Is this 7MC machine a lost cause?

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Joram

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Is this 7MC machine a lost cause?

#1

Post by Joram » Thu May 27, 2021 10:09 pm

A couple of years ago, my wife replaced her Windows 7 PC (HP model Pavilion p6234f) with a Windows 10 machine. As I had wanted to set up a WMC system for my office, I took the old computer, bought a Ceton InfiniTV4 PCIe tuner, and got a CableCARD from Verizon.

Things worked OK, more or less, until last month when all of a sudden the repurposed computer started turning itself off unprompted. I could still boot it back up, but after a few minutes it would shut down again on its own even if I wasn't stressing it with any operations. Then it stopped booting up, and after that it wouldn't even beep or POST at all.

Over time, the WMC system has built up a store of hundreds of recorded programs, most of them protected, so as you can imagine I really really would like to save this machine. Based on my (imperfect) knowledge of such things and on the research I've done, here is a list of the measures that I have tried during troubleshooting:
  • Dusted the inside of the PC case with compressed air
    Checked all the connections to the motherboard
    Plugged the power cord to a different electrical outlet
    Tried a different power cord
    Replaced the CMOS battery with a fresh one
    Reset the CMOS
    Removed RAM sticks
    Took out the graphics card
    Replaced the power supply unit
    Wiped the old thermal paste off the CPU and applied new paste
    Replaced the motherboard (with a matching one), using the original CPU
    Replaced the CPU (with a matching one)
I performed the above steps in roughly the order listed, going from the simpler to the more complicated as each step failed to fix the problem. Before switching out the CPU, the power switch LED wasn't even lighting up any more when I pressed it. Now it's lighting up again, but still there is no POST and no beeps. The CPU fan and the case fan spin up, but the case fan stops running after just a few seconds.

As far as I can tell, having replaced so many major components I have pretty much a whole new computer inside the case... and still, the thing won't boot up. Before giving up, what's left to try?

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StinkyImp

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#2

Post by StinkyImp » Fri May 28, 2021 4:22 pm

Joram wrote:
Thu May 27, 2021 10:09 pm
As far as I can tell, having replaced so many major components I have pretty much a whole new computer inside the case...
Agreed. By all outward appearances you've got a "different" computer that's exhibiting the same behavior.

Question... Are you using the same RAM for both the old and the new configurations? Memory faults can sometimes exhibit this type of behavior.

Joram

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#3

Post by Joram » Fri May 28, 2021 8:35 pm

Good idea to try different RAM, thanks.

Unfortunately, it didn't help. I put in a 1GB RAM stick that had come out of a different PC and the machine acted the same way as it had been, powering up but never POSTing and the case fan winding down after just a few seconds. Then I tried the same RAM stick in a different slot, and this time the computer didn't even start up. Moved the RAM back to the previous slot, and the machine still isn't starting (power switch LED doesn't light up and none of the fans spins). It's like I'm back at square one.

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StinkyImp

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#4

Post by StinkyImp » Sat May 29, 2021 3:19 pm

Joram wrote:
Fri May 28, 2021 8:35 pm
It's like I'm back at square one.
Back in the day when I was building and working on customer computers I would run into "hair pulling" scenarios like you're experiencing. What I'd do in these cases is actually go back to square one.

I'd put the mobo on an anti-static mat, plug in a power supply, keyboard, and monitor. Then turn it on. If the BIOS required a mouse, I'd plug one in. If it required RAM, I'd add it. Any "bare bones" items the BIOS required, I'd add.

My goal was to enter the BIOS. After that I'd add one peripheral (or item) at a time until it failed. That was usually the faulty component. In very rare cases it was more than one component.

The fact that both configurations exhibit the same behavior points to a "shared" component that's causing this. You can isolate it by going a single micro step at a time.

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#5

Post by Joram » Sat May 29, 2021 3:25 pm

Thanks, I'll give this a try.

Just to be sure I understand -- if everything else is disconnected, including the power switch on the PC case, I would then be turning this "skeleton" computer off an on by using the I/O switch on the PSU, is that right?

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StinkyImp

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#6

Post by StinkyImp » Sat May 29, 2021 3:36 pm

You can plug the power switch into the mobo. I used to have a jumper switch I could plug in to send the "turn on" signal.

Just to reiterate, if the BIOS requires something, add it. But only a single item at a time.

