stevan Lewis 1 Posted June 14, 2015 Share Posted June 14, 2015 While flying today (the first time with a second hand futaba 6ex 2.4) the model suffered 2 losses of signal and went into failsafe mode cutting the engine for about 1 second before continuing normally. Luckily the plane was quite high so my instructor was able to bring it in without damage, although on of the engine cuta happened on landing approach. We changed the receiver and the same thing happened. The Rx battery pack was 99% charged so this was not the problem. Also the battery voltage display on the Tx always reads 1v low. When the slave transmitter is attched with a buddy lead this Tx reads the correct voltage but the master Tx still reads 1v lower. The question is: are these 2 events connected, ie low voltage disply on Tx and loss of signal by Rx or is it just 2 separate problems. Further more is the voltage display really a problem or just an inconvenience? Any advise gratefully received Thanks all Steve Quote Link to comment Share on other sites More sharing options...
kc Posted June 14, 2015 Share Posted June 14, 2015 Whats the actual voltage reading? My 6EX 2.4 reads 11.7 volts when fully charged and never goes below 10.5 after 4 or 5 flights. Buying secondhand TX & Rx from unknown sources is not recommended! Why are they selling! Quote Link to comment Share on other sites More sharing options...
Former Member Posted June 14, 2015 Share Posted June 14, 2015 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
stevan Lewis 1 Posted June 14, 2015 Author Share Posted June 14, 2015 The reading starts at 10.4v and drops to about 9.8 after a few minutes then stays reasonably stable for the next 30 minutes or so. I have seen on another USA forum several people saying their 6ex's show about 1volt less than the battery monitor reading. I just wondered if the loss of signal and diplay voltage could be connected. Steve Quote Link to comment Share on other sites More sharing options...
Dave Hopkin Posted June 14, 2015 Share Posted June 14, 2015 Swapping the RX's out and getting a recurrence of the same problem would tend to eliminate the RX as the cause, I would do a through inspection on the power supply to the RX and the cables supplying it Quote Link to comment Share on other sites More sharing options...
kc Posted June 14, 2015 Share Posted June 14, 2015 If it was described as working well then it might be worth rejecting the TX & Rx as not in the condition described and getting a refund.if you can. Have to do it quickly though and consider all the legal aspects. Frankly buying into a FAAST system now is hardly worthwhile because they cannot make & sell new FAAST Tx and so you cannot replace with new Tx if it fails. You can ( at the moment) buy a new Spektrum 6i ( old model ) for 70 pounds with Rx from TJD Models so unless the 6EX 2.4 & Rx was much cheaper than that it was not a bargain unless everything including the nicad ( NiMH ) was perfect. If perfect a 6EX2.4 is great. But check the price of a new nicad before you consider servicing - it might be expensive. You may need Futaba to match your instructor so consider a T6J if you can get your money back. Edited By kc on 14/06/2015 17:42:47 Quote Link to comment Share on other sites More sharing options...
stevan Lewis 1 Posted June 14, 2015 Author Share Posted June 14, 2015 We swapped the Rx for a 35 Mhz Rx and Tx and everything performed perfectly for the rest of the day. It seems that the 6ex Tx is the problem. Steve Quote Link to comment Share on other sites More sharing options...
Former Member Posted June 14, 2015 Share Posted June 14, 2015 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
stevan Lewis 1 Posted June 14, 2015 Author Share Posted June 14, 2015 Thanks for all your comments. I will ring the seller and see where that takes me. Steve Quote Link to comment Share on other sites More sharing options...
kc Posted June 14, 2015 Share Posted June 14, 2015 Be firm and insist on a refund and see what he offers. Maybe you will lose the postage cost both ways - might be better than the worry of unreliable gear! But try for a full refund and compromise if necessary by losing return postage. Good luck.. Quote Link to comment Share on other sites More sharing options...
