Console repair: Help identifying components - Page 1
Forum section: electronics / repair

author: newtekuser
author_rank: Frequent Contributor
timestamp: July 12, 2024, 06:03:26 pm
content: Have a portable gaming console than doesn't power up (power LED stays red when charging and only blinks red once when pushing the power button), upon disassembling it I see what appears to be a blown 0603 component. From what I can tell, it is part of a power regulation circuit.It doesn't appear to be a diode because when I measure the other two identical components next to it there's no voltage flowing through them. None of the components in this area are shorted to ground and when I measure the other two identical components similar to the burnt black one I get about 0.40 ohm. This tells me this may be a current sense resistor.I'm guessing this component was blown by the in-rush current from the wifi chip which is in the biggest component in the area. I also don't see any diodes around which is very weird.As part of the same power regulation circuit I also see three mosfets marked "AHRP 590" but a Google search doesn't reveal anything of use about them. I'd like to see if any were taken down with the blown component if I can find any data sheets for them.In the two pictures you can see the board before and after cleaning.Can someone confirm if this is indeed a current sense resistor?What about the mosfet?

author: fzabkar
author_rank: Super Contributor
timestamp: July 12, 2024, 06:25:03 pm
content: The manufacturer of AHRP is Monolithic Power.Edit:MP8765GQ, Monolithic Power, 24V, 6A High Efficiency Synchronous Step-down Converter with Hiccup OCP, PWM/PFM mode pin and output discharge, marking AHRX+XXX, QFN3x3-16P:https://www.monolithicpower.com/en/documentview/productdocument/index/version/2/document_type/Datasheet/lang/en/sku/MP8765/http://markingcodes.com/search/c/ahrEdit #2:Could the "current sense resistor" be a ferrite bead?

author: newtekuser
author_rank: Frequent Contributor
timestamp: July 13, 2024, 04:07:24 am
content: Quote from: fzabkar on July 12, 2024, 06:25:03 pmThank you for the link! I went with my gut feeling and ordered some current sense resistors since I could not find ferrite beads of the same resistance. I also ordered a few of the MP8765 buck converter ICs just in case since they're cheap.

author: fzabkar
author_rank: Super Contributor
timestamp: July 13, 2024, 03:52:47 pm
content: I would make sure that the load side of the DC-DC converter is not shorted or overloaded.

author: wraper
author_rank: Unknown
timestamp: July 13, 2024, 04:36:10 pm
content: Blown component is a ferrite bead. Exact value not important, what matters the most is if it can handle enough current. FWIW you can replace it with a jumper and circuit will work just fine. Although I doubt it blew by itself, something else should have failed and caused a very large current flow. You should check if either side of the ferrite bead is shorted to GND.

author: wraper
author_rank: Unknown
timestamp: July 13, 2024, 04:40:02 pm
content: I see another ferrite bead above it that is either blown too or mechanically damaged.

author: newtekuser
author_rank: Frequent Contributor
timestamp: July 13, 2024, 06:18:46 pm
content: Quote from: wraper on July 13, 2024, 04:40:02 pmI found several components shorted:Top step down converter: PIN 9 (SW), PIN 8 (SW), PIN 6 (MODE) shorted to groundMiddle step down converter: PIN 6 (MODE) shorted to ground, PIN 5 (NC) shorted to ground (connected to GND on purpose?)Bottom step down converter: PIN 5 (NC) shorted to ground (connected to GND on purpose?)None of the components identified as ferrite beads are shorted to ground, but I found about six of 0201 caps shorted to ground to the right of the inductors as well as a larger polarized cap (what is this packaging/size?) to the right of the top inductor.

author: fzabkar
author_rank: Super Contributor
timestamp: July 13, 2024, 07:17:26 pm
content: I doubt very much that those capacitors are faulty. It's much more likely that an IC is shorted. I'm talking about those ICs that are powered from these stepdown converters, not the converters themselves.It would help if you could provide a photo of the whole PCB.

author: newtekuser
author_rank: Frequent Contributor
timestamp: July 13, 2024, 08:14:40 pm
content: Quote from: fzabkar on July 13, 2024, 07:17:26 pmAttached full PCB picture. I can only probe the Winbond flash chip which is not shorted, and I'm not able to get to the Super IO (ITE) IC, RAM or the CPU pins. From what I could gather on the Internet, the Super IO chip is what frequently goes out on the Steam Deck. None of the capacitors surrounding it are shorted though.I did manage to probe some of the caps on the CPU and they're shorted to ground, so hope it's not game over.

author: wraper
author_rank: Unknown
timestamp: July 13, 2024, 08:23:08 pm
content: What actual resistance is that "shorted"? CPU/GPU and RAM may have very low resistances on their power rails. Also those converters can easily get shorted to the ground.

author: newtekuser
author_rank: Frequent Contributor
timestamp: July 13, 2024, 08:27:31 pm
content: Quote from: wraper on July 13, 2024, 08:23:08 pmAh, I forget that these have very low resistancesI measure 4 ohm on one side and 0.3 ohm on the other side of the resistors.

author: wraper
author_rank: Unknown
timestamp: July 13, 2024, 08:44:42 pm
content: Resistance may be fine depending on what power rails those are. I'd expect converter IC to be dead if a ferrite bead in its input failed open/burned. The issue is that if upper mosfet (between Vin and out) inside the IC fails short first, it may take out (overvolt) the load as well.