mpaley

I have a flash 5x transmitter w/ 555 receivers. A few years ago, I seemed to have experience a radio glitch and my plane went down. When I checked the plane out, there didn't seem to be any problems. In addition, I checked the field and no one had channel 34 in use. So, I chalked it up to bad luck...

Two weeks ago, I used the same transmitter (on channel 34) w/ another 555 receiver on my four-star 40. It glitched twice during the air. Again, no one using the channel, and this one was a different receiver. I thought that the crystal on the receiver could be cracked, so we ran up the engine full speed and did a range check that way, but didn't discern any issues.

Last week, I was out on a buddy box training on the four star 40 again. On final approach the plan rolled over and crashed way out in the marshes. I have not yet been able to recover the plane after hours of searching. I'm considering it a loss.

Now, I'm finally getting around to rebuilding the 1st plane I crashed, and wondering if I can trust the transmitter w/ the receiver that is installed. I am considering just replacing everything with a DX7 or something like that. But, something tells me that 72Mhz w/ ch 34 should just work and I don't need a new setup.

Any advice?

-Mark

A.T.

If TX and model have been unused for any period, pre-flight checks must include total airframe and fittings as physical changes do occur with age. Nylon clevis and horns get brittle and pins break without warning as does the shrink wrap used to hold wires onto ARF push rod dowels. Wood around hinges and epoxy joints softens from moisture or oil. Balsa wood drys, becomes brittle and breaks under in-flight stresses. RC systems, even stored in their original boxes, are damaged from corrosion which due to moisture trapped at time of storage, is hard to stop.
A litle late in this instance, but when flying over brush, swamp and corn fields, a Lost Model Alarm is an asset. Hopefully the model is located in order to eliminate mechanical causes, especially the RX battery failing which your post suggests. A loaded battery checker used before flights is good because many losses/glitches are due to RX batteries failing to handle sudden load increases. (Recommend new batteries, especially NiMH be cycled 2-3 times before use)
If the Flash 5 TX was being used as the Slave unit, Master TX would have passed on any bad stick input but still have recovered the model on release of the trainer lever.
If the Flash 5 was used as the master, then check sub sections:
"Range check and Range problem solving"
"Receiver - FAQ, guides and aids to best reception..
"Transmitter - FAQ - Additions, Adjustments, Clonepacs & Repairs" especially Antenna cleaningon my web page.
All TX should be serviced and retuned regularly to ensure optimum performance, especially a wiring check on switches and pots as user may never have any sign until that flexing pot wire breaks the last black corroded strand. In need:
Hitec Support details
Hitec Repair Request PDF
Regards
Alan T.
Alan's Hobby, Model & RC FAQ Web Links

mpaley

Thanks for the feedback Alan!

Before I flew the four star 40, I did do a complete range check. It had suffered a minor accident due to some glitch the week before, and all the control horns were re-inspected. One was replaced. I have a battery checker that I use, and it indicated that the batter was okay prior to use.

One thing you did mention was the buddy box -- could this be a source of the trouble? It turns out that every time one of my planes has gone down, it's been connected to a buddy box. The flash 5x was the master. When the instructor saw the plane roll, he took over, but was not able to recover the aircraft.

I hope we can find the plane too, but it's not looking good. Do you have a recommendation for a lost model alarm?

thanks for the advice on the transmitter maintenance -- is that true for a buddy box as well? I'll check out your links.

Thanks!

-Mark

A.T.

DIY Lost Model Alarms are listed under electronics on my web page. Best commercial LMA for GP model cars/boats/planes include failsafe which also cuts motor when battery voltage falls or signal lost or in event of interference, is the ULTRA SAFE UTS-20B = Fail Safe with Lost Model Alarm great for those without PCM receivers. Alternatively, Lost Model Alarm with Low Battery warning or BE FOUND - Lost model alarm are also popular and your LHS should have some in stock. (perhaps with a different brand label on top of the first two OEM units).
Intermittant faults are very difficult to isolate but given yours occurred with the buddy box, I would start with the Trainer switch - if used infrequently it could have some corrosion or dirt on the contacts. Next check all plugs and sockets cleaning contact points with isopropyl alcohol or similar. Refer to Trainer - Buddy Cord Warning - Use only a Hitec One Way Cord between Futaba & Hitec TX - never use a Futaba cable. and the link to latest update on trainer box compatibility. Always hold a loop of cable against each TX to prevent any tugs or stress on the sockets when in use. The cable wires are very fine and one may be broken and pulling apart when instructor "awakes suddenly with a bit of body language".
A slow process working through all possibilities as "fault" may be as simple as orientation of the RX antenna, especially as range is reduced over damp ground and you did mention that the model was out low over swamp..If Guide to receivers - and solving apparent RX & "Interference" problems is down, email me direct for .pdf.
Best wishes
Alan T.
Alan's Hobby, Model & RC FAQ Web Links