ManicMechanic

I recently rang my mail order hobby shop as I want another servo. I have a Monster Pirate and have replaced the steering servo with a hitec 625. Very good, but I should have done my research and put a 645 on the steering. So, I want to replace the stock throttle/brake servo with the 625, and buy a 645 for the steering.
The guy at the shop was really slagging off hitec servo's saying they were crap and did'nt have the power quoted and the didn't deal with them (strange I thought, cos its the only servo you hear about on this forum and everyone thinks they're great....don't they?)
So he recommends a Multiplex?? (not sure) digital servo. (I have an analogue receiver). So I agree and he sends it. I attach it to the steering and I have to admit it was a little more powerful than the hitec, but as soon as plugged the hitec into the throttle, things go wrong. Everytime I move the steering, the throttle servo (hitec) goes nuts moving anything up to half its travel in both directions for about 2 seconds, then stops. When I operate both at the same time, the multiplex loses all its power.
If I swap them round, (the multiplex as the throttle servo) it just goes nuts until I unplug it.
Whats going on? I think I'm just gonna return the multiplex and a buy a 645 from another hobby shop. What do you think?

hitler75

Does digital and analogue mix? There could be a diffculty for the analogue receiver to transmit data to the digital servo for it to work properly and thus might have screwed with your other analogue servo. I think you need to understand how everything fits before using it. Any LHS who can shed some light?

ManicMechanic

I think they do mix, but he was feeding me some toss about how the hitec gave out interference.

Unstable

check your RX batteries digitals suck power luck a cheap...errr nevermind.

if your batteries arent fresh the draw of the digital might be dropping the voltage to real low making the rx send out bad signals.

ManicMechanic

Thanks unstable, I'll have a look tonight when I get in, it is a possibility. I don't use nicads yet, I use good quality alkaline batteries. The only thing is that if a digi servo goes nuts when battery power dips, isn't that a bit dangerous?

While on the subject of batteries, if I do get a nicad pack (5 cells) will I need to get a special charger? Or can I use an existing battery charger?I've got for charger the NimH batteries for my digital camera.

Ledgendary

Look on Ebay. They sell them as a combo at a good price ($25). If you get it from you LHS it cost a lot more ($25-30 just for the batteries).

mglavin

My Feedback: (31)

Digital and Analog servos are compatible as a rule. The RX has know idea if a digital or analog servo is attached to it. Same signal passed to the servo know matter what. Low voltage is not the problem as digitals consume more power they work within the same design parameters as other's.

Does the Multiplex servo work fine on it's? Did you try it on both channels, alone?

I suspect there may simply be something wrong with your servo. It maybe be emanating some type of RFI/EMI or maybe over whelming the AGC circuit if your RX.

ManicMechanic

I've tried the muliplex servo on its own in the throttle channel, and it just goes nuts. On its own in the steering channel its fine. No other servo's have any trouble (the hitec one or my old stock ones) so I'm beginning to think it is the servo.
Thanks for the info Michael.

adeoliver

My Feedback: (4)

Take the servo back and tell the dude he is full of crap!! If he thinks hitec is junk maybe he has never heard of their return policy!! I think he was just blowing smoke up your *****. Ive ran nothing but hitecs for along time!! ANd have yet to complain about any of them. If something goes wrong hitec will fix it, what more can you ask for!! Oh ya and when a digi servo is hooked up to a dead battery it will not go nuts, it will stop working and do nothing, it wont even make the humming sound anymore.

ManicMechanic

All is well thats ends well. I've sent the multiplex servo back and had a refund, and there's a brand new hitec 945 in the post as we speak (from another hobby shop).