09-28-2017 08:13 PM
My Pavilion 21 AIO sometime wont boot: After pressing power button, the power light is on, and the power connector light (on the back) is on.
But the hard drive light is off (looks like hard disk is not working).
The screen is black and show nothing.
I may disconnect the power cord and connect it again, press the power button, try this several times, but it just wont boot.
After 2 or 3 days (and sometimes just a few hours), it will boot normally. But will show wrong date-time. It is not the date-time when I turned off the PC. For example, I turned off my PC last night at 11:00 p.m. This morning it could not boot at 8:00 a.m. But it did boot normally at 10:30 a.m., and the system time was 6:00 a.m. (it looks like the system clock stopped at 6:00 a.m.).
I took this PC to repair shop several times. But it did boot normally when the technician was checking it. So they don't know what the problem is and did nothing.
The only time this PC did not boot in the repair shop, I left it for a few days. Then the technician called me and told me the PC was Ok now. I asked him what he did. He said he just took out the memory, cleaned it, and installed it again.
I brought back my PC, and it did boot and worked for several hours that day. But the very next morning, it could not boot.
I have tried some solutions with no result:
- Changed the CMOS battery.
- Turned off fast startup.
- Performed hardware diagnostic (pressing F2 when PC starting). It passed every test with no issue.
- A technician said he took out, cleaned and installed again the memory.
Thanks in advance it anyone can help!
09-28-2017 08:24 PM
> I have tried some solutions with no result:
- Changed the CMOS battery.
A loss of date/time information usually is fixed by a replacement of the CMOS battery.
It's possible that you installed a "dud" of a battery.
Do you have a electrician friend (or hobbyist) with a "multimeter", to measure both the Voltage and the Amperage of both the original battery and your replacement battery, and to compare with a brand-new battery?
But, a complete failure to "power-on" can be caused by an intermittent "open-circuit" on the motherboard.
It's possible that when the motherboard is "cold", it works fine.
But, as it warms up, that circuit opens.
Also, "flexing" the motherboard, when removing/reinserting the RAM, could have created/closed that "open-circuit".
Lots to think about.
09-28-2017 09:00 PM
Thank you for your ideas!
I installed a new battery with exactly the same specifications. And the technician who cleaned the RAM said he checked the battery too.
I think my PC worked well when it is warm. In fact, I use it all day long. It never failed when working.
However, it has problem when I try to power on in the morning (when it is cold).
09-29-2017 01:42 AM
> my PC worked well when it is warm.
> it has problem when I try to power on in the morning (when it is cold).
This also points to an "intermittent" circuit on the motherboard.
When the computer is cold, the connection is "open", when it should be "closed".
As the CPU warms-up, and the disk-drive warms up, the generated heat causes the connection to "close", as it should be, and then your computer works fine.
09-29-2017 08:26 AM
"When the computer is cold, the connection is "open", when it should be "closed".
As the CPU warms-up, and the disk-drive warms up, the generated heat causes the connection to "close", as it should be, and then your computer works fine."
If this is the cause,how can I fix it?
09-29-2017 09:39 AM
> If this is the cause, how can I fix it?
Finding a non-retired "board-level" electronics technician who can trouble-shoot all the circuits on the motherboard is nearly impossible, and, despite his/her efforts, it might not be repairable, and it will be expensive.
If that is the casuse, then the only practical solution is to replace the motherboard, or to replace the whole computer, thus avoiding paying the above technician.
HP's warehouse will have a replacement motherboard, but it will be very expensive to purchase it -- over 50% of the original purchase price for the whole system. It costs HP for the physical space, and for the warehouse staff, but part of the cost is "what the market will bear" --- "if you really need exactly this part, we have it for $ale".
It might be possible to "part-out" the AIO, for the residual value of the screen, the CD/DVD drive, the RAM, and the wireless networking card, to recoup part of your original investment.