Drakon wrote:
Pin 2 of the fme7 goes to a18 of the prg maskrom. Normally that would worry me but if you look at the solder side of the gimmick! famicom pcb:
a18 of the prg maskrom is connected to vcc, so all's good for using that pin of the 5b for the audio circuit when the cart is converted to gimmick!
The thing that troubles me about this is that they've switched one pin, and only one pin, from an output to an input, and subsequently exchange which IC any given PCB is using seemingly willy-nilly.
Specifically, these two games (
Gremlins 2 and
Dodge Danpei) both use GRM-E301. Because of your rework, we know that pin 2 is tied to ground on that PCB. But Gremlins 2 (here) is using a 5B (where that's an input), and Dodge Danpei is using an FME-7 (where that's theoretically an output)
BBW-E301,
DD2-E301, and
PYK-E301 have solder pads to tie PRG A18 to either FME-7 pin 2 or Vcc, but they're all pre-jumpered for Vcc.
FC-DBT, NES-JSROM, NES-BTR, and NES-JLROM all tie FME-7 pin 2 to PRG A18.
FC-GMK ties PRG A18 to Vcc (obviously)
I mean, my problem is mostly that this is damage-causingly bad electrical engineering; either the pin is externally shorted and the game could destroy the output driver for that pin, or the pin is a floating input to an inverter. (Or ... whatever is true for the 5A)