danlrc

DX7 and 7000Rx. Application - large sailing ship model with 5 big servos (draw 2 to 2.5A peak at 6V, but very low avg power) Power: 6V SLA, 7.5Ah. Tx V > 10.4. On first startup after install, went thru binding - all perfect. Programmed Tx, calibrated 6 servos and Ok'd operation of MTroniks viper 15 ESC (w 1.2A, 5.1V BEC). Rx powered by BEC. Servos wired to power bus, not thru Rx. This system has operated fine for the past season on the previous 75Mh system.
Day 1 install and everything worked extremely well. Day 2 - more set up/testing planned. Turned on Tx (binding was done on day 1) Turned on sytem/Rx poer and both Rx parts flashed for just an instant, then went off and nothing. No flashing, no solid LED - nothing. Turned power off. Powered up again and after a delay of maybe 5 sec got solid LED - all seemingly OK. Later in day, powered up TX, the ship power and Rx - no Rx LEDs again. This time nothing. Checked BEC V to Rx: 5V. Tried again a few times - no Rx LED. Finally put bind plug back on and followed that procedure. All went well.
What's going on? Very erratic start experiences. Could it be a V dip as the Rx first sees power along with all the system servos? Does the Rx need to be on a sep switch and or power supply? This system sees a lot of load variation as sail servos deal with the wind. It would be convenient to use 5cell, 6V NiMH packs I already have. But is that the issue?
Thanks,
DanL

jmohn

If you drop below 4.7 volts you will have problems. The system will lock you out until it restarts (re-boots).

PacificNWSkyPilot

My Feedback: (19)

I believe the correct number there is not 4.7 but 3.3 or 3.4 volts (which you wouldn't want to be that low anyway.), and the system doesn't lock you out, it just reboots, which means there is nothing there for that second.

Also, it's easy to put in a larger battery pack and make it one with the 5 cells, which starts you at higher power and higher voltage, which puts you farther away from the "low" number here, and pretty much makes it a non-issue. If you've got something there that is not a normal setup then you might want to do some further checking, but for most normal and even fairly large setups this will solve any issues.

Jim

danlrc

I checked the voltage to the Rx. Minimum was 5.4V (fed from a 6VDC 7.5Ah SLA).
Tx volltage was 10+
Hmmmm....

PacificNWSkyPilot

My Feedback: (19)

It can be microseconds, it can do it more quickly then you can see on a meter. But don't assume that it's voltage drop causing that. Make sure your battery connections are bullet-proof. On another recent thread there was a fellow who was able to wiggle his battery wires and cause the reboot, and he was saying"but it only glitches for a second, the system shouldn't reboot from that!", which of course is wrong. It will reboot from that. And it's a simple thing to prevent.

And a careful triple-checked installation never hurts anything anyway.

Jim

nobodytwo

After purchasing a Hangar Nine "system analyzer" (Digital Servo & Receiver Current Meter)
the are some important facts that have come to light!

1) A "ESV" or battery checker MUST have at least a 1 amp load! Most only do 250 to 500 mah, not near enough
2) A four servo system, using Hitech 325HD BB servos, sags 1.49 amps when all are in motion, ON THE GROUND

So why is this important? For years I've heard pilots say "I've been hit"...well looks like that they have
been under powered! The Spectrum receivers have brought this to light because there is a delay in function after a severe voltage "sag".

Tommy_Gun

I'd say Mainer Jim and nobodytwo have just about summed up what I believe to be the cause of most problems with folks that are having any trouble with a Spektrum of JR 2.4 ghz system.

PacificNWSkyPilot

My Feedback: (19)

It's just the result of the logical progression and advancements in radio gear. The radios have advanced, but the higher technology is subject to stringent power demands. So, I would say, logically the next thing we are going to be looking at is improvements in this technology relevent to keeping a closer (electronic) eye on the available power, and perhaps even some forms of alarms where the plane transmits a signal to us, the pilots, and tells us we need to land immediately. I can understand that some of the guys who have lost planes are upset over this learning & application curve from this new technology, but I think it is safe to say that literally hundreds if not thousands of planes have been saved this year alone from it. I would estimate an overall 99.95% reduction in crashes experienced by those using the Spektrum systems.

Never before in the history of radio control have such numbers even been imagined. I understand this doesn't feel good to the (very, very) few who have still lost planes due to these last remaining issues, but you have to admit when looking at the whole picture, these are impressive results.

On another thread a guy was calling them defective and unsafe, and I had to leave the thread before I flamed him hard. All he wanted to do was call names and he wasn't about to make sure he had good wires (yeah the wire-wiggling guy) or connectors, figured it was all up to Spektrum. Oddly enough, pretty soon he won't have much to worry about. Everybody else is going to be using the Spektrums and that will mean he'll be the only guy at his field using the older radios. So essentially he'll have good odds with that, so he'll probably be fine, or as good as he was before, at least. Problem solved!

Jim

gooseF22

Nobody

This is the quote of the year. every modeler read and heed. this is the truth. we built some manual load meters and got our eyes opened! my homemade one can do up to 3 amps, and it will sag alot of batteries.

if it drops badly under a 1.5 amp load. chuck it