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Old Aug 08, 2010, 06:11 AM
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FrSky V8FR - receiver burnout

Hi,

I have just bought two Frsky receivers. This is the first time iam using the Frsky receivers....never used them before.

Brought them home..plugged the first one couldnt bind...unplugged the battery and plugged it again and BANG! with bright orange glow started to burn...plugged the second one in and BANG! there it goes .

Am sure the battery wasnt connected the wrong way..cause i was using the Futaba Notch plugs cant go wrong.

The receiver I was using is...the 8-Channel V8FR (http://www.frsky-rc.com/ShowProducts.asp?id=26)


Their site shows I can use Operating Voltage Range(OVR) 4.0 - 7.2V. I was using the 5-Cell battery and I checked it gave 6.8Volt at that time the receivers blew...i opened up the manual and in it it says the OVR is 4.8 - 6V.

Can this be the reason...they blew up?...I always use the 5 Cell battery packs...what should i do....will the new V8FR-HV work fine? Whats the REAL! OVR for this receiver?

Has anyone had any such experience?
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Old Aug 08, 2010, 08:05 AM
60 years of RC flying
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Canada, ON, Ottawa
Joined Feb 2006
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It is generally understood that 4.8 to 6 volts is equivalent to saying 4 or 5 cell NiCd or NiMH pack. This means that the equipment must be able to take the full voltage of a 5-cell pack immediately after charge. I have used the latest FrSky 8-channel receiver on a 5-cell pack with absolutely no problem. I'm sure that is not the source of your trouble.

Since two receivers failed in quick succession with the same setup, there would seem to be only two reasonable explanations:
  • Both had the same internal fault, resulting from some sort of production error or bad component, or
  • There is something in your setup that applies reverse voltage to the receiver.
The first is possible but seems unlikely -- in fact, I've never heard of such a fault that could cause the problem you experienced. But you might want to contact FrSky about it. If there is such a fault, you probably aren't the only one to see it.

But first, go over your setup very carefully. It's not matter of reversing the plug that goes into the receiver, as doing that would not cause a problem anyway (the positive wire is in the middle). Rather, it's likely to be in the connection to the battery, the switch or something else along the way. Check every part of your power system, looking for things like wrong color wires or reversed connections. The first question is whether the polarity of battery wires is correct. Use a meter to check.

Good luck with your efforts. Keep us informed.
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Old Aug 08, 2010, 08:44 AM
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Quote:
plugged it again and BANG! with bright orange glow started to burn...plugged the second one in and BANG! there it goes
Most likely the voltage was reversed. The orange glow comes from the capacitor that burned out. If you are able to solder in a new capacitor, there is a chance that the RX might still work.
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Old Aug 08, 2010, 08:58 AM
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well its simple battery plugged in .....straight on the 8 chaneel..no switch in between.same battery ive been using on hitec supreme rx & assan 7 channel rx...& no problemo...wat do you mean by polarity & how do i check?
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Old Aug 08, 2010, 09:34 AM
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Originally Posted by hamza_b View Post
well its simple battery plugged in .....straight on the 8 chaneel..no switch in between.same battery ive been using on hitec supreme rx & assan 7 channel rx...& no problemo...wat do you mean by polarity & how do i check?
What we are both saying is that it looks as though the positive and negative connections got reversed -- that's called reverse polarity.

I looked at my 8VFR and agree it's impossible to insert a Futaba connector in reverse, so that's not the issue (and would not be anyway for a properly wired connector as the positive wire is always in the middle).

So what you need to do is to take your meter and determine the direction voltage between the centre pin (red) and the ground pin -- away from the extra flange on the Futaba connector (black or brown). Center (red) should be positive. Also check that there is no voltage between red and the other wire (white, yellow or orange) or between the latter wire and the ground pin.

Let us know what you find.
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Old Aug 08, 2010, 11:01 AM
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So this is what I have...

Battery with Futaba Connector

Black (opposite side of flange)
Center (red)
White (next to flange)

I checked with a voltmeter by putting the redstick on red and blackstick on black and it gives +ve 6.76 volts.

