Keyboard problem help please

[Foggy]

Hi all, I have a Casio AP-25V which has some keys which is not functioning correctly. The problem keys is in effect two 'sets' or 'groups' of keys, the first is from A to E (3rd from left) and the second being from C to F (3rd from right). Now what is strange is that all other keys work fine and the problem keys will function fine when power if first turned on. not long after they are dead. So my guess is a short but where?? Does anyone have suggests about what it could be or how to fix it?

Thanks in advance

 

[The Y_man]

Sounds like a crack in a solder joint which comes apart once heated.

The Y-man

 

[happyrat1]

Could also be dirty/oxidized contacts on a cable connector or header. Simply removing and replacing them a few times might fix it.

Gary