Another dead Primer2, U17 output is shorted to GND
Hi,
Having read the FAQ before using my Primers i decided that i'm safe because i clearly saw an additional wire soldered near U9 and that it's basically enough.
Apparently i was wrong because now i have a broken device and L6928D is not fast to source and not everybody has necessary equipment and skills to resolder it.
Now i read on the forum that to prevent misfortune events like that you exchange the tantalum caps with ceramic, well, nice, but: nowhere in the faq it's written that the first thing i should do with my primers is to replace the caps. It's stated as a vague "suggestion" but to me it seems important to understand and prevent the problem before it happens.
So please: if you have a good idea how to rework the units, express it clearly in the FAQ and add a sticky topic with information on recommended procedures.
Re: Another dead Primer2, U17 output is shorted to GND
Hi,
yrt, sorry for not being clear about it. When i said i've read the FAQ, i meant exactly the page you're referring too.
Let me rephrase my message:
If you know that all of the devices are suspectible to sudden premature "death", please express clearly and unambigously the recommended way to _prevent_ it. And please make it really visible (including adding a sticky topic to the forum) so all new users will fix their devices _before_ the problem occurs.
I hope you understand that not all users of Primer2 are experienced EE developers, some of them are just into embedded programming, so it's not really clear how to protect those dc-dc step-down converters.
So it is up to you to provide your users with a precise, concise and reliable solution to be applied to every device in the field.
Re: Another dead Primer2, U17 output is shorted to GND
Hi,
Bumping this topic. Francis, please give at least some feedback
I tried to evaluate options for substituting another regulator but it doesn't seem there's anything reasonably compatible, so the best option is obtaining the needed chip.
BTW, we finally got 5 samples of L6928D and so we have 4 spares left. If anybody in Moscow is interested in fixing his/her unit, feel free to contact me.
Re: Another dead Primer2, U17 output is shorted to GND
===== Russian ===== Я могу приобрести парочку (2 штуки). Я правда не в Москве. Для начала интересует цена и как лучше передать деньги (яндекс/WM/билайновский кошелек). Если есть возмжность выслать в обычном письме - было бы неплохо. Также как вариант - передать через проводника белгородского поезда.
Re: Another dead Primer2, U17 output is shorted to GND
We got those for free (samples from ST), so i can send you one-two in a regular snail mail for free as well. So if needed, contact me via e-mail: fercerpav@gmail.com .
Do you already have a broken device or do you want to get spares just in case? Have you already changed the capacitors to (hopefully) prevent problems? The reason i ask is because i'd like to be able to help local folks fixing their devices, i know there were quite some amount of them distributed at ARM Dev. conference here.
Re: Another dead Primer2, U17 output is shorted to GND
I have two Primers. One of them has broken U17 (Backlight & Audio) and currently fixed with another 3.3V regulator. I can't remember which one exactly. I just found one among some old circuits and installed. And i can't read the label - it's flipped upside-down. Also i can't use extension connector 'cause temporary fix attached to the ground pin directly. Plus it drains battery faster and screen brightness is limited. So i need one regulator to replace this one.
Second primer is healthy AND already rewired acording to FAQ from the factory. Caps replaced and additional wire attached to U9. I received it as it is.
And by the way - i burned the first regulator by touching it while trying to remove the battery jumper.
Re: Another dead Primer2, U17 output is shorted to GND
Ok, so just e-mail me your snail mail address, i'll send you the ICs in a week.
BTW, i'm not sure they have the caps replaced from the factory. The ground trace is factory-reinforced on most units, that's true, but i think they're still using tantalum (read "high ESR") caps.
Re: Another dead Primer2, U17 output is shorted to GND
For your information the Primer2 are now delivered with the ground connection fix (since v1.1), and the ceramic capacitors (since prevent batch production) . Because, as you said, ntrf.zns, a lot of Primer died when touch it or just at USB connection, a 3V3 transil has been added in parallel of C23 (VccIn), in order to prevent ESD issues. This concerns the last batch production manufactured at the begining of this year.
Re: Another dead Primer2, U17 output is shorted to GND
yrt, sorry for being slow but i still can't understand the details needed to ensure the device will be safe. Is there some reliable way to find out the manufacturing date and consequently determine what fixes are needed?
Can you please prepare a checklist every user is able to follow? E.g.: 1. PCB revision is written <there>, manufacturing date is written <there>. 2. If your manufacturing date >= 01.01.2010, you're safe, enjoy your cool toy 3. If <something>, you only need to add a 3.3V transil 4. If <something>, you also need to change the caps 5. If <something>, you also need to reinforce U9 ground trace.
I'd also expect you to make this instruction really visible, so every newcomer is aware of it. I hope it's apparent i'm asking for something important and it's not covered on the "Resolved known problems" page.
Re: Another dead Primer2, U17 output is shorted to GND
Hi,
Only the PCB revision is written on the PCB back side. Unfortunately, the manufacturing date is not available, and Primers may stay a long time in the distributor stocks. Add a transil and change the caps are the only workaround we got yet, but even with that modifications, we cannot ensure that the device is safe. ST could not give us the definitive solution. However, your remarks are usefull, and we will try to improve this topic.
Re: Another dead Primer2, U17 output is shorted to GND
If you are still in need, you might buy this part in www.farnell.com.
However it's not fair that ST, isn't repairing our bords for free. I can't even check where is part U17 My board primer2 v1.1, doesn't have any text on text layer.
My board primer2 v1.1, doesn't have any text on text layer. 