Next i put redstick on red and blackstick on white and a minor 0.06V or even less is there..


I put redstick on black and blackstick on white...get nothing.

Battery seems normal...just plugged the battery again on assan rx7 works fine.


Is there anyone who can plug his 5-cell running above 6.5 volts to his frsky rx. actually a friend of mine plugged his 5 cell running 6.2 volts and it seems to be working fine. really confused here.

wats the take on HV version of the rx? will they be okay with current over 6.5 volts? why did frsky make the HV version at first place...is 6.5 volt the top limit for the normal rx?

i wonder if people from frsky will read and answer this.
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Old Aug 08, 2010, 11:35 AM
60 years of RC flying
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Canada, ON, Ottawa
Joined Feb 2006
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Quote:
Originally Posted by hamza_b View Post
So this is what I have...

Battery with Futaba Connector

Black (opposite side of flange)
Center (red)
White (next to flange)

I checked with a voltmeter by putting the redstick on red and blackstick on black and it gives +ve 6.76 volts.

Next i put redstick on red and blackstick on white and a minor 0.06V or even less is there..


I put redstick on black and blackstick on white...get nothing.

Battery seems normal...just plugged the battery again on assan rx7 works fine.


Is there anyone who can plug his 5-cell running above 6.5 volts to his frsky rx. actually a friend of mine plugged his 5 cell running 6.2 volts and it seems to be working fine. really confused here.

wats the take on HV version of the rx? will they be okay with current over 6.5 volts? why did frsky make the HV version at first place...is 6.5 volt the top limit for the normal rx?

i wonder if people from frsky will read and answer this.
I can confirm that the 8VFR runs fine on a 5-cell pack reading 6.75 volts. Just tried it again. The red light simply comes on and flashes if there is no signal from a transmitter. The receiver works normally once the transmitter is turned on.

You don't need an HV receiver. Any receiver that says it can operate on 6 volts means using a 5-cell pack. The "6v" is nominal. (What it won't do is operate safely on the 8.4v of a 2-cell LiPo, for example. It's for that kind of setup that FrSky made the HV). So forget that issue.

Please confirm that when you talk about red on the battery connector, it is the center pin you are referring to. That's the critical issue now. If it was NOT in the centre position you could have reverse polarity to the receiver. I assume it's correct, as you say you are using it with other receivers (are you plugging directly into the receiver in that case too?).

If you can confirm this, then your battery sounds normal. If, when the two receivers were damaged, you simply plugged in that particular battery directly into the receiver, it sounds as though there might be a receiver problem. In that case, you would want to contact FrSky.

Anyone else have thoughts on this?
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Old Aug 08, 2010, 12:50 PM
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Reading through this he said red wire in center and from the meter readings and description it sounds like he is measuring them correctly. And since that same battery works correctly on other receivers it really does sound like the receiver was defective. Maybe they soldered the bypass cap in backwards and it popped.

AT any rate, he needs to contact the manufacturer or reseller to get two new ones.

As far as the voltage rating, I would expect they used a regulator that is good for at least 15 volts, someone should probably open up a receiver and take a look to verify the chip used.
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Old Aug 08, 2010, 01:07 PM
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yuh sure the red one is in the center. the battery is connected directly on the rx channel-8.

well i have returned the rx to the frsky distributor here in my country and he says he will get the replaced...meanwhile...i cant make my mind....ifr i should continue with frsky or not...

Can the burnout be related to C rating of the battery? any chances? ...

also another thing i might have forgot to mention is that...the receivers worked fine on the first couple of starts at the time of initial binding...but because the binding wasnt working i plugged it out and plugged it back in again...and probably on the second or third try the second they got in contact they burnt out.

am thinking...maybe you know how when you are connecting something to the rx and it aint setting in properly...maybe becoz the battery was direct some contact somewhere didnt sit in properly...can it be? maybe like the red one was in but the black wasnt...get what i mean?
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Old Aug 08, 2010, 01:45 PM
60 years of RC flying
Daedalus66's Avatar
Canada, ON, Ottawa
Joined Feb 2006
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Quote:
Originally Posted by hamza_b View Post
yuh sure the red one is in the center. the battery is connected directly on the rx channel-8.

