An odd Duo audio issue....

[Platinumfungi]

I'm having an audio issue on a PC Engine Duo that I don't understand...  I've gone through the usual troubleshooting methods I know of with no luck so far. I've replaced all caps on the pcb except the two dark blue through hole caps that are just in front of the cd-rom area (does anyone know what those two caps control?). I've replaced the laser. I've checked my work for errors. I've looked for any signs of damage at all but I can't find anything. 

The testing I've done shows that it is a consistent issue on specific sections of cd-rom games audio. It's not random at all. There is some common thread that links the problems in these cd games audio. 

Here are some examples of games that I've tested multiple times:

- On the triple CD disc of Bonk's Adv, Bonk's Revenge, and Gate of Thunder: Bonk 1 and 2 work 100%. Gate of Thunder has absolutely no background music but all sound effects play fine.

- Ys III: plays the town (where you start) music but no other music including title screen music. All sound effects work properly.

- Altered Beast: No title screen music but level music and sound effects play fine.

- Most games I try in general have absolutely no background audio but the sound effects play fine.

All hucards play 100%.  I've wondered about it being a Super CD2 or other specific type of cd issue but it varies within the disc type so I don't think there is a link there.

Could this be a dead chip?  Has anyone mapped out a Duo to show which caps, chips, etc relate to the various areas?  Any help is really appreciated.  I'm stumped for now...

I don't understand how some cd games audio can always play while others never play and some games only play selective sections.

[SignOfZeta]

It sounds like you have no CD audio. I can't remember exactly, but usually the town music in an Y's game is chip tune, and the outside areas and dungeons are CD. Bonk 1 and 2 play fine off the pack-in GoT disc because they have no CD audio, either to HuCards. GoT has no music because its all CD music, but the FX are stored in memory.

I wonder, maybe, about the condition of the little wires than connect the CDROM to the board. They are pretty easy to tear. More than likely though its an issue with the capacitors you replaced. Its probably a problem related to the CD audio as an analog signal, after it leaves the DAC.

[Black Tiger]

Are you playing original CDs or CDR's?

[Platinumfungi]

SoZ - Roger that. I'll check it out. I appreciate the wisdom. I knew there had to be some connection with the Bonk games and Ys town music and now I know.

Black Tiger - All games are originals.  Any thoughts?

[Black Tiger]

My Duo RX had problems playing the CD audio in the patched Ys IV. It soon began to have trouble running original discs until it stopped loading games altogether.

I installed a new laser lens and it then worked better than new.

[Platinumfungi]

Black Tiger - I have heard similar stories about Duos in general suddenly having issues reading originals after someone tried other cds and so I have avoided them like the plague.  I would think it would just be something about the calibration of the laser, and should be fixable, but I don't care to try at the moment.

SoZ - I just swapped the entire cd-rom unit (laser, motor, wires, etc.) with one that I know is working properly and it did not fix the audio issue. So your best bet sounds like it's correct. Has anyone mapped out a Duo to determine which pcb parts relate to hucards and which relate to the cdrom?  I can find a lot of talk, but no solid evidence...

[SNKNostalgia]

My Duo RX had problems playing the CD audio in the patched Ys IV. It soon began to have trouble running original discs until it stopped loading games altogether.

I installed a new laser lens and it then worked better than new.

Yep, my regular Duo is starting to do this crap also. It is having problems with some burns and my Gate of Thunder can take a while to load up in the 4 in 1 disc. It just recently started doing this. I guess from trying out too many burn games on the system. The trick is to make sure you have a good ISO to burn from and record them slow on really good Japanese made CD-R media. I downloaded too many not so great working games and used my laptop at 4x instead of my old Win 98 computer with 1x. I learned my lesson. Getting me a new Hop-M3 this week. My system still runs decent CD-Rom wise but could run better.

[Platinumfungi]

Is is possible to adjust the current laser you have instead of buying a new one?  I just assumed that the laser must get out of alignment (or whatever you call it) trying to read the different media type. Does it really damage it? 

[SignOfZeta]

It seems really unlucky to me that a CD-R could actually permanently damage the laser.

[SNKNostalgia]

Really the best thing to do is adjust the POT screw under the laser clockwise a little till CD-R games work the best you can get it. After that it shouldn't be a problem. This is the same method to get a Sega Saturn to read CD-RW discs. I ordered 2 HOP-M3 lasers for longer duration of my Duo. It is cheaper to order like 4 replacement lenses than it is to get another Duo. This way I can adjust the current laser all I want and not worry if it is completely messed up.

I can't even get Xak III to work with the English translation at all. It sounds bad when I get to the title screen and then doesn't go from there at all. The Ys 4 disc with translation seems to work 100%.

[nat]

I can't even get Xak III to work with the English translation at all. It sounds bad when I get to the title screen and then doesn't go from there at all.

I have the exact same problem and I've tried it on the three Turbo systems I own (SuperGrafx w/CDROM^2, TurboGrafx-CD, and TurboDuo). It always hangs after the title screen.

Has anyone had this patch work for them successfully on the real hardware?