XEGS Keyboard Problem

[ultrasteve]

Hi all.

 

I recently bought an XEGS from someone on eBay. The system works, and so does the Light Gun (Bug Hunt played perfectly well) BUT the keyboard doesn't. I've swapped it out for a known good keyboard from my 65XE and still no joy. When both of these keyboards are connected to the XEGS, ONLY the Break key works. If I put the faulty XEGS keyboard into my 65XE only some of the keys work (that, I guess, is almost certainly a problem with the Mylar?).

 

So I think this problem is two-fold: 1) The Mylar needs replacing, and 2) There is something wrong with either the XEGS, or the XEGS Keyboard Sub PCB. I'm leaning towards the latter, but I don't know enough about the guts of an XEGS, or about electronics. Using a multimeter I can tell there are no breaks in the traces on the sub PCB. Could it be that one of the 4051s is dead? If it was JUST the mylar I'd assume it wouldn't work at all once placed in the 65XE, same as when connected to the XEGS, so that's what makes me think there's something else at work. Is there anything in the XEGS itself that could cause this behaviour?

 

Sorry, I'm a bit of a novice at this sort of stuff. Not afraid to try stuff, but need some pointers please? By the way, I'm in the UK, so shipping costs will prevent me just ordering parts to keep trying to some extent!