gascort spiffed autopsy report

[dcb]

**pic host undergoing maintenance, pictures should be back soon**
This is the first time I got to see a kit up close, so let me document what is going on here. Hope gascort doesn't mind as it seems a few folks might be in a similar situation.

1. The patient arrives, LCD removed:

I jimmy the LCD on and power it up, serial works, lcd is top line of blocks like wingmn is currently experiencing.

2. Notice that the paint is scraped off the lcd tab where the lcd is touching CPU pin 27 (A4, middle button)


3. the paint is scraped off where the lcd is touching CPU pin 16 (D10, unused)


4. The USB shield is located in physical contact with the signal pins from two buttons and is wrapped in a single layer of tape to insulate it.


5. It appears the through hole plating was pulled out during the LCD removal procedure on a few pins. The pin should be solder colored after the operation instead of copper (more heat less force? less heat more force?)


6. Confirmation of #5, no conductivity from one side to the other on several LCD pads, and the interesting lcd traces are on the non solder side.


7. Usb shield not soldered down, don't want it to move around especially if its insulation is rubbing against pins.


8. A number of solders (like this power pin) were concave and a couple had a frosted appearance.


Prescription:

A. remelt the solder joints (just touch them with the iron a second time) and build up any concave joints. This is the most likely cause of the resets IMHO.

B. Shim and glue a small piece of milkjug plastic between the usb shield and solder tack down the shield.

C. Remove the black spacer from the lcd pins, then they can individually be re-heated and pushed in so the the extra length can be used to move the lcd farther away from the board (for insulation) and the pin can be soldered on both sides to compensate for missing through hole plating.

D. cut an lcd sized rectangle out of a milkjug (or cardboard or whatever) and glue it so there is a tough physical insulating layer between the sticking out lcd tabs and the cpu pins. Solder LCD back in place on both sides of the lcd pins.

E. Make an adapter from the phone plug style to the header pin style in my cars, plug it in and drive it around and try and break it.

[Wingmn]

Nice work dcb - I didn't realize that in the v2 kits we could put the usb and the rj11 jacks on opposite sides of the board...

I guess the board is the same? Except it's the user's choice where to put the jacks now? I did not look at the assembly for both v1 and v2, that would probably answer my question.

I'm looking forward to seeing what you find out - I did order a new LCD yesterday - the blue background w/ white letters - I'm not going to put it on until I get the green one working though.

I'll be following this thread closely

[dcb]

At A. here the LCD pins have been extended/straightened/had displaced plating removed (delicate procedure) and the LCD soldered on both sides since the through hole plating was displaced in several locations. Unused pins were simply removed.

At B. A piece of plastic was cut to cover as much of the lcd backing as practical (touches the pins) and tack glued into place to guarantee no shorting of cpu pins to ground or other random events.

At C. More of the plastic was used to insulate the USB shield from the button pins and the shield soldered into place.






Initial hookup looks promising, time for a road test

[Wingmn]

Nice! I have hope! Is that all you've done so far? Did you re touch some of the solder you identified as concave? Or did you just do what you described above?

[dcb]

I re touched the solder joints as well, as that seemed like the most likely candidate for the resets (all the shorts were to buttons and/or unused pins). It only takes a minute with the LCD off, but removing the LCD can be a "traumatizing" experience. Too many pins, takes practice with distributing the heat and pressure.

Just did 10 miles of errands with no issues to report (did some EOC and button pressing).

[wyatt]

Originally Posted by dcb

I re touched the solder joints as well... It only takes a minute with the LCD off, but removing the LCD can be a "traumatizing" experience.

When buying the kit, for an extra $0.90 you can get two 8 pin female headers that can be used to attach the LCD to the board. It would make the kit a lot more thick (probably as thick as the LCD or the board), but it would insulate the pins and make removing the LCD a snap.
If you want the headers to butt up to each other you have to sand the edges of both until they fit, but since the center pins aren't used anyhow, you could just leave a space in the center.

[Wingmn]

dcb - Looking at your re assembly pics gives me the idea to do the same tonight. The last time I resoldered everything my LCD was REALLY close to the main board.. It didn't look like anything was touching, but who knows.

How exactly did you remove the plastic from the header? an exacto knife?

Also - the pins that aren't used are 7 thru 10 on the header correct?

I noticed one of your older pictures of the home-built MPGuino and those pads/pins were not there because you guys soldered wires to every connection..

So - tonight I will attempt a repair.

[dcb]

I wound up cutting off the spacer with a knife (don't cut the board) by sliding it along the pins. But if I had cleaned off the pins first, I could have lifted it off. I cleaned the pins by wiping/flicking the chunks off with a hot iron, sweeping it towards the tip and onto the floor.

Moving the pins individually solves the problem of keeping 16 pins "hot", but requires some dexterity to keep the pins straight enough (still had to do some extra straightening).

The middle 4 aren't needed, 6 on each end are used. That would be 7-10.

The extra distance helped with soldering on the backside.

Don't forget to add the layer of plastic behind the lcd and under the usb shield, that looks like a design defect that needs special attention. And definately triple check all your solder joints before putting the lcd on. There should be no frosty looking joints or concave joints, keep everything very still while the solder is cooling.

[Wingmn]

Well - Here's my verdict.

I de soldered - re touched every solder connection that might have been considered grey - made a plastic backing for my LCD - resoldered everything because I thought maybe it was just the contact between boards -

And it still had blocks.............

So - I desoldered again. Pushed all the pins down - removed/cut pins 7-10 off. Did not get the plastic off (I was to anxious to see if the new stuff worked). I cleaned up the remaining pins.

I recieved my NEW LCD today - blue background/white letters - made another plastic backing - soldered it into place - a bit more space between boards this time...

Plugged it into my car - and It WORKED!! HOT DOG!

It came up with Ver .74 - so I know I was re flashing the sketch correctly all those times. Mine shipped with ver .73 when I initially powered it up.

So, Either pushed the pins and cleaning them up solved the problem / or my LCD was toast... Considering all the times I've soldered and desoldered that LCD who knows..

Thanks gascort for sending your MPguino to dcb - thanks dcb for giving me 1 more thing to try before I stomped on my MPGuino

Hey - dcb - if you want I'll mail you my LCD if you are curious. I'm done soldering for a while.

[gascort]

Wow, thanks DCB!
Yeah, I screwed up the LCD connections badly when I gave up on trying to remove it the "right" way.
Thanks for the tips on the soldering/insulation! I definitely should have gotten the clips to attach or remove the LCD easily!
Still no problems after Dr. Dcb's prescription?