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5V Dead, No Boot - MacBook Air 13" 2019 A1932, 820-01521

Posted by eFix Ltd on

In this case study, we have a MacBook Air 13" 2019 A1932 model (board number 820-01521) which is not booting or showing any signs of life at all. Connecting a USB C ammeter, the MacBook is pulling in 5V 0.05A on both USB C ports, instead of the usual 20V required for boot.

Disassembling the MacBook and removing the logic board, we can see there was no visual liquid damage to the device, and visually it looked clean. On closer inspection under a microscope, we could see U3000 (PI3USB32324) had a hole in it, and was burnt.

The PI3USB32 Had Two Holes In It

Firstly, we removed U3000, and could see 4 solder pads on the logic board had been completely destroyed as well, pin 15, 16, 18 and 19; meaning 4 wires had to be run from the PI3USB32 chip to D3090, D3091, D3092 and D3093, in order to repair these damaged pads and traces. U3000 acts as USB C support on these models, dealing with USB devices plugged into a USB C port.

Removing each diode and soldering a wire to the relevant pad of U3000, we then used UV solder mask to secure these wires in place. Once secured, we replaced each diode we removed, and then soldered a new PI3USB32 chip with hot air.

After cleaning up, we tested this and could see that the MacBook was now pulling the correct 20V and was booting up correctly, however the furthest USB C port was not charging the device, and was not reading USB devices. The non-working port was linked to U3200, the CD3215C00Z chip responsible for handling charging and data from this port, and replacing this managed to get the device fully working again. We successfully fixed their logic board (820-01521) which was dead and only taking in 5V.

New PI3USB32 and CD3215C00Z Chip Fitted, With Wires And UV Mask, Next To Old Chip

There was no liquid damage to cause this issue, but this problem was likely caused by a powered 3rd party accessory (like a USB hub), which has sent 20V down the data lines, blowing these traces and U3000/PI3USB32. This also damaged the U3200/CD3215C00Z chip, again, likely due to a 3rd party powered accessory, which is very common. To prevent this issue in future, we recommended the customer only use genuine accessories, stays away from powered USB hubs and made sure they were using a genuine charger, in case this was the cause.

If you have a similar issue with your MacBook Air A1932, we offer a free diagnostic service where we can check your device out and find out why it is not turning on, and only drawing 5V from the charger. 

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  • i have the same problem too.
    if I unsolder the chip can I try charging and starting the mac?

    matteo on
  • Excellent post. There is very little on the internet about the USB ic which actually is a USB switch for USB 2 devices according to the datasheet. That makes little sense I know but hey.
    Well done guys on a great case study.

    Martyn on
  • Well done! Working on a similar A1932 case where a cat bit the computer and display AND external use of type C to HDMI is dark. The HDMI adapter works fine on other boxes. Not negotiating 20V with the PD so will investigate the USB Mux and ACE controllers. Thanks for posting!

    Kumar Bhatia on

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