Via eyelets Pi zero and LCD soldering

[Duhjoker]

I want to lower the profile of my LCD screen to my Pi zero when it comes so last night I managed to remove the Female header pin on my 4inch LCD. Very slowly and carefully but I still ripped one out. Unfortunately it was a ground according to the gpio. 10th pin upper row.

I noticed also that there are 3 other ground pins in that section used by the LCD. Is there some way to turn off that pin and reroute it to another pin?

Can I do without that pin?

Here's a pic showing the damaged eyelet.....................

See pics on later posts

The other eyes I removed the pin using a soldering iron so the inner sleeves are fine. I used a small heated safety pin to open the other eyelet up. So the other eyelets should be fine.

Any body have any oppinions?

[Goraxium]

I've done that before... The only thing I can suggest is checking the other side of the board. If you haven't torn that side off with it, all you need to do is solder a small wire onto that side and link it to one of the other pins. Beyond that, the next option would be whatever that track leads to on the other side (assuming it goes anywhere). It's a little crude, but it works.

[Duhjoker]

Here's the other side.......................

See pics on later posts

Couldn't I fill the hole with solder then open it back up using my heated safety Pin?

No of any one that offers the soldering service?

[gregeric]

If it's one of four ground pin connections that you've lost it may not matter, I would expect them all to be connected together on the LCD, the other three will do the job.

[Goraxium]

Couldn't I fill the hole with solder then open it back up using my heated safety Pin?

From my experience: no. The solder won't stick to the board once there's hot metal around. All you need to do is make sure that that pin is eventually connected to one of the others. Depending on which side you put a new header / wires on, it will determine which side you run a small wire across. My advice: don't stress about it. Mark which pin it is, and the others it should be linked to, solder in the new header / wires, and solder in the wire as suggested. Think of it less like a mistake, and just another part of the build process.

[BMS Doug]

If it's one of four ground pin connections that you've lost it may not matter, I would expect them all to be connected together on the LCD, the other three will do the job.

I completely agree, Solder it up with all the other pins and see if it works (it almost certainly will).

[Duhjoker]

So i assumed since there are so many pics with the zero with pins already soldered or the pins off to the side that it would at least have the header in the bag.

Any way would y'all happen to know what size and type header pins i need to fit the Zero?

[fruitoftheloom]

So i assumed since there are so many pics with the zero with pins already soldered or the pins off to the side that it would at least have the header in the bag.

Any way would y'all happen to know what size and type header pins i need to fit the Zero?

https://shop.pimoroni.com/collections/r ... ero/header

[Duhjoker]

Does any one know the exact size of the eyelets?

Would the outer diameter be 2.57mm by chance.

[Goraxium]

Does any one know the exact size of the eyelets?

Would the outer diameter be 2.57mm by chance.

They're not that big. That's roughly the same size of the holes that the Pis mounting holes are. They're closer to 1mm (if that).

[Duhjoker]

What about these?

https://www.ebay.com/ulk/itm/321982271499

[Goraxium]

What about these?

https://www.ebay.com/ulk/itm/321982271499

Interesting little things... I assume you'd need a special tool (large machine capable of holding PCBs) to fold the ends of those out to actually meet the other side of the board... Unless you had a decent area to solder the whole thing to, but even then, you'd still have issues with it slipping through when it heated up (unless you had the cap on the top all the time).

You're overthinking it though. Stick with the simple idea of soldering the wire across. If you get a low gauge wire, it won't sit much further off the board than the blobs of solder. I kinda wish I took photos of the stuff I've done in the past to show you how simple it is... A quick Google search resulted in these:
http://www.planetz.com/satchurator-volume-mod/
^^ Note the blue wire in step 5 under "First let’s prepare the PCB".
http://www.sparqtron.com/core-services/ ... -reballing
^^ Check out the blue wires in the pictures on those pages.

If you're going to use a header, it will be held in place with other pins, so the one pin you're trying to jumper won't cause you any problems. If you're using a wire replacement for the header, solder it onto the good side first to hold it in place. Once either one is in place, solder a jumper wire across the back, to another ground track (if that's what they are).

[Duhjoker]

I would actually like to solder the two together using the male pin row.

The hardest part of putting in new vias seems to doing the flange. From the directions ive read and watched, you drill a hole through each old via then add the new one and flange it.

I found some vias with heads that are 1.6 D with inner D of .8mm and an outer of 1.0mm. Looks right when i measure using a magnafying glass to see the actual size.

I dont mind doing the wire at all, i was just thinking it might be better to replace each one. Plus i had to open the holes a lil more and might have lost some inside plates.

[gregeric]

Repairing that ground via is totally unnecessary. Slide the board onto the Zero's male header, then solder only those pins which are required (makes it far easier to remove). You'll only need to solder one of the four three grounds that are available.

Edit: Actually, looking at you photographs, it's not ground as you have identified, it's SPI0_MOSI. I'd repair it by scratching away the solder mask on the thin trace it connects to, some 5-10mm away from the via. Solder a thin strand of un-insulated wire to it, then poke it through the via. Mount the LCD on the male header, and solder only require pins. Because you connected some 5-10mm away from the via, it will get hot enough to unsolder when you make the connection to the male header.

