Problem with no audio despite all tests passing

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ChloeIsFab

New member
Hi, I wonder if you can help me please. I seem to have an issue with my dreamcast since installing the dcdigital. The audio does not play through the hdmi and if I play my dreamcast through the scart cable the audio plays but is slow, very slow. Like the audio was at 15khz instead of 44khz. All the tests pass on the test screen and I updated the firmware to the latest with no issues.I checked continuity and all the soldering was exceptionally neat with no shorts with the exception R335 and C313 on the cable side which look like they are supposed to be connected.
I have seen settings for vga and tried different combinations but still the same problem. Any ideas what might of caused it and how I could fix it please. This aside it is amazing :) I am using a mode ode as well.
http://imgur.com/00tMWc6
http://imgur.com/HQIcbt6
 
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ChloeIsFab

New member
Found the issue, the dcdigital was not mounted forward enough in my case. A millimeter or two was just enough that while the hdmi cable seemed to connect perfectly, indeed the video showed fine, it was just enough that the audio didn't connect, slight angle in the mounting perhaps or perhaps the audio pins in hdmi are slightly shorter? Anyway, I moved the dcdigital forward as far as it would go before remounting it and low and behold perfect video and sound :) Such a relief. No idea why the audio plays slow through the scart, but don't care. Hdmi only from now on :)

edit: solved the scart issue too, cheap scart cable the dc came with, tried it with a new dc certified one and it all works perfectly :)
 
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Yon702

New member
I'm going to piggy back on this if it's alright.

I'm not getting any type of audio coming out at all from the DCHDMI but I am getting from composite cables. I also checked with a multimeter and I seem to have continuity on all the audio IC pins and nothing bridging at all.

I also tried Remounting the board and I still get the same result.

Right now I ordered a mini hdmi adapter to see if that might help or not.

😬😬

http://imgur.com/a/YFkjrxl
 
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ChloeIsFab

New member
Could perhaps try to hang the ribbon cable to the side of the console as well as the dcdigital and try your hdmi cable inserted without the case in the way, it is how I caught my issue, the clearance tolerances seem very close. I'd try another mini hdmi cable if you have one too, you'd hope all these things were in spec but I find cable specs to be wildly difference between brands.
 
citrus3000psi

citrus3000psi

Administrator
Staff member
Yon702 said:
I wonder if L4 is something I might need. As now as I look at the board itself looks like I'm missing something.
Click to expand...
That is C48 and was removed for one revisions, its not needed as the ESP has onboard caps.

As for audio not working, the audio stream is encoded inside the video. So if you have video, then its not an hdmi connection. It has to be upstream, I would double check the flex connections on the audio IC chip.
 
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Burnz

New member
Hi, unfortunately I have the exact same issue. No audio despite having continuity on the pins for audio. Does anyone have a clue where certain pins from the 315-6232 have to go to the dchdmi board ? I would like to solder wires directly from the chip to the board to check if there is a problem either with the flex cable or the connector on the board itself. Thanks in advance!
 
citrus3000psi

citrus3000psi

Administrator
Staff member
There are 3 signals needed for the audio to function. The resistor pack is 47ohms as well.

1612376567638.png

The audio signals route to the HDMI Transmitter, ADAT, ABCK, ALRK

1612376667900.png
 
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Pickle Jar

New member
Yon/Burns did you figure this? I have same issue: video coming through, all hearts, no audio though HDMI. All continuities on the audio DAC and ribbon tested OK.
 
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Burnz

New member
I grabbed the digital audio lines from the adjacent IC303 and connected them to ADAT ABCK and ALRK (with 75 ohm resistors) as shown in Citrus' post. It worked! I will test everything with a new flex cable soon, but until then I'm happy that it works.
 
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Pickle Jar

New member
Good to hear!

I'm not following the diagram, is that on the DCHDMI board itself? Why would those need jumping, and with a new set of resistors? And how would a new flex cable help? I feel I'm missing something here ...

EDIT: No, I think I get it - you bypassed the whole ribbon cable to get straight into the DCHDMI? Do you mean you used a 47 ohm or is this a different 75 ohm package you jumped? Fingers crossed it's not the ribbon socket ... Don't forget to post updates! =)
 
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Pickle Jar

New member
Damn it, I was going to do a flex cable test install on a separate DC motherboard as a quick troubleshoot but they sold out since yesterday. @citrus3000psi you have any in a secret stash out back? Worth a try =)
 
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Pickle Jar

New member
UPDATE AND CLOSEOUT: Turns out I had a tiny bridge on the surface packet, between ABCK and ALRK picture left in Dan's post #9 above. Continuity along the ribbon and at the DC chips checked out all fine, it was only through "may as well check the ribbon surface packets" exercise that the bridge showed up. Audio is up and running, sounds glorious.
 
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