XOrionFe

Word of warning.

I bought my 8UAF about 4 years ago and it was a GREAT radio. I got out of the hobby for a year while building a new house and recently started flying again.

This morning after running a cycle on one of my planes and my Futaba 8UAF I noticed that the charge lights on the TX side of my Hobbico Accucycle were not lit. I pulled the transmitter off the charger and turned it on to check voltage. It did not turn on.....

Next, I took the battery pack out to check it on my voltmeter and it was reading 9.9v (should be fine)....

Then all of the sudden I smell burnt electronics. I look at the transmitter and smell the burning through the battery compartment. I slight puff of air into the compartment and I see a little faint smoke creep out.

Well, after opening the transmitter up and inspecting, it turns out that I burned up the main circuit board. I suspect that even though it worked for the past 4 years....jumping the diode that prevents discharging without removing the battery was a BAD idea. I think this caused it and now I have a worthless hunk of plastic.

Moral - If they prevent you from discharging through the transmitter jack...there must be a reason.

PS - I ordered a Futaba 9C today. Probably not worth it to send the 8UAF in for repair.

XOrionFE

Lynx

No Orion, there's no reason shorting a charge diode would cause the problem you're describing. Not unless the alteration itself finally failed and caused another short inside. The only reason they put a diode on the charger port is to prevent people from hooking up the battery wrong or shorting out the connector frying the charge leads. You can't hurt the internal electronics by shorting a charge diode, unless the modification you did was faulty.

XOrionFe

It is quite possible that the short failed after 4 years plus a move. I am not sure but have cycled many many times without problems. I suppose it could be something else...but what?

amcross

My Feedback: (2)

XO, sounds like it may have finally failed. or perhaps you accidentally plugged the leads in backwards? nope, you siad it had a positive charge so that can't be it....

FWIw, the 9C has a polyswitch instead of the diode, so you can discharge through the charge jack. however, it doesn't offer as much protection against reverse charging as the old diode system did.

XOrionFe

Spoke to Futaba service in Champaign today and the guy I spoke to said that replacing the main board (which is what got burnt up) would probably be a $400 replacement part. That pretty much sums up the value in trying to service.

Oh well,

If anyone needs a spare part for their 8UAF (beside the main board) let me know.

I am nervous that the Accucycle may have caused it so I am going to charge the new transmitter (9C when I get it) by taking the battery out. At least for the first couple charges...

Don't want to fry another radio due to a bad Accucycle.

dickj

My Feedback: (1)

I had the same trouble with my 8UAFS transmitter. I sent it in and Futaba turned it around for me in two weeks during the christmas holidays for under 50 dollars. THey stated the diodes were shorted out and put some new type in and also a retrofit of some kind. NOw that sounds like a shouldve been recall to me but the price was worht it. I have charged many times with my Siruius charger, they left the diodes shorted out so I could still do that while installing a protective diode to preclude burning the circuit board of which was repaired. Send it in I will bet they fix it very reasonable. Dont give up on field charges. I only charge that way.

smitymax

I had similar problem with my Futaba 8UAF, short in the charging jack. I had shorted the protective diode as well. Inspected the main board..the large circuit board and saw that a trace on the board was fried pretty good, however, looked like it was just between two junctions so I soldered a small wire between the two junctions. Everything worked fine. Subsequently due to other problems, broken switch after dropping the transmitter, I sent it in to Futaba for checkup and repair. Asked specifically about the circuit board repair that I had done and they said that it was exactly what they would have done, not replaced the board. They gave the transmitter clean bill of health. They installed the Polyswitch for about $3.00 for the part and labor was included in the overall checkup.
Check yours out and see what is actually fried, a trace can look messy but if that is all is easy to repair if your adept at soldering and have a small soldering iron. Use a piece of insulated stranded #22 or 24 hook-up wire.

XOrionFe

That is exactly what happened to mine. Hmmmm, I will take another look and see if the trace is between 2 points or multiple. Maybe it is worth sending in.

Thanks,
XOrionFE

Lynx

Orion, in his case he got lucky and a trace overheated and shorted out no-connect before something bad happened, like a fuse. Yours sounds like it shorted out but had enough power going through it to keep the current flowing long enough to take out most of the components and IC's on the board.

flytheedge

My Feedback: (84)

Good grief. That's a crapload of money to spend on repairing a TX. I'd just put that on a downpayment for a JR 10X!!!!
Clint

Spaceclam

i think that maybe you were charging it once or twice at a higher charge rate than that little jumper was capable of handling