EDIT: Going back to "square one" means using the onboard (probably VGA) video port, not a separate video card because that could be the culprit.

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#7

Post by glorp » Sat May 29, 2021 4:37 pm

I'd also try a POST with all the SATA and USB devices disconnected.

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#8

Post by Joram » Sat May 29, 2021 6:21 pm

Thanks @StinkyImp and @glorp for the ideas.

Out of curiosity, I took the old motherboard and CPU and plugged the old PSU and a monitor to it (onboard VGA port), then I touched the mobo power-switch wires with the head of a screwdriver to simulate pressing the power button. For the first time in weeks, I heard beeps coming out: one short beep (about 1 second) followed by one long beep (about 4 seconds).

Unfortunately, I can't seem to find any place that gives the meaning of this exact sequence of beeps for the IPIBL-LB (Benicia) motherboard in an HP computer.

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d00zah

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#9

Post by d00zah » Sat May 29, 2021 7:09 pm

https://support.hp.com/us-en/document/c02222922

1 short beep and 1 long beep - Memory problem

Joram

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#10

Post by Joram » Sun May 30, 2021 3:15 am

d00zah wrote:
Sat May 29, 2021 7:09 pm
https://support.hp.com/us-en/document/c02222922

1 short beep and 1 long beep - Memory problem
Thanks, nice find!

OK, after seeing this I went back to the new mobo and tried every one of the PC's original three RAM sticks in each of the four memory slots. Never got to the POST stage, let alone beeping of any kind. Also tried spare RAM I'd taken out of a different PC during an upgrade, and it didn't make any difference: no POST, no beeps. (But I did notice that with a stick in one particular slot, pressing the power switch would fail to turn the PC off and I had to power it down with the PSU's switch. Then if I flipped that back on, the LED on the power switch would come on automatically, as if it had gotten stuck in the On position.)

After trying these things, I pulled the power-switch connector off the mobo and tried the screwdriver-tip technique. This is the one action that had managed to get the old mobo to show signs of life, with those two beeps. But in the "new" (pre-owned) mobo, doing this still gets the same result as before: no POST, no beeps.

The screwdriver exercise -- I hesitate to go any further with the old mobo because not only did it already put me in this pickle already, but I would have to put a CPU fan back on it, as without it I got a message on the screen saying that it was turning itself off due to the lack of a fan to protect the CPU. Still, that's the one time I've gotten anything on the screen from this PC in weeks.

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d00zah

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#11

Post by d00zah » Sun May 30, 2021 11:19 am

I don't see anywhere that you've tried a different power supply? Multiple voltages are required (12v, 5v, 3.3v, etc.), even to POST. If even one rail were to sag under load, you could be SOL. Just a thought.

Edit: Never mind... from 1st post "Replaced the power supply unit". Old eyes...

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StinkyImp

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#12

Post by StinkyImp » Sun May 30, 2021 3:13 pm

If this [https://i.imgur.com/rAPlvxF.jpg] is your motherboard, here's how I would start.

Items with red border:
  • Install CPU with fan
  • Plug in PSU to motherboard
  • Plug in ATX CPU
  • Plug in CPU fan
  • Please note that this initial configuration does not include RAM (or anything else).
Numbered items:
  1. USB keyboard
  2. Monitor
  3. Power switch. I would recommend removing the power switch from the case and plugging it in here. I would strongly recommend NOT using a screwdriver.
Your goal is to get into the BIOS or at least have the machine stay on long enough to give you some information on screen.

In this minimal configuration you only have a few things that will cause failure:
  • Motherboard
  • Processor
  • Power Supply
  • Keyboard (or onboard USB port)
  • Monitor (or onboard VGA port)
If it stays on, then it should indicate what's required to continue, like "NO MEMORY" or "NO MOUSE" or something else. Just deal with each issue as it crops up.

NOTE ON RAM - Not all RAM is created equal. Use only RAM that is compatible with your system.

Specifically for this motherboard:

Dual channel memory architecture (They need to be paired in the same colored slots)
Four 240-pin DDR2 DIMM sockets
Supported DIMM types:
PC2-5300 (667 MHz)
PC2-6400 (800 MHz)
Non-ECC memory only, unbuffered
Supports 2GB DDR2 DIMMs
Supports up to 8 GB on 64 bit PCs
Supports up to 4 GB* on 32 bit PCs

It's a holiday weekend so I probably won't visit these forums for the next few days. GOOD LUCK! ;)

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