Raspberry pi 4 Model B Power Failure - Page 1
Forum section: electronics / repair

author: AmmarKurd
author_rank: Contributor
timestamp: March 09, 2024, 07:23:55 pm
content: Hello everyone,I have an RPi 4 model B that experienced a misfortunate accident while working on a robotics project, due to this the RPi didn't start afterward.I identified a short circuit on a component that I believe is a TVS diode its part number is (KE 2162K), it is also cracked as seen in the image below, but I couldn't find its datasheet anywhere online!I thought if it was really a TVS diode then I could just remove it from the board and it should work fine if not damaged, so I did.After removing it there is no more short circuit and the power LED lights up but the RPi does not boot, and the ACT LED does not blink.So, now I think maybe it is not a TVS diode? or my RPi is damaged?Is there anything I can do in this situation? any recommendations to try and save my RPi? Also, why can't I find the datasheet of this component?I appreciate any help I can get, so thanks in advance.

author: dobsonr741
author_rank: Frequent Contributor
timestamp: March 09, 2024, 07:31:53 pm
content: What was the misfortune event? BTW, the power manager MxL7704 is very sensitive to over voltage.

author: AmmarKurd
author_rank: Contributor
timestamp: March 09, 2024, 07:40:38 pm
content: I am not sure what exactly happened but some motor driver started to smoke, it might be incorrect wiring that caused it the pi was connected to the driver as well.

author: wasedadoc
author_rank: Super Contributor
timestamp: March 09, 2024, 07:42:19 pm
content: That is the TVS diode and it is the only one shown (top left corner with part number) on the reduced schematic available on the raspberrypi.com site.An otherwise OK RPi4B will work without the diode. That yours does not is a strong indicator that there is other damage which in almost all cases means the board is toast.

author: wraper
author_rank: Unknown
timestamp: March 09, 2024, 07:49:02 pm
content: Check all 4 output voltages (3.3V, 2x 1.1V and 1.8V) from MXL7704 or DA9090 depending on board revision. Also check if there is 1.1V from DA9121 if another smaller PMIC is present on the board.

author: AmmarKurd
author_rank: Contributor
timestamp: March 09, 2024, 07:50:53 pm
content: Quote from: wasedadoc on March 09, 2024, 07:42:19 pmIn the reduced schematics the diode part number is "SMBJ5.0A-TR", why is it different in my case?https://datasheets.raspberrypi.com/rpi4/raspberry-pi-4-reduced-schematics.pdf

author: wraper
author_rank: Unknown
timestamp: March 09, 2024, 08:01:24 pm
content: Quote from: AmmarKurd on March 09, 2024, 07:50:53 pmIt's actually SMBJ5.0A from Littlefuse on your board. Also looking on it, you have Rev 1.5 board. Which means DA9090+DA9121 PMIC ICs. If DA9090 is dead, tough luck since it's unobtanium. DA9080 may work instead of it but it's also nearly unobtanium, I ordered some a few weeks ago with 6 months dispatch time. Will see if they ever arrive.

author: wraper
author_rank: Unknown
timestamp: March 09, 2024, 08:08:14 pm
content: BTW you cannot replace DA9090 with MXL7704. You can sort of bodge it despite different center pad and terminal pad layout. However it won't boot past bootloader screen if you do so.

author: AmmarKurd
author_rank: Contributor
timestamp: March 09, 2024, 08:31:42 pm
content: I tested DA9090 and I didn't get any output voltage. So I think it is damaged.Thank you all for your help and replies.

author: Riad
author_rank: Newbie
timestamp: March 18, 2024, 10:17:14 pm
content: can you explain the reason

author: wraper
author_rank: Unknown
timestamp: August 14, 2024, 09:29:30 am
content: PiHut just started selling DA9090.