Is the serial interface available at the test points on the PCB?

[suddgummi]

Hi,

I recently aquired a PW2 where the device hangs on the boot-up screen. Having read a bit here about serial console and the possibility to unbrick it I thought that I'd have a go. Unfortunately there seem to have been someone else trying the same thing as both RX and TX pads are ripped off the PCB in the P800 serial debug square.

My question is thus; do anyone know if the test pads on the back is connected to the serial interface or is it just as good to leave the PW2 to the recycling centre?

[knc1]

Originally Posted by suddgummi

Hi,

I recently aquired a PW2 where the device hangs on the boot-up screen. Having read a bit here about serial console and the possibility to unbrick it I thought that I'd have a go. Unfortunately there seem to have been someone else trying the same thing as both RX and TX pads are ripped off the PCB in the P800 serial debug square.

My question is thus; do anyone know if the test pads on the back is connected to the serial interface or is it just as good to leave the PW2 to the recycling centre?

We have had other people here that needed the same sort of fix-up job on the pads.
There hasn't been any really-good method posted (yet).
It is hard enough to make the connections when the pad(s) are still there.

That sounds like the device is trying to recover a corrupted file system.
On the flash device used in the Kindles, that can take a long time.

So -
hook to wall charger -
re-boot -
wait -
And I do mean wait, like in days -
I have had some (earlier) models that took a week to ten days to recover.

PS: Ignore the little led light -
It is under firmware control and your firmware is not fully functional while recovering the file systems.

[suddgummi]

Originally Posted by knc1

So -
hook to wall charger -
re-boot -
wait -
And I do mean wait, like in days -
I have had some (earlier) models that took a week to ten days to recover.

Hi knc1
So it might be that it is doing its thing then. Thanks I'll hook it up to a charger and leave it for a fortnight or so and see if there's any response from it.

[geekmaster]

Originally Posted by suddgummi

Hi,

I recently aquired a PW2 where the device hangs on the boot-up screen. Having read a bit here about serial console and the possibility to unbrick it I thought that I'd have a go. Unfortunately there seem to have been someone else trying the same thing as both RX and TX pads are ripped off the PCB in the P800 serial debug square.

My question is thus; do anyone know if the test pads on the back is connected to the serial interface or is it just as good to leave the PW2 to the recycling centre?

I have my PW2 apart. I just examined it. The TTL serial pads have surface traces (hidden under the green solder mask) that run under the edge of the nearby metal can (RF shield). They are probably available to solder to under that shield. You could either find something like a resistor that they attach to (earlier kindles had series resistors on the TTL serial connections). Or you could carefully scrape off some solder mask (green paint) to expose a short segment of the copper traces (serial TxD and RxD) and solder tiny wires to those. I salvaged my tiny wires for my K4 with ripped off serial pads from the coil inside a dead CFL (compact fluorescent lamp). Tape down those soldered wires, fold them over the tape, and tape again. Then solder flexible (multi-strand) wires to those. And tape over the connections so they are held down (and apart) on the other tape. This makes it all insulated and physically secure. That is what I did anyway.

So yes, it looks like the PW2 can be salvaged like I did with my K4 (when TTL serial was the only known way to debrick it), before we discovered the "magic keys" and USB downloader mode (on the kindles with that feature).

[suddgummi]

Originally Posted by geekmaster

I have my PW2 apart. I just examined it. The TTL serial pads have surface traces (hidden under the green solder mask) that run under the edge of the nearby metal can (RF shield). They are probably available to solder to under than shield. You could either find something like a resistor that they attach to (earlier kindles had series resistors on the TTL serial connections). Or you could carefully scrape off some solder mask (green paint) to expose a short segment of the copper traces (serial TxD and RxD) and solder tiny wires to those. I salvaged my tiny wires for my K4 with ripped off serial pads from the coil inside a dead CFL (compact fluorescent lamp). Tape down those soldered wires, fold them over the tape, and tape again. Then solder flexible (multi-strand) wires to those. And tape over the connections so they are held down (and apart) on the other tape. This makes it all insulated and physically secure. That is what I did anyway.

So yes, it looks like the PW2 can be salvaged like I did with my K4 (when TTL serial was the only known way to debrick it), before we discovered the "magic keys" and USB downloader mode (on the kindles with that feature).

Thanks for the info geekmaster. I'll see if I can see the traces somewhere. Might have to invest in a better magnifying glass first

The RF shield is just attached on the solder pads you think? If I can't see the traces I mean.

[knc1]

Use a very strong light - the green solder mask is translucent.
and/or
Take a high-res digital photo - then examine that photo with a graphics program.

[geekmaster]

The solder mask also has some 3D depth -- it is raised where there is copper under it. You can shine a surface light (no need to be bright) at an oblique angle to see the edges of traces, even when covered in conformal coating. My ceiling light was adequate for this purpose, for me (on the PW2). Though a bright light helps see traces a layer down into a mult-layer PCB, and shining the light THROUGH a board from the backside helps follow some traces too (as long as ground and power planes do not block the light). I seem to recall that you talked about this in a post somewhere, knc1.

But for the serial traces on a PW2, plaining visible right there on the surface, snaking under a metal RF shield. With skill, they could be soldered to without removing that shield, if not peeled off along with the pads.

And yes, you can do gamma adjustments to a photo to bring stuff out of the shadows. RAW photos allow much more adjustment than JPEG does, so set your camera to save RAW images if it can (or hack it with "Magic Lantern" or CHDK to add that feature). Yes, I have run a "hello world" on my EOS-550D camera, which now has tinyCC in its firmware image. It even has a built-in fisheye dewarping app, now...