Hi Friends,

I have a three channel ACE Cougar transmitter and reciever which were working perfectly but one day one of My friend connected the battery pack in reverse polarity bymistake and turned on the transmitter and it didn't switched on, then I checked it and found the battery pack to be connected wrongly. I connected the battery pack with the proper polarity now but transmitter is not switching on.

Can Anyone suggest what might be the problem with the transmitter ?

Most probably the voltage regulator in your transmitter's circuit board might have burned.
you can repair it yourselves or get a electronics service personnel's Help.