Compaq portable iii

[Destiouj]

Hello i got a Compaq portable III and it won't turn on and the light s are blinking i checked inside and I see no burned capacitors when I disconnect the motherboard the power supply fan start spinning pls help

 

[mattg1974]

Maybe there is a Short on the motherboard or the drives? Did you already tried to turn it on without the drives connected. You can even unplug the power of the plasma screen. That plug is under the motherboard..

 

[Destiouj]

I already tried that and it didn't work

 

[3lectr1c]

That sounds like a shorted tantalum capacitor on one of the power rails on the motherboard to me. I’d check there first.

 

[twolazy]

I would check the caps on the -5V to start. Seems to be a common problem in earlier IBM and clone boards.

 

[pkhoury]

That sounds like a shorted tantalum capacitor on one of the power rails on the motherboard to me. I’d check there first.

I don't suppose you know what capacitance caps are on the motherboard? I plan on trying to repair a Portable III very soon myself, but haven't yet cracked it open. I tried three and all exhibit the same behavior as the OP, though I haven't opened any of them yet.

 

[Destiouj]

I replaced all the tantalums and now it works

 

[pkhoury]

I replaced all the tantalums and now it works

What are the specs on the tantalums you used? I ordered a whole bunch yesterday, but for replacing on IBM 5150/5160 motherboards. I think those are 10uF, 16V.

 

[Grizzly Adam]

What are the specs on the tantalums you used? I ordered a whole bunch yesterday, but for replacing on IBM 5150/5160 motherboards. I think those are 10uF, 16V.

I ordered 10uF 35v for mine. I had three of them pop, one of which was visibly exploded and two that showed no visible signs of damage but showed no resistance during continuity testing.