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Saturn doesn't properly boot bios

gorgyrip

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Jun 17, 2019
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gorgyrip
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The consol is VA 0.8 USA. I power the console and I can set the language, but the selection box is not present. After that I can set the clock. After this I get the "saturn" white text, but the big blue saturn logo is missing. Followed by a black screen.
I can boot the pseudo saturn from the cart slot, but it just hangs when starting the cd.
I made a cart with the saturn test menu (https://hiddenpalace.org/Sega_Saturn_Test_Menu_v1.0f). But i just get black screen after "licensed by sega".
I removed the bios and I installed a region free one. No differences.
I replaced the working ram at IC3 and IC4 without any difference.
I replaced the working ram at IC31 and IC32 and no difference.
If the ram at IC32 is removed, the console acts the same. And yes, this ram has all the connections to IC6 ok.
I've also checked all the connections on ECABUS and ECDBUS.
The board doesn't have signs of corrosion.
 

vougbour

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Nov 5, 2019
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vougbour
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Hello,

I have had similar problems with a recent saturn i changed the bios on. Was able to set the time, and get to the main interface page of the bios the sound was very weird. My initial thought was that i had killed something in the bios removal. So i put everything back together including all screws and wrote a note on it. Powered the unit back on, and now it works perfectly!! disassembled it again and tested by not putting all the screws back in, and back to the original problem.

so in the end, my problem turned out to be. must fully reassemble the Sega Saturn with all screws in place for the system to work normally.
 

Druid II

Well-known member
Registered
Jun 5, 2019
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The consol is VA 0.8 USA. I power the console and I can set the language, but the selection box is not present. After that I can set the clock. After this I get the "saturn" white text, but the big blue saturn logo is missing. Followed by a black screen.
I can boot the pseudo saturn from the cart slot, but it just hangs when starting the cd.
I made a cart with the saturn test menu (https://hiddenpalace.org/Sega_Saturn_Test_Menu_v1.0f). But i just get black screen after "licensed by sega".
I removed the bios and I installed a region free one. No differences.
I replaced the working ram at IC3 and IC4 without any difference.
I replaced the working ram at IC31 and IC32 and no difference.
If the ram at IC32 is removed, the console acts the same. And yes, this ram has all the connections to IC6 ok.
I've also checked all the connections on ECABUS and ECDBUS.
The board doesn't have signs of corrosion.
Sounds like VDP1 graphics are missing. I'd investigate around that area, IC10 to 13, reflow the solder, see if it gets the correct clock signal, check if the RAM is correct, etc. Also the VDP2 "reads" the VDP1 graphics for display, so may as well reflow VDP2 too, just in case.

IC3 and IC4 handle game logic, if those were bad, the entire machine wouldn't run. IC31 and IC32 is also main memory but it is slower so it usually stores code-insensitive data like extra level parts, graphics, sound, etc. I know for a fact that the BIOS runs fine without those working (I had a machine where those chips broke due to excessive hot air contact), and there are even some games which do not touch it at all (I think VF1 worked too without them).

Replacing the boot rom should not affect the VDP1 graphics so specifically so I'd rule that one out.
 

gorgyrip

Well-known member
Original poster
Registered
Jun 17, 2019
49
12
8
AGName
gorgyrip
AG Join Date
26 octomber 2007
Sounds like VDP1 graphics are missing. I'd investigate around that area, IC10 to 13, reflow the solder, see if it gets the correct clock signal, check if the RAM is correct, etc. Also the VDP2 "reads" the VDP1 graphics for display, so may as well reflow VDP2 too, just in case.

IC3 and IC4 handle game logic, if those were bad, the entire machine wouldn't run. IC31 and IC32 is also main memory but it is slower so it usually stores code-insensitive data like extra level parts, graphics, sound, etc. I know for a fact that the BIOS runs fine without those working (I had a machine where those chips broke due to excessive hot air contact), and there are even some games which do not touch it at all (I think VF1 worked too without them).

Replacing the boot rom should not affect the VDP1 graphics so specifically so I'd rule that one out.

Thank you. Assuming there's something wrong with the ram on vdp1/2 and i can't see the cd menu (the one after clock, language), shouldn't at least hear the sound?
About IC31 and 32. My console without them only displays the language setting, but I can't select anything. I must have ic31 to be able to select language and clock.
I will try to reflow those parts because that could be the problem. The person that game me this console kept disassembled in a barn. the board had the controller connectors ripped with pins missing or corroded. He wanted to make some flower pots form the cases :)))
 

gorgyrip

Well-known member
Original poster
Registered
Jun 17, 2019
49
12
8
AGName
gorgyrip
AG Join Date
26 octomber 2007
Thank you. Assuming there's something wrong with the ram on vdp1/2 and i can't see the cd menu (the one after clock, language), shouldn't at least hear the sound?
About IC31 and 32. My console without them only displays the language setting, but I can't select anything. I must have ic31 to be able to select language and clock.
I will try to reflow those parts because that could be the problem. The person that game me this console kept disassembled in a barn. the board had the controller connectors ripped with pins missing or corroded. He wanted to make some flower pots form the cases :)))

PS: why pseudo saturn (256k) boots and the test menu cart (512k) has a black screen?
I forgot to mention. If i connect a working cd drive, the disk spins in a weird way. Sometimes in the wrong direction.
 

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