Help after checking psu "no signal "

[sam67]

I recapped a couple of monitors the other week so i decided to open up my pc to write down the new caps that i was gonna get to replace the ones already in my psu.

Now i took out the hdd for more room and then took the psu out ,now i know this psu is not a good make it's a bestec 300w 12z model.

Now this has been in my compaq presario since i bought the pc in 2005 and have had no issues at all with the pc.

The pc has been running great right up till me removing the psu.I opened up the psu and the caps looked ok but i was gonna change them with some better one's just for more experiance

Now once i put the psu back in and turned on the pc the lights on the tower lit up ,the hdd spun and the monitor showed orange but said no signal when trying to press the power button on monitor which turns to green and says no signal.

The fans in the case all work and i have checked all connections .

All voltages are good even 5v stand by but yet nothing on my monitor except no signal when i put it on.I have not touched anything on mobo and it was only hdd that i removed to get psu out .

Anyone have any ideas as to why the monitor does not display ? i have tried my other monitors and it's the same so i know it's not that.Could i have disturbed anything in the psu even though the voltages are all good even on the main connection from psu to mobo when tested with DVM?

Don't have a spare psu to try at the moment..This is not a cap problem as this was running perfectly just before taking the psu out to check.

Mobo is a k8S-LA and pc is an athlon 64 compaq..No fancy graphic cards just what it came with when i bought it.

When removing psu i did drop the screwdriver on the mobo but it was not connected at the time it was unplugged.Screwdriver only fell a couple of inches and no damage was done.Can't for the life of me wonder why one min it was perfect and the next no image displayed even though the pc powers on ok and all fans work.Just hope mobo ain't dead lol.

Iknow it's not a great mobo but i wanna find the problem.

cheers

sam

[kc8adu]

Re: Help after checking psu "no signal "

i would look at the area the screwdriver hit.
or for something stupid like the p4 power not connected.
seen that a few times.

[sam67]

Re: Help after checking psu "no signal "

i would look at the area the screwdriver hit.
or for something stupid like the p4 power not connected.
seen that a few times.

Checked area again not a mark or anything ,my p4 was not connected to start with it's just a spare.. Any other ideas guys as i cannot understand it.Could there be a problem with this psu even though it's giving all the correct voltages while hooked up to all the loads after me taking it apart? Scratching my head now at this

[370forlife]

Re: Help after checking psu "no signal "

Are you sure you don't mean the pci-e connector isn't hooked up? It would have to have the p4 connector connected, almost every board that uses a p4/athlon 64 and up needs it.

[kc8adu]

Re: Help after checking psu "no signal "

+1

Are you sure you don't mean the pci-e connector isn't hooked up? It would have to have the p4 connector connected, almost every board that uses a p4/athlon 64 and up needs it.

[sam67]

Re: Help after checking psu "no signal "

Hi 370forlife, I have the 4pin connector that says p7 on mine connected to mobo and i have a 4 pin molex which actually says p4 on it but this connector has never been used http://www.plinkusa.net/products/ps575bk_2.jpg my 4pin looks like the 2nd bottom connector in that link that says p4 MB but like i say it says p7 on mine..the 3rd bottom one that says 4pin molex in the pic is the one that says p4 on mine and is not used..I guess they named them differently lol
still cannot get it working ..Even took psu out again and hooked it up to hdd just to test all voltages again and all are the same as it is when hooked up inside the pc with all loads.

Could my graphics card have gone ? it's just one that came with the pc when i got it,trouble is i don't have one to try.

This is doing my head in as it was working perfect till i checked on psu..I have had the psu out before and mobo without any problems just don't understand why it's not displaying anything on my monitor except "no signal"

Cheers

[370forlife]

Re: Help after checking psu "no signal "

Ahh, i see what you mean now. Bestec just puts p_ on their connectors to label them. What we were talking about is the square 4 pin connector with two negatives and 2 12v's. It's called a p4 connector (pentium 4, the pentium 4 processors are what started using this connector for power, hence the name,) ok was a little confused there.

[sam67]

Re: Help after checking psu "no signal "

yep thats right lol...still no luck ..Is there a possability that this mobo is gone even though i am getting all the voltages at the main connector from mobo..is there a better way of testing this mobo that anyone knows without swapping out with another mobo as i don't have one

Not sure what to do as i don't have a spare graphics card as this is intergrated on the mobo and no spare psu ..i do have 3 monitors though lol.

