Toshiba L355-S7915 won't boot, a/c power supply test 19.66 vdc at input

Specs for this laptop are here

Machine is used daily, has up-to-date MSE antivirus (complete scan 2 days ago = no threats), and Malwarebytes and SuperAntiSpyware paid subscriptions with real time protection enabled). I last used it yesterday and everything worked fine.

Today, when I pushed the power-on button nothing happened. I checked the voltage output from the a/c adapter and is has 19.66 volts at machine input connector (multimeter set to 20 vdc scale) and (which is within spec for this machine).
Also battery is installed and, although rarely used on battery power, battery has been performing fine.

What now? Is there a fuse I need to check?
I was going to disassemble it to check continuity on the power switch (if possible) but I figure I'd better check with you computer guru's before proceeding.

As always, thanks for any help !!!

Mike

 

sounds to me like a dodgey power switch/connection.

 

That's what I suspected at first, but I disassemble it since my last post.
Here's what I found so-far:

CMOS battery reads 3.24 vdc.
No boot when network card is removed.
Removed 1 stick of ram = same symptom.
Removed other stick of ram = same symptom.
Swapped ram into opposite sockets one-at-a-time = same symptoms.
Removed 'power on' switch and tested = '0' ohms resistance when depressed (could not probe motherboard connector due to plug socket too small for my meter leads, but I removed enough insulation on the wires to test) so I'm 99% sure the switch is not faulty unless a broken wire exist between where I tested and mboard connection = un-likely

Thanks Tueur !!!

 

Sounds like a dieing motherboard then. Just out of curiosity how are you testing with multimeter? If you have no load on the battery or psu input you will get full voltage readings regardless of the state of the battery. they will only drop under load. Also, You shouldnt ever get 0 resistance as everything has a resitance (even copper wire). If your multimeter is reading 0 when the switch is pressed then it is probably open circuit and has an infinately high resistance ie its broken. While you have it dismantled get a paper clip and unfold it into a U shape. use it to short the pins on the motherboard where the power switch plugs in (This replicates pushing the switch). If it boots then it probably is the switch. If it fails to boot it is probably a bad mb

 

Hi Lectrocrew,

Put the meter probes together. The reading you get will be very near the reading the switch closed should give. Most meter will show the resistance in the meter leads with the probes shorted together. Usually 1 to 2 Ohms.

Hope this helps a little.

Good Luck,

Jim

 

I'm testing on 20k scale.
Tried jumpering the power switch connector on motherboard with a piece of copper wire. Still did not power-on. I guess I have a bad mboard.
Thanks for the help.

 

The only scale testing the leads show resistance on is 200 ohm = 00.3
Anyway, with the reading I'm getting on the switch I think we can rule it out as the culprit.
Oh well, I have a hard drive, extra memory and an optical drive that will work in my HP 6715b if needed.
Thanks

 

Have a look on ebay. You may be able to get a replacement board. You have nothing to loose!

 

Hi Lectrocrew,

To test a switch you should be using the X1 scale on any Analog Meter. Digital meter would automaticly pick the scale. Are you using a Digital meter or Analog meter? 200 ohms would be way too much for any meter and/or leads and sounds like you must be using an Analog Meter. You wouldn't be able to see a couple of ohms but the needle would barely move on the X1 scale checking a switch.

Hope this helps a little more.

Luck, Jim

 

It's a digital meter but it does not have autoselect for resistance test. Manual test options are 2000k,200k,20k,2000,200.

 

Hi again Lectrocrew,

Use 200 Ohm scale for low resistance (switch) readings.
More good Luck, Jim