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NEC TG-16/TE/TurboDuo => TG/PCE Repair/Mod Discussion => Topic started by: wolfman on July 09, 2014, 11:31:00 AM

Title: Coregrafx Sound Issue
Post by: wolfman on July 09, 2014, 11:31:00 AM
Had to switch from my LT to my region-modded Corgrafx due to power problems  :?

From my Coregrafx I don´t get any sound...when I turn up my stereo all the way I can faintly hear game sounds...so at least something is coming trough.

Where would I have to look out for on the board? I can´t seem to find a chart or a hint on sound repairs for this model...

This is my current setup:

-Coregrafx with original AV-Cable ---> Cinch Adapter ---> Stereo Amplifier

Any hints/tips?

Title: Re: Coregrafx Sound Issue
Post by: thesteve on July 09, 2014, 12:47:27 PM
For starters on the CG sound issues are not common
Further is the sound missing from cards or CD games?
Does the sound work without the CD hardware (IFU/SCDR2)?
Title: Re: Coregrafx Sound Issue
Post by: wolfman on July 09, 2014, 07:18:43 PM
For starters on the CG sound issues are not common
Further is the sound missing from cards or CD games?
Does the sound work without the CD hardware (IFU/SCDR2)?

This is what I tested yesterday:

-Coregrafx is in my WORKING IFU, CDROM2 is also working correctly, so I can sort that out. Since I modded my IFU in a way that sound has to come through the output of the Coregrafx/PCE/LT, I can assure that its not briefcase-related.
-Sound issue came up with a Card game. I didn´t test a CD game yet on the Coregrafx (but it works fine with LT on the same setup).

Do you think its the DIN jack or cable? I get picture through the AV cable, and very very very faint sound when I turn up my stereo all the way. Will test another input today on my stereo...but since sound doesn´t come as well on my TV when I plug it in directly, I am somewhat puzzled as to what it could be......

Will test the missing setups from your last post today and let you know.

Any further hint perhaps that I could look for too? Is there a chance that there´s trouble with the region mod (although it works with US/JP when I flip the switch)?
Title: Re: Coregrafx Sound Issue
Post by: pulstar on July 09, 2014, 09:07:11 PM
It's not common on a Coregrafx system, but it could be the electrolytics in the audio section (or the amp). I'd check the AV cable first though.
Title: Re: Coregrafx Sound Issue
Post by: wolfman on July 09, 2014, 09:13:40 PM
It's not common on a Coregrafx system, but it could be the electrolytics in the audio section (or the amp). I'd check the AV cable first though.

Where´s the audio section on the board located?
Title: Re: Coregrafx Sound Issue
Post by: wolfman on July 10, 2014, 06:01:11 AM
For starters on the CG sound issues are not common
Further is the sound missing from cards or CD games?
Does the sound work without the CD hardware (IFU/SCDR2)?

So, I checked everything and found the following:

-ONLY IFU puts out CD sound thru its connectors, it doesn´t pass Sound thru Coregrafx/AV out
-L/R audio doesn´t seem to get to DIN connector on Coregrafx (no chiptune).
-I only get sound from Coregrafx directly when I connect L/R audio from expansion port to DIN connector (only chiptune, NO CD sound however).

So what could be the reason? The DIN connector seems fine, all contacts seem fine (otherwise there would be no output at all...)...

Caps? A defunct chip or controller? Bad traces? Where should I look for?

Title: Re: Coregrafx Sound Issue
Post by: thesteve on July 10, 2014, 06:24:32 AM
ok no need to test other setups (was just covering my bases)
the CG DIN will never pass CDA
DIN and EX Bus output the same sound (chip tunes only)
full sound must come from the IFU directly, as it mixes the chiptunes into its sound circuits
Title: Re: Coregrafx Sound Issue
Post by: wolfman on July 10, 2014, 06:30:52 AM
ok no need to test other setups (was just covering my bases)
the CG DIN will never pass CDA
DIN and EX Bus output the same sound (chip tunes only)
full sound must come from the IFU directly, as it mixes the chiptunes into its sound circuits

Thanks for the hint on the IFU,  this is new to me. However my LT mixes Chiptunes AND CD sound, putting it all out thru headphone jack! This way I got all sound on my stereo...so this is impossible with Coregrafx???

The strange thing is - without a direct bridge from the expansion bus to DIN I wouldn´t even get chiptunes! Where should I look for damages on the board? Or what could it be?
Title: Re: Coregrafx Sound Issue
Post by: thesteve on July 10, 2014, 06:43:14 AM
are you saying your not getting chip tunes to the ex bus or the din?
Title: Re: Coregrafx Sound Issue
Post by: wolfman on July 10, 2014, 06:48:04 AM
are you saying your not getting chip tunes to the ex bus or the din?

