How I solved the Saturn LCD problem. The exposure test was failing.

I received two new LCD screens for the Saturn from Elegoo support. The LCD was still not working as reported in the Saturn LCD Problems Continue post.

After I received the second LCD screen I was thinking the problem was caused by either firmware that was incompatible with the version of LCD screen Elegoo sent to me, or the ribbon cable was connected incorrectly. I sent photos of the failure, the system information screen, and the ribbon cable connectors to Elegoo support so they could check. 

Exposure Test Failure
System Information
LCD connector
Motherboard connector

After I sent the photos I received an email from Elegoo support showing the different versions of LCD screens that are used for the Saturn printer. I identified the LCD screen they sent me. It was the PJV5. The pictures also showed the model TM LCD screen that I removed from the printer because it had some hotspots. I replied that the new LCDs they shipped to me were model PJV5.


After I replied that I have the PJV5 version Elegoo support sent me another email saying this:

Hi there,

Thanks for your patience test and reply, it is helpful.
Yes, the LCD screen is PJV5 and the firmware is right.
Please check the ribbon cable connection of LCD screen.
It is easy to make mistakes when connecting the ribbon cable of PJV5 screen.
Please check if there is any problem in LCD screen ribbon cable connecting.
1.The side to connect motherboard.   
There is ‘接板BOARDS’ on this side.

2.The other side to connect LCD screen is prone to error.
There is ‘接屏SCREEN’ on this side.
And the number 1 corresponds to the number 50.


Now I knew the cause of the problem. I connected the ribbon cable connector to the LCD screen backwards.

The ribbon cable that came with the PJV5 has markings for pin 1 and pin 50. The PJV5 LCD screen also has markings for pin 1 and pin 50. Since I was replacing a TM screen with a PJV5 screen I didn’t have a reference for the cable connection and just matched pin 1 to pin 1 and pin 50 to pin 50. 

Once I reversed the connector I ran the exposure test. The test succeeded and the Saturn LCD problem was solved.


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