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Old Mar 25, 2010, 09:07 AM
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Brisbane, Australia
Joined Mar 2010
152 Posts
Help!
Fried my FPV gear (rev pol) - any chance of repair ?

Arghhhh ....

I am so upset. I have been looking forward to start FPV flying sooo eagerly.
I bought one of the bestofferbuy.com 1.28 GHz AV transmitters/receivers and one of the $25 Sony CCD camera boards off ebay.
Soldered the video and DC supply cables of these together and made a Y-cable from my main LiPO to power the two. Just finished that half an hour ago and hooked everything up .... and noticed the nasty smell of some electronics cooking.
Well, somewhere in my Y-cable I crossed over plus and minus. ... It is obvious, I should have seen it when checking but it has been a long day and I was (am) a bit tired.

It appears that both the camera and the video TX are toast. Not only was the DC input reversed, but because the video input of the TX and the video output of the camera share GND with the DC supply they had +12 V applied as well.
Is there any hope of repairing these ? Has anyone else reversed the polarity on one of these cameras or TXs and been able to repair it? On first sight it looks like SMD hell ...
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Old Mar 25, 2010, 09:11 AM
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Netherlands, NH, Edam
Joined Jul 2004
5,535 Posts
No, unfortunately this usually means you can bin them, sorry!

Cheers,

Sader.
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Old Mar 25, 2010, 09:28 AM
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syberjunkie's Avatar
Lees summit, mo
Joined Dec 2004
88 Posts
Look on the bright side, you now have a spare camera lens and antenna.
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Old Mar 25, 2010, 09:32 AM
Don't leave it Stock
mrfliboy's Avatar
USA, IL, Round Lake
Joined Feb 2004
2,512 Posts
http://www.rcgroups.com/forums/attac...mentid=3131414

On the Panasonic camera there is a fuse that can be removed/jumper to fix them.
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Old Mar 25, 2010, 09:35 AM
fast
fmkit's Avatar
ISRAEL
Joined Aug 2007
2,668 Posts
send the burned stuff to me, I'm unemployed and have time to overclock your camera or shift your TX into 700mhz band to get range never seen before
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Old Mar 25, 2010, 01:20 PM
Born to Live - Live to Fly !
stevekott's Avatar
Southern California
Joined Jul 2009
526 Posts
This may not help you technically, but it could help you emotionally.

http://www.rcgroups.com/forums/showthread.php?t=1195188

Sadly -- Welcome to GARP
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Old Mar 26, 2010, 07:08 AM
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Brisbane, Australia
Joined Mar 2010
152 Posts
Quote:
Originally Posted by mrfliboy View Post
http://www.rcgroups.com/forums/attac...mentid=3131414

On the Panasonic camera there is a fuse that can be removed/jumper to fix them.
thanks ... that's the sort of information i was looking for. Hopefully I can find something similar on my camera which has the Sony CCD.

Looking at the video TX I have to agree that all hope is lost . Unfortunately my stupidity will set my FPV ambitions back by a few months as I can't justify putting more hobby-related expenses on the credit card for a while.

good to know that I'm not the only one who has made silly mistakes
...
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Old Mar 29, 2010, 08:24 AM
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Brisbane, Australia
Joined Mar 2010
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Update: got time to do some testing today.

I was lucky, the camera survived, it must have protection against reverse polarity ...

Also, I identified the (or one of the) things that went up in smoke on my video TX. It is a 3 pin SMD chip on the PCB just to the left of where the black GND cable is soldered on. The chip has a tiny crater in it. I believe it is (or was) a voltage regulator (maybe of the 78XX type ?), however I can't identify any ID on the surface ... not sure whether any ID was visible before it went up in smoke.
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Old Mar 29, 2010, 08:16 PM
First to go over 106K feet
Crist Rigotti's Avatar
United States, TX, Waxahachie
Joined Mar 2008
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Quote:
Originally Posted by opticalflow View Post
update: Got time to do some testing today.

I was lucky, the camera survived, it must have protection against reverse polarity ...

