Dreamcast Video Issue (newb-ish)

So I decided to get into console repair lately. My main reason for this is seeing all the trashed $5 consoles at the flea market that will undoubtedly end up in a dumpster if not rescued. So I've bought a few things here and there to tinker with. Had some successes with some Gamecubes, PS1s, etc. So then comes the Dreamcast.

I bought this console for $5 bucks and it looked like total shit. It was caked in dust, the buttons were stuck, etc. Though the laser assembly looked ok from the outside, when i opened her up I found that the insides looked pretty damn good, actually. So I cleaned it up and actually got the system looking pretty nice. So I ordered a set of cables and waited. Once I received them, I hooked everything up and powered it on for it's inaugural flight and..... no video. no sound. But the system powers on and seems to be working properly otherwise. So I took it apart again to insure I didn't have any cables not hooked up, which I didn't. Then I cleaned out the AV port and what-not just to try and it still isn't working. Any ideas on how to fix this?

 

Sadly broken video DAC (digital to analog converter) is a common fault on Dreamcast consoles.

The only remedy is replace the DAC chip.

 

So is that something that can, reasonably, be done? I searched for it online and found little information. And by reasonably, I mean financially and practically.

Thanks!

 

Because mostly people don't know what it is, or how to fix. They only know that it gives you a Dreamcast which has sound on the sound leads but no video output on the video leads.

Unfortunately the video output chip is a proprietary part which is used only on the Dreamcast, Naomi or Atomiswave hardware (stuff that is Dreamcast based).

 

Ok. I gotcha. I had a feeling it was going to be a situation like that. Well I suppose I'll just hang on to her, maybe I'll find a Dreamcast with a busted shell or something. To the next project I go...

Thanks!

 

There is hope
Try another cable if you can; I have 3 dreamcast´s and sometimes I also have the same problem..

Check if the cable is connected correct also dreamcast is picky in the order how you connect the cables.
Power first then Video or the other way don´t remember exact. (Best do not connected video to TV )
When you connect the video to your tv first it can short-circuit....

My First dreamcast is open for the exact same reason... at first i thought lose connections...
But when i got another dreamcast and that one gave my the same problem, I tried a new video cable; and Picture and sound..
Few months later i got me another dreamcast same problem

But the 2 are running fine now..
So i hope its not DAC chip but thats what happens when you connect the video first to your TV....

 

Yeah I read something about how the order has to be exact. I'll try it again, I actually received a second cable to make this very attempt. So we'll see how it goes. But I will DEFINITELY keep the order of the cables in mind the next time I hook up a DC.

What I find quite humorous, is I looked for parts online, and i found Dreamcast motherboards (not my version, unfortunately) for half the price of just the DAC chip. So I guess there's always that option

Thank you once again everyone!

 

If you want to prevent that from happening, keep in mind that the LAST THING you plug is the wall outlet.

These things blow because the tip of the barrel plug (RCA) connects before the ground lane sending a jolt of voltage through the VIDEO output DAC. It happens on other systems too, like the PS3 and the original 2006 Wii to mention some.

 

Also, make sure the fan does spin and that the three pins are correctly connected. The third fan pin is used to sense that it spins at the right speed, if it doesn't, the DC becomes unresponsive, with a black screen and no sound. A busted video DAC should not mean no audio right? Unless both DAC are blown/on the same chip.

It's the same symptoms for some PSU troubles too.

 

Early Dreamcast units have a thermal fuse attached to the heatpipe. If it melts the clock generator is inhibited and you will have no system activity.

The OP said the thing make noises on the drive as if reading the disc. That does not happen if the master clock oscillator is inhibited.

On newer units it keeps monitoring if the fan is spinning. Should it stop for longer than two seconds the master clock is inhibited (that is why it "dies" in the way you said, FamilyGuy).

 

I like the information about the fan, and I"ll check it, but as I_oliveira said, I think I'm good on that (the console sounds like it's working) - but it's good to know down the road. Now, I am a little confused and I need some clairty. So exactly what order am I supposed to hook this thing up? I_oliveira said the last thing to plug in is the wall outlet. Yet, earlier dcnigma said, "When you connect the video to your tv first it can short-circuit". Maybe I'm reading that incorrectly, but it seems like I've been told two different things here. So which is it?

And once again, thank you guys for the responses.

 

He said "If you connect the video plug first it can short circuit". And technically he is right. But he did not explain that for it to happen you need to have the system plugged to the wall outlet (so sparking inside the plug can happen).

I suggest you connect the video lead first to the TV and only then connect the video lead to the Dreamcast console connector. That will reduce the possibility of sparking to the shielding contacts at the edge of the plug connector, greatly reducing the chance of damages.

It's a lowercase L ... sorry to be confusing.

 

If the DAC is dead, you could try OzOnE's universal HDMI mod board on it once it is released. It taps into the digital audio/video signals before they hit the DAC. That could at least test if the issue is just a dead DAC or if the problem lies beyond the DAC. On the plus side, you would get HDMI out.

 

Once again guys, thanks a lot.

For some reason, I haven't been getting my updates when getting replies; not sure why.

Anyways, l_oliveira thanks for clarifying that. I'll definitely keep that info in mind.

And MonkeyBoyJoey, do you happen to have a link for more information on this? I really don't want to give up on this Dreamcast (no console gets left behind haha), and the most cost-efficient means to fix it I've found is to replace the entire motherboard (I'm seeing them for about 15 shipped on ebay - though not my version). Ironically, the DAC itself costs more than a new console. So if this is a possible fix (and a fun sounding project), I'm definitely interested.

 

This thread is where you'll want to be for the universal HDMI mod board. It isn't out yet but pre-orders are being considered. If I had to guess, it's coming out later this year or sometime next year.

OzOnE also has a youtube channel where he has recorded the board in action on the N64, GameCube, and DC. This link will take you directly to his DC HDMI Tests playlist (some of the videos are 60FPS so use a compatible browser for best quality): https://www.youtube.com/playlist?list=PLrfCc0dbhppwvhcKyiHTcIhBM9eN21Vbg

EDIT: If you don't want to wait, there is a digital audio mod for the DC. If you get audio through TOSLINK or Digital Coaxial Audio (S/PDIF), either the DAC is dead or something on the way to the AV connector is broken. Here's a guide for that: http://gamesx.com/wiki/doku.php?id=av:dreamcastda

 

UPDATE: Well all the DAC chips I found were crazy expensive (I could easily acquire a working console for the same price). So instead I patiently waited for a version 1 motherboard to hit ebay, it finally did, and I bought it. After installing it, I hooked up the console according to your instructions and was very pleased to find I'm now getting video and sound. So thank you guys so much for advising me on this.

Though, hilariously, I realized that I have failed to purchase a controller since beginning this project (and the battery for the internal clock is dead) so I haven't been able to test the laser or controller ports. But, the disc is spinning perfectly and I'm definitely hearing the sounds of a working console. I just can't see if it loads since it starts on the "Set the Time/Date" screen haha. But regardless, my issue was resolved.

Thanks you guys so much for your help