WITHOUT modification I DON´T get chiptunes from DIN on Coregrafx, BUT on IFU thru EX. Thats what puzzles me...
Title: Re: Coregrafx Sound Issue
Post by: thesteve on July 10, 2014, 06:52:04 AM
if its there at the IFU then its usable by using IFU outputs
not sure if they have anything between the DIN and BUS on the CG
Title: Re: Coregrafx Sound Issue
Post by: wolfman on July 10, 2014, 06:56:21 AM
if its there at the IFU then its usable by using IFU outputs
not sure if they have anything between the DIN and BUS on the CG

Do you know if there is any board layout on the interweb? Tried searching but couldn´t find anything...don´t want to remove the whole shield from the pcb underside just to look where traces go...
Title: Re: Coregrafx Sound Issue
Post by: thesteve on July 10, 2014, 07:24:02 AM
I don't know of any layout info out there
I'd have to remove the shield and trace it
Title: Re: Coregrafx Sound Issue
Post by: Fidde_se on July 10, 2014, 09:30:50 PM
And even if there would be and decent signal at the CGs DIN
its still only mono for ADPCM and CDA as only pin B1 is sending that
those signals back from the IFU.
Title: Re: Coregrafx Sound Issue
Post by: wolfman on July 10, 2014, 09:36:04 PM
And even if there would be and decent signal at the CGs DIN
its still only mono for ADPCM and CDA as only pin B1 is sending that
those signals back from the IFU.

So there should be CDA on the Coregrafx? I am confused right now...
Title: Re: Coregrafx Sound Issue
Post by: thesteve on July 11, 2014, 03:24:16 AM
Wow
Just checked, and it does seem to work from CG DIN
Title: Re: Coregrafx Sound Issue
Post by: Fidde_se on July 11, 2014, 04:54:28 AM
Yes it does, the IFU is just a big audio mixer really, the game sound is mixed with the incoming mono signal from the IFU containing the ADPCM and CDA somewhere around its amps, it even sends it out on the RF on the white PCE
Title: Re: Coregrafx Sound Issue
Post by: wolfman on July 11, 2014, 05:02:13 AM
Yes it does, the IFU is just a big audio mixer really, the game sound is mixed with the insamling mono signal from the IFU containing the ADPCM and CDA somewhere around its apps, it even sends it out on the RF on the white PCE

Ok, so how is it mixed INSIDE the Coregrafx? As I don´t get CD sound BUT chiptune, there must be some mixer inside the CG, as there is a SND IN on the Exp connector. From there I guess it is mixed in relation to chiptune, right?

So where would I have to look for? I guess there must be some kind of bad trace or broken connection somewhere...
Title: Re: Coregrafx Sound Issue
Post by: turbokon on July 11, 2014, 05:18:17 AM
I know for the tgcd and tg16 setup,  you can't get sound from ADPCM and CDA coming thru on the tg16 sound output itself.  I had tested it a component vid/stereo modded tg16 deck.
Title: Re: Coregrafx Sound Issue
Post by: wolfman on July 11, 2014, 05:58:44 AM
Ok, I have to correct myself on something:

I DO get CDAUDIO when I play a pure audio CD (very very faint, have to crank up volume high), but I DON´T any kind of audio from a CD GAME!

I tried with Lords of the rising sun. There is NO SOUND whatsover from the CG.

It must be CG-related, since it works with my LT. Looks like the mixing circuit or whatever there is has a malfunction.
Title: Re: Coregrafx Sound Issue
Post by: Fidde_se on July 12, 2014, 04:55:06 AM
1. So on the LT you get them all? Game sound, ADPCM and CDA.

2. CG you get game sound, ADPCM (weak?) and no CDA

3. CG with only audio CD you get faint CDA.
Title: Re: Coregrafx Sound Issue
Post by: wolfman on July 12, 2014, 05:57:12 AM
1. So on the LT you get them all? Game sound, ADPCM and CDA.

2. CG you get game sound, ADPCM (weak?) and no CDA

3. CG with only audio CD you get faint CDA.

Ok, I have tested it again now:


PCE LT

-PSG sounds from LT headphone jack seems to be stereo from what I hear
-All sounds coming from CDROM2 via LT headphone jack are mixed together and play fine


IFU

-all sounds from CDROM2 are mixed togehter and come out thru IFU Audio ports
-PSG sounds come thru as well and seem to be stereo from what I hear


CG

-via AV DIN cable I only get PSG in good quality and probably in stereo from what I hear
-CD-Audio faintly audible when stereo is turned up in volume all way, so actually it should be regarded to as "no sound".
-NO ADPCM or CD-ingame audio audible at all (tested with ICFTD - no sounds, just a little noise)
-with Output jacks from IFU ALL SOUNDS are audible and mixed like in the above example like I use my LT.


Hope this helps. I already have a conversation with Charles Macdonald on this, I am waiting for his response as well.
Title: Re: Coregrafx Sound Issue
Post by: Fidde_se on July 12, 2014, 10:16:21 AM
Check pin B1 on the ext connector on the CG (middle row)
And were it goes, this is where it comes from, and somewhere
 from there to the DIN the problem lies.
Title: Re: Coregrafx Sound Issue
Post by: thesteve on July 12, 2014, 10:31:34 AM
can someone check if the CDA works on the RF out of the TG-CD setup?
Title: Re: Coregrafx Sound Issue
Post by: Fidde_se on July 12, 2014, 11:56:24 PM
Keith maybe? I can only confirm that it does on the briefcase setup.

One day I might even make a EXT extender cable to run TGs in the IFU, RAU-30 should work to some extent, but surprise it's nowhere near full pin, not even video signals are sent threw if I remember correctly.
Title: Re: Coregrafx Sound Issue
Post by: Fidde_se on July 13, 2014, 12:04:30 AM
Oh, and any one listening out there donate me non working white PCE and CoreGrafx so I can do PCB layouts of them and lift and measure every SMD capacitor =)