I'm not aware of any Futaba TX that is damaged by attempted discharge that has the diode protection. The diode's purpose is to prevent damage due to discharge by disabling the ability to discharge. Hooking up a discharger won't hurt anything, but it also won't work because current flow in the discharge direction is not allowed by the diode. As long as the diode is in place, nothing can be damaged by attempted discharge. However, you can melt down the radio if the user attempts a high charge rate, and the diode won't prevent that action. I believe the customer was misinformed when he returned the charger.

It is true that older generation technology (like a decade ago) nicads had some "memory" issues, but modem quality nicads (like sanyos) really don't suffer from memory issues. The only common reason to discharge nicads is to test pack capacity, which only needs to be done occasionally. I only test my packs about 2 times a year. I had one pack that I accidentally discharged thru the RX for a week or more. The pack was very dead, but even after that abuse, the pack still read an open voltage as Rodney posted. After recharging, the pack tested out just fine.

Cheers.