PC Graphics card

[newtothis]

Re: PC Graphics card

Nope, had a crap DIY one that quit working after I forgot to discharge a cap

[stj]

Re: PC Graphics card

damn
well you located the area of the short,
but the black caps re probably not the cause.
it's probably a ceramic cap near them.
if you had an esr / low ohms meter you could narrow it down like that, but as it is you need to make a list of all shorted ceramics etc and then try lifting them one by one.

i'v done this a few times myself, so i know it's a long task.
btw, just hope it's not the actual gpu or ram!

[newtothis]

Re: PC Graphics card

Let me double check I am doing this right, Where do I put the - probe of meter?

[newtothis]

Re: PC Graphics card

damn
well you located the area of the short,
but the black caps re probably not the cause.
it's probably a ceramic cap near them.
if you had an esr / low ohms meter you could narrow it down like that, but as it is you need to make a list of all shorted ceramics etc and then try lifting them one by one.

i'v done this a few times myself, so i know it's a long task.
btw, just hope it's not the actual gpu or ram!

When I had the GPU and RAM off I did a quick resistance check, They seem to be ok

[stj]

Re: PC Graphics card

you took all the bga off? damn!

[newtothis]

Re: PC Graphics card

Yup, Total reball across all parts to make sure its all good Done properly with my IR station etc

So just to make sure where do I have my - probe when checking this card for shorts?

[stj]

Re: PC Graphics card

across each ceramic cap.
most are in parallel so a low ohms meter may have helped narrow that down.

[newtothis]

Re: PC Graphics card

Ok MOST ceramic caps are giving less than 1ohm resistance in cct, out of circuit they are not allowing continuity at all (on ones I have pulled) if I put my probes to both pads from 1 cap it is giving me very little resistance. This normal?

[c_hegge]

Re: PC Graphics card

^
Yes. That is normal. It means that something else in the circuit is giving the low resistance, not the cap itself.

[newtothis]

Re: PC Graphics card

Still it seems odd to me that BOTH pads off the cap will allow continuity when nothing is bridging them. No doubt my logic is flawed with series vs parallel ccts

So when will I know when I have got it... Will removing it from cct change my reading in the cct itself or do I have to test every bloody little cap on this board out of cct?! Only around 200 of the f'ers!

[stj]

Re: PC Graphics card

you will know when it shows less than 1 ohm off the board.
at that point, you will probably find that you dont see a short across the pads on the board anymore.

[newtothis]

Re: PC Graphics card

board is looking rather unpopulated already lol

[newtothis]

Re: PC Graphics card

OK just finished removing ALL the ceramic caps... Still continuity from pad to pad

[newtothis]

Re: PC Graphics card

Thought I would nosey round under the microscope... Looky at what I found.

[stj]

Re: PC Graphics card

nice foto's
time to lift it - what is it, a smart fet?

[newtothis]

Re: PC Graphics card

Found another, Fluxed them up and flowed to remove the bridges, No difference to readings

I think its a Smart Fet yes, Havent looked it up yet as getting late now

[stj]

Re: PC Graphics card

maybe one of the fets is shorted, i hope you checked the board each time you lifted one.

[newtothis]

Re: PC Graphics card

Yes lift, check, lift, check.

Have 72 components off the board so far! lol

[stj]

Re: PC Graphics card

got a foto of the other side?

[newtothis]

Re: PC Graphics card

here