Dave Bran Posted June 14, 2015 Share Posted June 14, 2015 "The reading starts at 10.4v and drops to about 9.8 after a few minutes then stays reasonably stable for the next 30 minutes or so." Then you do not have a problem with Tx supply as a 6EX will happily work down to 8V, usually their audible low volt alarm triggers at around 8.3/4v. "The Rx battery pack was 99% charged so this was not the problem" How measured? What voltage output, and was this voltage measured under working load of servos? Aerial placement? I have a 10CG and two 2,4GHz 6EX's from when they first appeared, never had a low voltage issue. What you have experienced is extremely unusual for FASST and IF a Tx/Rx signal fault suggests signal masking just as much if not more so than a circuit or voltage fault. However, as you had the problem when buddied I would suggest that if the buddy system had not been used for some time (or at all) it prob had a bad connection on the buddy lead plug/sockets which from experience (with 35MHz 6EX's with the same rectangular plugs, of which I have four) is the most likely issue. They need periodic cleaning with evaporating contact cleaner and working a few times while wet (with the battery out and wait for the cleaner to fully dry out) Quote Link to comment Share on other sites More sharing options...
Andrew767 Posted June 14, 2015 Share Posted June 14, 2015 Stevan....If you are looking for a Futaba set,i have a T7CAP and Rx for sale that is genuinely ok. PM me if it would be of interest to you . Andrew Quote Link to comment Share on other sites More sharing options...
stevan Lewis 1 Posted June 14, 2015 Author Share Posted June 14, 2015 The problem occurred when used alone not buddied. The voltage display was noticeably different between the master and slave when buddied, the master showing at least 1volt less than the slave and they are using the same battery. The aerials are placed according to the futaba manual, at right angles about 5inches apart. I cant think of a reason why there should be a loss of signal except a transmitter fault. Steve Quote Link to comment Share on other sites More sharing options...
Phil Green Posted June 16, 2015 Share Posted June 16, 2015 Its extremely unlikely it will be an electronics fault with the tx, but it could be a broken aerial or feed. I'd check the ufl connector is seated squarely, check the coax end to end especially where the aerial hinges. Are you absolutely certain it went into failsafe Steve, I mean, there are many non-RF reasons for an engine to cut or splutter for second or two. Regarding the battery, all 2.4g transmitters & receivers are 3.3 volt devices and 9.8v is ample. Like Dave, I'm a bit concerned about the "99% charged" receiver battery. No device on earth can tell you that a NiMh pack is 99% charged. What matters is that the pack holds sufficient voltage and that its ESR is low enough that it maintains that voltage for the duration of the flight under the heaviest in-flight loads. As an extreme example, you'd be safer doing a 10-minute flight with a half-flat A123 pack, than you are with a fully charged 3000mAH pen-cell pack. High-capacity AA's have a notoriously high ESR and simply collapse under load. Conversely an A123 pack will give 70 amps right down to exhaustion. Obviously you wouldnt do that but it illustrates a point. Cheers Phil Quote Link to comment Share on other sites More sharing options...
stevan Lewis 1 Posted June 16, 2015 Author Share Posted June 16, 2015 Thanks for you input Phil. The fact that 2 Rxs were used and exhibited the same problem precludes a Rx problem The battery pack continued for the rest of the day with a 35Mhz system installed and performed faultlessly. I have agreed a refund with the vendor and am in the process of ordering a new RC system Steve Quote Link to comment Share on other sites More sharing options...
XK50 Posted June 16, 2015 Share Posted June 16, 2015 Prompted by the thread on Black Wire Rot, currently active on this forum, I suggest checking out the battery connection on the Tx's innards. I recently bought a second-hand 6EX, fitted with ni-cads and had to clean the plug and socket. John Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted June 16, 2015 Share Posted June 16, 2015 Have you thought about the buddy lead connection ? It's often overlooked but can cause the symptoms you describe . I have had something very similar while teaching with a buddy system . Quote Link to comment Share on other sites More sharing options...
stevan Lewis 1 Posted June 16, 2015 Author Share Posted June 16, 2015 The loss of signal occurred without the buddy lead attached. Also the contacts must be OK because the slave 6ex showed the correct voltage reading, which it gets from the master battery. Thank you all for your comments but I have returned the 6ex and bought a new Spectrum DX6. Steve Quote Link to comment Share on other sites More sharing options...
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