CD-ROM audio crackles with PC Engine RGB mod

Hey guys. Ages ago, you guys helped me RGB mod my PC Engine but at the time, I didn't have a working CD-ROM2 unit to try playing some CD games on it. Now I've got one, but I'm having a weird issue with the audio. When I play a Hu-card game, the audio sounds fine, but when I play a CD-ROM game, the audio is nothing but quiet crackles. The odd thing is, this seems to only effect the CD audio (i.e recorded voices, CD music etc) as effects that are generated by the PC Engine itself (i.e some music) sound normal. It's not like there's something wrong with my hardware, as when I plug the console in normally with some RCA cables via the interface unit, everything sounds normal. Any idea what the cause of this might be?

 

Have you tried to output sound from the mini jack on the CD rom? If the music is normal then there's probably something wrong with your RGB mod.
Check the cable first, if it's not that then double check the audio left-right soldering points. But since the sound from HU Cards is ok, I guess it's the connection between CD Rom and IFU that might be the culprit.
But first be sure that the CD rom output sound correctly by checking the mini jack.

 

Cable seems to be fine, I've got continuity from both ends of it.

You mean the headphone jack right? Yep, CD music comes out normally when I plug some headphones into them. For my soldering points, is it possible to be in this situation by soldering to the wrong points or something? Even though audio on the Hu-cards is fine? Would there still be a problem between the CDROM and the IFU if there's no problems when I plug some RCA cables into it's audio plugs?

 

Since audio comes out fine from the headphone jack, and since it comes out fine from the PC Engine as well, then it has to be a problem between the CD Rom unit and the IFU. Try to clean the connectors, remove dusts if any, might also help to clean inside, see if it helps.

 

Cleaned the pins on the PC Engine itself, as well as the contacts on the CD-ROM unit and the CDROM connector on the IFU and also compressed aired the expansion connector on the IFU. Didn't help :\

 

Do you think moving the rgb amp to the ifu would help? That way, I could just use the existing audio, which I know works. You you think I'd be able to connect the red green and blue signals up to some component connectors to get component out, or do you need to do something to the signal to get component out? Or maybe modify the cable so it outputs audio from the ifu instead of the pc engine itself?

 

Could be a grounding/audio interference issue, I don't have any hands on experience of the IFU.