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Author Topic: Question: What is this chip? wm1801b?  (Read 1315 times)

Offline Eren_Ackerman

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Question: What is this chip? wm1801b?
« on: November 04, 2021, 04:54:39 PM »
I just finished installing a d92003mw chip on a jdm-040 and realized that the controller has the exact same problem it had before I changed the chip: no usb connection.

After inspecting the board now (newbie mistake), I noticed that (what I believe are) 2 capacitors were purposely shorted with solder. From what I'm starting to understand, they probably did this to force the controller to share the EXT's 5v line to the USB's 5v line.

My question is: did this "trick" likely kill the wm1801b chip? I think this chip was actually the one handling the usb connection, but that is also part of the question: is that correct? If not, what does this chip do?

Thanks again <3



Photo: I undid the bridge, but this was after I had already tried the new d92003mw chip.
« Last Edit: November 04, 2021, 04:59:34 PM by Eren_Ackerman »
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Offline RDC

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Re: Question: What is this chip? wm1801b?
« Reply #1 on: November 05, 2021, 02:12:28 AM »
The USB data lines run to the Spansion chip on the top side of the board. They connect only to that chip thru a couple of 27ohm Resistors. That WM1801B does the onboard audio and who knows what else.

If the USB board is good, and the FPC cable is also good and the Common Mode Choke is still on there, and the traces for the USB lines are good, then remove the 5 lead chip just under the FPC connector where the USB cable plugs in. That is a TVS array for protecting the data lines and if it shorts the USB will not work.

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Offline Eren_Ackerman

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Re: Question: What is this chip? wm1801b?
« Reply #2 on: November 05, 2021, 06:08:40 PM »
Got it.

Thanks again, RDC <3
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Offline Eren_Ackerman

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Re: Question: What is this chip? wm1801b?
« Reply #3 on: November 06, 2021, 05:08:19 PM »
Update:


I removed the d6f protection diode under the FPC connector, but it's the same again :(

I used a new flex cable, new jds-050 (compatible with jds-040 but different side), and I made sure that all the lines on the board were in good condition. Maybe it's time to reflow the Spansion chip? :(


Edition and update 2:

I reflowed the Spansion chip, aaaand rip :(

I heard an explosion , so I think there was still air under the chip that could have been rounded by the flux because I applied the flux all around the chip when it was cold. I removed the chip, and stored it in case one day I feel like reballing it (hoping that it's still good, that is) xD
« Last Edit: November 06, 2021, 05:57:57 PM by Eren_Ackerman »
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Offline wickated

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Re: Question: What is this chip? wm1801b?
« Reply #4 on: November 08, 2021, 04:38:41 AM »
spansion chips just die inside, no help of reflow or smth
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