DX-7 Rx reset - possible cause
09-03-2007, 06:01 AM
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DX-7 Rx reset - possible cause
Hi All,
I have been reading the posts re the receiver re-setting in flight with the predictable crashes following, and the many theories being offered. Most seem to centre around the receiver sensing a low battery voltage causing the reset and the loss of control for some time - usually long enough to hit the ground. While not discounting battery capacity, here is another idea:
Some time back while carrying out my model - engine running - I lost control of the throttle. It would just hunt anywhere from idle to max power and back. No response to the throttle stick at all, but all other controls worked fine. Immediate thoughts were to blame the new DX-7, followed by the servo. Of course back in the pits (and at home) there was no problem....
I eventually traced this problem to the servo extension lead, more specifically the plug. With the connector housing removed I found the extension lead pin would slide into the servo lead socket very freely, in fact with a gentle shake would fall out. This was the case with all three wires. An easy fix for me, but think about it a while.
Imagine these connectors on the battery supply to the Rx, all would work OK under little load, but add some current drain and vibration and the Rx could easily see low voltage due to the poor connection/high resistance joint......... Of course all would work fine during the post mortem!
I cannot say what brand the servo extension lead is - just no brand assembly. Measuring the pins they are a different size to the OEM leads (0.003" smaller), but you'd never pick this by eye, and the plastic housings hold things together. Incidentally this also solved a battery charging/cycling issue I had, a known good battery kept failing capacity during discharge but change the lead and all OK.
Needless to say I've carefully checked my leads etc to remove the suspect ones - I do this with a known bad pin/socket set and test each new connector for fit - all my OEM ones have been OK.
Something to think about anyway, but it does show how critical even the cheapest component on our models can be!
Cheers,
JD.
I have been reading the posts re the receiver re-setting in flight with the predictable crashes following, and the many theories being offered. Most seem to centre around the receiver sensing a low battery voltage causing the reset and the loss of control for some time - usually long enough to hit the ground. While not discounting battery capacity, here is another idea:
Some time back while carrying out my model - engine running - I lost control of the throttle. It would just hunt anywhere from idle to max power and back. No response to the throttle stick at all, but all other controls worked fine. Immediate thoughts were to blame the new DX-7, followed by the servo. Of course back in the pits (and at home) there was no problem....
I eventually traced this problem to the servo extension lead, more specifically the plug. With the connector housing removed I found the extension lead pin would slide into the servo lead socket very freely, in fact with a gentle shake would fall out. This was the case with all three wires. An easy fix for me, but think about it a while.
Imagine these connectors on the battery supply to the Rx, all would work OK under little load, but add some current drain and vibration and the Rx could easily see low voltage due to the poor connection/high resistance joint......... Of course all would work fine during the post mortem!
I cannot say what brand the servo extension lead is - just no brand assembly. Measuring the pins they are a different size to the OEM leads (0.003" smaller), but you'd never pick this by eye, and the plastic housings hold things together. Incidentally this also solved a battery charging/cycling issue I had, a known good battery kept failing capacity during discharge but change the lead and all OK.
Needless to say I've carefully checked my leads etc to remove the suspect ones - I do this with a known bad pin/socket set and test each new connector for fit - all my OEM ones have been OK.
Something to think about anyway, but it does show how critical even the cheapest component on our models can be!
Cheers,
JD.
09-03-2007, 09:50 AM
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RE: DX-7 Rx reset - possible cause
That is why on my most "electrically powerful" models i run a futaba heavy duty on/off switch. I leave the reciever lead on but use deans on the battery leads. Whole system can easily handle 10amps with is alot for an electrical system
