Help! Dimension 4700 will not boot

Question

My Dimension 4700 has suddenly died.  The symptoms:  as soon as I plug in the power cord to the power supply, the front panel power LED comes on green briefly, then blinks green once, and then goes to yellow continuously.  At the same time, the rear fan that cools the CPU fan comes on full speed and stays that way.  Now mind you, I have NOT hit the power on button on the front yet;  when I do though, nothing else happens;  the front panel power led stays yellow and the fan keeps blowing like crazy but there nothing on the display.    I have tried a different power supply but got exactly the same thing.  I tried disconnecting the optical, floppy, and hard drives.  I pulled out the PCI modem card.  I tried different memory.  Still nothing but a yellow LED on the front and the CPU cooling fan running full speed.  Anything else I can try?  Any help or suggestions would be greatly appreciated.  Thanks!

shesagordie · Answer

jakster   What is the sequence of the diagnostic LEDs at the back of the case?   http://support.dell.com/support/edocs/systems/dim4700/sm/adtshoot.htm#wp1043338   Bev.

jakster · Answer

Bev, none of the diagnostic leds ever come on.   Thanks for your post! Message Edited by jakster on 05-17-200601:06 AM

jakster · Answer

Thanks again for your suggestions Bev. I did all that you suggested before my first post, except for pull all the memory. I am using the on-board video and I did pull the PCI modem card and the cables to all drives. With no memory, no PCI cards, and no drive cables -- I still get no beep codes and no diagnostic LEDs light up. Again, as soon as I insert the power cord into the power supply (without touching the front power button) the CPU fan comes on full force, the front panel power LED turns on green briefly, then blinks green once, and then goes to steady amber. Nothing else happens when I do push the power button.

Must be a motherboard problem right?

shesagordie · Answer

jakster

Try removing all the PCI cards, the video card and memory, disconnect the IDE/SATA and FD cables, then check that the front panel cable is connected to motherboard, with nothing else connected to the case, except the power cable and then power the system on. If you do not get any beep codes or no LEDs in the back, then it would appear that the motherboard has died.

If the LEDs light up and there are beep codes, then add the parts one by one, rechecking that the LEDs etc, still work.

Bev.

shesagordie · Answer

jakster   Basically check that the retention bracket holding the heatsink on the processor is still intacted.    Bev.

jakster · Answer

I did try pulling the memory per your suggestion before my last post, but got the same results. I have not done anything with the CPU. What would you suggest?

(Keep in mind that this computer was working fine for over a year until this suddenly started happening.)

Thanks again!

Jim

shesagordie · Answer

jakster

So it would seem so.

But, try again with the memory pulled. A steady yellow power LED, suggests a device might be malfunctioning or incorrectly installed, did you check the the processor?

Bev.

jakster · Answer

Bev, I will have to wait until tonight to check out the CPU and CPU heatsink.   Is there any way to disable the onboard video controller, just in case that is causing the problem?  (I mean other than in the BIOS setup of course, because I can't get to that.) Message Edited by jakster on 05-17-200603:01 PM

shesagordie · Answer

jakster Sorry, I don't know of any way to disable the on-board video, without entering the setup. Maybe another member can step in with answer. Bev.

jakster · Answer

1. I put in a known-good PCI video card (don't have a PCI Express card) but still no go.  I was hoping that if the onboard-video was causing the problem that it might automatically switch to the external video card as some do and boot.  Still nothing, but oh well, worth a shot.   2. I removed the heatsink and processor and found both looked fine, but after reinstalling both, still the same.   I guess it has to be a motherboard or CPU failure.  Care to guess which is causing the problem?  Usually when there is a component failure on the motherboard (in my limited experience) it is faily obvious, but everything looks fine and my nose doesn't detect anything either (you know, the nasty fried-component smell).   Thanks!  -- jakster

jakster · Answer

Long story short;  I remembered that a friend of a friend has a Dimension 4700 and he let me borrow it to swap parts.  It only took a few minutes to determine that the processor was the culprit in mine and I have already replaced it with a new one from a local computer supply store.  My former pile of useless plastic and metal is a fully-functional Dimension 4700 computer again.   Bev, thank you very much for all your helpful suggestions in diagnosing the problem.    Best regards,   Jakster

jakster · Answer

In my experience, processors going bad for no obvious reason is very unusual, so I totally agree with you Bev.  In fact, I was all ready to order a replacement motherboard when I thought of the guy who let me borrow his 4700 for testing.   Hey, you have a great weekend too Bev and thanks again for your help.   Jakster

shesagordie · Answer

jakster   Pleased to hear that the system is running and thanks for the heads up.   Failed processors are rare, unless rhey are fried, but failed retention brackets seem to occurr quite often.   Have a great weekend.   Bev.

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Help! Dimension 4700 will not boot

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