old mobo + old cpu = no post. which one do i swap? how to test?

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giantbucket

giantbucket

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i have this old used mobo with cpu, but the system doesn't POST despite me trying 3 different power supplies and even removing the ram sticks.

is there ANY way that i can find out if it's the mobo or the cpu that's dead? i could buy a used old cpu on ebay from china but that's $10 and won't be here for a month.

i would prefer if it was the cpu that's hosed, since the mobo has features & ports that i really want to make use of for a fun / vintage / don't-ask-why Win98SE build.

board is ECS L7VMM2
processor is Athlon XP 2400+ socket 462
 
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TbsToy

TbsToy

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Are you you are sure your monitor and cables are good and working? Does anything light on the monitor at all? Motherboards and/or CPUs are not easy to check. The usual way is to swap em with a known good one. Otherwise, ya need someone who really knows their electronics and has the right test equipment. Not the response ya want but it is what it is.
Good luck,
W.P.
 
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giantbucket

giantbucket

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i know the monitor and cable is good since plugging the same cables (even mouse / keyboard) into another machine works perfectly.

weird thing which might actually say something - during the first 2 power-on attempts, the fans spin up for less than a second and then shut down. takes 3 attempts before the system actually KEEPS power, at least to the fans.

i might try that without a CPU and see if it's any different...

i'll double-check the onboard VGA connector just in case, though. maybe it's loose / unsoldered, but i would think that wiggling it would tell me if it was iffy to begin with.

i've got multimeters and can likely hook up a digital mini-scope, but to what? the VRM outputs? some other worthwhile points?
 
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TbsToy

TbsToy

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TbsToy

TbsToy

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Mmmmmmm. That the fans started and stopped definitely shows a problem, (s), with either. It is hard to guess these things but if ya want our guess it is the mobo.Was gonna ask ya that very question. Don't know what starting without a CPU might do. Be cautious here.
W.P.

P.S. Ya really need an oscilloscope and the schematics and the various volt/ohm/ wattage values.
 
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Chicano

Chicano

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CPUs are rarely the cause, unless you have reason to believe it suffered overheating or electrical damage, the CPU is probably ok.

With the PSU removed from the list, a relatively accurate way to check the motherboard is through BIOS beeps.. the presence of beeps, tells the motherboard is working... the absence tells either the motherboard or BIOS is dead, or that there is no motherboard or case speaker/buzzer or it's not working... sometimes the buzzer may beep but without identifiable beep code.

One other symptom of a dead BIOS or motherboard is fans don't work or they work momentarily and stop a second or two after pressing the power button.
 
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giantbucket

giantbucket

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i'll hook up a mini-speaker and see if it beeps at all, with and without the CPU. i'll start pricing out a different-but-similar board on eBay. it's supposed to be just a fun project - rather than spend money on smokes-n-booze, i spend it on this stuff.
 
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