PDA

View Full Version : DX7 just stopped working - fixed but for how long?


deswong
10-27-2007, 06:24 AM
Hi Everyone.

I have just got a new DX7, 2 days old, and busy setting up my 450 yesterday.

Today's plans were thwarted though :( I turned on the transmitter today and although it appears to be working, the receiver lights on the receivers just didn't come on solid. They flashed and then stopped. The Gyro was still working so I thought the receiver must have become 'unbound' somehow.

So after 20 minutes or so of attempting to bind, nothing worked. But the back of the receiver got hot. Like, really hot... :(

What I found after pulling apart the receiver is that the LM2937 decided to deliver a nice 10.2V to the 2.4GHz part of the radio, and that was causing everything in there to overheat and not smell so good.

The voltage regulator seems cooked, on circuit it was giving a 1.45V output on the output line, but the board got incredibly hot really quickly.

So I took out the voltage regulator, debating whether to claim warranty or not.

I was going to do the Dimension Engineering mod on it, and then tested the unit with a known 3.3V source to ensure the radio was still working, which it was, thank goodness!!!

So I have done the DE mod and it seems to be working ok.

Is there anything else I should look out for after this experience? I can't find any evidence of a short or other parts that are pointing to where the problem started from...

The Voltage regulator is dead - just puts out what voltage comes into it.

How do these just 'die' like that? Is that common? Or a short somewhere else could have caused this?

From what I can tell this takes the voltage directly from the battery/switch and the first component it goes into is the voltage regulator. So my 'assumption' is that now the unit will be okay.

I have patiently been waiting 6 weeks for my DX7 to arrive from the USA, and don't really want to have to send it back for warranty service if I can avoid it.

Suggestions, comments?

Des.

DavidH
10-27-2007, 10:42 AM
So I have done the DE mod and it seems to be working ok.


No need to send it back for warranty claim after doing the mod. I would have sent it back when it first quit. Now all you can do is use it and hope for the best.

David

deswong
10-28-2007, 05:15 AM
Yeah, I should have. But I think it should be ok now. The DE will shut off if it detects a short circuit on the output so if that happens I will at least know where the fault lies.

I think I might invest in another spare transmitter lol, just in case...

(The cost of two from the USA believe it or not works out close to the amount of a stripped down transmitter/receiver only kit here in Australia!)

Coop
10-28-2007, 08:59 PM
If it's any consolation, I installed the DE regulator in my DX6 over a year ago. The radio works flawlessly with the unit installed. Proving in my mind at least that the DE regulator is a good product. Oh, and battery life went way up too!

0636
10-29-2007, 10:53 AM
deswong,

What is current consumption after DE mode? Can you measure it and post it here?
If you going to measure it, do it when RX is binded to TX, for more realistic scenario.

ChasHeliCop
01-06-2008, 09:13 PM
My voltage regulator went out in one of my DX7's I did the DE mod and it works great. Only thing I caution people on is desoldering the connections. be sure to get it hot enough you don't pull up the pads. Also, instead of desoldering the regulator itself, I couldn't get mine off, so I took a dremel and cut off the top of the old regulator. Battery life went up tremendously. I installed a 3s lipo in the other DX7 and the battery life is close. Both work flawlessly.