Dreamcast lights up, motor spindles, seems to work... but no audio or video

Hi guys,

I have disassembled a Dreamcast in order to clean it up thoroughly. The case was washed and the motherboard cleaned with anti-static brushes for dust and such. However when I have assembled it again, there is no audio/video out.

The cable worked before, so I discard it (though I'm going to test it on another DC), also I switch it on without a controller but I know that is not the fault (also, I'm going to attach one just to see if the game loads up and shows something on the VMS).

While I'm at it I wonder if any of you have had this problem or if there is something obvious with the AV part that I'm missing.

Thanks!

 

Mixed up the long and short bolts for the Drive assembly?!

...or you forgot to plug in the fan's cable. (which would also make it auto-shutdown in a short time)

 

If I mixed them I could have smashed tracks on the motherboard which would explain a lot... however when I disassemble a machine I always tag the bolts carefully and group them. I'll have to recheck, though.

The second is not the reason. I forgot indeed to reattach the fan but did not worry because I tested the DC without the upper half of the case, I just pushed manually the lever which tells the console that the lid is down. Then I attached the fan, just to check that the DC was not complaining about it and it still does the same.

 

I don't understand how people manage to put the wrong screws in around the drive array it's really not that difficult. Black screws are only found round the edge of the shielding and for screwing the plastic case together, the four long non-black screws are only for the controller ports.

Might i suggest that the AV port is loose or you broke the drive connector on the motherboard, does the fan spin and if you leave it for 30-60 seconds does anything pop up on the screen then?

 

sometimes it may be a power supply with a bad connection i once had a dreamcast with the same problem, and was that the power supply pins weren't making good contact with the metal bars in the sockets, it could be that too.

 

As I thought, screws are not the problem and the tracks on the PCB seem perfectly fit. I haven't had time to look at the DC but I know these facts:

-The GD seems to work correctly. I don't find my VMU but a colleague will lend me his to test.
-The fan spins without problem.

I took off the drive assembly and reattached it. The console behaves the same, I doubt it's the drive connector.

So I'll check closely the AV-Port and will detach and reattach the power supply board, just to test if it's that.

@Hedgeyourbets: I'll try to keep it a couple of minutes on. What would it indicate if it behaves like you say? What will I see on screen? It's some sort of Power-On self test?

 

If you have a black screen for about a minute followed by the dreamcast swirl which just sticks there, it means that there's an issue communicating with the GD-rom drive, whether it is the drive connector itself or the traces leading to it

 

Going to check that as soon as I'm at home. Thanks!

 

After taking out the power daughterboard and cleaning the contacts, I had no changes. So I disassembled the DC entirely and assembled it again carefully and it simply worked! My guess is that somehow the AV port was bent or something (it was rough to take the motherboard out again, and the first time around it was easy). So if you ever do as I, be extra careful when putting together the machine.

Now, I'm going to desolder the CMOS battery and replace it with a vertical socket. I've found some rechargeable replacements and the socket will allow me to replace the battery in the future with no desoldering.

Time to test that SD-Card adapter at last...

 

Final update on this issue! I got the drive assembly out and connected the machine and like Hedgeyourbets said, the DC logo appeared on screen. So I was sure that it was nothing with the video AND nothing with the drive itself... so...

It was one of the screws on the left side of the drive. It seems that it was too much screwed and somehow lifted slightly the connector linking the drive with the motherboard. That was it. The machine did make contact with the drive but not enough.

Hope this can help anybody with a problem like this.