get it to boot it runs great, but getting it to boot is like rolling dice weighted on 1. I think if I invested in a full recap it would stabilize, but there are like 30 small caps.

Main pc: Asus ROG 17. R9 5900HX, RTX 3070m, 16gb ddr4 3200, 1tb NVME.
Retro PC: Soyo P4S Dragon, 3gb ddr 266, 120gb Maxtor, Geforce Fx 5950 Ultra, SB Live! 5.1

Reply 5 of 8, by PcBytes

Posted on 2017-11-14, 13:36

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ODwilly wrote:
My old Soyo 478 motherboard is like that. All the primary caps were blown and replaced with fresh Rubycons. However all the secondaries are the same junk brand. When I can get it to boot it runs great, but getting it to boot is like rolling dice weighted on 1. I think if I invested in a full recap it would stabilize, but there are like 30 small caps.

Do a full recap. Believe me, most of the times you get those symptoms, a full recap will fix that.

One question though - is it one of these Dragon boards? If so, it's definitely worth a try to recap one.

"Enter at your own peril, past the bolted door..."
Main PC: i5 3470, GB B75M-D3H, 16GB RAM, 2x1TB
98SE : P3 650, Soyo SY-6BA+IV, 384MB RAM, 80GB

Reply 6 of 8, by amadeus777999

Posted on 2017-11-14, 18:34

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Which caps are the best for such a task?
What about using all tantalum capacitors... overkill/bullshit or feasible?

Reply 7 of 8, by ODwilly

Posted on 2017-11-14, 19:05

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PcBytes wrote:

Do a full recap. Believe me, most of the times you get those symptoms, a full recap will fix that.

One question though - is it one of these Dragon boards? If so, it's definitely worth a try to recap one.

Yes, yes it is. P4S Dragon Ultra. I'm not equipped for a full recap but I think I'm just going to send it off to bad caps or have a friend do it for a few bucks.

Also found a boxed kt880 dragon ultra and 3200+ on the curb last week. Won't post but everything gets warm which is a good sign. Also needs a recap.

Main pc: Asus ROG 17. R9 5900HX, RTX 3070m, 16gb ddr4 3200, 1tb NVME.
Retro PC: Soyo P4S Dragon, 3gb ddr 266, 120gb Maxtor, Geforce Fx 5950 Ultra, SB Live! 5.1

Reply 8 of 8, by BLockOUT

Posted on 2017-11-16, 22:42

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im not sure if full recap can fix these issues. I also have them from time to time

older boards are full of 22uf 25v caps everywhere. You can get a 486 board with more than 20 of those 22uf caps. do those make any difference at all? or the bigger caps are the issue?

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