I have been having experience purchasing and fixing YLOD PS3's... 4x so far ok (2x 60GB CECHH and 2x 40GB CECHG, so not that much experience. to give you a rundown of what I have been doing (knew nothing about PS3's and just started doing this a few weeks back as a favour to a friend).
Id like to think I have a pretty good handle on general electronics and am very familiar with PWM fans and modification/reflowing BGA's etc etc (havnt reballed one myself yet, but would like to at some stage).
I rework reflow using heat gun and a temp gauge (makeshift reflow station you could say! :P) trying my best to keep to a profile given to me by a friend that runs a few true reflow stations of similar sized BGAs.
I use AS5 between CPU/GPU and increase spring tension mounts(although in future I will also be cutting off RSX chip heat cap and doing under there too)
I set the fan to a good medium speed using a small half watt resistor, going from wherever I find 3.3v (diff wire on PSU, depending on model) which on the 2x 60GB and 1x40GB PS3's was 39Kohm, and the other (still CHECHG) 40GB it needed only a 900 ohm resistor - and wire that to the PWM line of the Fan. Basically when I measured the first 2 I did I think I was getting a drop of 2.06V or so, meaning the PWM line was now getting 1.24V (I read somewhere stock they vary from 0.6V to 1.1V full heat).
Anyways, that is what I do, and on one of them only, after playing for a week no probs.. I tried to turn it on and it would turn on with green light, but no display... after 30 seconds it turns itself back off.
I can boot it into the front end by holding down the power on button, however it thinks it has no hard drive connected? Whats strange about that, is if i disconnect a hard drive from one of my others, they will still turn on and provide video without needing to go into that front end (sorry totally not up with the PS3 lingo re: operating systems/bios).
I have been naughty and tried to rework it again however still same issue - and I really feel this isnt the problem... has anybody else had a ps3 respond like this? (P.S the solder joints on hard drive connector to the mainboard appear fine)
