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Fixed! - Was: Need a ROM file to repair a Super Contra...

channelmaniac

channelmaniac

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I need a copy of the ROM "775F08" at K22 to repair a Super Contra. I've already replaced a few dead Fujitsu logic chips, a 7407, a 2016 SRAM, 3 corroded EPROM sockets and 1 EPROM... and 1 custom.

The file can be found in the scontraa.zip MAME file (that I cannot find using Google) or on a Super Contra that uses the 4Mb 16-bit ROMs

The ROM is an HN62404 Mask ROM, similar to a 27C400, but NOT a 27C4096.

Thanks!

RJ
 
Thanks!

Received and replied - 2 more Mask ROMs are bad... only one of the 4 (77F05) checksums properly. The 775F07 is filled with "C3" and the 77F06 is filled with "00"
 
Thanks,

@Nebula sent me the 3 files and I got 3x MX27C4100 EPROMs programmed. Now I can see that it boots, does the self check, and then gives an OK screen before rebooting.

Odd thing is if I short data pins on G17 it says H17 is bad, and vice versa. The DIP switch to go into "service mode" does not work. It reboots before going into that mode.

Also, the hybrid gets uncomfortably warm. I'm wondering if it's bad - thinking so based on the red text. Luckily I have one on the way from Caius. It's just taking forever for the post offices involved to get it here. Also wondering if I need to replace the 051961 custom since it's connected to the 051962 that I already had to replace.
 

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For those keeping track:

That makes F19, F22, and G22 (all LS153) plus I15 and I16 (LS74) as Fujitsu bit rot. B14 (7407) and the 051962 custom were fried. The ROM at F6 had rotted legs so it and the socket were replaced. The Program ROMs at K11 and K13 had scummy legs and were cleaned. Their sockets were replaced. Now I've socketed all 4 Mask ROMs and replaced the three that were bad with freshly programmed MX27C4100 EPROMs.
 
OK...

Yet another Fujitsu LS153... This one had chattering outputs. Also a dead trace to pin 22 of the hybrid.

Now I have the proper color text and the crosshatch showing up before it reboots.
 
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OK!!! Pin 87 of the 051961 custom was dead. That's the NIRQ signal to the CPU that gets buffered by a 74LS367. The CPU was waiting for the interrupt to be returned and it never arrived... Watchdog reset hit the CPU.

Replaced the custom and it's working... BUT... There are graphics problems with the player elements. Time to look at the 051960 and the 051937 customs. I'll start with the custom that had the dead ROM attached to it.

1651105973926.png
 
Down to 1 ROM error... and it's a ROM image in the last mask ROM... but I ran out of those oddball pinout EPROMs in the parts drawers. Have to go dig in boxes now to find more.
 
Got the 27C400 EPROM from China - real Intel chips too...

Super Contra is fixed. That last EPROM would properly checksum but not work at speed in the circuit. Replacing it finished the repair. :)

So that repair consisted of 2 dead Fujitsu 74LS74 and sockets, 3 dead and 1 chattering Fujitsu 74LS153 and sockets, a fried 7407 buffering the sync output and socket, 4 custom ICs, 4 Mask ROMs and sockets, 2 Program ROM sockets, 1 2018 SRAM, and a Sound Program ROM (rotted pins) and socket.
 
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Edited the post to add a few more things I forgot that were replaced. There was a bad SRAM, rotted pin Sound ROM, and corroded program ROM sockets. I was able to clean the pins and save the Program ROMs, but the Sound rom left multiple pins behind when I removed it from its socket.

Another shout out THANK YOU to @Nebula for the help with the ROM code files.
 
Congrats! That was a hard one…
again, Fujitsu curse on those Konami boards
 
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