Jump to content


 


Register a free account to unlock additional features at BleepingComputer.com
Welcome to BleepingComputer, a free community where people like yourself come together to discuss and learn how to use their computers. Using the site is easy and fun. As a guest, you can browse and view the various discussions in the forums, but can not create a new topic or reply to an existing one unless you are logged in. Other benefits of registering an account are subscribing to topics and forums, creating a blog, and having no ads shown anywhere on the site.


Click here to Register a free account now! or read our Welcome Guide to learn how to use this site.

Photo

Dead Motherboard?


  • Please log in to reply
9 replies to this topic

#1 Kenmc

Kenmc

  • Members
  • 14 posts
  • OFFLINE
  •  
  • Gender:Male
  • Local time:08:39 AM

Posted 27 January 2012 - 03:41 PM

Hi,

This is my first question. I have 11 Hp/Compaq D530 CMT computers that won't post. They have a 2.8GHz Intel Pentium 4 processor with a 533MHz Front Side Bus, a 40GB hard drive with 512M of memory. When I turn them on, the fans come on, the on/off LED turns on and that's it. This is what I have done to troubleshoot them thus far.

Replaced the power supply with a known good one from the same model computer that works.

Disconnected the hard drive, Floppy, and CD ROM.

Swapped CPUs from a known good computer.

Put the CPU from a dead computer into one that works and the CPU works.

Measured the +5, +12, +3.3 and the CMOS battery with a Fluke bench meter. Can't find a place to measure the CPU core voltage though.

Replace the CMOS battery with a new one just to sure, although even if the battery was dead, it would still post as far as I know.

I have used an Oscilloscope to make sure the voltages are clean.

Installed memory from a known working computer.

Installed both AGP and PCI video cards to see if there is something wrong with the on board video.

Rest the BIOS. These computers have a push button instead of a jumper.

Inspected the capacitors and they look fine. No bulging or leaking. They could still be bad, but I have always seen leaking and bulging.

Here is the kicker. When I remove the memory, the computer beeps 5 times, pauses and beeps 5 times again and again just like it should.

The BIOS IC is not one that I can remove and replace. All of the ICs are SMT and soldered. I don't have the proper tools to work with SMT ICs and don't know which IC is the BIOS anyway.

I think that's it as far as I can remember. I've burned myself out on these computers, but at some point I'm going to remove the motherboard and set it up outside the case and try and find a place to scope out the CPU core voltage. I may get a capacitor kit and replace the capacitors, but would rather take a look at the CPU core voltage first. If I have missed anything or if there is something else I can do, I would appreciate any help with this.

Thanks,

Ken

Edited by Kenmc, 27 January 2012 - 03:44 PM.


BC AdBot (Login to Remove)

 


#2 cryptodan

cryptodan

    Bleepin Madman


  • Members
  • 21,868 posts
  • OFFLINE
  •  
  • Gender:Male
  • Location:Catonsville, Md
  • Local time:01:39 PM

Posted 27 January 2012 - 04:04 PM

have you tried assembling the computers outside the case to mitigate any shorts?

#3 rotor123

rotor123

  • Moderator
  • 8,093 posts
  • OFFLINE
  •  
  • Gender:Male
  • Location:New Jersey
  • Local time:09:39 AM

Posted 27 January 2012 - 04:42 PM

There are certain lines of capacitors that are known to fail wthout bulging.

Within the last six months I picked up the capacitor kit from badcaps.net and replaced all the capacitors that had replacements in the kit. None of the ones I replaced were bulged or leaking but when I was finished I had a working Dell Precision 650 Dual Xeon workstation.

Evidently D530 CMT are known for capacitor problems. As are Dell SX280

http://h30434.www3.hp.com/t5/Desktop-Hardware/unbootable-HP-d530-CMT-HDD-not-recognized/td-p/325894

Hi:
The d530 is a nice PC. However, many of them were plagued with bad capacitors on the motherboard. I would inspect all the capacitors on the motherboard for bulging/leaking at the tops or residue leaking out the bottoms. You can find most of these capacitors by the processor area.

http://www.google.com/#sclient=psy-ab&hl=en&source=hp&q=D530+badcaps.net&pbx=1&oq=D530+badcaps.net&aq=f&aqi=&aql=&gs_sm=e&gs_upl=12484l17734l0l18531l13l10l0l0l0l0l1031l3968l0.3.4.5-1.1.1l10l0&bav=on.2,or.r_gc.r_pw.,cf.osb&fp=39d4c75cd492ccc4&biw=1024&bih=593

If I had eleven of them I'd visit badcaps.net for advice on what capacitors to replace and do a trial run on one or two and see what results I got.

Edited by rotor123, 27 January 2012 - 04:44 PM.

Fortune Cookie says: Fortune not Found: Abort, Retry, Ignore?

Sent from my All-In-One Desktop. Perfect for Internet, Not for heavy usage or gaming however.

How Does a computer get Infected? http://www.bleepingcomputer.com/forums/t/2520/how-did-i-get-infected/
Forum Rules,    The BC Welcome Guide

167 @ June 2015


#4 Kenmc

Kenmc
  • Topic Starter

  • Members
  • 14 posts
  • OFFLINE
  •  
  • Gender:Male
  • Local time:08:39 AM

Posted 27 January 2012 - 05:15 PM

Thanks, I'll go with the caps on one of them. The last time I looked, badcaps.net didn't have a kit. Maybe I could ask for one or just replace every cap that is 470uf and over. The reason I have 11 of them is because they are from my churches school. I keep around 120 computers running. My Pastor gave me these to check out because they were dying over time and he would replace them with another one.

