Futaba 4VF transmitter encoder chip

[jonboy]

Hi Electronic whizzes,
I have a Futaba Skysport 4VF transmitter which has a slight problem...servos jitter a little here and there...earlier I thought it to be a receiver problem,but my friend who checked it out on the scope says the problem is with the transmitter...In the encoder...
Could some of you electronic experts help me out by letting me know which is the encoder IC in the transmitter,also do let me know the other chips incorporated in the 4 VF Tx. Is there by any chance I can get a schematic for the transmitter ckt.
Thanks a lot
Jonboy

[chaitanya]

Its impossible to know which encoder chip is used as giants like futaba use custom chips manufactured specially for their application or use microprocessors with no access to their sourcecode. AFAIK CD4017 is used for encoding. theres also not a single chance of getting a futaba tx schematic. It might seem harsh but you cannot get a schematic or hack a tx, its illegal too.
better way send it to a authorised futaba center for repair.

if u wanna build some encoder stuff of ur own then these might help
http://w1.859.telia.com/~u85920178/use/rc-prop.htm
http://www.norcim.fsnet.co.uk/Radio6.htm

[Comatose]

Chaitanya, its certainly not illegal to reverse engineer a schematic from a PCB. Now, if you were to start manufacturing clone TXes, then thats not okay, but just for repair purposes, there's nothing wrong with it.

jonboy, if your friend with the scope traced the problem to one chip, then why not ask him which chip it is?

[chaitanya]

even though if he finds the part number printed of the chip then its highly possible that theres no manufacturer's part number associated with it, as it is usually a part number of Futaba and not any manufacturer.
camatose- agreed but its not a decent thing to do :-)

[jeffs555]

It sounds like he just looked at the output of the encoder and saw it jittering. That doesn't mean the encoder is bad. The most likely cause of jitter is dirty pots. You might try spraying them with a good contact cleaner.

PS Like Chaitanya said, in most countries, it is illegal for anyone without government approval to modify or repair a transmitter. In the US, RC transmitters are type accepted by the FCC, and any unlicensed repairs or modifications not specifically listed in the approval documents are technically illegal. This even includes simple things like changing crystals, or replacing broken antenna. That said, as long as you don't cause interference to some government or emergency radio service, your odds of getting a visit from the FCC are almost nil.