[momaka]

Re: Help after checking psu "no signal "

Try running the computer without the RAM. Does the motherboard beep?
Also, what brand and series of capacitors did you use as replacements in the power supply?
Visually check all of the smaller components where the screwdriver hit. If one is missing or even just slightly cracked, that's all it takes.

[sam67]

Re: Help after checking psu "no signal "

Try running the computer without the RAM. Does the motherboard beep?
Also, what brand and series of capacitors did you use as replacements in the power supply?
Visually check all of the smaller components where the screwdriver hit. If one is missing or even just slightly cracked, that's all it takes.

Hi mamaka, Tried running with no ram but i don't here any beeps (to be honest i don't think i have heard it beep on start up when it was running fine,or maybe i just never took notice of it)

I never did replace the caps in psu in my post at the start i said i opened up the psu to take down the caps i would need so i could order the right ones .This is not a cap problem that i am sure of .

One minuete it was working and the next it was not.I keep trying to think of things that might have caused this problem.There is no visable damage on the board .

When testing for voltages on the mobo connector that comes from psu the pins are very close when back probing i am even thinking maybe what if i touched on a wrong pin by mistake what damage would that have caused ?just grasping at straws now so i can rule out any possible causes as to why the darn thing is not working.

Thanks

[everell]

Re: Help after checking psu "no signal "

One thing I would suggest you try. Unplug your computer from wall outlet (and let all the electrons drain off). Then plug in to wall outlet. Before pushing power-on button, does fan come on? Then push power-on button. Does fan come on AFTER pushing power-on button? This will tell you if your south bridge is fried or not.

[370forlife]

Re: Help after checking psu "no signal "

Also something to take note of, most emachines don't have a onboard speaker, so that may be one cause of no beep codes.

[sam67]

Re: Help after checking psu "no signal "

Hi Guys,thanks for the replys.. I did go and take it to pc world here and was explaining my situation to there tech guy when i was looking at cheap cards and he said bring it in and i'll try a card for you as there's no need buying summat that might not work just to see if it was my onboard graphics that had gone ..He put in a card but no luck..But it did show the compaq logo on screen a few times but it would not display it all the time just every now and again..

He reckons board has gone but it's just bugging me and i'd love to trouble shoot it but don't really no owt about mobo's lol..i reckon i i must have touched summat wrong when back probing ..My fault as i should have done it using better lighting when playing around.

I never managed to get the compaq logo on screen like he did and i thought yes it's done but then

[sam67]

Re: Help after checking psu "no signal "

One thing I would suggest you try. Unplug your computer from wall outlet (and let all the electrons drain off). Then plug in to wall outlet. Before pushing power-on button, does fan come on? Then push power-on button. Does fan come on AFTER pushing power-on button? This will tell you if your south bridge is fried or not.

Fans only come on when i press the front panel button,but i think that's how it has always been as i could always just slightly here the fans in the past start when button pressed.

[momaka]

Re: Help after checking psu "no signal "

...But it did show the compaq logo on screen a few times but it would not display it all the time just every now and again..

So the logo did display a few times? In that case, the motherboard might still be okay.
Start by disconnecting everything from the motherboard, all cables, add-in cards, and hard drives. Leave nothing but the PSU ATX cable, 4-pin CPU cable, a stick of RAM, as well as the connector that leads to the switches/LEDs to the front of the case. Have your keyboard and monitor connected too, but nothing else. Try running the computer and see if you get the Compaq logo. If you do, reset and go in the BIOS. If you do get in the BIOS, your motherboard should be okay.

Also, just a question - before you did anything to the computer, did you unplug the PSU first? Does your mouse/keyboard have a PS/2 or USB connector?

I never did replace the caps in psu in my post at the start i said i opened up the psu to take down the caps i would need so i could order the right ones .This is not a cap problem that i am sure of .

Sorry about that , not sure how I got it into my head that you did.

[sam67]

Re: Help after checking psu "no signal "

Hi guys
momaka i thought the same as you about the logo screen...so what i did was remove the cmos jumper on board (don't know why but tried it) then i removed all ram dvd writer hdd and then i got quite a few beeps from comp and then a a message saying "disc boot failure insert system disc and press enter " ..So i thought hmm that's good as i had nothing before.

I then put 1 stick of ram in and connected the hdd ..restarted and the compaq logo came on ,i did this a couple of times as it seemed to me power supply was struggling ..Then my windows screen came on and i could see my log in screen powered down and put the mouse and keyboard back in and it would not come on so i took them back out and restarted this time i was able to log in and now i am using my pc to type this on here ,it did take a few goes at getting the compaq logo screen to appear . Some times it come on and sometimes it struggles.My guess is hopefully it's the psu that for some reason is struggling since i opened it up.

