Sega Saturn Black Screen Repair

Hey folks,
Got a couple broken Saturns here I'm trying to get one working one out of. One is water damaged and VERY dead. The other boots up to just a black screen. Laser focuses, checks, and spins the disc. However, upon closer inspection it had a dead regulator "TR5" which produces 3.3v for the SDRAM (according the service manual). I built another regulator to make 3.3v and still no dice...any other ideas? I was thinking of swapping the BIOS from the water damaged board but I'm wondering if perhaps the RAM is just fried? Also wondering what caused this regulator to fry...maybe a bad mod chip install.

-Segasonicfan

 

SDRAM can be run at overvoltage, just depends on how much. When overclocking, I would be able to push SDRAM really far as far as voltage goes (+.3 volts). If it had a mod chip install, it could have destroyed it and taken the SDRAM with it. Salvage the laser, case, and power supply for parts, as well as caps/components on the motherboard and trash the rest.

 

Thanks for the reply. What I'm curious to know is what a modchip install would have killed. It seems silly to give up on a repair without even knowing the full diagnosis (and having 2 broken systems to swap parts from).

Also, when the voltage reg died it just grounded the output. So it didn't actually put more voltage onto the SDRAM. Not sure what fried it since a 3.3v reg in its place works great.

 

Hrm... Check the traces on the board and your solder joints for bridges/shorts?

 

Tried a different power supply? The system is getting enough juice to power the video encoder to produce a valid black signal but I've seen this from all sorts of crazy crap.

Probably a bad trace or IC though. Have fun!

 

yeah, I checked around for stuff, it's a really clean board and I'm almost positive it's fried from a bad modchip install. PSU is fine, even tried another one. Voltage doesn't drop at all on it either and it wouldn't explain how TR5 got blown.

I tried swapping in a BIOS chip and controller IC from another board but the problem remains. I'm guessing the SDRAM got fried...which is WAY too much work to replace all that.

 

check near video encoder for bad capacitors check the 4x 220uf ones can cause black screen aswell.

 

thing is there is no sound either, and like I said TR5 was blown so...I don't think it is a simple cap issue. :/

 

just saying i had one before with a slimmer issues before.