TG16 color/graphic woes.

[DeshDildo]

Hello!  Let me start by introducing myself.  I am an avid retro gamer and collect for many old systems.  My friends and I even have a YouTube channel dedicated to our travels (Cartridge Crusaders).  I am no stranger to a soldering iron or modifying/ repairing old consoles.  I purchased a very nice TurboGrafx 16 in the box about a year ago.  I instantly fell in love and I can honestly say it has certainly become one of my favorite consoles to play.

I recently decided to start getting into some of the disc based games so I purchased a CD dock and power supply and got a heck of a deal on a PC Engine CD ROM2 drive.  Due to the astronomical prices for North American 3.0 Super System cards I decided to buy the Japanese counterpart at a fraction of the price and region mod a TG16.  This, however, put me in a dilemma.  I did not want to mod or in any way hack up my pristine console.  I decided to search for a cheap unit online that I didn't care about modding.

I finally found a broken TG16 console only for a reasonable price.  When I first received the console I tried to fire it and got nothing but a blank white or solid color screen.  I made up my own cleaning tool and went to work cleaning the cart slot contacts.  This at least allowed the games to start for a moment (I had sound and garbled graphics) but then nothing.  I opened the console and saw no visible signs of damage.  I started by ohlming out all of the cartridge contacts and checking continuity from them to the board.  This required me to remove the cartridge slot all together to follow the traces that went under it.  Everything checked out OK so I reinstalled the cartridge slot.  The only issue I had with this was that the pad on the bottom side of the board for the ground pin came up when I desoldered the connector.  No big deal I just ran a new trace wire to a good ground.  After this I decided to test the console again.  Now, I have some more signs of life!  The games all load immediately but the colors are all off and some games have garbled/ incomplete graphics. 

It doesn't matter whether I use the RF or A/V through the CD dock the result is the same.  I assume it is some sort of RAM issue but I don't know for sure as I am unfamiliar with the inner workings of the TG16.  Please help.  I have included pictures of the glitch.  Any information to steer me in the right direction would be much appreciated.  Thank you!

[EvilEvoIX]

Looks rough, I hope it is an easy fix.

[thesteve]

the service manual has been found and uploaded
seek it here (search)

[DeshDildo]

Thank you thesteve I didn't know that was available when I did my original searches related to this problem.  I found the link for the PDF download but it won't let me get to the download page.  I have made a post in that thread to see if I can get my hands on a copy of the service manual.

[Bernie]

Here it is hosted on tg16.com https://archives.tg-16.com/MISC/TurboGrafx-16-Service-Manual.pdf

And here it is hosted on my Dropbox Turbo share folder.  https://www.dropbox.com/s/gqdxhq9tw67il28/TurboGrafx-16-Service-Manual.pdf

[Tatsujin]

TG16 on LSD.

[DeshDildo]

Bernie, thank you so much!

[Psycho Punch]

TG16 on LSD.

Xak's Adventure.

[NightWolve]

Same thing eventually happened to the TurboGrafx-16 that I had won from a contest. I had upgraded to a Turbo Duo by then, so no loss, but I didn't understand why it happened cause I took good care of my consoles.

[thesteve]

its likely either bad video ram, or a bad trace near the huc6270