PC Engine Duo Video problems with video

[twoquickcapri]

Hi I have a Duo that has some video problems with Super CD-ROM² and Arcade CD-ROM². Works fine with card and normal CD-ROM² games.

You can see it in this video.

[Zeon]

What an unusual problem. Based on your description of the problem, I would guess that the built in extra ram used for the super cd-rom and arcade games is bad. However if the ram in general was bad i would think the game would be experiencing all sorts of erratic behavior, unless there is a specific ram module solely responsible for holding video data in arcade and super cd-rom games.

Are the graphical glitches 100% consistent, or do they vary each time you play the game? By this i mean by both when they happen and how the graphics are glitched up each time.

You are playing 100% legit pressed games, correct? From the video it looked like the games were legit. A crappy bootleg, even a pressed one, will most certainly have such problems.

How many arcade and super cd-rom games do you have? Have you tried them all? Finally, try playing super cd-rom games without the arcade card and see if this fixes the problem. If so, then the arcade card has gone bad, but try cleaning it first.

[twoquickcapri]

Yes the game are legit and glitches are consistent. And the glitches are the same with the arcade card in or out. I did try and burned copy of Popful Mail and got the same glitches.

The only arcade game I have is Fatal Fury 2. With the arcade card in it doesn't load. Without I get a screen that says something about needing an arcade card.

I did try a few more of my game to test the problem.

Games with glitches:
Fatal Fury 2
Macross: Eternal Love Song
Popful Mail
4 In 1 Turbo Duo Super CD

Without:
Wonder Boy III:Monster Lair
Cyber Knight
Heavy Unit
Neutopia
Street Fighter II Champion Edition
Buster Bros.
Fighting Street
It Came From the Desert
Monster Lair
The Addams Family
Valis II
Ys Book I & II

[esteban]

Yes the game are legit and glitches are consistent. And the glitches are the same with the arcade card in or out. I did try and burned copy of Popful Mail and got the same glitches. ...

These glitches have happened to me, as well. It's time for Spring Cleaning:
1. Seated on the floor, close your eyes, and take a deep breath.
2. Open a sealed copy of China Warrior, taking care not to open the wrong side (where the styrofoam is).
3. Eyes still closed, remove the jewel box and open it.
4. Take a deep breath, noting the exquisite, nuanced bouquet that wafts up from a fresh HuCard.
5. You are done. You have refreshed your soul and collected your thoughts. Now you can solve any problem.

[Charlie]

If you assume the problem is in the video ram (U106), and you are guessing the problem is capacitor related (for obvious historic reasons), the supect caps are C631 (which is actually one of the audio caps, but it's on the same power source), C310, C135 and C139 as part of the power supply.  Also, C962 is a video coupling cap to pin 3 of the AV out connector.  You might try replacing all of these as a relatively easy first step.


Good luck
Charlie

[twoquickcapri]

If you assume the problem is in the video ram (U106), and you are guessing the problem is capacitor related (for obvious historic reasons), the supect caps are C631 (which is actually one of the audio caps, but it's on the same power source), C310, C135 and C139 as part of the power supply.  Also, C962 is a video coupling cap to pin 3 of the AV out connector.  You might try replacing all of these as a relatively easy first step.

Thank you. This was the info I was looking for. I'm going to try replacing the caps first. I was just going to start with a total cap replacement first but I will try the caps you listed first.

[twoquickcapri]

If you assume the problem is in the video ram (U106), and you are guessing the problem is capacitor related (for obvious historic reasons), the supect caps are C631 (which is actually one of the audio caps, but it's on the same power source), C310, C135 and C139 as part of the power supply.  Also, C962 is a video coupling cap to pin 3 of the AV out connector.  You might try replacing all of these as a relatively easy first step.

Where is C139. I can seem to find it.

[twoquickcapri]

Well I replaced all the caps suggested by charlie minus c139. Because it one of those small square caps and doesn't an uf number on it. I guess I'm going to try the ram next. 

[Charlie]

Sorry, typo, C139 is C149;  it's 47uf @ 6V, same as C135.

Also, although U106 is the Video Ram, it's not the source of the video signal.  That signal is generated by U903 (HUC6260) at  pins 20, 26, 33 and 40.  These guys are mixed in a set of transistor drivers/amps, before being applied to C962 (which you have changed).  U903 and these transistors use a different 5V supply than the video RAM and it's associated caps (also which you have previously changed).  So, I would try this set of caps next:
C312 and C961.

Finally, U903 also has a bunch of .22 caps on it, but since I don't know how the insides of this ASIC are configured, I don't know if they are significant. They are C953 through C960.   

It is really difficult to diagnose this without more in depth investigation, like with an Oscilloscope; also, we are still assuming that the silicon is OK and that the problem is related to caps....for which we have only legacy evidence.

Good luck, again!

Charlie

[twoquickcapri]

So I made a little progress with the duo. After replacing all the caps suggested in this topic I got an idea. I put in my cd 2.1 card to see if would still boot up 3.0 or 2.1. Well it boot up as a 2.1 system and wouldn't play 3.0 games at all. So next I put in my Arcade Pro card and guest what with the Arcade Pro card in it works great. But I still wouldn't call this a fix.

[kattare]

Are you saying that with the Arcade Card you can play Super CD's without the issue?

My understanding is that the Arcade Card Pro includes the system software + a bunch of extra RAM, and by popping it in, you're bypassing the use of the onboard system software and RAM, so that'd point at an issue with the onboard system RAM?

Good to know you can use the Arcade Card to still play!

[twoquickcapri]

Yes with a Arcade Card Pro card it works with no problem. And Yes the Pro has the system 3.0 ram with Arcade ram too.

[ceti alpha]

Are you saying that with the Arcade Card you can play Super CD's without the issue?

My understanding is that the Arcade Card Pro includes the system software + a bunch of extra RAM, and by popping it in, you're bypassing the use of the onboard system software and RAM, so that'd point at an issue with the onboard system RAM?

That's really interesting, actually. I didn't realize that the Arcade Card bypasses the onboard RAM.