Turbo Duo: Voices on low volume (e.g. Gradius II announcer)

[Andy-Antsinpants]

I've been a frequent guest on NFGgames for years now. With all its great articles found on the main site and threads in the forums, I see this site as the most reliable ressource for videogame hardware related information on the whole web. Since I've run into a strange issue lately, I decided to register for the forums.

Both the Wii Virtual Console and the Youtube episodes of GameSack introuduced me to the world of NEC consoles. This led me to get my hands on a Turbo Duo last month, which came premodded with a Hu-Card region switch and RGB video out.
The console works fine so far in both Hu-Card and CD-ROM²-/Super CD-ROM²-mode - and as you can guess, me and my friends are enjoying playing on this machine a lot.

The strange issue I mentioned in the first paragraph appeared when I played the Super CD-ROM² Gradius II: Gofer no Yabou. The voice of the announcer ("Destroy them all!" "Shoot the core!" etc.) plays on just half of the volume as the rest of the background music and sound effects. During regular gameplay, he's barely noticeable. As far as I can remember, in the Wii Virtual Console port of the TG-16 Gradius II, the announcer is just as loud as the rest of the game.

I think I ran into a similar phenomenon with the in-game voices of Popful Mail, where merchants are speaking at low volume, or in-game scenes of Dragon Half. I tried some other games with digitized speech (e.g. the intro scenes of Ys Book I & II and Valis I), and they are playing just fine at the correct high volume, redbook CD soundtracks are also fine.



Do you guys know of such an issue? To me, there's just no logical explanation why this is happening, so I would appreciate your advice very much.

FYI, here are some pictures of my Turbo Duo's guts:

The capacitors don't look very suspicious, do they?


Left side: What's the deal with the loose end of the black wire? I received the Turbo Duo just like that. To prevent the wire from getting in touch with anything else, I've wrapped the end up.
Right side: The loose white wire is connected to ground. I wrapped it up, too.

When I opened the Turbo Duo, I noticed the ground wire (not related to the one above) wasn't attached to the RGB video out. I guess I may had detached it accidentally during the process. I've resoldered it to the correct pin on the DIN-8-socket. However, I had a fine connection before opening the machine and after closing it as well. The issue with the digitized speech remains.

[ApolloBoy]

The capacitors don't look very suspicious, do they?

It doesn't matter whether they look bad or not, replace them all regardless. It could very well explain the problem you're having.

[Andy-Antsinpants]

Oh well... thanks anyway.

Replacing ALL the caps is way out of my soldering skills.  In this case, I'd need somebody to do this for me, and let me guess: It won't be cheap due to all the labour needed. Are they any people in Europe offering such a service for Turbo Duos? Other locations would be fine, too, but the shipping costs may be excessive.

[Andy-Antsinpants]

Please excuse the long wait for an update.

The Turbo Duo is now under repair for full cap replacement. The kind person who's doing the labour has found one of the caps to be leaked. The cap caused damage to the circuit board underneath, up to the point where he has to trace another solder joint.

From what I know, he's a very competent fellow (he did the same job on his Amiga 1200 and does SNES mods and repairs on a regular basis) , but now a Turbo Duo circuit diagram or something similar would come in very handy. Is there any available?

I guess the PC Engine Duo's circuit diagram might be almost identical, so I would appreciate either of them.

[Fix_Metal]

Is there any available?

I don't think there's any available if nobody leaked them out.
Anyway, google is your friend! 

[Andy-Antsinpants]

I just want to let you all know the replacement of all the caps helped to solve the sound problems I had with my TurboDuo. It turned out at least four of them were pretty much shot and leaking badly.

There's one issue left, though: On some screens (e.g. dark blue backgrounds) I can see vertical lines. I asked the person who did the repair about the PCE jailbar fix:
http://shmups.system11.org/viewtopic.php?f=6&t=44262
http://pcengine.freeforums.org/jailbar-fix-t233.html
He told me that the value of the capacitor (22µF) in the 2nd link were wrong, and thus used a 22pF cap for applying the fix. Since this didn't helped me to get rid of the lines, I think 22pF isn't correct or the tutorial was misleading.

Do you know the correct value or a better tutorial for the jailbar fix?

[Andy-Antsinpants]

I'll try different cap values by myself.

In the meantime, the Turbo Duo started to have trouble reading discs. Original game discs sometimes won't load farther than the game's title screen, and burned media always cause a Load Error or Set Disc Error in the system startup screen.

According to a Duo repair guide found on the pcenginefx.com forums, it's time to recalibrate the pots on laser pickup unit or replace it for an entirely new one (HOP-M3).

I'll try both methods if necessary. Just in case, I've ordered a HOP-M3 anyway.

Please stay tuned.