hello guys i have a customer with a partner acs system 5x9. i think its a r7. he had a couple dead phones and when i got there they had 5 dead phone ports. im goin to get an exp card to give him more ports. question is why did so many go dead. they make driveshafts. there did appear to be metalic debree on the cabinet, and they do use arc welders. im wondering if high current draw could make trouble or if metal bits could cause minor shorts in the system. any ideas. also would it hurt if he used some canned air and blew out the card. thanks dave