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Electric noob....did i fry my receiver rx?

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Old 04-11-2017, 04:25 AM
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bikz
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Default Electric noob....did i fry my receiver rx?

Having never had a single EP or lipo battery till today, I might have made a blunder.

Got a second hand EPP plane with a 2cell (7.4V) Lipo battery.
Being used to & out of habit of just connecting 4.8V/6.0V NiMh batteries straight to the rx, i did the same and now i suspect i fried the rx. (only thereafter i realised that i wld need to hv connected the battery to the ESC which had an input connector! I had never dealt with ESC or lipos prior to this so kindly excuse the ignorance!)

I tried connecting the rx with the usual 4.8V NiCd thereafter and it isn't working. So have i fried it for good???

Can anything be done to save the rx? It is a nice brand new 40Mhz futaba micro rx.

also, would it have harmed the crystal in the process because the crystal from that rx, when fixed onto another working rx isn't responding either.

thanks for the answers guys.

Last edited by bikz; 04-11-2017 at 04:36 AM.
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Old 04-30-2017, 06:05 PM
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It has been several weeks since you posted this. Did you save the receiver or was it fried?
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Old 05-01-2017, 03:27 PM
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i still have not done anything to it as I do not know what to do!

can anyone help me shed some light if it can be saved and if so, what am I to do plz?
I have a friend who repairs handphones/cellphones. I'm sure he could help me out but I need to tell him what components to be changed.

thank you guys.

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Old 05-01-2017, 04:46 PM
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Hi,
The ESC if working properly , will provide 4.8 volts to the receiver via the plug that connects to the throttle port of the receiver. There is no need for a receiver battery . Make sure the ESC is plugged into the proper receiver port and make sure the polarity is correct. You typically won't short out a receiver by plugging in an ESC plug backwards but the receiver will not get power.
If the suspect crystal is of the same frequency and band as the working receivers crystal and it will not work in the other receiver then that crystal is dead.

List the radio ,receiver make and model , the band and frequency, and the make of the ESC you have.
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Old 05-01-2017, 07:50 PM
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Originally Posted by bikz View Post
Having never had a single EP or lipo battery till today, I might have made a blunder.

Got a second hand EPP plane with a 2cell (7.4V) Lipo battery.
Being used to & out of habit of just connecting 4.8V/6.0V NiMh batteries straight to the rx, i did the same and now i suspect i fried the rx. (only thereafter i realised that i wld need to hv connected the battery to the ESC which had an input connector! I had never dealt with ESC or lipos prior to this so kindly excuse the ignorance!)

I tried connecting the rx with the usual 4.8V NiCd thereafter and it isn't working. So have i fried it for good???

Can anything be done to save the rx? It is a nice brand new 40Mhz futaba micro rx.

also, would it have harmed the crystal in the process because the crystal from that rx, when fixed onto another working rx isn't responding either.

thanks for the answers guys.
Originally Posted by bikz View Post
i still have not done anything to do to it as I do not know what to do!

can anyone help me shed some light if it can be saved and if so, what am I to do plz?
I have a friend who repairs handphones/cellphones. I'm sure he could help me out but I need to tell him what components to be changed.

thank you guys.
First, many modern receivers can handle up to 9V so you may have done no damage at all.

Right now there is not nearly enough information to determine if you damaged anything as we don't know if anything was working before you did this.

In an electric airplane the battery is connected to the Electronic Speed Control, ESC. The ESC is connected to the throttle channel on the receiver and delivers power and signal to the receiver. It is quite surprising that the battery had the correct connector to attach it to the receiver directly. Normally battery connectors for electric airplanes are not the same as servo connectors that go in the receiver.

You say this is a new 40 MHz futaba micro receiver. Model number please. I am surprised that Futaba is still making 40 MHz receivers as all new equipment is 2.4 GHz and has been for many years. Read the manual and see what the maximum voltage is that the receiver can take. It may be printed on the receiver too.

What airplane did you get?

What radio are you using?

What receiver?

Are the radio and the receiver on the same channel?

Some Futaba receivers are either high range or low range and don't work well if you cross the mid point.

We need more information.

Had that radio been bound to the receiver/airplane?

We need make, model, link to a web site. If you can't provide that then we need you to post photos of the plane, the radio, the receiver, the battery and connectors.

Do you have the manual? Does it have a binding procedure?

Please provide more information.

Last edited by aeajr; 05-01-2017 at 08:17 PM.
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Old 05-01-2017, 09:21 PM
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Originally Posted by aeajr View Post
First, many modern receivers can handle up to 9V so you may have done no damage at all.

Right now there is not nearly enough information to determine if you damaged anything as we don't know if anything was working before you did this.

In an electric airplane the battery is connected to the Electronic Speed Control, ESC. The ESC is connected to the throttle channel on the receiver and delivers power and signal to the receiver. It is quite surprising that the battery had the correct connector to attach it to the receiver directly. Normally battery connectors for electric airplanes are not the same as servo connectors that go in the receiver.

You say this is a new 40 MHz futaba micro receiver. Model number please. I am surprised that Futaba is still making 40 MHz receivers as all new equipment is 2.4 GHz and has been for many years. Read the manual and see what the maximum voltage is that the receiver can take. It may be printed on the receiver too.



Please provide more information.
Firstly thank you sir for having given a reply. Really appreciate it. Almost gave up on that receiver due to lack of response from here. thank you once again. The following are my answers to your questions:

What airplane did you get?
SKY WING 32-INCH EPP YAK 55

What radio are you using?
FUTABA 9CAP

What receiver?
FUTABA 4CH MICRO RX R114F 40MHZ


Are the radio and the receiver on the same channel?
YES- I tested it with a 4.8v battery and the crystal which corresponds to my TX at the shop. this was an old stock brand new rx (the very last) from an rc store closing down here.


Had that radio been bound to the receiver/airplane?
no binding needed as both tx and rx will work on the same frequency


ps: unfortunately i was unlucky as the lipo battery had infact a connector which plugged into the rx directly and all the servos went berzerk at that point which indicated that power did pass through the rx. only thereafter i realised there was a port from the ESC to connect the battery.

I hope the above info can shed some light into reviving the rx as correctly pointed, it is unobtainium as it has been discontinued.

the 72mhz version i found from google is posted below which says that 6V is the max voltage...sigh....

https://hobbyking.com/en_us/futaba-r...___store=en_us

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Old 05-02-2017, 04:39 AM
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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 2.0V
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


EVERYTHING YOU WANTED TO KNOW ABOUT ELECTRIC POWERED FLIGHT
An on-line book I did that is published on this forum.
Everything you want to know about electric flight - RCU Forums

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Old 05-02-2017, 03:08 PM
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thanks once again Aeajr for the great update on modern radio. I did not even realise and know there are synthesized rx-es available for ppm/pcm fixed frequency tx-es as everyone here flies on 2.4 radios as well!
a friend has given me a FrSky Module for my tx and i'll take it from there......thank you once again and i guess that's the way i'll head or rather have to head! cheers.

as for the fried mini tx, yes i have tested it on working crystal and servos and its no good.....no response....any idea if a voltage regulator can be changed internally to save it?
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Old 05-02-2017, 04:11 PM
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I would not trust it.
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