Freitag, 7. April 2017

Epoxy Block, a good Protection in the 80's, not so good today!

Brian sent me two epoxy blocks from two Dodge City boards. Merit covered the CPU, a PAL and an 2816 eeprom inside an epoxy block. Mainly for protection reasons!
I have already seen this kind of protection quiet a lot of times on different gambling pcb's. Video Klein for example used this on basically every board they made.

The Merit games have some code inside the 2816 eeprom, so a dump of it is needed to get the games running! MAME has already three different revisions of Dodge City included, but all are missing the 2816 dump, so none of it is playable!

remove the epoxy to get to the chips, now!

heatgun, flat screwdriver and the 2 epoxy blocks

one Epoxy Block

use the heatgun to heat the epoxy to about 330° and you can brake it away with your screwdriver. this was done within 10 minutes

removed epoxy pieces

some minutes later, the 2816 and the PAL are desoldered and  can now get dumped

same procedure on the second epoxy block, as i now knew where the interesting chips are located, i only removed the epoxy at this area.

So it was possible to brake this protection for two games within 60 minutes. The good thing, it looks like these two blocks are from different revisions of Dodge City, so hopefully two revisions can now get playable!

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