Forums

The ASOD Absolute Silence Of Death; Dead Mother Board or Something Else

Started by Bret Cahill September 11, 2015
The Dell Studio PC is dead.  I tried to turn it on and got _nothing_ except the yellow green LED on the power supply which, from what I understand, only means it's plugged in.  I checked the "on" switch with an ohm meter and it works.  (Turning it on with the big toe is not damaging apparently.)  I removed the power supply and ran a jumper from pin 3 to pin 4 on the 24 wire connector to bypass the mother board.  This turns on the PS fan and provides voltages from 5v - 12v to the 21 other pins with wires.

On the plus side everything seems to be intelligently engineered [idiot proof] enough to give another new or used mother board a try.  This would be done under the assumption a whole lot of other things didn't also go wrong at the same time.

If something _else_ could be wrong I don't want to throw good money and time after bad.


Bret Cahill






On Thursday, September 10, 2015 at 8:02:18 PM UTC-7, Bret Cahill wrote:
> The Dell Studio PC is dead. I tried to turn it on and got _nothing_ exce=
pt the yellow green LED on the power supply which, from what I understand, = only means it's plugged in. I checked the "on" switch with an ohm meter an= d it works. (Turning it on with the big toe is not damaging apparently.) = I removed the power supply and ran a jumper from pin 3 to pin 4 on the 24 w= ire connector to bypass the mother board. This turns on the PS fan and pro= vides voltages from 5v - 12v to the 21 other pins with wires.
>=20 > On the plus side everything seems to be intelligently engineered [idiot p=
roof] enough to give another new or used mother board a try. This would be= done under the assumption a whole lot of other things didn't also go wrong= at the same time.
>=20 > If something _else_ could be wrong I don't want to throw good money and t=
ime after bad.
>=20 >=20 > Bret Cahill
I've revived quite a few dead motherboards by replacing bad power supply ca= ps. Motherboards often solder directly to ground or power planes meaning yo= u need a GOOD soldering iron and possibly a small hot air gun to get a litt= le more heat than can be conducted down the wire.=20 New mobos are often equipped with solid polymer caps (MUCH better for life = and performance). I've 'upgraded' some caps to polymers with good results. = The most troublesome caps are often the ones closest to the processor. 1000= -2000 uF at 6.3 volts are common.=20 While bulging caps are bad, non bulging ones are not necessarily good. An E= SR meter isn't all that helpful either as many time I measure the board aft= er the cap is removed and it still reads 'good'. Obviously it can't be. It's not for the inexperienced but it isn't a big deal to replace caps. BUT= , the question is, why bother? We have some PCs at work that require older = OSs or some peripheral that needs the old board but the new ones are SO muc= h better. BTW I wouldn't have a Dell for any reason but then again I'm a curmudgeon. G=B2
On Thu, 10 Sep 2015 20:02:15 -0700 (PDT), Bret Cahill
<bretcahill@aol.com> Gave us:

>The Dell Studio PC is dead. I tried to turn it on and got _nothing_ > except the yellow green LED on the power supply which, from > what I understand, only means it's plugged in. I checked the "on" > switch with an ohm meter and it works. (Turning it on with the big > toe is not damaging apparently.) I removed the power supply and > ran a jumper from pin 3 to pin 4 on the 24 wire connector to bypass > the mother board. This turns on the PS fan and provides voltages > from 5v - 12v to the 21 other pins with wires. > >On the plus side everything seems to be intelligently engineered >.[idiot proof] enough to give another new or used mother board a try >. This would be done under the assumption a whole lot of other things > didn't also go wrong at the same time. > >If something _else_ could be wrong I don't want to throw good money > and time after bad. > > >Bret Cahill >
Every stop to think that a failure of a device connected TO the power supply is dragging it down, and it will not even switch on to protect itself? The engineering failure is all yours. Could be the vid card. could be a hard drive spindle driver FET. Could be the mobo itself. Could even be the PS and it does not appear bad when hooked up no load.
> >The Dell Studio PC is dead. I tried to turn it on and got _nothing_ > > except the yellow green LED on the power supply which, from > > what I understand, only means it's plugged in. I checked the "on" > > switch with an ohm meter and it works. (Turning it on with the big > > toe is not damaging apparently.) I removed the power supply and > > ran a jumper from pin 3 to pin 4 on the 24 wire connector to bypass > > the mother board. This turns on the PS fan and provides voltages > > from 5v - 12v to the 21 other pins with wires. > > > >On the plus side everything seems to be intelligently engineered > >.[idiot proof] enough to give another new or used mother board a try > >. This would be done under the assumption a whole lot of other things > > didn't also go wrong at the same time. > > > >If something _else_ could be wrong I don't want to throw good money > > and time after bad. > > > > > >Bret Cahill > > > Every stop to think that a failure of a device connected TO the power > supply is dragging it down, and it will not even switch on to protect > itself? > > The engineering failure is all yours. > > Could be the vid card. could be a hard drive spindle driver FET. > Could be the mobo itself. Could even be the PS and it does not appear > bad when hooked up no load.
I'll try a mother board tester and then gamble.
The 5V and 12V voltages drop by 10 - 20% even drawing just 15% of rated maximum amps.  Everything is within 5% no load.

ATX power supplies are sophisticated with feedback controls, etc., aren't they?


Bret Cahill




On 2015-10-08, Bret Cahill <bretcahill@aol.com> wrote:
> The 5V and 12V voltages drop by 10 - 20% even drawing just 15% of rated maximum amps. Everything is within 5% no load. > > ATX power supplies are sophisticated with feedback controls, etc., aren't they?
Yeah, you shouldn't see the 5V dropping much when 5v is loaded sounds stuffed to me: a failed repair attempt could easily cost more in damage than a new one. -- \_(&atilde;&fnof;&bdquo;)_
> > The 5V and 12V voltages drop by 10 - 20% even drawing just 15% of rated maximum amps. Everything is within 5% no load. > > > > ATX power supplies are sophisticated with feedback controls, etc., aren't they? > > Yeah, you shouldn't see the 5V dropping much when 5v is loaded > sounds stuffed to me: a failed repair attempt could easily > cost more in damage than a new one.
That was it. The load test is easy and needs to be hyped more. Thanks. Bret Cahill