Marble Madness LSI Cartridge woes

cwilbar

Well-known member
Joined
Sep 8, 2015
Messages
1,209
Reaction score
31
Location
Massachusetts
I have been working on a Marble Madness LSI cartridge.

It came with the EPROMS, security chip, and SLAG chips missing.

I installed 4 NOS SLAGs, burned and installed all of the EPROMS, and installed a Road Blaster's security chip (verified working in a Marble Madness TTL version board).

It is watchdoggging, and once in a while I can get it to flash an error on the screen about ROM at address 200.

I suspected the LS244s so I removed those, installed sockets and replaced those.

Same behavior.

Not sure where to look next.
 
Have you verified that all jumper positions (OP1,OP2, etc.) are correct, and that there's continuity between the jumpered pins?
 
I'll re-review them. I did not test them with a DVM, but I believe they were in their correct positions.
 
I mention checking for continuity because I had one a few months ago where one pin had broken at the header base, but was being held in place by the jumper block.
 
I found the problem.... 2 badly corroded pins on the socket for program ROM 201.

Now, I do see a video glitch at one point in the attract mode, so I'm suspecting a similar problem with the graphics/tiles ROMs or the SLAGs.... so I think I should just plan on replacing all the sockets (yuck) used by MM.
 
Good deal. Yeah, hate replacing sockets too, but it's unavoidable with some boards (are you listening Atari?).
 
Atari wasn't listening in the day.... it sure isn't listening now :)

I did have one of the lands? come up when I replaced that one socket, but the connection to the circuit was on the component side, and I was able to get the heat on the pin and the plating and get it soldered regardless..... it's just frustrating.

Some boards are so good about having components desoldered and others not. I had not expected a system 1 cart to have this problem like an Asteroids, Centipede/etc era Atari boards did.

I'll need to be a bit more careful on the remaining 15-16 (ouch) sockets.

Might see if I can locate any other bad sockets (like the high resistance on one pin for EPROM 201 that was my no boot situation). Replace those, and deoxit/inspect the rest....

I wish I could use my heat gun to remove all these sockets.... but in my working with junk boards, some take the heat fine..... others.... well, after component removal they looked like they had blast marks on them in places :)

Thinking that after removing the tops of the sockets, I'll run a small wire in the loops of the pins, and put a bit of tension on it and pull the pins from the ends (if that would work). Doing it one at a time is tedious.... I could use my wide tip of that one works and hit 3-4 pins at a time....

Then just use the desoldering iron on just enough temp for a quick melt/hole clearing.

I'm sensing 'hours' of fun ahead :)
 
Seriously, if you don't have a Hakko, then get one right now! I know they're a little pricey, but makes wholesale socket replacement like that a breeze. I don't even flinch now when I get a board with crummy sockets.
 
Yeah. Hakkos rock. One botched board and you just paid for it. Im not sure I even know where my Soldapullit is now.

Sent from my phone. Please excuse tpyo's.
 
Back
Top Bottom