[8525, TyTN, MDA Vario II, JasJam General] dtkenmo:
My findings...

..pretty much echo all those who point at the xilinx chip on the d-pad board. I've been battling with this problem for more than a year now on two different Hermes (both HERM200), both bought on eBay (one to swap parts from to debug the issue in the first).

Well got temporary relief with the foam fix but the problem returned. A post I read somewhere suggested the chip on the d-pad and so tried various fixes that put pressure on the chip, with greater success than I had previously but still the problem returned... and now it ws getting worse like so many others have experienced.

So I did an exhaustive net search & finally found a seller in Chine that stocked these d-pad boards at $20/pop so I ordered a couple... after a long wait they finally arrived. Now I had strongly emphasized to this seller that I wanted the proper Hermes style not the 8525 style which would no match my keypad. Guess what they sent me :rolleyes: Yep 8525 ones. I emailed them back but got no reply :mad:

So I ordered another one from a seller in Hong Kong on eBay @ $35. A day or so after I received that one, I get an email from the first folks wondering if I had received the package. What package? Well they had originally sent me the 8525 ones due to a picker's error when putting my order together previously and now had sent me out replacements :D

By this time I had my phone working already and so set aside the latest spares. It's still working some months later. :) But there's more...

A while after that decided to restore the other phone which needed both a screen & flex cable. When I got those, I quickly found out that those spares had the same white screen problem, as did both the leftovers from the two phones. Anyhow one of them was a little better than the rest and after carefully examining the d-pad & it's board came to the realization that the pivot point of the right screen button/OK button was right on top of that Xilinx chip :eek:

So I glued a little square chunk of an old credit card in the center of the chip and now I could restore the screen at will by going in & out of standby while pressing on the center of the button :)

But all that pressing was making the problem gradually worse until the only time I could ever see a proper screen was while pressing there... as soon as I released, within 10 sec the screen would go misty then white out completely. I grew to really appreciate bluetooth & voice dialing which allowed me operation w/o the screen.

BTW I had all the classic symptoms, non-working LEDs & keypad as well as the white screen.

As an electronic tech, I had access to some good equipment but was inexperienced with BGA chips... was going to try reballing the chip & reflow using a hot air tool, but was hesitant... besides I didn't have the flux liquid.

Then I happened upon a post by someone who had fixed their ailing video card in a toaster oven and they didn't use any flux. So there's a small proper reflow oven where I work and I took the worst of the d-pad boards in & put it through a relow cycle without using flux. Bought it home, put it in the phone and bingo... worked perfectly :cool: So did a second one... again success :D

I have come to the conclusion that the cause of the failure is not bad soldering as some have suggested but cracked solder connections due to repeated flexing because of some idiot designer's decision to use the chip as a pivot point. :rolleyes:

So I will do the remaining three boards after I get some flux as I don't really trust the connections without it. And I have the two 8525 boards as they didn't seem to want them back. Dono if they work or not... maybe I'll test them if I'm feeling ambitious sometime (hafta remove the d-pad for that).

Anyhow thanks to all the folks here that provided clues that sent me down the path to eventual success :cool: And from all of this I can now teardown, replace d-pad board & reassemble in 12 min. flat :D