TG16 Region Mod question (IC based)

[Kazia]

My question: Is there any difference between doing a region mod on a USA NEC system compared to a JPN one (with the exception of grounding pin 29 on IC HUC6280 for the JPN units)?

I've been attempting to perform an IC based region mod on my Turbo Grafx 16 using the following instructions: http://mbrandel.vizionaires.net/?page_id=48

I have performed the mod before on JPN units and it worked just fine. I checked all my solder connections, wire placement, etc multiple times but I'm still having an issue.

My problem:
- some games just give me a pure black screen and won't load at all
- others will play for a few seconds or minutes and then lock up or have extreme glitches
- and one game (Don Doko Don) seems to play just fine

Strangely enough, I removed the mod from the TG16 that had the glitches and installed it in a PC Engine Duo and it worked 100% right off the bat.

I'm thinking I must have just missed something on my part when I installed it in the TG16, but I felt that it was a clean install. I checked everything multiple times and even did the mod twice with all different components yet still had the same exact issue.

I also moved around the tapping points of the +5V and Ground lines with no luck.

So I thought I'd double check with others before I go spend more time on it.

Thanks for any thoughts!

[duo_r]

No there isn't any difference besides pin 29, and the 8 data lines are reversed.

quick question - was your TG-16 docked in a CD unit or anything else in the exp port?

[Kazia]

Nope. Just the bare bones TG16 unit.

I continued to tap the +5V and ground off of different points on the pcb and had different results depending on where I tapped them.

When I tapped straight off the bottom of the power transistor (near the front of the system) I had the best results. With the points tapped here I was able to play for 5 - 10 minutes  before Legendary Axe locked up.

Not sure if this helps troubleshoot anything, but when L.Axe locked up, the picture turned black and white and split the screen into 4 equal sections - all a mirror image of where it froze. I hadn't come across that before...

I have tapped from the hucard pins with no luck. They had the most instability with playing so far.

I've modded multiple Japanese systems with absolutely no problems so I'm rather confident nothing is wrong with the work I installed. 

I'm thinking of trying to get another TG16 unit to test with and see if perhaps there is just something wrong with this particular unit I have...

[ken_cinder]

I don't know anything about this hardware, but if it's working inconsistently based on +5v tap point, then maybe you have a dry joint somewhere regarding the power input?

You can measure 5v off a hair size strand of wire with no load, but as soon as there is a load on that little tiny wire the voltage is going to take a dump. I'd check solder points on whatever handles the power in this thing.

[Kazia]

Thanks for the input guys!

Cinder - That sounds like good advice. I'll comb over everything and see what I can find.




Update - By "dry joint" do you mean a bad solder joint? So re-flowing the solder would help?

I've been going over all the power components and any spots that look odd at all and re-flowing the solder. No luck so far though. I feel like I've about got them all so far...