Charging a Spektrum DX7 (old style) Nimh battery

[Lynx.1677]

Hey all,

I've not touched my transmitter for some time and I wanted some sim action but the battery is dead and I have no idea where the wall charger is. I no longer have a charger or lipo so don't really want to spend £100 just to be able to use the Tx I already have. Does anyone know where I can get a replacement charger that will charge the stock Nimh that came with the DX7? Note this is not a new one, it's a few years old and not the new 'S' variant.

Thanks,

Dan

[choppaholic]

take any 9V charger look at your appliances some will have a 9V adapter, cut the wires and swap negative and positive, even a 6v adapter will do but will charge slower.
if you haven't got one, flebay or maplin. but i am sure everyones got one lying around, i have about 10 lying around the house running various modems, land phone etc...

[Lynx.1677]

Thanks fella, you mean cut the cable to the plug that goes into the Tx I assume and not the mains plug (Dan blows himself up)!

[choppaholic]

yes the tx side the one with round tiny plug first make sure it goes into the dx7 keep the charger off while you test before cutting, DX7 is basically a normal charger but the polarity is reveresed compare to 99% of all other appliance that use such a plug

[choppaholic]

find one with this sort of plug, dont worry about measurement as long as it fits in the dx7 its fine, pics just an example.

40172.jpg
then change polarity to this use a multimeter if you have one, usually the black cable with white/gray line is positive and full black is negative, cut and swap round.

Untitled.jpg

[Lynx.1677]

I'm assuming it has to be 9v with 500mAh charge?

I have everything but a damn 9v so will pop tp Maplins today.

Thanks again for the help!

Dan

[scallybert]

Also, be careful with a DX7 with a low battery.

There's a scenario where you power it up with a near-dead battery, and it corrupts the firmware.

[konceppt]

I used to just use one of the multi connector type charge leads (5 quid on ebay) which also had both futaba and spektrum type connectors on as well as the usual jst, deans etc and used my normal lipo battery charger to charge it

[trillian]

Hey Dan! Long time no see.

If I wasn't out of town at the moment I'd post you a charger as I have lots of them lying around. The original charger for the DX7 was something like 50ma and would take a very long time to do a full charge. I have one I got from Weston UK that's (I think) 150ma or something like that. I don't think you can charge them much faster though, so the point being, it takes quite a few hours.

[Lynx.1677]

Hey Trillian, yes. I'm back, I couldn't stay away too long.

Well, I got one of those multi charger doodads from Maplin which allows me to charge at 5, 6, 7.5, 9, 12 and 13.2volts. It also allows me to change polarity which is handy.

Now, the transmitter battery was totally dead but has been on charge for around 5 hours today and when I turn it on it goes to 7.9 volts but then very quickly goes down to 7 within around 30 seconds and then turns off.

Does this sound normal? How many hours do you think it needs to be charged?

Thanks all!

Dan