• Please review our updated Terms and Rules here

Help Compaq Presario 7210

Sounds like you have covered all the bases...if the power supply is good, everything but the CPU removed (including disconnecting all drives), and no beeps...sounds like a motherboard problem. Troubleshooting motherboard problems on a pentium-class machine is out of my league...
 
I'm going to make a longshot suggestion:

Does the hard drive cage extend over the motherboard? What if when the hard drive cage got pushed, the cabling or whatever actually pressed the motherboard down into the case frame or mounts underneath and created a short. Have you tried actually removing the motherboard from the case and powering up independently? Sometimes mounts are not where they should be or may actually be loose underneath or an extra missing screw wedged underneath. Put in the original processor, original ram. Get the speaker hooked up and the front panel with the power LED all outside the case. Also take some good photos of the component side of the motherboard. There are some sub-regulators on the board because I think the processor requires a 3.3v power supply? The best assumption right now is a fried motherboard ... From what theory I can Google, the powergood signal from the power supply goes to the clock generator which starts and gives a ready signal to the processor which then gets provided a reset to start diagnostic routines. I'm pretty sure your power on LED is enabled when the processor starts running. Most motherboards I've dealt with have an onboard LED that if on, means the processor is running. If blinking, there is an issue diagnosed by the processor. Memory is not required to get that LED on. At this point, you've got nothing to lose and everything to gain ...
 
Everything seems to be tight underneath, no lose screws. But yes, the harddrive cage does hang above the MOBO. Original CPU and ram has been installed. I just tried connecting it off the case, lights still fail to turn on.
Here are some high resolution photos, you can use the webpage to zoom in and out, a lot:

https://www.dropbox.com/s/8uwetatjbvojygo/fullboard.JPG?dl=0
https://www.dropbox.com/s/jcer3nog9xoaulg/boardp1.JPG?dl=0
https://www.dropbox.com/s/6tu26xvg0qo3inw/boardp2.JPG?dl=0

What about the chips, including the CPU, getting warm? or is that just that they're powered, but not doing anything? No blinking, no beebs. Would a POST code PCI/ISA card help with this?
I guess that you can't test the chip outputs of a running system without an oscilliscope? what would keep the power light from burning? if its the power-good signal, I could try to replace the chips its trace leads to one by one.
 
The situation is pretty hopeless BUT ...

I see an onboard fuse in the corner by the power connector - I assume you checked that?
I see many surface mount components symbol FBnn. Measure some and see if they're zero ohms. If so, they could be a fuse component so check all you can find for continuity.
I see a couple black transistor type cases symbols U1 and U8 by the power connector. Do they only have two leads? If so, I've seen those used as fuses also. They should read zero ohms.
I see an in-line IC with a heatsink sticking up near the power connector. That is probably a regulator and should get warm also. That heatsink may not be ground. Could it have gotten touched
by your hard drive cage?

Yes, IC's getting warm should indicate they are at least getting power. I think trying to trace the power LED back is kind of pointless. It is an output indicator. We need to know what input it is looking for.
If there was a datasheet of the chip that would help but I doubt one exists.

Larry G
 
retrogear said:
The situation is pretty hopeless BUT ...

Yes, IC's getting warm should indicate they are at least getting power. I think trying to trace the power LED back is kind of pointless. It is an output indicator. We need to know what input it is looking for.
If there was a datasheet of the chip that would help but I doubt one exists.

Larry G
Click to expand...

Hello Larry G,

Thanks a bunch for helping me out here, all of you. I've done a few tests.

I tested fuse F1 and F2, both are intact and continue power.
I have tested the FBxx components, all seem to work fine and continue the circuit.
U1 and U8 are three-leaded transistors, they could be regulators though.
Transistor U19 (A flat one between a jumper and cap) warms up, but Q1 (The long one with a heatsink) does not. I had the original 8MB of compaq memory installed when testing. The harddrive caddy could never have hit Q1's heatsink.

This is the closest datasheet I could find, I think that it covers a few models hence the 'X': http://www.datasheetarchive.com/dlmain/Datasheets-29/DSA-563589.pdf
I had a quick look, it does cover the power-on LED somewhere. Maybe we need to look at the 'soft power management' part of the IC and check of its conditions are met. But with ICs warming up, this could indicate that one or more ICs are shorted. I guess this is difficult to check without an oscilloscope?

Again, thanks everyone for their help,
Niels
 
I'm still puzzling over what happened. If the failure happened because of the hard drive cage moving then one of two things:

1) It created a short circuit, which we seemed to have chased that as far as we can.

OR

2) The motherboard got flexed, something dislodged by the cables putting pressure on the board or your bumping it.

You tried another processor so that's been reseated. Here's what we do:
Put in all original parts or memory you know worked, the processor, etc.
Remove all cables to any devices and remove power to them.
In other words, we only want what is necessary to try and boot up the motherboard ROM.
Make sure the motherboard has sufficiently discharged by removing the backup battery (I forget what you had but I assume not soldered in)
and has been powered off (AC unplugged) for at least an hour, THEN pull out the ROM chip partially raising each end with a flat screwdriver and reseat pushing in firmly.
If there are any other socketed chips do those also (within reason, at least push on them firmly) then make sure you have a speaker (if there is an onboard one or speaker)
Reconnect AC power, hook up your vga display and power on to see if anybody's home :stern:

PS - for all we know the power on LED could get turned on during the ROM boot program which does some diagnostics also.

Good luck

Larry
 
I remember now that you said you heard what amounted to a power supply short but anything is still possible. The datasheet is the floppy controller and yes I have seen that chip fail so the floppy drive won't read disks but still
the bios would boot to the menu.
 
retrogear said:
I remember now that you said you heard what amounted to a power supply short but anything is still possible. The datasheet is the floppy controller and yes I have seen that chip fail so the floppy drive won't read disks but still
the bios would boot to the menu.
Click to expand...

It controlls much more like that... it talks about the power_on led on some pages. It handles everything from IRQ, DMA to BIOS buffer, LEDs and IDE controllers.

So if somene wants to find out the conditions of a power_on led turning on, it must be somewhere in the datasheet.
 
Yea, it's at the point where it would take someone with more letters after their job title than I have :)
Besides, how to replace an IC like that anyway? If there's not a simpler solution it's KIA ...
 
You must log in or register to reply here.
Back
Top