Ken

#5 Kenmc

Kenmc
  • Topic Starter

  • Members
  • 14 posts
  • OFFLINE
  •  
  • Gender:Male
  • Local time:08:39 AM

Posted 27 January 2012 - 05:19 PM

have you tried assembling the computers outside the case to mitigate any shorts?


Thanks for your reply. It has been a while, but I'm pretty sure I did remove the motherboard and set it up on my bench with no luck.

Ken

#6 James Litten

James Litten

    Ԁǝǝ˥q


  • BC Advisor
  • 1,946 posts
  • OFFLINE
  •  
  • Gender:Male
  • Location:New Jersey
  • Local time:08:39 AM

Posted 27 January 2012 - 08:11 PM

They aren't giving you beeps for CPU detection. Hmmmm... Try pulling the CPU out of one and starting it. If it doesn't beep (I think the beep code is 3 beeps) then you're getting closer to the problem.

I've replaced some electrolytic capacitors that I did not know were bad until I took them out and really looked at them and some that looked half melted (thanks Dell). I wish there was an easy way to test them without pulling them :(

James

#7 dpunisher

dpunisher

  • BC Advisor
  • 2,234 posts
  • OFFLINE
  •  
  • Gender:Male
  • Location:South TX
  • Local time:08:39 AM

Posted 27 January 2012 - 08:59 PM

As far as the caps go.................. also look at the bottom of the caps where they are against the board. They will sometimes push out the rubber plug instead of bulging the top of the cap. Hard to see with the board in the case. Also, it is usually the caps around the CPU vregs/coils that cause the no boot/dead symptoms. First place to look.

Usually when caps on the southbridge go bad you lose IDE/SATA channels and USB ports act flakey. Digikey and Mouser are two companies I have used in the past for parts.

I am a retired Ford tech. Next to Fords, any computer is a piece of cake. (The cake, its not a lie)

3770K @4.5, Corsair H100, GTX780, 16gig Samsung, Obsidian 700 (yes there is a 700)


#8 Kenmc

Kenmc
  • Topic Starter

  • Members
  • 14 posts
  • OFFLINE
  •  
  • Gender:Male
  • Local time:08:39 AM

Posted 27 January 2012 - 10:26 PM

They aren't giving you beeps for CPU detection. Hmmmm... Try pulling the CPU out of one and starting it. If it doesn't beep (I think the beep code is 3 beeps) then you're getting closer to the problem.

I've replaced some electrolytic capacitors that I did not know were bad until I took them out and really looked at them and some that looked half melted (thanks Dell). I wish there was an easy way to test them without pulling them :(

James


If you go to badcap.net, you will see that Dell has the most kits available for motherboards. Another thing about Dell is their power supply. Until they began to make computers with Intel Pentium 4 Processors, the 20 Pos. connector was wired differently than a standard power supply.

Ken

#9 Kenmc

Kenmc
  • Topic Starter

  • Members
  • 14 posts
  • OFFLINE
  •  
  • Gender:Male
  • Local time:08:39 AM

Posted 27 January 2012 - 11:39 PM

As far as the caps go.................. also look at the bottom of the caps where they are against the board. They will sometimes push out the rubber plug instead of bulging the top of the cap. Hard to see with the board in the case. Also, it is usually the caps around the CPU vregs/coils that cause the no boot/dead symptoms. First place to look.

Usually when caps on the southbridge go bad you lose IDE/SATA channels and USB ports act flakey. Digikey and Mouser are two companies I have used in the past for parts.


Thanks for your reply. I have taken one motherboard out and inspected it with a magnifying glass and I can get into the case with a magnifying glass too. They look fine, no venting, bulging and they are sitting flat on the motherboard. That's why I was hesitant about replacing them. Not a single one of them showed any sign of failure on 11 computers. I guess the only way to tell is to replace them on one and go from there. Someone recommended that I remove the CPU and turn the computer on and see if it beeps and I will try that tomorrow. I have recapped many motherboard using capacitor kits from badcaps.net. As you problably know, badcaps.net have high quality large value caps in a small footprint to replace the caps on a motherboard. As you have indicated, the large ones are around the CPU and toroid coils, but there are others scattered around the board like the memory slots and in between PCI slots and as you know, the southbridge. The kits from badcaps.net look like they are replacing any cap that is 470uf or above as far as I remember. I could be wrong though.

One question. I have never seen a schematic for a motherboard. Are they taking the 12V on the 4 Pos. connector near the CPU, pulse with modulating it and filtering the crap out of it to get the 1.5V CPU core voltage?

I sincerely hope that I'm not coming off as a "know it all" when I should be shutting up and listening. If I am, please tell me so I don't put anyone off. I've been in the electronics industry since 1980, first as a tech and then an engineer and it's lonely. None of my friends have any idea about what I'm talking about. I'm hoping I get the chance here.

Thanks again for your reply,

Ken

#10 Kenmc

Kenmc
  • Topic Starter

  • Members
  • 14 posts
  • OFFLINE
  •  
  • Gender:Male
  • Local time:08:39 AM

Posted 27 January 2012 - 11:46 PM

They aren't giving you beeps for CPU detection. Hmmmm... Try pulling the CPU out of one and starting it. If it doesn't beep (I think the beep code is 3 beeps) then you're getting closer to the problem.

I've replaced some electrolytic capacitors that I did not know were bad until I took them out and really looked at them and some that looked half melted (thanks Dell). I wish there was an easy way to test them without pulling them :(

James


I'm sorry I didn't mention this before. Pulling the CPU out and turning the computer on to see if it will beep will be very informative. I haven't tried that. Thanks. It's easy and I will do that tomorrow.

Thanks,

Ken




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users