well i have returned the rx to the frsky distributor here in my country and he says he will get the replaced...meanwhile...i cant make my mind....ifr i should continue with frsky or not...
FrSky is an excellent system. Your bad experience has nothing to do with the quality of the system in general.
Quote:
Can the burnout be related to C rating of the battery? any chances? ...
No. No connection whatsoever. C-rating simply tells you the maximum current the battery can deliver.
Quote:
also another thing i might have forgot to mention is that...the receivers worked fine on the first couple of starts at the time of initial binding...but because the binding wasnt working i plugged it out and plugged it back in again...and probably on the second or third try the second they got in contact they burnt out.

am thinking...maybe you know how when you are connecting something to the rx and it aint setting in properly...maybe becoz the battery was direct some contact somewhere didnt sit in properly...can it be? maybe like the red one was in but the black wasnt...get what i mean?
Interesting that they worked at first, but I'm not sure what it proves.
As for intermittent contact, it certainly shouldn't affect the receiver.

What exactly happened when the receivers failed? You said there was a bang and they "started to burn." Do you mean there was smoke? This does perhaps sound as though a capacitor was reversed within the receiver -- its failure could make a noise and produce smoke, or at least a burning smell.

Anyway, at this point I think you should stick with FrSky and work with the distributor to figure our the problem. Keep us informed.
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Old Aug 08, 2010, 02:05 PM
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most certainly...bang! smoke! flash! smell! all of this was there

am thinking ill give the left over frsky rx another chance this time via switch.

But before that wanted to confirm that you are sure that the non-HV version of V8FR works fine on voltages between 6-7 volts?

Just a thaught that in assan and in others they give these capacitors that sit on an exta channel...they do say that these capcitors protect from surges or from low voltages...will this help?
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Old Aug 08, 2010, 02:30 PM
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Joined Feb 2006
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Quote:
Originally Posted by hamza_b View Post
most certainly...bang! smoke! flash! smell! all of this was there

am thinking ill give the left over frsky rx another chance this time via switch.

But before that wanted to confirm that you are sure that the non-HV version of V8FR works fine on voltages between 6-7 volts?

Just a thaught that in assan and in others they give these capacitors that sit on an exta channel...they do say that these capcitors protect from surges or from low voltages...will this help?
It does sound like a capacitor. And it could have been installed backwards. And the fact that you had two faulty receivers suggests that they came from the same manufacturing batch and there are probably others out there with similar problems. So FrSky are probably aware of the issue. They are generally eager to deal with such problems. I think you should give them another chance.

The FrSky is rated as one of the best 2.4 systems. See:
http://www.rcmodelreviews.com/2.4ghzshootout.shtml

As for the voltage, here's the answer from the FrSky website:

Model: V8FR/V8R7/V8R4/V8FR-HV
Operating Voltage Range: 4.0V-7.2V, 3.0V-16V (HV Version)
Operating Current: 30mA
Resolution: 3072
Latency: 22ms

As you can see, the receiver you have is rated up to 7.2 volts.

The so-called "voltage protection" capacitors are intended to protect against momentary drops in voltage that could cause the receiver to reboot. They would not help to protect against an internal failure of the receiver, which is what you appear to have.

Stop looking for alternative solutions and go straight back to the distributor for a replacement. Ask the distributor to test the new receivers before sending them to you. If you still have problems, contact FrSky directly.
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Old Aug 08, 2010, 03:10 PM
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sounds good to me...ill give another rcvr a try what the heck i cant live in a scare

meanwhile ill buy the HV versions to be on the safe side.
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Old Aug 08, 2010, 05:12 PM
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Joined Feb 2006
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Originally Posted by hamza_b View Post
meanwhile ill buy the HV versions to be on the safe side.
Unnecessary unless you want to use LiPo or other HV supply. It won't protect you from the kind of event you suffered with the first ones. But it won't hurt. Good luck!
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