Investigating the Black Screen Faults in the Sega Saturn
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Hi I’ve been modding and repairing a bunch of Sega Saturns, many have been successfully restored and modded and sold to happy customers. But with others, I have been unable to repair them, and it’s because of a specific fault that plagues Sega Saturns. And it’s the infamous Black Screen fault and I’ve repaired some black screen faults by reflowing the IC Chips where the solder looked cold as well as cleaning up the corrosion, and others by replacing the Capacitors. The blown SMD Inductors that are on the motherboard L1 through L10, L7 and L8 are the high powered inductors. And the faulty PSU’s that some of these consoles have. But there are still those few that continue to give me a black screen despite me reflowing it even to the point of reflowing every single chip.
And testing it with a known working PSU, checking the SMD Fuses, Recapping it and none of it helps the console escape the Black Screen fault. Now a bad PLL IC is known to cause such an issue sometimes displaying a messed up HZ signal, Black Screen or nothing. Sometimes a light reflow of that chip can get it working again. But there is no replacement for that chip currently available. Other times that isn’t always known to cause such a fault. In my case with one of the consoles. A reflow of that chip didn’t fix it and I’m not sure if i made that console worse off due to the PLL chip being heat sensitive. So I decided to tear down the other 2 Black Screen consoles, down to the motherboard still in it’s shell with the controller board on these specific revisions connected.
I installed a Pico PSU board on to it and powered the console on. I decided to touch the top of each IC Chip making sure not to touch anything else such as the leg to prevent a short circuit and I discovered that on the two consoles. I tested this on, one IC Chip gets hot to the touch on my 2 Model 2’s with a Black Screen and it’s IC 6 (315 5963) on both my VA SD and VA SG Revisions which is an early Model 2 essentially a Model 1 in a Model 2 shell. So it still has the same PLL chip as a Model 1. Now IC6 sits right underneath the Bios and the SRams chips on these revisions. And I’m not sure what’s causing this issue. Perhaps the excess heat from replacing the SMD Bios which usually has glue underneath caused this chip to fail.
On the VA SG’s and beyond the PLL chip sits further away from the bios, so I’m not sure how the heat sensitive PLL chip can fail. More investigation of this fault is needed, will likely need to get somebody else that works with Oscilloscopes to have look into my 7 other Sega Saturns with Black Screen faults. But at least I know why these two aren’t working. I think i will be harvesting that chip from another Saturn that has a black screen with a working IC6 chip. The 315 5963 along with the PLL IC is another chip I would like see get cloned this could save many Sega Saturn with stubborn black screen faults. Does anybody have any info on this chip? I would like to know what this IC6 (315 5963) chip is responsible for.
Here is my previous post on the PLL chip fault: https://videogameperfection.com/forums/topic/the-sega-saturn-and-the-dreaded-pll-chip/
It’s definitely not always, as I have repaired a bunch of Black Screen faults which indicates general hardware failure. Usually excess heat getting to the PLL damages it, but that’s not always the case. Sometimes a reflow, 1 person fixed there’s by reflowing the PLL chip though recommend to be quick with the reflow using flux and lead free solder, and or a recap, or replacing the Clock battery, PSU, bad inductors labelled L1 and beyond, or replacing the VHC04 IC fixes it or there could be a bad trace somewhere. It’s always worth diagnosing it to determine what’s really going on. I wish I had and knew how to use an Oscilloscope, since this will need a Schematic level investigation. But I do wish somebody with the skills can manage to reverse engineer the heat sensitive PLL IC’s code since there are likely substitute IC’s out there to replace it, perhaps integrate the DFO mod into it with the ability to switch from 50 to 60hz.
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