Greg Wilson Posted March 29, 2008 Share Posted March 29, 2008 I would like to know which one is the positive wire from the DX7 supplied battery. any help would be appreciated Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted March 29, 2008 Share Posted March 29, 2008 You have lost me there Gregory - are you referring to the tr battery, or the receiver harness or what?PS how about telling us a bit more about yourself in your very first post ? Quote Link to comment Share on other sites More sharing options...
Greg Wilson Posted March 29, 2008 Author Share Posted March 29, 2008 I have recently got a Spectrum DX7 and having problems setting up. I am referring to the DX7 Tx battery which is 1500mah ni-mh. I have blown up my JP charger so now i need to charge my batteries using my field charger - therefore i need to know the polarity of this battery. Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted March 29, 2008 Share Posted March 29, 2008 JR ( and Spektrum I think too ) use red as positive and brown as negative. On the charge jack of the set, the outer "ring" is positive and the centre "pin" is negative. THis is OPPOSITE to that of Futaba gear. Have you not got a simple voltmeter for double checking this sort of thing?? I chucked out my supplied DX7 battery ages ago when I fitted a LiPo pack...and used my own wiring config, and dont use the charge jack either so forget the original - but I am pretty sure they were as above. Quote Link to comment Share on other sites More sharing options...
Roy Hill Posted March 30, 2008 Share Posted March 30, 2008 Quite right Timbo,centre pin is neg. Be careful to use the correct polarity as you could blow the internal fuse, as there is no reverse polarity protection diode as in the JR 35 meg trannys, good luck Gregory regards, Roy. Quote Link to comment Share on other sites More sharing options...
Gregory Wilson 2 Posted March 31, 2008 Share Posted March 31, 2008 Many thanks for your advice Timbo and Roy - you really got me sorted out. What a fantistic forum this is. Many thanks once again! Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted March 31, 2008 Share Posted March 31, 2008 Your welcome...in return, could I ask you to fill a bit in on your profile. Ta muchly Quote Link to comment Share on other sites More sharing options...
squeek Posted October 10, 2008 Share Posted October 10, 2008 what is the max charge you can put into a dx7 transmitter without blowing a fuse Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted October 10, 2008 Share Posted October 10, 2008 Well that kinda depends on what battery it is. Most Nixx based batteries will not like more than 1C - so assumng a 2500 mahr pack, thats 2.5 A - but probably kinder to use .5C ( 1.25A ) and I should think the fuse will take this easy enough. Not even sure that the fuse is in the charging circuit....? Quote Link to comment Share on other sites More sharing options...
squeek Posted October 12, 2008 Share Posted October 12, 2008 dx7 has a diode setup in charge line. some people are saying you can only charge at 0.1 amps without damaging transmitter. Sprectrum manual has nothing on the subject.battery is 1100mah standard with tx Quote Link to comment Share on other sites More sharing options...
'Widget' Posted February 28, 2009 Share Posted February 28, 2009 If the fuse is blown can you replace it without sending the Tx to Horizon ? Martin Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted February 28, 2009 Share Posted February 28, 2009 charge rate alone will not damage the Tx - and most NimHs will accept 1C charge rate, but as I said - try .5C which on an 110 ma battery is 550ma. Yes, the fuse ie easily changed by the user -Take the battery out, remove the back cover by undoing the 6 self tapper screws, pull the cover away and you will see the fuse. Replace with same type and rating...many are "slow-blow" type fuse links., which should be available from the likes of maplin. Quote Link to comment Share on other sites More sharing options...
'Widget' Posted March 1, 2009 Share Posted March 1, 2009 Thanks Timbo, Fuse replaced and Tx working fine, only wished I had checked for a reply last night as missed out on a good Sunday for flying !!! Many thanks again, Martin Bye the way, I think the blown fuse was caused either by trying a plug in the charge socket of an old power supply with the centre pin to positive. The P/S had not been used for years and just wanted the plug to make a charge lead, the transformers used in power supplies can have residual current in them and I think this caused the fuse to blow, OR when I had cut the plug from the P/S and plugged it into the Tx to check if there was current flowing out of the socket with a multimeter (for cycling purposes) did the multimeter cause the fuse to blow ? Any idea's ? Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted March 1, 2009 Share Posted March 1, 2009 reverse polarity of the charger is the most likely cause I think - however there is a diode in the circuit to prevent this from causing damage. Quote Link to comment Share on other sites More sharing options...
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