Hi, here I have Toshiba Laptop L500 LA-4982P.After turning on - power led light up, but no video on LCD or external display. It has dedicated AMD graphics (removable separate PCB ).
tried so far:
1.Light re-flow all BGA chips (usual reaching 150C), this is easy technique to identify BGA solder problems but not fix them. - some thing happening.
2.Remove all external devices - some thing
3.Remove Dedicated graphics(it has integrated intel graphics as well) - some thing
4.Check for bad caps - no nec/tokin caps found, ESR looks good on all larger caps.
5.Checked DC-DC ripple voltages - some 50mV, some 100mV p-p. - not sure if it is bad. 100mV sounds a lot, please confirm this.
6. Checked SPI bus to bios flash chip - data bursts about once a second in power off state, Continuous data flow in power on state (Is it right?)
Not sure if ripple voltage is too big and I have no idea if constant data flow from spi flash chip is right, I thought ROM was read from flash chip at system start at once.
Any Ideas guys ?
tried so far:
1.Light re-flow all BGA chips (usual reaching 150C), this is easy technique to identify BGA solder problems but not fix them. - some thing happening.
2.Remove all external devices - some thing
3.Remove Dedicated graphics(it has integrated intel graphics as well) - some thing
4.Check for bad caps - no nec/tokin caps found, ESR looks good on all larger caps.
5.Checked DC-DC ripple voltages - some 50mV, some 100mV p-p. - not sure if it is bad. 100mV sounds a lot, please confirm this.
6. Checked SPI bus to bios flash chip - data bursts about once a second in power off state, Continuous data flow in power on state (Is it right?)
Not sure if ripple voltage is too big and I have no idea if constant data flow from spi flash chip is right, I thought ROM was read from flash chip at system start at once.
Any Ideas guys ?
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