power switch gone bad

I have a compaq dc7600. When I press the power switch, all I get is a led as long as I keep the switch pressed in. If it is the power switch where can I get one, or is there a simple fix?

 

It may not be the power switch, and it may not be simple. As a first option, turn it off at the wall and leave it for a minute, then try turning it on again.
How old is it?
Check the connections inside.
Did you do anything when it was last running, like install some new software?

 

I would try removing the battery, and trying to turn it on using only AC (wall) power. If it still does the same thing start removing peripherals like HDD, RAM, DVD-ROM, etc. and keep trying to start it up as you go. Like GCWesq mentioned, it's not necessarily the switch. In my opinion, it's probably something else.

 

Hi Deca,

The power switch is a simple momentary contact switch. If it can cause an LED to lite then there is nothing wrong with the switch. Stay with the guys.

Luck, Jim

 

okay, I disconnected everything; dvd,hdd,floppy,graphics,everything but modem card and power supply; still no results

 

And you took out the RAM and the battery too right?

 

are you talking about the cmos battery?

 

No just the regular power battery

 

Here's what's going on now. I removed cmos and ram,got nothing. So I pulled the 20 pin and 4 pin and checked with PS tester again. I can get HDD to start with tester plugged into PS. As soon as I plug in 20 pin back to MB I get nothing to work.

 

My bad. For some reason I thought the 7600 was a laptop, That's why I was referring to removing the battery. What sort of PS tester are you using? I'm a little confused about what you were saying about the HDD starting with the tester plugged into the PS.

 

I'm using an Ultra PS tester. You can test all your PS lines at one time or one at a time. When I plug in the (my bad on count) 24 pin line to the tester, power goes to the HDD. I've unplugged everything to do with the PS, and still cannot get anything to work.

 

And the tester is showing the PS as functioning properly? If it is, then maybe the switch is worth checking out. Do you have access to a multimeter?

 

Here'a another thing; the power supply will work plugged into the tester, but not when plugged into MB

 

yes,I've got a multimeter

 

my power switch has 6 wires to it. 2 white at the top; one white and one green on the bottom left; and one red and one black on the bottom right

 

I'm getting 7.96 volts on one pole of the MB switch plug,and 1.4 on two others

 

From what I've been able to find out about that switch, 4 of the 6 wires are for the 2 LEDs and the other 2 are for the switch itself. I'm not 100% on which colors are which though. You should be able to look and see which 4 are going to the LEDs, then do a continuity check on the other 2 (which are the switch wires). Firstly, disconnect the switch from the mobo. Then, you should have unlimited resistance when the switch is not depressed, and no resistance when pressed.

 

Okay, it's the two white wires on top. When I press the switch it goes to .000; when I release it ,it goes to .994 for just a second.

 

So just so I'm clear... WHen you check the 2 white wires without pressing anything, it's at 1 (or .994), then when you press and hold it, it oes to .000 and stays there until you release it. Then once released it goes back to .994 for a second then to .000 again?

 

Not to interfere with your and Jool1976's technical diagnosis but this page from the HP diagnostics pdf (starting on page 75) tries to differentiate between harness problem and power supply problem based on whether or not the 5v_aux light is lit on the MB.

And just a quick heads up that the power lights have a diagnostic light function that causes one to blink red on specific errors so that it isn't blinking red might mean something to you or Jools.

 

no, it goes back to one, but let me double check. it goes back to one.

 

no red lights

 

It sounds like the switch is working properly. Looking at the document that sach2 found the link for, you could try the first 2 steps in that next. So, check to make sure that the switch is set to 120V, then take a look at the 5V_aux light to see if it's lit up.

 

This PS doesn't have a 120v switch like I've seen on other PS. As for the 5v light, if it's the one on the MB, then it's on.

 

Hmmm... Do you have another PS you can throw in just to completely eliminate the PS as the problem?

 

I've read the page that Sach said to look at. So, do you agree that the switch could be bad? If so,would it hurt to try and tie the wires together momentarily to see if it will come on?

 

I don't have another PS on hand at this time. I'll try to find one tomorrow.

 

Based on the tests we ran on the switch it seems to be working fine. You can try jumping the 2 wires together though, but be careful not to short anything.

 

To be on the safe side, I'll wait until I can find a PS. I don't need to buy another comp if I can fix this one . I'll let you know tomorrow what I find out. Thanks for all your time.

 

No problem.

 

Hi,

From what I see here your problem is the motherboard. Power switch is only 2 wires and is working. Power supply works on the tester. Jump the Green wire to any black wire and the PSU should start. That's probably how the tester did it. Hope this helps a little.

Good Luck, Jim

 

I think trying another power supply is a good thing if you can get your hands on one.

I don't know electrical but I had seen this last night and thought it might be useful if you are talking about shorting pins and multi-meters. Maybe someone can read it and help decide which two pins would be jumped to mimic the power switch. I believe you said in another thread that your PC is the CMT version on the right of the diagram.

 

Alright,back again. I replaced the PS with another one. Now all I get is the led on the MB to continuosly flash.

 

Okay good folks, I'm ready to call it quits on this one. I've had it a long time and it's been a good one. I think we have tried everything under the sun to get it going, but I guess it's get up and go is gone... My thanks to everyone that has pitched in , it's been fun.

 

Hate to give up on a good fight. Up to you though.
Just read something that suggested it could be a USB plug. Suggestion - disconnect all but HDD, one stick of RAM and CPU. Also disconnect USBs from MB. Also take out CMOS and reset. Turn of at the wall plug for a minute or so. Then try.:confused

 

Don't worry; I'm not giving up entirely. I'm just going to let it mull around in my head for a day or two. I've got an old comp I built back down the road. It's usable, Asus p4p MB.I've got a new PS ordered so I don't have to wait the next time. Later