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Toaplan Twin Cobra with Black Screen

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Alfredo_CRG

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Hi :)

this is my first thread on the repair forums, Im trying to save this TOAPLAN Twin Cobra board that I got in a batch of boards, when I got it, my local seller told me it was just giving a black screen :(
IMG_6920.jpeg

IMG_6921.jpeg


the first thing I did was a physical inspection and it looks ok, I removed a lot of dust and clean the ribbon connectors with 99% IPA and verified the ribbin cables were good, after that I took the ROMs and made a dump of it to check it on MAME, Im not a big user of MAME, I´m still learning but with some help of the internet I was able to learn how to use some commands.

I tried first the command "romident" to see if my dumps matches the ones in MAME and to my surprise most of them did =O but some others did not :( specifically B30-6,7,8,26 and 27
imagen_2026-05-05_171008760.png


Then I tried the command "romcmp" to compare with other MAME set of ROMs that I got from the internet, and here I found that my ROMs B30-6,7,8 did match the set of MAME ROMs :S
and my ROMs 26 and 27 were match some portion of the ROMs, so this means my ROMs could be potentially corrupted ?? :huh:
imagen_2026-05-05_171321678.png


By any means Im an expert on mame, so if someone on the forums could guide to understand this results that would be really apreciate it :), in the meantime I checked the voltage rails and all looks fine, no shorts, but also I checked on the MAME driver and I notice on the quick layout that is there, there is no mention of B30-26 or B30-27 instead is calling for B30-2 and 4
https://github.com/mamedev/mame/blob/master/src/mame/toaplan/twincobr.cpp
imagen_2026-05-05_171846466.png


so this got me confused, then it means I need have those other 2 ROMS instead ? ?(

Hope someone with more experience repairing can guide trough this, thanks in advance :)

Alfredo
 
To me looks like B30-6/7/8 were dumped using an incorrect ROM type.
For now I'd focus on getting the main CPU to start, the other ROMs even if faulty will result in corrupted graphics or bad sound that you can deal with later.
 
What voltage do you set you JAMMA rig at ? My Twin Cobra PCB does not boot up and remains with a black screen at 5V. I have to set it a ~5.20V to boot up
 
Ape Cosplay said:
To me looks like B30-6/7/8 were dumped using an incorrect ROM type.
For now I'd focus on getting the main CPU to start, the other ROMs even if faulty will result in corrupted graphics or bad sound that you can deal with later.
Click to expand...
What do you recommend me to check, I check on the Data lines and I see some activity, also checked the clk lines and I see it at 10MHz, the MAME driver says it should be running at 7 but the 10MHz clock is the one connected to the 68K clk
 
B30_6, B30_7 and B30_8 contain graphics (characters) data so, if they are bad, they cannot be the cause of the black screen.
B30_26 and B30_27 are program ROMs, they store the main 68000 code, they are mentioned in MAME in World and US ROM sets :



Code: 
ROM_START( twincobr )
    ROM_REGION( 0x30000, "maincpu", 0 ) // Main 68K code
    ROM_LOAD16_BYTE( "b30_01.7j", 0x00000, 0x10000, CRC(07f64d13) SHA1(864ce0f9369c40c3ae792fc4ab2444a168214749) )
    ROM_LOAD16_BYTE( "b30_03.7h", 0x00001, 0x10000, CRC(41be6978) SHA1(4784804b738a332c7f24a43bcbb7a1e607365735) )
    ROM_LOAD16_BYTE( "b30_26_ii.8j",      0x20000, 0x08000, CRC(3a646618) SHA1(fc1ed8f3c491f5cf16a17e5ce08c5d8f3ce03683) )
    ROM_LOAD16_BYTE( "b30_27_ii.8h",      0x20001, 0x08000, CRC(d7d1e317) SHA1(57b8433b1677a390a7c7e00a1464bb8ed9cbfc73) )

Code: 
ROM_START( twincobru )
    ROM_REGION( 0x30000, "maincpu", 0 ) // Main 68K code
    ROM_LOAD16_BYTE( "b30_01.7j",   0x00000, 0x10000, CRC(07f64d13) SHA1(864ce0f9369c40c3ae792fc4ab2444a168214749) )
    ROM_LOAD16_BYTE( "b30_03.7h",   0x00001, 0x10000, CRC(41be6978) SHA1(4784804b738a332c7f24a43bcbb7a1e607365735) )
    ROM_LOAD16_BYTE( "b30_26_i.8j", 0x20000, 0x08000, CRC(bdd00ba4) SHA1(b76b22f03eb4b821a8c555edd9fcee814f2e66a7) )
    ROM_LOAD16_BYTE( "b30_27_i.8h", 0x20001, 0x08000, CRC(ed600907) SHA1(e5964db9eab2c334940795d71cb90f6679490227) )


B30_02 and B30_04 are the labels of the Japanese revision "Kyukyoku Tiger"

Code: 
ROM_START( ktiger )
    ROM_REGION( 0x30000, "maincpu", 0 ) // Main 68K code
    ROM_LOAD16_BYTE( "b30_01.7j", 0x00000, 0x10000, CRC(07f64d13) SHA1(864ce0f9369c40c3ae792fc4ab2444a168214749) )
    ROM_LOAD16_BYTE( "b30_03.7h", 0x00001, 0x10000, CRC(41be6978) SHA1(4784804b738a332c7f24a43bcbb7a1e607365735) )
    ROM_LOAD16_BYTE( "b30_02.8j", 0x20000, 0x08000, CRC(321e2be6) SHA1(03b2c530326d1859b66829b49555d862be235643) )
    ROM_LOAD16_BYTE( "b30_04.8h", 0x20001, 0x08000, CRC(c3f960ff) SHA1(cbebf576d677cc02f4d0f22dcc226e898d4832c6) )

