Thanks to everyone for the feedback and tips. I'm still learning how to properly solder so mistakes are definitely bound to happen...
I actually ended up programming a new chip and used that one for my final cartridge.
This time, I made sure to not go too long on each pin and leave some time for it to cool off before moving to the next ones.
I also triple checked each solder point on my PCB with a multimeter and made sure everything was soldered properly.
OP - Did you cut the legs of the old EPROM and solder the new EPROM to the legs?
I was actually following this video from Voultar
and he cuts the pins at 11:20 because of the adapter that is used (the red PCB in the video)
When removing the EPROM, I did it properly and desoldered everything with braid and a pump (that took ages...)
and be careful to test the continuity of every pin to its neighboring pin after soldering
Yes, lesson learnt now, this is also what got me at some point: I had a faulty adapter (it's failing a simple continuity check, just the adapter itself) and it took me quite some time to diagnose. I still have to contact the seller and see what can be done about this.
As for the old chip, I wanted to try soldering some wire to each pin and reconnect it to my programmer (TL866II with an adapter for the 27c322) to test if it's working or not.
Or is that too much trouble ? Should I not bother and just trash it ? Is there any better way to test it ?
Finally here's a picture of the two finished carts, both are working.
