Screen stopped working (need to buy a 223F capacitor)

[asimov-solensan]

Hello everybody,

I started a video the other day and the screen just died. No PTOD, no change while tilting the screen, and no answer even doing a hard reboot.

I remember that almost the same happened a long ago when the screen closed abruptly and the hit took the capacitor 223F out of place.

I soldered the component again as well as I could and worked ok since then.

So I thought that it was the same problem again. I opened my pandora but the capacitor was still in place, I reseated the LCD cable from the PCB and from the screen board and still no answer (I'm pretty sure it's not a problem with the LCD). Then I tried to desolder the capacitor to put in place again, but while handling it with small clamps it broke leaving the contacts still soldered in the board.

I can easily take out all the soldering iron alongside the contacts and put again a new capacitor, the board is not damaged.

Now I don't know where to get this capacitor and don't see it in the dragonbox shop. I will ask at a couple of electronic shops but I think they don't sell smd components.

Besides this I want to ask if there is any other known problem that makes a screen die this way. Because as told, the capacitor was still at his place when I opened the console.

Regards.

 

[TrashyMG]

I heard of one of the coils going out of place and screwing up the LCD, but never a capacitor.

Well you will most likely need to buy another one from a major parts seller like Digi-key, Newark or Mouser.

The Pandora design has been open sourced, there is a BOM (Build of Materials) in the zip file you can download here: https://pyra-handheld.com/boards/resources/pandora-pcb-open-files.4550/

That BOM should have the exact part number of any component on the Pandora.

Edit: Actually if what you broke is L4, a bit back from the right shoulder button, then that IS a coil not a capacitor. 223 indicates 22uH, the F indicated +/-1% tolerance for a coil. It's handy to have the ED signed Pandora PCB around...

 

[EvilDragon]

Yep, that's most probably it.
To make sure, hold the display into a good light source. You should see a fainted picture, as that coil is only for the backlight.

 

[levi]

If that coil goes the screen itself doesn't die, just the backlight. If you can still see something if you take it outside or shine a torch on it, it might be that, if not something else has happened.

Edit: Ninja'ed by ED!

 

[asimov-solensan]

You are right it was a coil not a capacitor. Now I see why was unable to find a replacement on the web.

Checked I'm able to see something in the screen, and indeed there is a very dark image, I can see even how the menu opens when pressing pandora key.

Knowing the the problem is just the coil is good news, I was afraid that something else was broken.

Thanks a lot.

 

[asimov-solensan]

I might need some help here. Can't find any place to buy them in units and the only place in my town will just get me pieces from the provider farnell.com

Is there any compatible coil from that provider? How is it called the encapsulation (physical format) used in pandora?

If anyone knows a shop that ships to spain let me know please.

 

[levi]

The Pandora's components are all surface mount (aka SMD). But there's no reason you need to make a repair using the same type of part, as long as it's compatible - I've replaced plenty of leaked SMD capacitors with radial submini types just fine. Where that particular inductor is on the board I reckon you've the space to be creative with the packaging myself.

Looking at the schematics, I concur with Trashy - it's a 22uH part bridging the IN and SW pins of the TPS61161 (a TI backlight driver). I don't know of the top of my head how much current is passing through it, but it you can guestimate that then that and the number of Henries define all the qualities of the part you really need to meet.

I can't help you with spanish shops unfortunately. But given farnell puts a premium of some 15GBP on orders, it's probably cheaper just to suck it up and order locally, if you can find anywhere decent.

Looking up the BOM file from Trashy's excellent tip, it seems it is quite a beefy power inductor, but a part that can handle 700mA or so should do you fine.

 

[asimov-solensan]

I don't feel comfortable using a non official parts. But the pandora is dead anyway it won't get worse than this.

Followed your advise levi and found this piece that seems to fit all values and is physically similar but I would like to have a second opinion before ordering. Can anyone see any critical difference between this coil: LQH44PN220MP0

http://www.farnell.com/datasheets/490895.pdf?_ga=1.20934587.2026260095.1482258337

And the one used in Pandora?

http://datasheet.octopart.com/LPS4018-222MLC-Coilcraft-datasheet-14354302.pdf

Thanks a lot.

EDIT
Great, I found almost exactly the same coil in the page. It's numbered as: LSP4018-223MR

Instead of LSP4018-223ML

Now the R makes reference to:
RoHS compliant matte tin over
nickel over silver.

While L means:
RoHS compliant silver-palladium-
platinum-glass frit.

I can see that talks about building materials but can't see any difference in the datasheet.

 

[asimov-solensan]

Just wanted to update the thread. Installed the new coil and my Pandora is working again.

By the way farnell.com is a great page to find replacements. I bought 5 coils and with taxes and shipment I payed 16€.

Thanks everybody for the help. This kind of things is why I love the project and invested in a Pyra.