shorted celeron cpu?

[JorgeHernan]

Hi guys

I have a non-working combo ECS socket 478 motherboard with a celeron 2.1 Ghz .When i test the resistance (with the celeron still in the socket) of those four 3300uf x 6.3V capacitors near the cpu socket (the resistance between positive and negative leads of these 3300 uf caps) i get 4.00 Ohms.But when i remove the celeron from the socket i get 92.1 Ohms.Does this mean i have a shorted celeron?
Thank you
Jorge

[smeezekitty]

Re: shorted celeron cpu?

No, it means its flowing thru the CPU and it is normal. You must unsolder the cap to test it properly.
P.S. Do not do that anymore because it could cause damage to your board.

[hardwareguy]

Re: shorted celeron cpu?

Caps really should be tested out of circuit...the less connected to them, the more accurate the test.

[i4004]

Re: shorted celeron cpu?

>P.S. Do not do that anymore because it could cause damage to your board.

what could damage it, connecting the multimeter and measuring?

[ratdude747]

Re: shorted celeron cpu?

>P.S. Do not do that anymore because it could cause damage to your board.

what could damage it, connecting the multimeter and measuring?

slip with probe, split a trace. i did that once

[i4004]

Re: shorted celeron cpu?

you probably did that while mobo was on.
here we're discussing resistance of the unplugged mobo's cap.

[JorgeHernan]

Re: shorted celeron cpu?

i did it with the mobo unplugged!!I mean just the mobo and the celeron without any other part(without power supply, without anything).Just the mobo and cpu.Otherwhise i would have caused a short circuit.
I repeat this measurement was done on the mobo and cpu unplugged!! using the ohmeter.

[i4004]

Re: shorted celeron cpu?

i know jorge......i was talking to ratdude.

don't worry you won't destroy anything by measuring resistance while mobo is unplugged.

[ratdude747]

Re: shorted celeron cpu?

no, i made the mistake of shapening my probes (to measure really small contacts), slipped, spit a trace which killed the board.

[JorgeHernan]

Re: shorted celeron cpu?

i suposse the celeron is shorted 4.00 ohms looks like a shorted cpu to me

[i4004]

Re: shorted celeron cpu?

find some other cpu and compare.

i can test that on my i815 mobo and celeron1.3.

it's about 20 ohm.
-------------

more interesting question(s) for me are this:

can shorted cpu destroy the mobo?
(any SC protection on those VRMs that supply the CPU?)

and

can faulty mobo destroy the cpu(in a way of VRM misbehaving and frying it)?

[JorgeHernan]

Re: shorted celeron cpu?

I4004
beforei i carried the resistance test both with and with the cpu removed from the mobo (of course everything UNPLUGGED) i did voltage measurements but this time with the mobo-cpu ON (a mean plugged to power supply).The following results were obtained

mosfets near the cpu socket 1.30 Volt


Tested the remaining voltages(agp slot, chipset) and they are working fine

Its a celeron D and according to the cpu-world site celerons D works with 1.25 to 1.35 volt so this motherboard cpu power supply(mosfets, etc) are working well.Did not suffer any damage from this shorted celeron D.At least for me is shorted because yours is 20 ohm, mine is 4.00.
I learned the hard way that a shorted mobo(shorted mosfets) kills a cpu.Because when they are shorted give the cpu (according to the mobo)12volt or 5 volt and kills the cpu instantly.

[Toasty]

Re: shorted celeron cpu?

Wouldn't a shorted CPU cause the PSU to not start or shutdown?

Does the PSU run?

Power light (if any) on mobo on?

Remove the BIOS battery before you go probing around too.

Toast

[i4004]

Re: shorted celeron cpu?

>Wouldn't a shorted CPU cause the PSU to not start or shutdown?

cpu is supplied by VRM, so any cpu SC should be dealt by VRM, not the pc psu.
and as jorge says, when that vrm(part of which are mosfets) is blown, then expect damage to cpu, but still not psu shutdown....psu shuts down when current goes beyond "pretty damn high"...

oh yeah jorge, if you were already plugging it in with that cpu(and there was no damage), you could measure the voltage while plugged in...if it's SC, then voltage will drop considerably....ie it won't be 1.30v anymore....
it will barely be there.

[Toasty]

Re: shorted celeron cpu?

Notice these are ?? for the OP, NOT speculative troll!

[i4004]

Re: shorted celeron cpu?

it doesn't matter who they're for, i told you why they're worthless questions.
that's all.

mentioning psu here makes no sense, esp. if he said above:
"The following results were obtained

mosfets near the cpu socket 1.30 Volt "

and after 9hrs you ask him about psu.

also, some basic calculations would show you: 12V into 4ohm load is 3A.
what psu can't give more than 3A at its 12V rail?

read the thread, and understand it.
don't troll with irrelevant questions, don't insult for no reason.
ok?

[i4004]

Re: shorted celeron cpu?

>12V into 4ohm load is 3A.

and even less for 5V rail.
<wink>

[JorgeHernan]

Re: shorted celeron cpu?

i bought a celeron 1.7 yesterday and it gives me 30.7 ohm.
Apparently the celeron D 2.5 Ghz (the 4.00 ohm one) suffered extreme overheating and as a result some internal parts of the chip got shorted.I didnt mention that when a took off the case cover the fan didnt spin at all because of dirt that caused extreme overheating on the celeron D so i dissassembled the heatsink/fan unit and cleaned it. Anyway the motherboard still gives no video signal.I have replaced the four 3300uf with new ones, but still cant get the 1500uf x 16v at the electronics stores.The 1500uf x16v are part of the cpu VRM too.

[i4004]

Re: shorted celeron cpu?

what's the next higher capacitance you can get?
20 or even 30% more shouldn't be problematic.

[JorgeHernan]

Re: shorted celeron cpu?

what's the next higher capacitance you can get?
20 or even 30% more shouldn't be problematic.

I can get several capacitances in low esr form but the problem is none of them is higher than 10v.I can get low esr 1500uf x 10v , low esr 2200uf x 10v so i thought about putting six 3300uf x 6.3 in series, in place of the three original 1500uf x 16v .