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NEC TG-16/TE/TurboDuo => TG/PCE Repair/Mod Discussion => Topic started by: wolfman on December 30, 2017, 08:45:15 AM

Title: Graphics Issue - white PCE
Post by: wolfman on December 30, 2017, 08:45:15 AM

Hello,

I am having an issue here. I hoped it would go away after a re-cap, but it is still there:

(http://up.picr.de/31384588pz.jpg)
(http://up.picr.de/31384589gh.jpg)

In the first picture the darker parts of "CD Rom System" are affected.
In the second picture it is the letters in the lower part of the screen - they are hardly noticable, but actually should be greyish on a working PCE.

EDIT: I have tested alongside with my Core Grafx - this error only shows up on the white PCE.

Sound and animation are not affected (no artifacts noticeable), only this colouration issue.

Where should I look for? What is causing this?

Title: Re: Graphics Issue - white PCE
Post by: LowRes on December 30, 2017, 11:18:09 AM

I had a similar issue but much worse.  I’d be looking at the two 20256 ram chips or the HuC6270 chip.  Look for broken traces related to those 3 chips

I’m sure guys on here will have some better advice for you, but that’s where I would start.

Title: Re: Graphics Issue - white PCE
Post by: wolfman on December 31, 2017, 09:57:49 AM

I have checked all data lines from 6760 to both RAMs - there is connection on all data lines.

What else could it be?

Title: Re: Graphics Issue - white PCE
Post by: Ergot_Cholera on January 05, 2018, 06:50:29 AM

I have had a few original PC Engines with graphical issues, I fixed them by replacing the HSRM20256LM chips. Try searching SRM20256 for the part.