Dumpster Dive - HP Envy Touch PC Repair

[EEVblog]

Troubleshooting and attempted repair of a HP Envy touch PC found in the dumpster.

[woox2k]

Try to take out external graphics card. It might be dead and very often the internal one will not even turn on if external one is present.

[NiHaoMike]

Put in a USB stick with Knoppix on it and see if it asks for a DHCP lease.

[hayatepilot]

People in the youtube comments already pointed out that it's likely caused by a corrupted BIOS.
You need to reflash the BIOS chip with a PIC/IC/EEPROM programmer.

https://h30434.www3.hp.com/t5/Desktop-Video-Display-and-Touch/HP-Envy-23-touchsmart-won-t-boot/td-p/5218493/page/2

And

https://youtu.be/fnbVVwMbZCA

[poot36]

And I have found if it is not the bios then the memory controller traces are going bad on some models so try it with the smallest single memory stick you can find.  If you pull all the ram the power light should flash orange if I remember correctly.

[M4trix]

@Dave,

you made a fundamental mistake... you turned it on before taking it apart !   

[JustMeHere]

The fact the fan never changes speed is a good indicator UEFI or BIOS is not loading.   Most computers slowdown their fans fairly early in the boot process.

[EEVblog]

People in the youtube comments already pointed out that it's likely caused by a corrupted BIOS.
You need to reflash the BIOS chip with a PIC/IC/EEPROM programmer.

Yes, likely, as it's not the RAM or graphics card.

[Electro Detective]

If it has a hidden or obvious Bios backup battery/coin cell, keep reading...   

Put all the components back where they were,

check the DVD drive is empty,

plug in a spinning hard drive not SSD,   

attach a USB keyboard and mouse in the USB 2 slots only, don't use the blue ones

pull out the Bios backup battery/coin cell

wait a few minutes or longer

Start up the HP without the battery and see what happens 



If nothing happens, pull out both ram sticks and alternate one at a time in the ram slots and cold boot PC every time

Keep the battery out during this possible futile time waste and check it for 3 volts using Low-Z on the meter 


You may get lucky as I have a few times with zapped AIO PCs   

[tecni]

Hello I have an equal problem with a hp touchsmart 320 the machine had burned 2 mosfet to change it now turn on,  sound of start windows but no video signal by any side I measured it with the oscilloscope and there is no signal in the uma_lvds in the uma_dvi does not even give video with a usb to vga converter that always helps me in these situations I leave photos of the mainboard
Do not know where to get the schematic of this mainboard the number is AAHD3-NK
sorry for the bad English I speak Spanish

[M6YRU]

here is some things to think about Dave, 1st, the center pin is usually a comms pin to the psu,,, in dell laptop they use it to tell what type of charger, without the comms it will power but not charge...
you might have a 1.8 or 3v sense line going back from the BL board to confirm its on...
the PC buzzer might be via the soundcard, plug some speakers in and see if you hear anything?
have you got an old usb diag device that shows what commands going around the bus as its booting.
it could be a courpt bios?

[luc_vienna]

I know this is old, but if someone is interested i had the same problem with a very similar HP envy.. all in one.
You have probably thrown it away since, if not try this:
Remove the RAM (i had a 4gig brick in it originally)
Replace it with a 2 GIG brick..
That allowed me to start it again. I had kept the old harddisk with win 8.1 on it.. this allowed me to flash the bios with the latest hp version (wont work under win10)
that repaired the bios and it was booting again.. it now works with win10 and 16 gigs of ram..
Some how some windows 10 otional update corrupted the bios. and it would not even beep.
Dont ask me why (some other users had that solution) using a 2 gig brick alone would let it boot again... and so i could update the bios.
I posted that solution on the hp forums.
https://h30434.www3.hp.com/t5/Desktop-Boot-and-Lockup/Envy-23-touchsmart-All-in-one-cannot-boot-Black-Screen/td-p/8135233

But i fear you have probably thrown that thing away... 

Take care
Luc