Cant Draw Diagonal Lines After Screen Replacement: Difference between revisions

Cant Draw Diagonal Lines After Screen Replacement
Device	IPad Pro 11in 3rd Gen, IPad Pro 11in 4th Gen, IPad Pro 12.9 3rd Gen, IPad Pro 12.9 4th Gen, IPad Pro 12.9 5th Gen, IPad Pro 12.9 6th Gen, IPad Mini 6
Affects part(s)	Display
Needs equipment	JCID V1S or JCID 1Vs Pro
Difficulty
Type

VisualWikitext

Latest revision as of 21:40, 20 September 2025

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Problem description

After replacing the screen the Apple pencil can not be used to draw diagonal lines.

Solution

The Solution is simple however we need a special tool made by JC.

You can use the JC V1SE or the JC V1S Pro.

You have must have iPad Screen Repair Adapter.

First Connect the flex cable to the right adapter for your model

Then Connect the adapter board to the iPad like this

Now Connect the ORIGINAL screen the iPad had installed, and power on the device.

Next on the Programmer use the buttons to select the Model of your device

Then connect the Flex to the programmer like this

Now press the power button to light the screen up and press the read button on the JCID Programmer

After reading the old information from the screen you can turn off the iPad and plug your new screen in.

With the new screen in connected press the power button to light up the screen and click on Write in the JCID Programmer

After this you can turn off the device and remove the JCID adaptor and plug in the new screen like normal.

Final Testing

Open the notes app and make sure your diagonal lines made with the Apple Pencil are in a straight line.

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+{{stub}}
+{{Repair Guide
+|Device=IPad Pro 11in 3rd Gen, IPad Pro 11in 4th Gen, IPad Pro 12.9 3rd Gen, IPad Pro 12.9 4th Gen, IPad Pro 12.9 5th Gen, IPad Pro 12.9 6th Gen, IPad Mini 6
+|Affects parts=Display
+|Needs equipment=JCID V1S or JCID 1Vs Pro
+}}
+== Problem description ==
+<!--
+Provide a concise description of the issue here. Be  as specific as possible to help readers quickly determine whether or not this is the exact problem they are facing.
+ -->
-'''820-3662 NO NUMERIC KEYS / CAPS LOCK INVERTED / INPUT DELAY - TOUCHPAD ISSUES'''
+After replacing the screen the Apple pencil can not be used to draw diagonal lines.
-The device arrived with the numeric keys on the internal keyboard non‐functional, despite a complete keyboard replacement. Visible moisture and sulfation were detected near the keyboard’s SPI controller (U4801).
+[[File:Diagonal issue.png|thumb|Example of issue]]
-🔍 '''Step-by-Step Diagnosis'''
+== Solution ==
+<!--
+If the issue has a single, specific solution, provide it in this section and delete the sub-headers below. Otherwise, if there are multiple potential causes for the problem, outline the process of identifying the root cause and offer corresponding solutions below.
-Visual inspection: Corrosion was found near the keyboard/trackpad controller area (U4801).
+-->The Solution is simple however we need a special tool made by JC.
-Voltage drop across R4814 (relevant resistor in the SPI circuit) was checked and confirmed expected values.
+You can use the JC V1SE or the JC V1S Pro.
+[[File:JC V1S Pro.webp|thumb|JC V1S Pro|center]]
-'''''Chip replacement attempts:
-'''
-'''First attempt:'''
+[[File:JC V1SE.webp|thumb|JC V1SE|center]]You have must have iPad Screen Repair Adapter.
-Replaced U4801 with a donor chip from board 820-3476 (MacBook A1502).
+[[File:IPad Screen Repair Adaptor.webp|thumb|iPad Screen Read And Write Adaptor Fix Wavy Lines With Apple Pencil - JCID|center]]
-🟡 Result: Keyboard worked, but Caps Lock LED was reversed (lit when lowercase, off when uppercase).
-'''Second attempt:'''
-Used a chip from MacBook A1278 (Unibody).
+First Connect the flex cable to the right adapter for your model[[File:Flex Connected.png|thumb|center]]Then Connect the adapter board to the iPad like this
+[[File:Flex Adapter.png|thumb|Flex Adapter|center]]
-🔴 Result: Severe input delay, no trackpad and overall poor keyboard behavior.
-'''Final solution:'''
-Replaced with U5701 from donor board 820-3332.
+Now Connect the ORIGINAL screen the iPad had installed, and power on the device.
-✅ Result: Keyboard fully functional, Caps Lock LED working properly, no delay, trackpad also fully operational.
+Next on the Programmer use the buttons to select the Model of your device
+[[File:Ipad model.jpg|center|thumb|Choose iPad Model]]
-'''⚙️ Technical Conclusion'''
+Then connect the Flex to the programmer like this
-The U4801/U5701 keyboard SPI controller contains firmware/configuration specific to each board model. These chips are not freely interchangeable between different MacBook series (A1278, A1502, A1398, etc.).
+[[File:JCID Flex Connected.png|thumb|JCID Flex Connected|center]]Now press the power button to light the screen up and press the read button on the JCID Programmer
-⚠️ '''Using an incompatible IC can cause:'''
+After reading the old information from the screen you can turn off the iPad and plug your new screen in.
-Reversed Caps Lock LED logic.
+With the new screen in connected press the power button to light up the screen and click on Write in the JCID Programmer
-Noticeable input delay on keys input.
+After this you can turn off the device and remove the JCID adaptor and plug in the new screen like normal.
-Malfunctions with the trackpad or power button.
+== Final Testing ==
+Open the notes app and make sure your diagonal lines made with the Apple Pencil are in a straight line.
-✅ '''Key Takeaway'''
+[[File:Issue Fixed.gif|center|thumb|Issue Fixed]]
-“The keyboard IC (U4801/U5701) must come from a firmware-compatible logic board. Although they are electrically identical, their internal configuration depends on the board model and its interaction with the SMC.”
-— Diógenes el Perro
-🛠️ Note: Neither the BIOS nor the SMC were reprogrammed during this repair.