Author Topic: Touchpad(JDM-030) with short circuit  (Read 1159 times)

Offline LSL

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Touchpad(JDM-030) with short circuit
« on: November 11, 2019, 06:51:34 AM »
Hi!

This JDM-030 doesn't sync and doesn't recharge. I found 2 capacitors with short (C1 and C2).

Could you help me with the values of them? The touchpad works without these capacitors, but I want replace them.




Offline RDC

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Re: Touchpad(JDM-030) with short circuit
« Reply #1 on: November 12, 2019, 06:42:40 AM »
I took a couple JDM-030 apart here, as well as a couple other versions, and none of them had that version TP board in it, so I can't get you the exact values, but I doubt they are anything more than a couple of decoupling caps. I'd just put something like a 1uf and an 0.1uF in there.
Screwing up is one of the best learning tools, so long as the only thing you're not learning is how to screw up.

Offline LSL

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Re: Touchpad(JDM-030) with short circuit
« Reply #2 on: November 12, 2019, 07:07:36 AM »
Thanks RDC!

So should I put 1.1uf (1uf+0.1uf)?

I will search for the IC datasheet to make sure the other capacitors (C3 and C4) have equal values.
« Last Edit: November 12, 2019, 07:09:20 AM by LSL »

Offline RDC

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Re: Touchpad(JDM-030) with short circuit
« Reply #3 on: November 12, 2019, 07:25:31 AM »
If the chip is the MXT112, good luck finding the DS. If it's something else please let me know, as all the TP boards I have hare use the MXT112 chip.

Correct, 1.1uF total, but anything at all would really work from 1nF to 10uF if it's just for some decoupling. I doubt they are doing anything else, as it would mess with the TP with them missing.
Screwing up is one of the best learning tools, so long as the only thing you're not learning is how to screw up.

Offline LSL

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Re: Touchpad(JDM-030) with short circuit
« Reply #4 on: November 12, 2019, 07:52:31 AM »
I guess isnt MXT112 chip because it's has a different package from another TP IC comparing with JDM-040's TP.

Soon I will telling you if this chip is a MXT112 or not, probably tomorrow.

Thanks!
« Last Edit: November 12, 2019, 08:01:56 AM by LSL »

Offline LSL

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Re: Touchpad(JDM-030) with short circuit
« Reply #5 on: November 13, 2019, 08:26:01 AM »
It is a mXT112S.  :cry2:


I found 2 datasheets: mXT144U and mXT224.

On mXT224's datasheet, pages 7 and 8, shows an association with 100nF and 1uF, the same you said yesterday.

On mXT144U's datasheet, page 9, shows 2 associations: 22nF + 2.2uF and 22nF + 1uF.

I will remove C3 and C4 capacitors to check respectives values and compare them with the datasheets.

Offline LSL

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Re: Touchpad(JDM-030) with short circuit
« Reply #6 on: November 14, 2019, 07:07:23 PM »
C3 = 100nf
C4 = 1.5uF

I will put same values to C1 and C2.

Offline LSL

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Re: Touchpad(JDM-030) with short circuit
« Reply #7 on: December 16, 2019, 10:19:47 AM »
The same problem, same board, same TP:

https://youtu.be/ICn3RPxeQYU?t=559

 

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