HELP: USB jack torn off

[dunbarton]

I'm on Day 3 with the Crazyflie and enjoying it a lot. I've charged it probably 10-20 times via USB; the jack was always a VERY tight fit with the cable, so I've always been careful with it when inserting/removing the cable. But even so, this time the USB jack tore off the board.

I'm slightly confused as to how the jack is attached mechanically and electrically, not having worked much with surface-mount components. As far as I can tell, it was attached mechanically by four "feet" (tabs extending outward from the bottom surface of the jack) soldered to pads on the board; these pads appear to have torn off with the jack. The electrical connection is presumably through the four tiny conductors at the end of the jack, which appear to connect to four corresponding tiny conductors on the board -- but apparently they're held in electrical contact solely by pressure. Is that right?

If I'm right about the solder pads for the mechanical connection being torn off, do I have any hope of supergluing or otherwise reattaching the jack precisely enough to restore the tenuous electrical contact of the four tiny conductors? Can you suggest any other means of repairing?

[marcus]

Hi,

Yes, it's only surface mounted so the four big pads are used for mechanical purposes (make the connector steady) but are not connected to anything. Four of the five traces on the back are connected. It's power, ground and two data lines. Currently the data lines aren't being used for anything (still no firmware for communicating via USB) and the power and ground are used for charging. Are the pads still on the PCB or are they thorn off? Could you post an image of it? As long as the five traces on the back are connected you can glue to connector to the board instead if the bigger pads have broken off.

If you cannot reconnect the USB connector you can still charge the Crazyflie using the P8 pads.

Have a look at the schematics and component placements here.

/Marcus

[dunbarton]

Hi Marcus:

Thanks for the quick reply. Attached are photos of the torn-off USB jack (pads facing up) and the mounting location on the CF board. It definitely looks to me like the solder pads have torn off with the jack; the color is off, but in case the board photo isn't clear, the four surfaces where the jack should attach to the board are a dull non-metallic brown, while the other surfaces are shiny metallic silver. Do you still think some kind of glue might reattach the jack strongly enough?

CF_USB_jack_b.jpg (110.84 KiB) Viewed 11784 times

CF_Board_USB_pads_02_b.jpg (163.79 KiB) Viewed 11784 times

I looked through the schematics. I may try your suggestion to use the P8 pads for charging. Question: a 2x1 piece of the 2x5 header included in the kit would fit those pads, right?

On the other hand, traces #1 and #5 of the USB mount are 2.6mm or just about 0.1" apart, so I may try soldering a 2x1 piece of 0.1" female header onto them and charge that way. Question: there are two large square pads between the edge of the board and the five USB traces (they're normally covered by the USB jack; directly under R13 and R14 on the top side). Could I use them as solder pads to help anchor the header, or are they in fact electrically connected to something?

(Still, not happy that the USB data connections are now lost...)

Any other suggestions? All help much appreciated,

dunbarton

[jamisnemo]

Thanks for the pictures! I'm totally getting out the hot glue gun and slopin' some on my jack! :porngroove:

It looks like the physical mounting pads have indeed been pulled off the board. However, the actual USB connections look like they may have been cold solder joints in the first place. They look okay. Maybe some extra solder but the pads are still there.

How good are you with a soldering iron? Have you done SMD soldering before? You might be able to just reattach the usb jack using those 5 tiny pins... And then use a bunch of hot glue as the actual physical connection.

Be careful with those pads though... and maybe you can solder everything up with a usb cable in the jack itself so you can do a quick connectivity test before you put hot glue on the thing...

Also, I haven't tried putting hot glue on the jack yet. I don't know how much it will affect trim... so take all of this with a grain of salt.

[dunbarton]

Jamisnemo: Interesting idea. I had assumed, since the five tiny traces on the board looked so shiny and undisturbed, that there never was any solder on them and that the pins on the jack were just being held against them by pressure from the mechanical connection. Can you state authoritatively that the pins are normally soldered to those traces in these Micro-B situations?

(By the way, since the accident I've been charging the thing by clamping the torn-out jack against those traces, so I can vouch for the fact that the electrical connection can be maintained by pressure alone if the jack's in the right position.)

