OK, let's see what we can learn. This is going to get long but I think it will be worth your time. I make a recommendation to move to 2.4 GHz at the end.
I too fly the Futaba 9C. I have a pair of 9C Supers. Both converted to 2.4 GHz with a swap of the module but I can switch back to 72 MHz at any time.
This appears to be the airplane
Wattaplane! - Skywing 32-in EPP Yak-55 (Profile Red)
Receiver specs
SPECS: Narrow Band: 20kHz Power Requirements:
4.8 to 6.0V (shared with servos) Current Drain: 10mA Length: 1-1/4" (31.75mm) Width: 1/2" (.02mm) Height: 7/8" (.28mm) Weight: 0.35 oz (9.9g)
First, the servos. Most likely they were cooked but the only way to tell would be to put them in another receiver and test them. Do you have another to use for the test?
Do you have any spare servos to test with the receiver?
Do you have a spare crystal?
At the time that that receiver was released all receivers ran on 4.8V and some could take 6V too. There were no high voltage receivers that I recall. ( I have been flying since 2003 )
It is my expectation that you cooked the receiver, the crystal and the servos. But you need to test everything.
However you may be better off replacing the receiver as even if it works it might be unreliable.
I found this Corona Synthesized receiver.
https://hobbyking.com/en_us/corona-synthesized-receiver-4ch-40mhz-v2.html?gclid=CjwKEAjw3KDIBRCz0KvZlJ7k4TgSJABDqOK7 meea6GvSemg8PC_iYXO-rOCRHp7GAuUlh-4i1U-68xoCX1zw_wcB&gclsrc=aw.ds
Weight 0.14oz/4.0g(without shrink wrap)
Sensitivity about 2.0ìV
Selectivity ±8kHz at 65dB down
Number of channels 1-4
Filtering Dual turned RF circuitry
Filtering Dual 4 pole ceramic filter
Filtering DSP filtering in MCU with mild algorithm
Shift polarity Positive or negative (auto-detect)
Case Shrink wrap
Operating Voltage 4.8V~6.0VDC
Operating Current 11mA
Modulate FM/PPM(pulse position modulation)
This should work with your Futaba 40 MHz radio. It is quite inexpensive so it should be an easy fix. You might buy two so you have a spare and one ready to go in your next aircraft.
I also find this 6 channel.
https://hobbyking.com/en_us/corona-s...6ch-40mhz.html
And a 9 Channel
https://hobbyking.com/en_us/corona-s...9ch-40mhz.html
All are PPM so you will only be able to use 8 channels on your 9C but that should be enough.
A better alternative might be to switch to 2.4 GHz. No frequency control needed as the receivers can all work together. My 9C radios are now on 2.4 GHz.
This is a FrSky system for your Futaba 9C. FrSky has an outstanding reputation and I would use their products without hesitation. Pull you 40 MHz module and insert the FrSky module. Now you are flying on modern 2.4 GHz. FrSky receivers are readily available and are popular among USA competition sailplane pilots. The costs shown in the article are WAY out of date. Prices have come down dramatically. I suggest you follow this path.
https://hobbyking.com/en_us/frsky-ff...module-rx.html
There will be some learning as you bind the receiver to the transmitter. Similar to binding a blue tooth wireless headset to your cell phone. And once bound it will only listen to your transmitter. No more shoot downs and no need for frequency control.
The antenna are VERY short, which means no more long antenna trailing behind the plane. In a carbon fuselage you need to get the antenna outside the fuse, usually by drilling holes and setting them out like cat's whiskers. Just read the instructions and you should be fine.
I suggest you update your radio.
Here are some resources that may be helpful. This link leads to a 2 part series I did on converting from 72 MHz to 2.4 GHz. While it is centered on sailplane pilots it applies to all aircraft. It appeared in RC Soaring Digest in 2012
Low cost sailplane radios – RC Soaring Digest
Two part series – July and August 2012
Upgrading 72 MH Sailplane Radios to 2.4 GHz
http://www.rcsoaringdigest.com/pdfs/...SD-2012-07.pdf
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