Hi David,

I had that exact failure on my Bobcat just last Friday - both hard over. Fortunately this happened as I prepared for my next flight, rather than during flight. When did yours happen ?

I took the beast home and pulled brand new 3421's out of their packing, only to find problems with these new ones too. Out of 6 brand new servos that I had available, one moved occassionally but not very often, and another is completely dead.

Re Tony's question about battery - I'm running a 5 cell 1800. Initially this was unregulated and typically sat at about 6.6V at the battery, and obviously less at the servo. After I cycled the RX battery though, it's voltage increased to about 7.1 V peak, so I decided to add a regulator (6V) before putting the battery back in the aircraft.

Of course, although the on-board failure happened within a regulated setup, the servos that failed in the aircraft had by then already been subjected to an unregulated 6.6 V previously, so it could be that the voltage was too high and affected the first 3421's...

For the replacement servos though - I actually found these failures while testing on the bench with just 4.8V - so there's no way that the brand new servos were toasted by the setup - they were just flat out bad right out of the package. That surprised me really, as I've been using JR equipment for about 15 years now, and only once previously found a failure on a brand new item - so to find 2 out of 6 to be bad right out of the box worries me a little.

IIRC, there was also a discussion on 3421 failures (either here or on the jets list) a few months ago. I seem to recall a number of replies from people who had switched to a mini airtronics servo...

Regards,
Gordon