Dreamcast Dreamcast no video signal and no sound (its really not the AV cable)

[venom]

Okay so I have stumbled on this broken Dreamcast. I am completely new to the Dreamcast but I like a challenge

I received it without a PSU, so I was like, no wonder it won't boot... dUh...

anyway I attached an ATX PSU and voltage checkout 3.3v 5v and 12v. The LED lights up and the fan starts to blow. When I insert a disc and turn the lid switch it starts to rotate, it sounds like it is reading.

On further inspection I noticed the AV port was damaged.... darn. I decided that it would be easiest to check if the Dreamcast is working to solder a wire to the composite pin (13) and a wire to the audio pins (2 & 3).

Now when I power up the console it doesn't give a video signal and it will not output any sound.

While googling for answers I found some topics where people damaged their motherboard by using the longer screws from the controller ports for the GD-rom. I can't find this type of damage on this motherboard.

I am really not sure what could be a next step to check.

 

[Anthony817]

I know you had to solder directly to the AV pins. But even when running from cable it is good to make sure the AV cable is snugly plugged into the port on the back of the Dreamcast. Even many of us have thought it was fully plugged in but was not making connection and then after pressing a bit more firmly it would work. Seems it is a common enough problem that you want to rule it out. Has happened to me on more than 1 occasion after setting my system up after pulling out of storage for a while.

 

[bart_simpson]

i have a spare ports if you want i have a few scrap boards here

 

[venom]

Well a spare port would be nice! but before I replace it I want to be sure it works and as of now it's pretty dead. I wonder if this is a bios problem, is there any way to confirm bios problems?

 

[bart_simpson]

Well a spare port would be nice! but before I replace it I want to be sure it works and as of now it's pretty dead. I wonder if this is a bios problem, is there any way to confirm bios problems?

If you wish send it to me I can see if I can bring it back to life

 

[venom]

After some more searching the interwebs I learned about the video DAC, that seems to break because of the AV bad connection to ground. So I'll try to find the 315-6258 DAC and see if it fixes the problem. Trouble is now where to get one... Or is the 315-6145 interchangeable?

edit

ah, there is some very nice info on the DAC over at shmups

 

[bart_simpson]

yeah the av port damage could have shorted the video dac i have spares here i will dig them out and take a look i have smd hot air tools ect here so i can sort it i am sure of it