TX fast charging

On Thu, 5 Jul 2007 11:04:50 -0500, topgun77 wrote in :

I'm not clear on the JR circuitry. I use a peak detecting charger with mine, but at a slow rate, so I'm not fast charging.

You can test the jack by seeing whether you can read the battery voltage through it. If the same voltage shows through the jack as you see when you check the battery out of the TX, the jack is probably OK.

I think there is a very slight difference between Hitec/Futaba TX charging connectors and JR's. I have occasionally had trouble getting a connection to my Hitec transmitters from my charger. I just twiddle the connection until the green light comes on and leave things alone until the battery is charged.

Marty

As far as I know all JR transmitters have a blocking diode inside and they are all center pin negative on the charge jack.

All other brands that I have seen are center pin positive.

Hugh

Mart> On Thu, 5 Jul 2007 11:04:50 -0500, topgun77

wrote in :

Hi thanks for the info.

I tested test the jack and could not read the battery voltage through it. Does this mean it is faulty ? Note the tx works fine with the battery inserted

-- topgun7

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On Thu, 5 Jul 2007 14:30:39 -0500, topgun77 wrote in :

Possibly.

I can read the voltage on my three JR transmitters through the charge jack.

783, 8103, 9303.

Here's another test: does your charger have a light that shows a connection? When you plug the JR charger into the TX, does the red light come on?

That would be another way to distinguish between a diode preventing voltage testing and a bad connection.

Marty

All known modern TX, except AM, have diodes in the charging input which must be bypassed to allow fast charging. Refer to examples and how to by-pass. Sirius Electronics-TX Diodes bridging =

do not charge at greater than 1.2A as TX circuit may be damaged. regards Alan T. Alan's Hobby, Model & RC FAQ Web Links

I've had several JR Txs, and currently have an 8103 and a DX7. I've fast charged all of them stock with no modifications between 800 and 1000maH with no problems.

PCPhill

Hi , thank you all agiain fo the info. The charging diode problem a

stated by A.T makes sense. I have read up on it and apparently a charging diode ca cause no voltage to be present at the tx jack (I see no voltage at the tx jac with my multimeter) and hence cause a fast charger not to work.

But others have stated they have they have measured voltages on thei JR tx jacks and can use fast charges.

Since I do not have an original charger is there anyway for me to check the tx jack and ensure it is not faulty. I bought thi jr662 recently and want to know if it is faulty and hence try to retur it

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On Fri, 6 Jul 2007 08:34:41 +1200, "A.T." wrote in :

Their table doesn't list the three JR transmitters that I checked today:

783 8103 9303

The 6102 is on their list. Topgun77 has a 662. On balance, I'd bet that his TX does have a diode and might be fixed following the 6102 instruction sheet.

Marty

On Thu, 5 Jul 2007 17:45:20 -0500, topgun77 wrote in :

Does the charger you use detect a complete circuit?

On two of mine, an LED lights up when I plug in a TX to be charged, so I know that there is a circuit.

Be careful: the polarity on JR transmitters is opposite that of Hitec/Futaba. If you use a Hitec/Futaba charger on a JR TX, you will blow a fuse (if you're lucky) or let out some good smoke elsewhere in the circuitry.

All things considered, my current guess is that the

6xxx series has a diode and that the 7xxx, 8xxx, and 9xxx transmitters don't have a diode.

It's just a guess ...

Marty

Prolly got a diode. I had to remove the diode from my Futaba 6XAS to be able to use a fast/cycling charger. Wasnt interested in fast charging per se but I did want to be able to run it thru several cycles to re-condition from time to time. It did come in handy to be able to fast charge on the mountain top after a long afternoon of sloping tho.

Some JR transmitters use a fuse in the charging circuit instead of a diode. I believe that most, if not all of the transmitters that use a replaceable transmitter module use a fuse.

I know that the X-388 uses a fuse. The 783 is a 7 channel version of the X-388 so it (probably) also uses a fuse.

The analog trim 8103 uses a fuse. I believe that the digital trim version does as well.

I believe that the 9303 system uses a fuse as well, but I don't own one so I haven't looked.

If your transmitter has a removeable transmitter module, remove the module and look inside where the module goes, there should be a rectangular hole in one of the walls, and the fuse should be visible thru the hole.

My recommendation to the original poster would be to borrow the correct JR charger from someone, and see if the transmitter battery will charge using the JR charger. If the battery will charge using the JR charger, but not charge with a fast charger, there is probably a diode in the circuit.

Ken

Hi Marty ,

Thanks for the info.

Unfortunately it does not

Thanks for the warning. I am already aware of the reverse polarity o the JR equipment. Why they do this who knows

-- topgun7

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Open the case up and start taking stuff apart, until you can find where the charge jack connects into the printed circuit board. Follow the trace coming from the positive (jack part, outside or pin) and you will find that the diode is the first component you get to on the circuit board.

I charge my JR with my Triton all the time - just removed the battery lead from where it was connected to the diode and soldered it to the other end of the diode, and all was well (worked with my Swallow charger too)

David

t> Hi does anyone know if you can charge a TX battery with a fast charger

Wrong guess for the 8103 - it has a diode

David

"Mart>

David,

You are the one who is guessing wrong. It has a fuse. The fuse can be found by removing the transmitter module, and looking in the hole below the serial number sticker. Look in there, and you will see a short "Buss" type fuse on the circuit board.

Ken

"quietguy" wrote in message news: snipped-for-privacy@REMOVE-TO-REPLYconfidential-counselling.com...

Thanks for everyones help. In the end I just wired the wires from th

jack staight to the battery. This was much easier than bypassing the diode. My charger ha reverse polaity protection on it. Fast charging from the Jack now works like a charm. Thanks again to al

-- topgun7

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On Sun, 8 Jul 2007 18:32:58 -0500, topgun77 wrote in :

Way to go!

Thanks for letting us know what worked for you ...

Marty

Nope, mine has a diode - I have seen it, checked that it was a diode, and then bypassed it (according to the instructions that came with my Swallow charger) - it probably has a fuse as well, though I didn't look for that when I was doing the mod.

David

Ken Barnes wrote: