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HelicopterRadio - Spektrum DSM › DX7 Tx left on ???
01-22-2007 10:13 AM  10 years agoPost 1
G-DAVE

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Tyne and Wear , England

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Looks like I left the Tx on after flying yesterday - now it won't take a charge - How do I spark up the battery ? or is it F##ked ?

Dave

If it's not fun, your not doing it right !

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01-22-2007 10:51 AM  10 years agoPost 2
bobj

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United Kingdom

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Hi Dave

I know the JR radio's have a diod (sp) in line so presume the Spektrum's do as well, this might prevent a fast charger locking onto a totally flat pack, have you tried removing the pack from the TX and charging it directly?

Cheers
Bob

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01-22-2007 01:16 PM  10 years agoPost 3
G-DAVE

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Thanks for that Bob - took it back to Alans Models and they found a small glass fuse had blown - not sure how this happened - the battery was charged so me thinking I had left it switch on was wrong.
One of the ways this fuse can blow is if the charge socket is shorted out as it appears there is no diode ??
Mystery unless you can think of anything else??
Dave

If it's not fun, your not doing it right !

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01-22-2007 09:28 PM  10 years agoPost 4
SRH990

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Birmingham, UK

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There may well be no diode as the DX7 is basically a US spec JR transmitter and I belive that US market JR transmitters don't have the diode fitted that we get in the UK spc models.

Steve -Trex 700N, Trex 600N, Raptor 550E, 450SE, Mini Titan, Logo 5003D, Beam E4

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01-23-2007 08:51 AM  10 years agoPost 5
TrexRookie

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San Francisco, CA

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since you left your tx on for a long period of time, the fuse probably fried to protect your circuit boards... I'm assuming that the undervolt resulting from an over-discharged pack fried the fuse... I can't remember the exact terminology, but at the end of the day, that lil glass fuse probably saved your transmitter...

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01-23-2007 05:25 PM  10 years agoPost 6
TYREE

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Sonoma county

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Fuses dont....

blow from under voltage etc. They blow from excessive current draw due to a short circuit etc. The more current they draw the hotter the wire gets...and if too much heat builds up in the wire...the wire melts.

That fuse is most likely there to stop excessive charging current.

Ty

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01-23-2007 05:32 PM  10 years agoPost 7
MikeC

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Mosinee, WI

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[quote]That fuse is most likely there to stop excessive charging current.

And reverse charging. With the battery that low the inrush is what took out the fuse.

Mike

Century Swift, TREX 450, Blade MCX, Spektrum DX7

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01-23-2007 05:36 PM  10 years agoPost 8
G-DAVE

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Tyne and Wear , England

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Try this Scenario

I use a charging lead with two banana plugs at one end - so how about this scenario - you stupidly plug the Jack plug into the Tx first leaving the two bare ends of the banana plugs dangling - they touch fuse would blow - Yes/No ????

Dave

If it's not fun, your not doing it right !

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01-23-2007 06:08 PM  10 years agoPost 9
RCHeliJim

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Orem, UT USA

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Hehe, sounds like a winner Been there, done that



Go Fly, Have Fun!!
-Team Quick UK

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01-23-2007 06:36 PM  10 years agoPost 10
Barney

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Inverness Scotland

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Could it be you connected up the Tx with reverse polarity when you went to charge it?..That would pop the fuse

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01-23-2007 07:35 PM  10 years agoPost 11
G-DAVE

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Tyne and Wear , England

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Could it be you connected up the Tx with reverse polarity when you went to charge it?..That would pop the fuse
Didn't happen this time but it's a possibility - why can't we put a diode in and give the Tx some protection from possible accidents.
Dave

If it's not fun, your not doing it right !

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01-24-2007 02:32 AM  10 years agoPost 12
kthane

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Pensacola

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If you put a Diode in, you can't cycle the packs in the TX. Fuses are cheap.

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01-24-2007 05:42 AM  10 years agoPost 13
NORTHERNLIGHTS

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Riverview FL

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I`m here to tell you that if you hook a Futaba lead to charge you will blow the fuse.( should have noticed the center pin being NEG) When I replaced the fuse it blew the second, and third one. It powered up, but only momentarily. Gotta send it in for Horizon to have a look.

B.O.A.T. Break Out Another Thousand!

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01-24-2007 10:39 AM  10 years agoPost 14
G-DAVE

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Tyne and Wear , England

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Nothern Lights - yes but did you not notice that the Futaba Plug is smaller than the one required for the DX7 - maybe it was rattling around in the socket and shorted out??

By the way it's simple to reverse the polarity in the Tx - just switch the wires on the back of the Tx Socket.!
Dave

If it's not fun, your not doing it right !

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01-24-2007 11:22 AM  10 years agoPost 15
Don1127

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Manhattan, NY

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Same happened to me on my JR. Since my charger has a JR/STD switch it can be easy to make a mistake. In my case the switch got bumped and I missed it... The fuse is really there to protect the radio. I keep a spare just in case.

It's easy. Just pretend it's the simulator...

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01-24-2007 01:08 PM  10 years agoPost 16
NORTHERNLIGHTS

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Riverview FL

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I actually had hooked it up to my multiplex charger. So it was an oversight. Also the fuse inside is only .3 amps. When I get it back from repair it will only see the wall charger.

B.O.A.T. Break Out Another Thousand!

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01-24-2007 01:23 PM  10 years agoPost 17
MikeC

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Mosinee, WI

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the Futaba Plug is smaller than the one required for the DX7 - maybe it was rattling around in the socket and shorted out??
That wouldn't happen. Coaxial power plugs are made with several I.D and O.D dimensions and if you have a plug that has an I.D that's larger it will simply not make contact. If the I.D. is too small it obviously won't go in.
By the way it's simple to reverse the polarity in the Tx - just switch the wires on the back of the Tx Socket.!
A very good thing to do especially if you have other TX's that use the positive tip polarity! I did this on the JR 622 that I had as well as my DX6 and I'll be doing it shortly on my DX7.

I did the reverse polarity thing on my DX6 before I changed the polarity on the TX jack and because I was using an overnight wall charger at low current it didn't blow the fuse right away but it did take the battery down to almost nothing. The battery charged up OK afterwards but I was reluctant to use it.

Mike

Century Swift, TREX 450, Blade MCX, Spektrum DX7

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01-24-2007 02:21 PM  10 years agoPost 18
G-DAVE

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Tyne and Wear , England

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Thanks for that MikeC - the only other thing I can think happened is if something small - that's rolling about in my Tx case happened to fall into the Tx socket - that would short it Y/N
I think I'm getting a little paranoid about the whole thing -
Dave

If it's not fun, your not doing it right !

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01-24-2007 02:56 PM  10 years agoPost 19
bobj

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United Kingdom

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Hi Dave

Over the years we have had a few JR radio's pop their fuses for no reason.
It really doesn't happen often and in the all the time I used JR it never happened to me.
I really won't worry about it too much unless it happens a few times of course!

Cheers
Bob

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01-24-2007 03:50 PM  10 years agoPost 20
NORTHERNLIGHTS

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Riverview FL

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After talking to Horizon Tech...It is a 3 amp fuse not .3 amp my mistake.

B.O.A.T. Break Out Another Thousand!

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HelicopterRadio - Spektrum DSM › DX7 Tx left on ???
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