[Duhjoker]

Heres what i have on the solder side after opening up the holes to where they will accept pins.

Think its got enough to make connections........

See pics on later posts

[Duhjoker]

What if i took a piece of copper wire the same size of the hole in there so its touching all the layers, then clip it down where its flush and solder it from there?

[gregeric]

I expect there will only be two layers, top & bottom. The important thing is to re-connect that track. It's difficult to tell from your photos, the bottom side is obviously completely gone, but I can't see whether on the upper the track is still connected with remnants of the pad. If there is some pad/track connectivity left on the bottom then you may bet away with a good hot iron & relying on gravity /wicking to have the solder flow down the male pin onto what's left below. It'd be a gamble. To be sure, solder a thin strand wire to what's left of the track/pad connection, poke it through the hole, slide the LCD board onto the PI's header, then before soldering wrap the strand a few times round the pin to provide mechanical anchorage & stop the wire moving off the track/pad remnant during the soldering process.

[Duhjoker]

Repairing that ground via is totally unnecessary. Slide the board onto the Zero's male header, then solder only those pins which are required (makes it far easier to remove). You'll only need to solder one of the four three grounds that are available.

Edit: Actually, looking at you photographs, it's not ground as you have identified, it's SPI0_MOSI. I'd repair it by scratching away the solder mask on the thin trace it connects to, some 5-10mm away from the via. Solder a thin strand of un-insulated wire to it, then poke it through the via. Mount the LCD on the male header, and solder only require pins. Because you connected some 5-10mm away from the via, it will get hot enough to unsolder when you make the connection to the male header.

Is there any way you could show me what you mean about the trace and soldering a wire too it.

Can you see the trace that needs to wire? Do you need more pics?

[Duhjoker]

Ok ive been looking at this board all day through magnafying glasses and from what i can tell there seems to be a glint of metal.

Im also seeing no visible traces on the top or bottom surface.

The trace near the via here is for power on the solder side.




On the flip side here there doesnt seem to be a visible trace for it either.




So im thinking its trace is sandwhiched in the inner layers.

If im seeing this wrong please tell me.

[gregeric]

Hi - I misidentified the pad in question in my last message as MOSI, I was looking at the pin at the other end of that row with the track showing exposed copper - is that pad OK?

The pad you have now clearly identified with arrows is GPIO4. It is almost certain that your board is 2-layer, and that this pin is unused.

If all other pads look good, go ahead & mount it, soldering only the required pins to make removal easier should you need to.

It may be worth testing the board without soldering to re-assure you. Slide the board over the header, then tilt it to attempt to make better contact with the pins. Wedge it firmly like that if you can. It's not guaranteed to make contact with all required pins, but if you see it working you know you are good to go ahead & mount permanently.

[Duhjoker]

looks like i was worried about nothing on that pin i pointed too. Lol.

I looked at this link.....

http://www.waveshare.com/4inch-rpi-lcd-a.htm

Under interface and its not used.

The via you mention on the opposite side has metal inside and out from what i can tell.

The others that might need help, i can scatch a lil of the mask away to the trace its connected to and stretch the solder to cover it.

[Duhjoker]

Ok i made this diagram to help me with pin placement......

1--3.3v----------------5v-----------2
3--NC-----------------5v-----------4
5--NC-----------------GND--------6
7--NC-----------------NC----------8
9--GND---------------NC---------10
11--TP_IRQ------------NC---------12
13--NC-----------------GND-------14
15--NC-----------------NC---------16
17--5v--------------LCD_RS--------18
19--LCD_SI-TP_SI------GND------20
21--TP_SO------------RST----------22
22--LCD_SCK/TP_SCK--LCD-CS-24
23--GND-------------TP_CS-------26


My question now is.....does it really need two 3.3v ports and two 5v ports to operate? And all the grounds?

[gregeric]

Hi - you've mislabelled the second 3V3 as 5V in your diagram. You'll only need connect 1 each of 3V3, 5V & GND. You can see there's a trace linking the two 3V3's on your board. Same with 5V.

Solder up & away you go.

[mosespi]

Sorry I don't have more to add then has already been said to help with your current situation.. but I will say that most of those pads look pretty bad. I don't know if it's from the picture itself, but some of the holes don't appear to have pads anymore and what pads are left are distorted.

If its not from the picture and it actually looks like that.. you may want to practice desoldering on some old boards. Whatever you use, braid, desoldering pump or other rework tools, you need a good 'solder eye' and have to learn when to start pulling parts off the board to avoid tearing it apart.

Regards,
-Moses

[Duhjoker]

My solder pump came today so i decided to steal some header pins from some old boards.

I ended up soldering both of the 5v ins and 3.3v ins and two grounds. The number 2 pin + was loose. The others feel tight.

Ive put the Zero board over the pins with out soldering and the back light comes on but thats it.