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NEC TG-16/TE/TurboDuo => TG/PCE Repair/Mod Discussion => Topic started by: jarlord on March 16, 2022, 10:52:56 PM

Title: PCE Duo -- Corrupt Audio - Caps replaced
Post by: jarlord on March 16, 2022, 10:52:56 PM

Hi everyone!
I recently got a PC Engine Duo. I replaced all capacitors and installed an RGB amp. I have two problems:

1) CD errors. Games seem to load fast -- it doesn't seem to be struggling to read or anything, but there are specific errors. For example, in Dracula X certain sound fx (like the creaking door when you first hit Run to start the game) are annoying beep sounds. So are enemy death sounds.
Also, certain cutscenes display garbage instead of the intended graphics (The end of the opening cutscene in Rondo of Blood/the mission select screen and some parts of the cutscene opening to Last Alert). These are burned CDs, but I tried two different burners, two different cd-r brands.
I don't get these kinds of errors on hucard based games at all.

2) I have a line of garbage/noise that scrolls across the screen vertically. I have Voultar's RGB amp installed.
Here's an example where you can see both issues: (the game loads slow in this video, but i had a disc door issue that I've since resolved)
https://photos.app.goo.gl/StRKTkYzx8twibnt7

I've searched the forum and found other threads with similar issues and checked for broken traces, but haven't been able to find anything. I do have a detached pad C101 (it's still connected to the trace, but lifted from the PCB)
(https://i.imgur.com/lUy2ORj.jpg)


Does anyone have any advice?

I truly appreciate it!

Thanks

Title: Re: PCE Duo -- Corrupt Audio - Caps replaced
Post by: jarlord on April 15, 2022, 12:41:47 PM

Looking like I might not get help here, but I replaced the opamps and m5205 chip but the issue with ADPCM audio persists.

I just wanna hear lil bonk speak :(

Title: Re: PCE Duo -- Corrupt Audio - Caps replaced
Post by: Keith Courage on April 15, 2022, 04:10:09 PM

ADPCM comes from the M5205 chip. However, usually these chips are not bad. The problems you describe sound like bad traces in between the M5205 chip and the Large GD chip. It's the Largest chip on the board IC501: NEC D91317GD

Unfortunately, in some cases it's actually a faulty GD chip in which case the system isn't typically worth fixing as the only place to source said chip is from another DUO or Super CD-rom2 CD drive. Plus they are a pain in the ass to change since they are so large.

One thing that puzzles me though is you mention some display garbage in Last Alert which sometimes mean bad CD system ram but that bad graphics could also have just been CD lens reading issues. So get the CD lens dialed in better and you'll know if that's a problem or not.