Verifying steps needed to replace roms in cart with translation

[keropi]

Well I have checked the soldered TMS27C020 eprom: Vpp + PGM + Vcc are all connected to the +5v line
I have found the datasheet and the way they are connected atm seems fine to me:



I am all out of ideas atm regarding the 27C020 part...

I will try now and remove pin30 of 27C010 and get it out of the equation (maybe it does not like +5v) and connect the floating Vpp pin to VCC, since it's datasheet recommends it (though floating pin1 works just fine on the Gargoyle's Quest eproms... and I've been playing it lots... maybe the KONAMI board is different)

[keropi]

Yes it's random 80sFREAK ...
The 27020 marking are: TMS JL 27C020-15 , so I assume it is 150ns like the original mask rom (the amd 27010 eproms are 120ns AFAIK)

I did some rework to be exact like in datasheets:

on the 27C010: disconnected pin 30 from the pcb (since it was N/C and was getting +5v) , and soldered a wire on the +5v pcb hole that connects all 3 remaining pins: Vcc + PGM + Vpp  , just like the suggestion on the datasheet:



on the 27C020 :  I did nothing   but I did manage to find the original mask rom's datasheet: everything is 1:1 with the eprom, it really needs no re-wiring.

... but nothing helped   , maybe the TI 27C020 is incompatible

edit: I have replaced the 27C020 with another one (same model/specs) and this time it seems to work fine... I am now at 1.5hrs and the game still runs.
I also tested the old eprom on the programmer, it's data is OK. Maybe it's not a good part in regards or access speed , or it just develops errors after some time of usage.

edit2: everything is OK  after replacing the 27C020 eprom, apparently the first one was flawed. 

[GohanX]

I didn't have any luck with mine, but I wonder if there is an issue with the rom files themselves. I am using AMD chips which have always been rock solid for me but the program I use to split the files didn't work and I used a different one, I wonder if it screwed up the splitting.

[keropi]

I didn't have any luck with mine, but I wonder if there is an issue with the rom files themselves. I am using AMD chips which have always been rock solid for me but the program I use to split the files didn't work and I used a different one, I wonder if it screwed up the splitting.

If you can wait until morning (~9hrs , have them in my office pc) I can send you my split files that work so you can compare them... I've been playing several hours today  , no problems whatsoever 

[keropi]

^ it looked new and was bought as new... both chips were different (can't remember what the other's markings were though, it's now in the cart....) but the problematic one has these:

TMS JL
27C020-15
LU65A0CEP
SIGNAPORE