The thing thats thrown me is all voltages are correct even when it spins the fans and what not when using my dvm.Even the guy i took it to said psu were fine .It just got me thinking when he got the compaq logo to appear which i could never get untill now.

I nearly did order a new mobo last nite but thought i would sleep on it and try again (hope it is psu) Gonna have a look for another psu on ebuyer any one recommend one that is good but not to pricey from ebuyer just in case i do get the same probs with new psu

Will keep you guys informed as i go along ,this is weird if it defo is psu which to me seems more likely as it did struggle .Still only got 1 stick of ram in and hdd that's it.

I was thinking up all-sorts thinking i had touched summat with the dvm probes ,guess i might have been looking to blame myself as it was working before ,maybe psu was ready to cause me a few issues and the timing was wrong when i was probing about.
Cheers

sam

[momaka]

Re: Help after checking psu "no signal "

That's good progress, but it still doesn't isolate the problem to the PSU only. Since the computer can run now, it's probably a good idea to first test the RAM and CPU under high load. From what I gather from here, you can do that with either Memtest86 or Prime95. Not sure which one to recommend you, though. Hopefully someone else here with more experience on that can point you in the right direction.
Meanwhile, find out what brand (and series) of capacitors your motherboard has. I know it would seem unlikely that the caps went bad just as you took your computer apart, but it's not impossible. Here's why actually:
https://www.badcaps.net/forum/showthread.php?t=5496

Also, if your keyboard or mouse has a round PS/2 connector and not USB, make sure to unplug the computer before connecting/disconnecting it. Otherwise this can damage your motherboard. Same when you connect/disconnect any hardware from the computer - always have it unplugged. I think you know that already but just wanted to make sure.

Lastly, as far as getting a power supply from ebay - there's lots of cheap "cheap" ones there that you should definitely avoid. If your Bestec is indeed an ATX-300 12z model, you'll be much better off recaping it than buying a new one. Except for the ATX-250 12E model, Bestec power supplies are actually pretty decent.

[sam67]

Re: Help after checking psu "no signal "

This pc is weird , i ran memtest no errors and tried prime 95 all ok..Yet it will not always start once i turn the pc off but after a few attempts it starts (still only using basic hardware ,mouse keyboard and hdd and 1 stick of ram ) but say if i click on start menu and click restart the pc it will work every time ,i may just need to try a new psu and rule it out i suppose it will come in handy for testing in the future.

By the way momaka when i said about new psu i said ebuyer not ebay ebuyer is a decent online shop lol. It's appreciated that you are helping me out .

The pc once it is on will stay on for however long i want it to ,it's just when i switch it off and then power on again that it can take a few attempts to come back on.It kinda makes a noise like the psu has slowed down for a split second and then it comes on ..I actually now can tell with the sound whether or not it will display on the screen.

Got me puzzled lol.

[stj]

Re: Help after checking psu "no signal "

yep, use ebuyer a lot here

[momaka]

Re: Help after checking psu "no signal "

The pc once it is on will stay on for however long i want it to ,it's just when i switch it off and then power on again that it can take a few attempts to come back on.

This strongly suggest a capacitor problem then. Capacitors tend to have higher ESR at lower temperatures. As the computer gets warmer, their ESR decreases and computer becomes stable. But like I said, we need to find weather it's the motherboard or the power supply that is causing this (or both). I'm pretty sure your Bestec has either Jamicon or CEC caps (Pce-tur/Pce-tul). Those do go bad sometimes, but also see what the motherboard has. If your motherboard has something similar to what kc8adu had in thread above (Lelon/Ltec, etc.) or any other brand that is listed as bad in this forum, I'd suspect those more than the ones in the power supply.
Kind of hard to tell without an ESR meter, though.

By the way momaka when i said about new psu i said ebuyer not ebay ebuyer is a decent online shop lol.

Ah, I see. I just conveniently assumed it was ebay since I didn't know what it was or if there was a typo .
Anyways, now that I looked there, ebuyer does seem to carry some decent power supplies.
This is what I like personally:
http://www.ebuyer.com/product/150985
But if not, there should also be other decent units for less money. Or you can recap the Bestec.
Either way, get the cap brands on the motherboard first. Even if a new PSU fixes the problem, it might only be temporary if the motherboard caps are bad.