Dimension 4600 boot up problems

Question

I am posting this as a new thread, but it is based on a few older messages that did not address my problem (or did not get addressed).

I have a Dimension 4600 that does not power up consistently when pushing the power button. There are several behaviors observed. After shutting down the PC, I have come back to it later and it will not power up. If I unplug the power cord and plug it back in, sometimes about an hour later the PC will go into a power reset cycle (on-off-on-off...) but never gets to a point that anything is displayed on the screen. If I push the power button during this power reset cycle, the PC will then boot up to Windows and run fine. However, once I power down and turn on several hours later, it may or may not boot up normally. Then there are times when I can shut down and come back the next day and power it back up with no problem.

I've pulled and reseated all cables, and at times it seems that afterwards the PC will magically start to boot normally again. I've tested the power supply as noted in other postings by jumping the green and a black wire on the main PSU cable to the motherboard and confirmed that the PSU fan does turn on. Also, a green LED on the motherboard is lit when the power cord is plugged in. I've "massaged" all cables several times checking for loose connections. There are no battery backup power supplies or other power filters connected to the PC. I've plugged the power cord in several different power outlets in the house as well.

One other observation... whenever I shut down I hear a weak beep (from somewhere) as it powers off. Don't think that happened before.

I've read that the PSUs on the 4600 tend to fail, but I also read that that the symptoms I observe could be related to the motherboard. I could go out and get a new PSU to test further, but before I do this, is what I describe clearly either a power supply problem or a motherboard problem, or is it hard to determine without swapping out parts?

Any further insight or troubleshooting suggestions are appreciated.

Thanks,

Mike

Message Edited by michkal on 07-26-2007 10:15 AM

Message Edited by michkal on 07-26-2007 10:33 AM

Message Edited by michkal on 07-26-2007 11:17 AM

michkal · Answer

Thanks for the feedback.  I did initially reseat the ribbon cable going to the front panel microswitch and actually took off the front bezel thinking that the plastic cover to the microswitch had broke, buteveryting seemds fine and I have not touched it since.  I'll give it another try.  I will also break out the multimeter and test the switch, just to remove that from the picture.   Mike

ManyDimensions · Answer

The Dimension 4600 was built during the same time frame of the capacitor fiasco that totaled hundreds if not thousands of computers. Not just Dell brands but all motherboards built during that time period. The failure rate was phenomenal. Very few have survived to this late date. I doubt your start problem is motherboard (capacitor) related.   Power supplies can be likened to incandescent light bulbs. It may fail the day it is installed or last fifteen years. Normally when a power supply goes south, it really goes south quick.  I doubt your start problem is power supply related.   It seems from your post that the cable massage has had a somewhat lasting effect, moreso than anything else that you have tried. This may be the culprit.   If memory serves me correctly there is only one board mounted to the front of the case but has two ribbon cables attached. Only one ribbon leads from the front of the case to the motherboard. The on/off microswitch is mounted directly on the front case board. This board also serves as a transfer for the front USB and status lamps for power on and hdd activity.   If this were mine, I would remove the front bezel, remove both ribbon cables and reset them.

shesagordie · Answer

michkal

When this happens, what is the reading of the power button LED, solid green, blinking green, solid amber, blinking amber?

What is the Sequence of the Diagnostic LED's on the Back Panel?

Bev.

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michkal · Answer

Bev,

During all scenarios observed, the power button LED appeared solid green once there were signs of power running through the system, otherwise off if nothing powered up. I don't remember seeing the power button flashing green, even during the power cycling, but I will confirm that. I never saw an amber color.

During the continuous power cycle, I did observe the "power light" (the LED to the left of the power button) flash amber, then the hard drive light to the right of the power button flash green. It was hard to capture a pattern because the power would reset quickly, but this light pattern appeared to repeat.

I don't remember the state of diagnostic LEDs on the back panel during the continuous power cycle, but all other times I remember them green. I will follow up on this.

Thanks for the feedback.

Mike

Message Edited by michkal on 07-27-2007 08:21 AM

michkal · Answer

Ok, I have verified that the microswitch is seated properly behind the front panel bezel and that the ribbon cable connecting to the motherboard is secured. The switch seems to be ok.

I also observed the 4 diagnostic LEDs on the back panel during the time it attempts to boot and they follow a pattern that looks consistent wit the normal boot up which eventually go to all green.

Playing around more today, it seems that once I remove the power cable and then plug it back in later is when I get back into this booting problem. After a period of time goes by from plugging in the power cord, I notice that PC turns on briefly (the PSU fan spins, the PC fan spins) but immediately turns off. If I then attempt to push the power button on at the point, the PC will boot up normally. If I power the PC off and then power up again later, I have some regular success in booting up.

I don't know what else to do now (besides swapping out parts). I know this is not an easy one to diagnose based on the info I am providing, but if anyone has any further suggestions or thoughts on this, I appreciate hearing them, and appreciate the suggestions already provided.

Mike

Message Edited by michkal on 07-27-2007 08:25 AM

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Dimension 4600 boot up problems

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