PC Engine DUO-R sound issues

Hi,

I have very recently bought a DUO-R with box etc.
Hu-Cards load just fine, so do CD MUSIC and CD Games. No issues with the cd unit making weird noises or not loading properly. No issues with cd music, i.e. the heat issue. But there is one problem that is pretty annoying. Some games, in particular Shinobi Hu-Card has this background interference/hiss sound. It is worst in the title screen or other parts of the game where sound is completely silent. The sound is also present in the actual game but less so as it is hidden among the sound effects and music. But you can clearly hear the sound when you die and sound/music stops.
The sound can also be described as the sound you get with bad cables cut in and out, the "bzzzt" sound but much more gentle than that. The sound is also present in Aero Blasters HU-Card but only in the intro when they present the two different space ships. It is however not present in the actual game at all no matter how hard I try to listen for it. The sound is not present at all in R-TYPE HU-Card, be it in the title screen or actual game. Some CD games can also produce the sound, for example the KONAMI logo when it animates, at the end of the animation you can slightly hear that sound and then it fades out completely. You can also hear it in Dracula X when some particular sound effects are heard, but it is very uncommon and well hidden when you actually hear it. Shinobi is by far the worst here. Why is it that some games have the sound issue louder and more often than the others? Can it also be a video issue? I discconnected the video cable and nothing has changed. Tried to swap around white/red audio cables, removed one of them and the sound is still present. Connected the white/red aucio cables to the stereo receiver that I have and the sound is still present. Tried the DUO-R on two different tv's aswell with no success of eliminating the sound. The AC adaptor and video cables are original and look to be quite new. Also I am using a step down converter as I am residing in Europe. The step down converter is also making a constant "bzzzt" sound, although it isn't loud and you can only hear it if you're close to it.

Anyone has experienced a similiar problem with PC Engine's or any other console?
What should I do? Live with it or is there a fix for it?

Thanks in advance!

This sounds like rf crossing over from the video color signals to the audio. I get this pretty bad with my 4-slot, but not as bad on the 1-slot. The 4-slot has much better video output, though. Could be the reason why this cross-over occurs more on the 4 slot is that the color signals are stronger.

The only way I know of to fix this is to put some good shielding on the audio circuitry, video circuitry, and use shielded cables for audio and video (especially composite video). If you could figure a way to isolate the video ground and the audio ground this could cause the problem to cease.

Using good thick shielded AV cables should help a lot if this is your problem (not the really thin ones that come with dvd players, tv's, etc.). If you are using "rf out" to the tv, then stop, that should help a lot too.

cheers,
-DT

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I dunno if its relevant but I have found the NEC psu's to be pretty dodgy when being used via a stepdown,they are really prone to just dying for some reason..

Why not use a PSOne psu with it and see if that's any better?When I had my Duo-R thats what it came with and I had no problems at all.

Thanks guys for replying so fast and so detailed! I really appreciate it.

Unfortunately I don't have any extra video/audio cable here that fits the DUO-R. It has the old video/audio port that the original Mega Drive had. The video/audio cable is not shielded very good I don't think. Basicly yellow/white/red plugs are connected to thin cables, the 5USD kind of cheap cable you see in stores.

Unfortunately I don't have a PS One, only the regular Playstation and the PSU in that one is inside the unit itself. I do have original NES, Sega CDX AC adaptors, but unfortunately none of them fit the DUO-R as the DUO-R AC adaptor plug is not completely round, more like elipse shaped.

The house I am testing the unit in is kind of old. Cables have not been exchanged since it was built, wich is 40 years or so. My SONY tv has intereference thanks to that. But none of my other consoles etc. have any problems at all, including older systems like SMS and NES.

I do think that the problem is related to the video as some games do not have the problem at all, and some others do but very little like Dracula X, and some very much like Shinobi.

Btw, what is the PS One AC adaptor retaded as in volts and current?

Thanks again.

Shompola said:

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Btw, what is the PS One AC adaptor retaded as in volts and current?

Thanks again.

Click to expand...

it's 7.5v and 2amps.I still have the adaptor here as when I sold it the buyer already had a spare psone adaptor and didn't need it(saved a bit of weight for postage)

The nice thing about the PSOne adaptor is it is universally compatible as it is able to input voltages from 80-240v so can be used anywhere.

Thanks.

I saw that my SEGA CDX/MULTIMEGA AC Adaptor has the same plug as the DUO-R one. Tried it and unfortunately it did not get rid of the sound the sligthest. AC Adaptor is rated at 9.5V 1.3A. DUO-R one is 9v 1A.

I doubt power supply is your problem, or your home's wiring. There are quite a few places on a board that can leak rf signals that will be heard in the audio output. Not only could it be from video (sync signals?), it also can bleed from cpu clock circuitry, bad timing crystals, etc.

I would start by making a cable that would plug into the a/v out, then VERY short into female plugs for video, left, and right. Use shielded cables and shielded rca jacks. Now you can plug any 3 cable RCA plugs in. Use heavy duty shielded cables to run from your new jacks to the tv.

It would look a lot cleaner and probably work better to mount the rca jacks in the console itself, but that requires cutting up and soldering on your PCE and I'm not sure how you feel about that.

cheers,
-DT

Could it be the PAL/NTSC or voltage barrier?

Thanks again for the replies, especially you dogtoy as I think I understand more now why some games are worse than others.

dogtoy, if I leave the problem and try to live with it, will it damage the console or games in the long run? It shouldn't, correct?

I will try my best to make a small shielded A/V cable with female contacts and see what happens next. Too bad the DUO-R is using the ancient DIN-9 pins or something like that, makes shopping for quality cables a bit harder if I don't modify them.

Hello again all of you,

Found something interesting... Lets say a game has that annoying buzz sound in the background, I soft reset the game to the PC Engine Super CD ROM boot screen with pressing RUN + SELECT BUTTON.... If I do this sometimes the annoying buzz sound will get stuck in the Super CD ROM bootscreen! aswell until I boot a new game and the game hopefully depending on how it utilizes the sound chip resets the sound completely, and if it doesn't reset it completely it will get stuck in whatever game aswell. So this is an indication of a shielding problem?

Shompola said:

Hello again all of you,

Found something interesting... Lets say a game has that annoying buzz sound in the background, I soft reset the game to the PC Engine Super CD ROM boot screen with pressing RUN + SELECT BUTTON.... If I do this sometimes the annoying buzz sound will get stuck in the Super CD ROM bootscreen! aswell until I boot a new game and the game hopefully depending on how it utilizes the sound chip resets the sound completely, and if it doesn't reset it completely it will get stuck in whatever game aswell. So this is an indication of a shielding problem?

Click to expand...

I think that is an indication of a software problem, like bad coding causing the hardware to hang if certain conditions are met. Like how win95 locks up all the time.

Another option to the shielded cable would be to add audio isolation transformers to each channel. This will remove background noise (ground loop problems, etc.) might give much better sound.

http://www.epanorama.net/documents/groundloop/audio_isolators.html

cheers,
-DT

Thanks a lot, found one of the mentioned audio isolators mentioned in the homepage you linked. Will buy it and see if it fixes the problem.

Btw I have recorded the buzz sound from Shinobi if anyone is interested.

http://www.csd.uu.se/~shma7099/pce.mp3