Anyway, B30_26 and B30_27 EPROMs should be 27(C)512, can you confirm it on your board?Please, after dumped them send me the dumps and I'll check the code for you.
 
caius said:
B30_6, B30_7 and B30_8 contain graphics (characters) data so, if they are bad, they cannot be the cause of the black screen.
B30_26 and B30_27 are program ROMs, they store the main 68000 code, they are mentioned in MAME in World and US ROM sets :



Code: 
ROM_START( twincobr )
    ROM_REGION( 0x30000, "maincpu", 0 ) // Main 68K code
    ROM_LOAD16_BYTE( "b30_01.7j", 0x00000, 0x10000, CRC(07f64d13) SHA1(864ce0f9369c40c3ae792fc4ab2444a168214749) )
    ROM_LOAD16_BYTE( "b30_03.7h", 0x00001, 0x10000, CRC(41be6978) SHA1(4784804b738a332c7f24a43bcbb7a1e607365735) )
    ROM_LOAD16_BYTE( "b30_26_ii.8j",      0x20000, 0x08000, CRC(3a646618) SHA1(fc1ed8f3c491f5cf16a17e5ce08c5d8f3ce03683) )
    ROM_LOAD16_BYTE( "b30_27_ii.8h",      0x20001, 0x08000, CRC(d7d1e317) SHA1(57b8433b1677a390a7c7e00a1464bb8ed9cbfc73) )

Code: 
ROM_START( twincobru )
    ROM_REGION( 0x30000, "maincpu", 0 ) // Main 68K code
    ROM_LOAD16_BYTE( "b30_01.7j",   0x00000, 0x10000, CRC(07f64d13) SHA1(864ce0f9369c40c3ae792fc4ab2444a168214749) )
    ROM_LOAD16_BYTE( "b30_03.7h",   0x00001, 0x10000, CRC(41be6978) SHA1(4784804b738a332c7f24a43bcbb7a1e607365735) )
    ROM_LOAD16_BYTE( "b30_26_i.8j", 0x20000, 0x08000, CRC(bdd00ba4) SHA1(b76b22f03eb4b821a8c555edd9fcee814f2e66a7) )
    ROM_LOAD16_BYTE( "b30_27_i.8h", 0x20001, 0x08000, CRC(ed600907) SHA1(e5964db9eab2c334940795d71cb90f6679490227) )


B30_02 and B30_04 are the labels of the Japanese revision "Kyukyoku Tiger"

Code: 
ROM_START( ktiger )
    ROM_REGION( 0x30000, "maincpu", 0 ) // Main 68K code
    ROM_LOAD16_BYTE( "b30_01.7j", 0x00000, 0x10000, CRC(07f64d13) SHA1(864ce0f9369c40c3ae792fc4ab2444a168214749) )
    ROM_LOAD16_BYTE( "b30_03.7h", 0x00001, 0x10000, CRC(41be6978) SHA1(4784804b738a332c7f24a43bcbb7a1e607365735) )
    ROM_LOAD16_BYTE( "b30_02.8j", 0x20000, 0x08000, CRC(321e2be6) SHA1(03b2c530326d1859b66829b49555d862be235643) )
    ROM_LOAD16_BYTE( "b30_04.8h", 0x20001, 0x08000, CRC(c3f960ff) SHA1(cbebf576d677cc02f4d0f22dcc226e898d4832c6) )

Anyway, B30_26 and B30_27 EPROMs should be 27(C)512, can you confirm it on your board?Please, after dumped them send me the dumps and I'll check the code for you.
Click to expand...
Thanks for the Help Caius :) I really aprecciate it :)

B30-26 and 27 are 27(C)256 not 512 :O
IMG_6969.jpeg
IMG_6970.jpeg

is this wrong ?? this are the settings I used to make the dump, Im using a Wellon VP598
imagen_2026-05-07_131110029.png


Im sending you the Dumps over PM thanks :)


Alfredo
 

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OK, I analyzed the dumps and compared them with MAME, they match the 'twincobru' set.SO, the black screen is cause by something else.Keep in mind that the boot procedure on this board is quite slow, you must wait some time before you will see the POST screen.
 
@caius aren't there common issues with the custom T.T-1, etc' chips that you have created repro's of? Is there any way of testing or knowing if these could potentially be the issue? I too have this pcb that just posts a black screen.
 
Many, many things can cause this game to black screen, as it has the same self-test issue as Hishouzame (see here: https://forums.arcade-museum.com/threads/toaplan-romstar-sky-shark-tp-007-black-screen.506905/)

I fixed a K Tiger board with the same symptoms recently (the Japanese version of this game), and made some very bodged hacked roms that would turn the screen on as soon as the board gets power, and also skip the ram/rom checks so it boots into the main game.
I just tested the roms in mame with the Twin Cobra romset and whilst they don't boot into the game (probably because of the different T.T-4 chip), it should still be useful for you as you'll be able to see what your board is doing when it tries to boot up.

Good luck!
 

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