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Solved BIST test failure. Psu fan not working. On/off button- one amber flash then nothing.

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Boneychil

PCHF Member
Dec 12, 2021
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#1
Had computer powered up and was worki g fine, then i heard a sound like paper flipping in a fan blades then my computer completely shut off.

When i pushed the on button, the tower light goes amber for a quarter second then goes off. At the same time cd drive light blinks once then off. At the same time all fans run, (except for psu fan) and also no signal to tv monitor. So i am getting power, but no boot.

There is a bist button on the psu. After unplugging power cord and all other cords, i pushed the on/off button for thirty seconds as was suggested somewhere online. Then i connect ac cord back up and do BIST test. The BIST test fails in two ways.
1. The pcu fan does not turn on (but all other fans do turn on).
2. On/off button goes amber then off. No green. (The green light on the pcu DOES turn on though. )

If the pcu fan was the problem, wouldnt it shut down the computer?
I have looked through the list of led codes at dell. Says nothing about a quick amber then off completely. Also no tones happen either.
Not sure what to do. Hope someone can help.

Dell computer https://www.dell.com/support/manual...uid=guid-8ee9e22b-b7ae-4a40-b63d-32bfce61a578
 
#2
Boneychil said:
Had computer powered up and was worki g fine, then i heard a sound like paper flipping in a fan blades then my computer completely shut off.

When i pushed the on button, the tower light goes amber for a quarter second then goes off. At the same time cd drive light blinks once then off. At the same time all fans run, (except for psu fan) and also no signal to tv monitor. So i am getting power, but no boot.

There is a bist button on the psu. After unplugging power cord and all other cords, i pushed the on/off button for thirty seconds as was suggested somewhere online. Then i connect ac cord back up and do BIST test. The BIST test fails in two ways.
1. The pcu fan does not turn on (but all other fans do turn on).
2. On/off button goes amber then off. No green. (The green light on the pcu DOES turn on though. )

If the pcu fan was the problem, wouldnt it shut down the computer?
I have looked through the list of led codes at dell. Says nothing about a quick amber then off completely. Also no tones happen either.
Not sure what to do. Hope someone can help.

Dell computer https://www.dell.com/support/manual...uid=guid-8ee9e22b-b7ae-4a40-b63d-32bfce61a578
Click to expand...
Link is to the service manual of my particular dell. Hopefully all the info on specs is there for you. Manufactured 2018 if that makes any difference. Thanks in advance.
 
#4
As a matter of fact i do have one. I dont know why i didnt think to try that. Not sure if its the same size but it would work just for a quick test wouldnt it? Even if smaller?
And thanks for the reply.
 
#6
Just for clarity. What am i testing for? To hook everything up to the swapped psu and and see if it gets signal to the monitor? And to see if it boots up the operating system? Im not completely sure if the swapped psu works. Its on my old computer and i cant remember exactly what was wrong with it. It failed 3 years ago. Pretty sure it wasnt the psu though. I think it was my graphics card and i decided to buy a new computer rather than a graphics card. Anyways, I’ll try it and see what i come up with.
 
#7
On the main power supply Pin 12 and pin 16 have no wires going to them. (On my current computer. The dell)

But the other psu, all of the pins have wires. Does it make any difference? (My old computer psu. Is an old hp compaq presario. 2008 or so).
 
#8
this is the pin out diagram for the ATX 24 and 20 pin plugs.
1639482482238.png

which one do you have?
and are you refering the the correct pin 12 and 16 is in the diagram?
 
#10
So i didnt realize it until i actually pulled it out. The HP atx is actually a 20+4 pin atx. On the HP if you count it as a 20 pin, pin 18 has no wire.

If you count the 2 atx’s as a 24 pin then it is pin 20 that has no wire.

So the only difference between the two is the dell does not have the blue wire at pin 14, whereas the HP does have the blue wire.

Everything else is the same.
 
#11
Are you usually active around 4am pst. I will make a point to be up at that time so i can hopefully speed this up. Thank you very much for your help. I am not complaining at all. I highly appreciate your help. I just want to do what i can do to help the process. Thanks
 
#12
It's all good, I'm not up till 6am. :)

not sure why the Dell PSU has that missing cable, but Dell has history of using non-standard stuff.
normally I would say, just use the other PSU but Dell are weird and I don't won't to blow your mobo.
having said that, I've always simply swapped PSU around willy-nilly without ever checking the pin outs, without damage, Dell included, so who knows. (but some Dell are standardised)

in theory you could always remove that blue wire from its socket, or since the PSU wasn't used, just cut it and fix it up later if you ever do want to use it.
 
#13
Yeah. I was thinking of just cutting that wire and trying it too. Just wanted to get your thoughts.

When i fire up the HP, psu fan spins from the get go, but after that, it shuts down. Tries to refire, then shuts down, tries to fire, then shuts down. I didnt let it do that more than three times before I switched off the psu. But i assume the psu is working fine
Could you suggest a psu to buy or do you need more info (specs)?
I think buying a new one might be the prudent thing to do.
I have a multimeter. I could test DELL psu and/or the HP if i knew what pins to test and what voltage to put the meter on. If thats in the scope of your knowledge.
 
#14
So an update where im at.

In the DELL theres the 5 wire SATA going to the hard drive and it pigtails to a 2 wire SATA that goes to the dvd. I assume i dont need to have the dvd hooked up to test the HP psu. It doesnt have that 2 wite SATA anyways.

So to test this HP psu on the dell, i will be…

…connecting the 20+4 atx (with the blue wire cut)…

…the 4pin CPU ATX…

…and the 5 wire SATA to hard drive…

…and should i have the hdmi monitor connected up? So i can see if the monitor is getting signal?

Then thats it.

But i will wait to hear from you about testing with multimeter
 
#16
Ok. Seems mission is accomplished. Operating system fires up. Everythings seems to be operating nominally. The pigtail that comes ofF the HD is too short to get to the dvd. Can i just use one of the other wire sets for power to the dvd or does it have to be on the same pigtail as the HD? Thank you so much for the help.
 
#17
Oh. One more question. Should i just keep this psu until it fails, or is it possible it could harm something if there i a psu failure. Can a psu sometimes harm the hard drive or cpu or motherboard when they it fails?
 
#19
what was the make/model of the old PSU?
and what is the new one?

any cable coming from the PSU, with the correct connector, will work in the DVD.

yes, when PSU's fail, I've seen them affect other components.
no, tower LED will be connected directly into the mobo front panel header. maybe you are not referring to the power LED but maybe the drive activity LED???

does the Dell have an add-on graphics card, or a dedicated one on the mobo? if only the inbuilt one, then the HP PSU will probably suffice but it'll depend on the wattage.
 
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