On Sun, Jul 26, 2020 at 10:54:27AM +0100, Luke Kenneth Casson Leighton wrote:
On Sun, Jul 26, 2020 at 10:33 AM Pablo Rath pablo@parobalth.org wrote:
I am very sorry to inform everyone on this list that I had a severe power problem with my Micro Desktop 1.7. I applied power to the DC Jack and the area right to the jack burned out. (see attached picture).
thank you for sending this to the list, as i asked, after you sent it initially privately. i had this happen to a 1.5 MD board 3 years ago, but no others, despite them running for prolonged periods of time.
what i noticed about that board was that the inductor was not properly soldered down. this would be insufficient contact, introduce resistance, and at that point the RT8288 would go unstable.
Ok. As you have probably deduced from my questions I am not really into hardware. Thank you for all your explanations and clarifications. I still try to wrap my head around what should work straight away, what could work with the right modifications and what can never work...
[...]
As I said I am very sorry that I screwed up. Luke, do you have any ideas what went wrong?
not in the slightest. or - maybe: have a look at the contact points where the inductor sits on the PCB. there should be quite a lot of solder, there.
Sorry for the dumb question but where can I find the inductor?
Do you think this +also destroyed the computer card?
when it happened for me it did no damage. all i did was (because i didn't have any spares) find a USB2 back-to-back power cable (i may have made one by cutting a plug off a USB device and wiring it to a 5.0v supply), plug it into one of the USB2 ports and provided "direct" 5.0v power that way. you *need* a stable supply to do that (1.5 preferably 2.0 A) designed *specifically* for providing USB power. UNDER NO CIRCUMSTANCES plug the 12v PSU into the USB socket. and DO NOT use an "off-the-shelf generic 5.0v wall wart". use something SPECIFICALLY designed for providing USB power because it is (a) stable and (b) current-limited.
I have a power supply from a Huawei Tablet (Output 5V, 2A) and one from an old Ipad Mini (Output 5V, 1A) both with a wall plug and a female USB socket. Can I use one of them with a standard USB 2.0 USB A to USB A (male to male) cable? The term 'back-to-back' power cable yielded limited search results in my case. Another option is an official PSU for the Raspberry Pi, 5V, 2A with wall plug and a non-detachable micro-usb cable. I can buy a micro-usb to USB A adapter if this is going to work. So I have to either buy a cable, an adapter or a whole new USB Power supply depending on your opinion.
if you plug the Card directly into a socket (OTG, removed from the MicroDesktop) - not via a USB hub - "ls" should show the familiar USB ID for the A20.
My initial thought today was: "NO, now everything is lost." so your reply made my day. Tested the Card standalone and 'sunxi-fel version' shows an Allwinner Device in FEL-Mode. Computer Card still alive!
Pablo