Need help on this lenovon Power supply

[ivtec]

Hi guys,i was given this Lenovo Desktop but it´s dead now i'm trying to figure out what's wrong with the power supply,took some pic,i suspect this


http://www.alldatasheet.com/view.jsp?Searchword=2045CT






http://www.neweggbusiness.com/Produc...82E16883205400

[Mad_Professor]

Re: Need help on this lenovon Power supply

Did you check to see if it's supply 3.3, 5, 12v? You may have to short it to get the PSU on, get a DMM and check yellow 12v, orange 3.3v and red 5v for voltage, if you do and they are within 10% of the expected voltage then your problem may be as simple as dried/bad caps.

[selldoor]

Re: Need help on this lenovon Power supply

Pictures are not big enough/clear enough for troubleshooting - if you mean the middle of the three transistors yes it does look burnt. Perhaps under too much pressure from rippling caps

[ivtec]

Re: Need help on this lenovon Power supply

Hi guys; i removed 2 of the STPS2045 and made some measurements with my Fluke on diode side and came up with this,see pic attachments below best i could get,
also disconnected the power supply from the PC and checked voltages red probe on green wire(PS-on) and black probe on most of the colored wires all i got was .05.00 volts so no 0.3,or 12vols

[Mad_Professor]

Re: Need help on this lenovon Power supply

Hi guys; i removed 2 of the STPS2045 and made some measurements with my Fluke on diode side and came up with this,see pic attachments below best i could get,
also disconnected the power supply from the PC and checked voltages red probe on green wire(PS-on) and black probe on most of the colored wires all i got was .05.00 volts so no 0.3,or 12vols

You did it wrong.

green jumper ground/black *PSU should come on
black probe on ground/black *doesn't have to be same as the jumper wire, any black will do.
red probe to test RED 5v, ORANGE 3.3v, YELLOW 12v.

Quickest way to test is get one of those cheap PSU testers. If all voltages are there, just recap the PSU.

[ivtec]

Re: Need help on this lenovon Power supply

You did it wrong.

green jumper ground/black *PSU should come on
black probe on ground/black *doesn't have to be same as the jumper wire, any black will do.
red probe to test RED 5v, ORANGE 3.3v, YELLOW 12v.

Quickest way to test is get one of those cheap PSU testers. If all voltages are there, just recap the PSU.

Well i did test it correctly,and only have the 5v,i can say it's bad cause i have two other working pc power sup,and jumped those and i can see them working also can test voltages and they are their ,the problem is cannot use them cause they are bigger the plugs are smaller and do not fit
i took out those Schottky Rectifiers that i posted in the previous post but i don't know for sure they're ok.what other components should i look for?
thanks in advance.

[selldoor]

Re: Need help on this lenovon Power supply

Not all PSU's are the same - you might want to read this and see if it helps
https://www.badcaps.net/forum/showth...rey#post222842

I think your diodes are ok - pictures of the backs are no use for troubleshooting
- use daylight - no flash.

[ivtec]

Re: Need help on this lenovon Power supply

QUOTE=selldoor;260704]Not all PSU's are the same - you might want to read this and see if it helps
https://www.badcaps.net/forum/showth...rey#post222842

I think your diodes are ok - pictures of the backs are no use for troubleshooting
- use daylight - no flash.[/QUOTE]

Thanks; i made it work don't ask me how but i just replaced those two rectifiers that i took out ,i also res soldered the third one and had also to make the connection on one of the lines that broke when i had to bend the hit sink in order to remove the rectifiers,ha and also had removed a cap that in circuit looked short but it was good out of circuit,i
but now that the pc is working it asks me for name and password

[selldoor]

Re: Need help on this lenovon Power supply

but now that the pc is working it asks me for name and password

Well done - try just hitting "enter"?

[ivtec]

Re: Need help on this lenovon Power supply

Well done - try just hitting "enter"?

thanks: when i hit enter upon starting up it goes to bios and PC setup and start up safe mode i tried to change admin pass word but no avail,still asking for password i went to the person that gave the PC and for my surprise they told me to look for a Computer shop to format the disc and reinstall windows,what a great help,thanks but no thanks i don´t want to spend any money on this, i have plenty of computers in the house,if i can get this to work fine if not keep it for parts,.

[rogfanther]

Re: Need help on this lenovon Power supply

If the OS installation is corrupted, you could just format and install some linux distribution in it.

[selldoor]

Re: Need help on this lenovon Power supply

Can you post a screenprint pic of the password required screen so we know exactly which one we are talking about.

[tom66]

Re: Need help on this lenovon Power supply

Or use "ophcrack" - very effective at getting the password. Or, even better, replace winlogin.exe with something that does nothing...

[ivtec]

Re: Need help on this lenovon Power supply

Can you post a screenprint pic of the password required screen so we know exactly which one we are talking about.

Hi: here some pics the last one is when upon start up i press enter. thanks in advance

[ivtec]

Re: Need help on this lenovon Power supply

Or use "ophcrack" - very effective at getting the password. Or, even better, replace winlogin.exe with something that does nothing...

Thanks tom.could you please be more detailed on this and how to go about it apreciate it .( replace winlogin.exe with something that does nothing)

[rogfanther]

Re: Need help on this lenovon Power supply

try with user "Administrator" and leaving the password field blank.

Or download chntpw, burn a cd and change that password.

[tom66]

Re: Need help on this lenovon Power supply

Thanks tom.could you please be more detailed on this and how to go about it apreciate it .( replace winlogin.exe with something that does nothing)

Just use chntpw as rogfanther suggests, or ophcrack. (Thanks for the hint rog - I have needed a program like that for some time so will look into it when I need it next.) Winlogon replacement would require logging in via say a Linux live CD which is a lot of bother when the two other programs make it easier, also it means you won't get a logon prompt...

[rogfanther]

Re: Need help on this lenovon Power supply

chntpw ( you can download a bootable iso with it , and it is present also in "Hiren´s boot cd" alog with other tools ) is easier because one doesn´t need previous access to files in the "victim" computer. With ophcrack I believe one would need to copy the registry files to other machine , or not ?

Also, I did reply, and only later realized that I don´t know if we are allowed to discuss this kind of utility in the forums.... so, if I should not have posted about it, I beg the forum´s pardon.

[ivtec]

Re: Need help on this lenovon Power supply

Hi guys,After so much trying to start up and restarting now it doesn't go to the win log in password anymore,send pic where it goes and get stuck there no matter what i do.I guess this has to do with hard drive security that's what it's asking now.

[b700029]

Re: Need help on this lenovon Power supply

There's no BIOS startup or HDD password as you've gotten as far as the Windows login.

There does appear to be a BIOS admin password though, but that can wait for later, unless it's not letting you boot to one of the password-changing utilities recommended above. In that case try clearing the CMOS battery.

(I don't recommend "inheriting" a Windows installation from someone else, better to just format and reinstall. This is something you can do yourself.)