Lynx II with glitched screen

[Norrecito]

Hi all,

I have recently bought a faulty Lynx II. It wasn't cheap but I wanted one for a long time. The seller said that the system would power on and turn off after a second so I suspected that there are some leaking capacitors that needs to be replaced. When I got the console it was already partly disassembled. (The 5 screws holding it together were taken out and all cables were unplugged) According to the seller, no repair was attempted on it. The guy who took it apart got scared because this is quite a rare system in Hungary and he had no experience with handhelds so he sold it instead. After inspecting the main board I have indeed found some leaking capacitors so I have replaced all electrolyte capacitors. I was pretty confident here because I have recapped quite a few Game Gears in the past.

 

I have reassembled the Lynx and tried to turn it on with the only game I have. (Turbo Sub) It powered on just fine. The game was playing and there was even sound, loud and clear. Everything was working...expect for the screen which was glitched up heavily. I could only see colored vertical lines. They were not static though, they kept changing as the game was playing. For example the title screen of Turbo Sub showed up as blue lines.

 

 

I thought that this might be a problem with the LCD itself but now I am not so sure. I've read a bunch of forum posts and most people either have a partially visible screen (like 1/3 of the screen has only lines or is blank) or no screen at all. I wish there is a way to prove that this is an issue that is related to the LCD (or one of its components). I don't want to order a replacement screen (McWill/BennVenn) only to find out that the problem was something else. Unfortunately this is quite a rare system here in Hungary so I can't just buy another faulty one and switch the screens either. I could order one from eBay but for that price, I could probably buy a working one here. 

 

Any help which would pinpoint the problem is much anticipated!

 

I have already:
(-Recapped the main board)
-Cleaned the pins of the game
-Cleaned the cartridge slot
-Re-seated the ribbon cable a couple of times
-Cleaned the pins on the ribbon cable
-Cleaned the ribbon connector

 

I was thinking about looking for connections on the PCB that look "cold" and start to resolder them. I wanted to avoid taking the shielding off but I don't have a better idea now...

[rj1307]

Please enter the number of the motherboard and the number on the display (or take pictures).

[Norrecito]

Of course!

 

The number of the motherboard is "C104471-001 REV.A" and the number of the display is "C104159 REV B"

 

 

I have since taken the shielding off and reflowed all legs of "Suzy" and also reflowed the ribbon connector but it did not help.

[rj1307]

Write me a private message and provide your address, I will send you a functional display because it is the cause of your problems.

[Norrecito]

Hi all,

 

I have an update on this issue. Unfortunately it is still not fixed.

 

rj1307 was very kind to send me a working LCD. (Thanks for that!) Surprisingly it is not an LCD problem...I get the same result even with the newly installed LCD.

 

Based on his suggestions and my ideas, I made some additional checks:
-Checked the quadruple RPxx resistors at the LCD connector with my multimeter. All of them seems to be okay (They are between 459 and 465 ohms)
-Reflowed all chips (including Suzy and Hayato)
-Reflowed all small SMD parts that seemed to go in the direction of the LCD connector
-Replaced "74HC04" (labeled "U7" on the PCB)
-Checked continuity across the LCD connector (while the ribbon cable was seated).

 

The next logical step would be to replace Hayato however I don't own a hot air rework station (just yet) so I can't replace him even if I had a spare.

 

If anyone can suggest some other things to be checked, I would gladly do them even if there is only a slight chance that the problem lies somewhere else

[Norrecito]

FIXED!!!

 

I have revisited this Lynx II when I was fixing another Lynx II for one of my friends and it turns out that I made such a rookie mistake: for some reason I have managed to cross-solder two capacitors which can apparently cause such screen issue.

 

After soldering the two capacitors the way it was intended, the issue is gone.

 

Lesson learned.

 

Thanks for the help everyone!