Also, i identified the (or one of the) things that went up in smoke on my video tx. It is a 3 pin smd chip on the pcb just to the left of where the black gnd cable is soldered on. The chip has a tiny crater in it. I believe it is (or was) a voltage regulator (maybe of the 78xx type ?), however i can't identify any id on the surface ... Not sure whether any id was visible before it went up in smoke.
78l05
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Old Mar 30, 2010, 01:14 AM
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Brisbane, Australia
Joined Mar 2010
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Quote:
Originally Posted by Crist Rigotti View Post
78l05
Do you know for sure, or is this just a guess ?

On the one hand it would seem a bit odd to have 12V input voltage and then go directly down to 5V, but I guess some of the ICs on the board would require 5 V whereas other components may require 12 V.
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Old Mar 30, 2010, 01:25 AM
my karma ranover my dogma
galaxiex's Avatar
Edmonton,Canada Eh
Joined Jun 2007
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Quote:
Originally Posted by OpticalFlow View Post
Do you know for sure, or is this just a guess ?

On the one hand it would seem a bit odd to have 12V input voltage and then go directly down to 5V, but I guess some of the ICs on the board would require 5 V whereas other components may require 12 V.
Actually I think most of these "12 volt" vid Tx operate at a circuit board level of 3.3 to 5 volts.

They use regulators to enable operation at 12 volts because 12V is the standard for security systems, which these vid systems are originally designed for.

I have operated a few so called 12V tx down to 7.5 - 8 volts reliably, and the Tx does not get so hot at the lower voltage because the regulator doesn't have to "waste" so much energy as heat.
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Old Mar 30, 2010, 04:03 AM
Registered Loser :)
mark hitchman's Avatar
New Zealand
Joined Sep 2009
1,932 Posts
voltage reg

When I reversed my vid t/x I had to replaced the voltage regulator. Mine was a 7808 which is 8 volt and I could not get a smd so I put in a normal size one, bit rough but works sweet.

http://www.rcgroups.com/forums/showthread.php?t=1212188

Thanks
Mark
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Old Mar 30, 2010, 09:18 AM
First to go over 106K feet
Crist Rigotti's Avatar
United States, TX, Waxahachie
Joined Mar 2008
2,483 Posts
Quote:
Originally Posted by mark hitchman View Post
When I reversed my vid t/x I had to replaced the voltage regulator. Mine was a 7808 which is 8 volt and I could not get a smd so I put in a normal size one, bit rough but works sweet.

http://www.rcgroups.com/forums/showthread.php?t=1212188

Thanks
Mark

Different transmitter...does not apply in this case
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Old Mar 30, 2010, 07:08 PM
Registered User
Brisbane, Australia
Joined Mar 2010
152 Posts
Quote:
Originally Posted by Crist Rigotti View Post
78l05
I photographed the unit today to upload a picture. I also took a macro shot (by holding the lens in front of the camera the wrong way round - with the bajonet facing outwards) ... and on the macro shot I can still read the 05, so Crist got it right.

(pictures attached)

Now the questions are where to get an SMD 7805 as the case is too small to fit a full-size one in there and how on earth I'm I going to replace it. Maybe my best bet is to leave the old one in and solder thin wires to each of the pins which I then hook up to the replacement 7805. Not sure whether it is going to be worth the effort (other parts may have fried up as well) but an interesting challenge.
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Old Mar 30, 2010, 07:23 PM
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Brisbane, Australia
Joined Mar 2010
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Quote:
Originally Posted by galaxiex View Post
Actually I think most of these "12 volt" vid Tx operate at a circuit board level of 3.3 to 5 volts.

They use regulators to enable operation at 12 volts because 12V is the standard for security systems, which these vid systems are originally designed for.

I have operated a few so called 12V tx down to 7.5 - 8 volts reliably, and the Tx does not get so hot at the lower voltage because the regulator doesn't have to "waste" so much energy as heat.
That makes sense although I would have thought that such a tiny 7805 would get incredibly hot when it has 12 V input voltage.

I just tried figuring out what package this is but http://www.national.com/mpf/LM/LM78L05.html#Packaging doesn't show a package type that looks anything like the one in this unit.
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