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by jmuellers
Thu Mar 28, 2019 8:29 am
Forum: General discussion
Topic: STICKY: Introduce yourself!
Replies: 3497
Views: 82151

Re: STICKY: Introduce yourself!

Hi all!
My name is Johannes, I'm a physicist from Germany. I have worked very little with the Raspberry Pi so far :? .
I came here to get help reviving my 3B+ (viewtopic.php?f=63&t=236442) 8-)
by jmuellers
Wed Mar 27, 2019 2:58 pm
Forum: General discussion
Topic: Defective? Blinks 4 long 7 short
Replies: 12
Views: 535

Re: Defective? Blinks 4 long 7 short

Hi jamesh, I have confirmed once again that the new PMIC is operating as expected. VOUT1: 3.29V VOUT2: 1.79V VOUT3: 1.35V VOUT4: 1.20V 5VSYS: 4.92V LDO: 3.29V PP30, which shows the "power good" (PG1) signal, is low, however this is not surprising as it lacks a pull-up and is most probably open drain...
by jmuellers
Fri Mar 22, 2019 9:05 pm
Forum: General discussion
Topic: Defective? Blinks 4 long 7 short
Replies: 12
Views: 535

Re: Defective? Blinks 4 long 7 short

It's not a BGA, it's a QFN. Soldering QFN (or even BGA) is not a problem for me, it's part of my job :) Since I saw the same error when I used a lab supply (I'm fairly positive to have figured out where to apply which voltage), I figure that whatever killed the PMIC in the first place probably took ...
by jmuellers
Fri Mar 22, 2019 8:02 pm
Forum: General discussion
Topic: Defective? Blinks 4 long 7 short
Replies: 12
Views: 535

Re: Defective? Blinks 4 long 7 short

I've replaced the PMIC since it was broken. Before I did that, I powered all five rails from a lab supply, it behaved exactly the same. I was under the impression that there are no further regulators on the board, right? I'll let you know after the weekend if all voltages are as expected, I didn't c...
by jmuellers
Fri Mar 22, 2019 4:06 pm
Forum: General discussion
Topic: Defective? Blinks 4 long 7 short
Replies: 12
Views: 535

Re: Defective? Blinks 4 long 7 short

I believe the interface is initially in a reduced mode which just uses one data line. Once bootcode.bin is loaded it switches to the full 4-bit mode and tries to find start.elf. If one or more of the three extra data lines are damaged on the board, or the interface on the Broadcom chip has partiall...
by jmuellers
Fri Mar 22, 2019 3:32 pm
Forum: General discussion
Topic: Defective? Blinks 4 long 7 short
Replies: 12
Views: 535

Re: Defective? Blinks 4 long 7 short

I believe Jamesh was referring to GPIO damage ;) Sorry but I don't understand your comment. The SD card is connected to the ARM with SPI if I'm not mistaken, so I wouldn't refer to those pins as GPIO, right? I have some experience with PCB design, microprocessors, power supplies, etc. Feel free to ...
by jmuellers
Fri Mar 22, 2019 2:56 pm
Forum: General discussion
Topic: Defective? Blinks 4 long 7 short
Replies: 12
Views: 535

Re: Defective? Blinks 4 long 7 short

Hi jamesh, thanks for your answer. Yeah I've read that section. There's nothing about the slow blinking though, I thought that might yield some additional insight. If there's something wrong in HW with the SD card interface, I would have imagined the errorcode issued is the one for start.elf , not f...
by jmuellers
Fri Mar 22, 2019 2:31 pm
Forum: General discussion
Topic: Defective? Blinks 4 long 7 short
Replies: 12
Views: 535

Defective? Blinks 4 long 7 short

Hi all, I registered today to ask the community for help in repairing my Raspberry Model 3B+. On my desk it was probably exposed to so metal and suffered a short circuit. I figured that the MXL7704 broke, it seems to be known for not being short circuit proof (actually the part is listed as "not rec...

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