Dreamcast Black Screen Issue

So i've had this problem for a while with one of my Dreamcasts where i'll be playing a game for about 45 minutes and then all of the sudden it loses video and the screen goes black (though I get a "no video signal" message from my TV so it seems as though the video fails over all). The power remains on throughout all of this and the dreamcast never turns off/resets itself. If I restart the console immediately after this happens, it'll turn on but I get no video signal, the disc won't spin, and I never even see the BIOS boot screen. After leaving the console idle for 5-10 minutes and then turning it back on, the console starts up fine, and plays the game, and then will cut out about 15 minutes later. I've tried the classic power board trick where you bend the pins to give it a better connection but havnt been successful.

Could the CD Drive be going out somehow or overheating? I believe that the disc drive does stop spinning as soon as the video cuts out.

The behavior of the console working after 5-10 minutes led me to think it was a heating issue since maybe it had time to cool off but the fan is running fine and the console doesnt seem excessively hot after the issue occurs. Does anyone know what could be causing this issue?

I appreciate the help!
Ghudda

 

Try leaving the dreamcast on the system menu (the one you get when there is no game inserted) for a hour. If it stays on then the problem is likely the the laser cutting out mid play and the system needing time to reset, if it stops displaying while on the menu then you can narrow it down to overheating.

 

Awesome, thanks. i'll give this a try this morning and post back with results.

 

Update: I left the Dreamcast on at the menu screen and the video went out after about 45 minutes. How could I diagnose the overheating issues?
Could it be bad/expanding solder joints? What should I be looking for as far as faults on the board?

 

First I'd check if the cooling fan was spinning. Then sometimes if the system is dusty the ventilation won't flow right.

 

Actually before you open it, have you tried another video cable/tv?

 

The main exhaust fan on the side is working fine it seems. It's clean and there doesnt seem to be any dust keeping it from moving.

Yeah i've tried it on multiple TV's. It first occurred when I had connected it to a Dell CRT monitor via VGA and it's still occurring on my Sony PVM monitor. It occurs both with my VGA adapter, and standard S-Video cable.

 

It sounds like a bad heat transfer between the metal sheet that touches the CPU and GPU. You have a few options. Either add arctic silver thermal paste to the CPU and GPU then tighten up the screws connecting said metal plate to the motherboard or add entirely new heat sinks (and still apply arctic silver) like this guy

http://www.instructables.com/id/How-to-make-a-Sega-DreamCast-console-into-a-batter/step5/Heatsinks/.

 

Hey thanks for the insight, I'll give this a try early this week and update with the results. I appreciate your help so far and thanks for the link to the instructables.

 

Ah so it looks like the Dreamcast uses thermal pads instead of paste initially, I bought some thermal paste but that won't cover the gap between the chips and the metal heatsink plate. Should I buy thermal paste that would replace the pads or should I buy a pair of heatsinks to replace the metal plates?

EDIT: Adding brand new heat sinks seems like it's a lot of work. I'd have to cut away at the old steel sheet in order to make room for the heat sinks to sit on the chips. Is there a more reasonable way to accomplish the cooling issue?

 

You don't actually need the metal shielding itself. So if you replace the heatsink, you'd just have to put something to raise the gd-rom daughterboard a bit. My test DC has run without the heatsink and metal casing for years. Though it's caseless and never powered on for extended period of time.

Also, I believe the heatsink part of the metal casing around the motherboard can be separated from the rest, saving you from exposing too much of the motherboard and raising the gd-rom daughterboard while allowing you to fit low-profile heatsinks.

 

I appreciate it.
I suppose I could put my dremel to work on it. Does anyone have a suggestion on which heatsinks to buy and where I should look? I believe I need a 1.5" x 1.5" and a 1" x 1".

 

I don't think you'd need a dreamel: See the part over the mobo on this pic: http://www.gametechwiki.com/w/image...ardown_07.jpg/587px-Dreamcast_teardown_07.jpg

Well, when you remove it you got the shield itself, and a shinier metal plate that's actually the cpu/gpu heatsink. You can remove this piece without tearing the shielding too much. It attached to it via the 4 diagonal indents you can see.

Then it's a matter of finding a low enought heatsink to fit under the shield. Any piece of metal would do honestly. The DC doesn't produce too much heat, as long as it can be evacuated by a thermal contact and sufficient airflow it should be fine.

 

Yeah, I know what you mean by the metal plate underneath the main shielding that is the actually heatsink, I just am trying to brainstorm on what to use for the replacement heatsinks, as I don't have much scrap metal laying around my apartment :/

 

Well you could use the original heatsink, but instead of sticking it to the shield glue it to the chips (without forgetting thermal paste) as suggested by bacteria.
On the plus side it's sure to fit under the shielding

 

Awesome, I seperated the two plates and think I can get it to fit flush on the CPU and other chip but need a way to keep the heatsink mounted in place.

Would it be safe for me to apply minor amounts of super glue to the chips in order to keep the heat sink in place?

 

I think this is what bacteria did on the guide linked earlier on this thread. You ought to be sure you're getting it right on the first shot though.

 

Alright, well cross your fingers. I applied the paste and a few dots of super glue to the chips and it looks like the heatsink is laying pretty flush ontop of the chips so all should be good. I'm going to give the glue time to set and then i'll put it back together and test it.

Update: put back together enough to test it. Booted up fine so now i'm just going to let it run for an hour or so and see if it encounters the video loss.

Update: No video after 10 minutes. Now no video upon bootup at all. I'm going to let it sit and see if it'll come back on after cooling off.

 

Could be a bad solder joint that moves due to thermal expansion. Hard to say where you'd want to reflow due to the fact that no video could be a number of different places.

 

Yeah. I may just let it be. I'll keep it around and I could always use the disc drive and any other parts off of it if need be in the future. Feel free to shoot me any suggestions if something comes to mind but I don't necessarily have the patience or skills for the soldering work this may require. Thanks again for all the input/advice so far though, I appreciate it!