I've never soldered surface-mount, but I've got a Hakko and a pointy tip, so I think I could manage with a few hours and some cursing. I don't think a glob of hot glue would affect the trim much, because losing the jack itself doesn't seem to have affected it. But there is the matter of extra weight... Still, knowing what I know now, I certainly would have slapped on a preventative glob. If you do try that, let me know how it works out. Also, I'm no expert on USB connectors, but it looks to me like those two little raised metal strips on the USB Micro-B plug affect how much force is required for insertion/removal; again in hindsight, I'd poke them down with a small screwdriver to try to minimize the necessary force.

That said, I tend to favor my 0.1" header solution, if and when Marcus/CF can confirm that those two big pads aren't electrically connected to anything. If they are, I guess I can insulate them with tape and then hold the header on mechanically with hot glue...

[atomicdog]

Those pads definitely had cold solder joints. Which is probably why the pads didn't get ripped of along with the USB connector (like the mechanical pads did). This type of connector is definitely meant to be soldered on.

[tobias]

Those pads are not electrically connected so you can use them without any problem.

Just a quick question. Was the USB connector tight? We might have to consider changing the connector brand for the future.

[san84]

In my case the springy protrusions on the usb plug that engage with the slots in the connector cause some difficulties during removal. I already used 2 different cables but sometimes the protrusions just hold on too tight to the slots. I then have to push the protrusions inward with a pointy object to be able to remove the cable.

Circled in red the protrusions from the top.

plug.jpg (10.91 KiB) Viewed 11710 times

Circled in red the protrusions from the side.

plug-side-view.jpg (2.96 KiB) Viewed 11710 times

Circled in red the slots in the connector.

jack.jpg (4.93 KiB) Viewed 11710 times

Edit: I managed to completely remove one of the protrusions and sort of disable the other one and this makes insertion and removal of the USB cable a lot easier and reduces the risk of tearing off the USB jack.

[jamisnemo]

Honestly, a through-hole USB jack would probably be a lot stronger... but I'm not sure if they come in that size...

I CAREFULLY put hot glue around the usb jack just in case and it doesn't seem to affect flying much at all so I'd recommend it for anyone scared of ripping off the jack.

Also, I had luck not inserting the usb plug all the way. If you have a dremel tool maybe you can shave off the "springy protrusions" on a usb cable and specifically use JUST that cable with the flie...

[dunbarton]

@Tobias: Yes, the connection between the cable and the jack was incredibly tight. I realized this the first time I charged it and tried to be gentle -- not gentle enough. Like san84, I tried two different cables, so I feel safe in blaming the jack, particularly since I'm being told the solder joints on the five traces look cold. It occurred to me that the two big square pads might also be intended as mechanical solder connections for the jack, and if so, they look to me like they were also weak (if they were even soldered at all.)

Update on my progress: I bit the bullet and attempted to remount the USB jack. I was much too optimistic about my ability to solder surface-mount. I got the jack mechanically soldered to traces 1 and 5, figuring I'd do the other traces after I tested the charging connection -- which was in fact bad. In the process of desoldering to try again I ripped traces 2 and 3 off, and trace 1 was left hanging by its far end. So, no USB data connectivity for me, ever. But: I was still able to attach a piece of 1x2 female 0.1" header to trace 5 and the ripped trace 1 (the power traces), anchoring it at the big square pads; it seems mechanically sound and, after decapitating a USB cable and slapping some male header on it, the CF charges just fine. The edge of the header extends out beyond the edge of the board; because of this and/or the weight difference (I'm betting the header + mechanical solder globs are heavier than the USB jack) I think maybe the CF is now a little wobblier on descents than it was, so I've decided not to possibly aggravate the situation by putting any hot glue on for now.

(angry muttering at whomever assembled board)

@san84: Yeah, I did some tests with the now-useless USB jack and was definitely able to minimize the insertion/removal force by poking at the protrusions on the cable plug. I'd recommend people do so with whatever cable they usually use for the CF if they're having any trouble removing it.