JeeNode SMD regulator warning.

Jee Labs Talk » Uncategorized

JeeNode SMD regulator warning.

(12 posts) (5 voices)

Tags:

No tags yet.

tankslappa

As I mentioned before, I bought a couple of JeeNode SMDs. I bought a pair because I'd never done SMD soldering before, so thought a spare would be a good idea.
The first one went together smoothly with my trusty Antex 18w iron and a 0.5mm tip and a pot of flux.
Hooked it up to my ISP programmer, and after a few issue getting the pins to make reliable contact, set the fuses and loaded the bootloader. I was a happy man. I then put together an FTDI interface on a protoboard, all set to make it my ISP programmer (and free the JeeNode V4 I am currently using). I couldn't get it to work. I poked it, prodded it, hooked it up via the ISP again, put test programs on it with AVRDUDE, everything worked, but not via my FTDI board... Which isn't exactly complicated (See JC's diagram http://news.jeelabs.org/2010/07/09/assembling-the-jeesmd-part-2/).
So I thought I must have screwed something up on the SMD board, so I built the second one.
Exactly the same. Connect via ISP, works great. Connect via my FTDI, no go.
Then a thought dawned on me (The ISP programmer supplies power to the 3.3v rail, the FTDI supplies it to the 5v PWR). I checked the 3.3 rail... Sure enough, both boards are dropping the 5v supply on the pwr connection to 4.5v, not 3.3v. This in itself wouldn't be an issue (I'm not connecting any 3.3v boards), except I bet it's not a clean 3.3v (I might scope it later).
A bit more testing, and breaking out the power from the FTDI connection, using a full size regulator and feeding it back into the 3.3 rail proved it. It works. Both regulators look like they are fried!
So a word of warning, be very very very careful when building the SMD board. Neither regulator caused me any problem when I put them on the board. Each pin soldered in a fraction of a second (I'm using lower temperature lead solder), yet the little chap still died. Maybe I should have done one pin, then moved onto something else to let it cool before doing the next.
The funeral will be performed as soon as I can extract the corpse from the board. No flowers please.

Posted 21/07/2010 02:49:15
ull

Or regulators are of wrong type? I suspect that regulators in my JeeSMD kits are 5,0V versions and not 3,3V. It even says HU50 on the regulator. I hope you did not bury your regulators alive!

Posted 05/08/2010 18:57:42
tankslappa

Your eyesight is better than mine! I can just about see it has something written on it... Whatever it is it wouldn't work when connected to the USB-BUB when it was installed, and does work when connected to a USB-BUB now it has a regular (large) 3.3 250mA regulator sitting across the PWR,3.3v and GND pins.

Posted 08/08/2010 01:52:08
jcw

Uh, oh... my fault. Regulator pins 2 and 3 (in and out) are swapped, I think!
Will follow up when I get to the bottom of this...

Posted 14/08/2010 10:22:06
tankslappa

Oooh... So are you officially back now JC? Hope you had a great vacation. Sorry to welcome you back with a Murphy!

Posted 14/08/2010 19:17:35
epokh

ahahaha a murphy!

Posted 14/08/2010 23:04:05
jcw

(@epokh - you seem to be enjoying that...)
I've ordered updated boards. Will take about two weeks before I can test and replace them for everyone who got the JeeSMD (not that many yet, fortunately). I also need to re-wire my Multi-ISP programmer, even though it's pretty harmless there - looks like the MCP1703 produces a 0.4V drop with IN and OUT mixed up.

Posted 18/08/2010 15:15:55
tankslappa

JC, which pins are reversed? Is it the two that share a common edge? i.e. if I mount it on its back like a dead 3 legged spider with a couple of bits of jumper wire, will it work? I think I have still got the one I removed from my ISP programmer board somewhere... Unless I sneezed, or the cat ate it.

Posted 18/08/2010 23:11:22
jcw

Here's the worst part - I already messed up once in the same way:
Has all the details, if you want to try flipping pins. I'll probably do just that for the JeeSMD's I have in use here.

Posted 18/08/2010 23:29:17
tankslappa

Oh well, such things happen. It's very easy to repeat a mistake when you are using the same part.
It's very odd that it creates a 0.4v drop.
On the plus side: Excellent that you have a documented work round. Excellent that I didn't actually murder two 3.3v regulators with my basic 18watt iron and until then, untried SMD soldering skills. Which now appear to be 2 boards attempted, 2 boards fine! Not a bad success rate even if I do say so myself! (Which I just did!).

Posted 19/08/2010 00:04:24
jasper

Looking at the schematics of je JeeSMD http://cafe.jeelabs.net/lab/js1/jlpcb-069.pdf the pin numbers for the voltage regulator are correct but the labels aren't, right?

Posted 13/09/2010 09:59:13
jcw

No, the pin numbers are wrong too :(
The JeeSMD v1 has been superseded by the JeeSMD v2 with the regulator chip connections fixed. If you have a v1 board, email me (preferably with the order# so I can find your address quickly) and I'll send a replacement board.
Update - I've adjusted the links to the new v2 product info page.

Posted 13/09/2010 10:16:30