I think you may have nailed it.

Never even crossed my mind (I'm used to working with indoors-type stuff) but a device intended to go outside with very long cables attached to it would need strong arc-type suppression. My eye kept being drawn to the layout of the PCB, and the fact that both legs of that missing part seem to be placed on power planes, which is why I was unconvinced that it was part of the video circuit. Question for Full_Tilt_Boogie: The connector which you have labeled as "video" is actually video, power and ground, right? If so, then all of this stuff is power protection. The yellow device is probably a polyfuse, and the white cylinders are probably suppressors as Davezorz postulates.


And I still think that none of these parts are at fault in your failure. Whatever part exploded on the CCD side of the board generated enough heat that it caused the solder under the missing white cylinder to melt.




Random observation: When you apply 120 VAC to a device like this, that's exactly the kind of destruction that you see.

 

please pardon my inexperienced eyes, but are you saying that both legs appear to be connected to power planes? or a power plane and a ground plane?

It seems like an odd circuit to me. If they are arrestors, they seem to be rated for 900 Volts, which is pretty high(telephone ones are typically 300). It appears they placed a thyristor in parallel with one of the tubes, which is good practice. but then it seems to get weird from there. There does not appear to be a solid state arrestor elsewhere on the board for the other discharge tube, are they ok with up to 900 volts being on that part of the pcb? If the other device is a polyfuse, and FTB's circuit routing is correct, it would appear that if it was hit by lightning, the thyristor would fire and shunt large amounts of current to ground until the polyfuse opens, then you would have up to 900 volts sitting on the supply side of the polyfuse until the other arrestor fired. It would appear to be a race to see if the 900 volt arrestor could fire before you had arcing all over the pcb.

 

I'm using the term "power plane" as a blanket to include ground.


I agree. But mostly because I'm accustomed to dealing with indoorsey small-signals stuff.


A direct lightning hit is going to annihilate anything it touches, period. Even $100,000 broadcast transmitters usually pop when a lightning hit occurs on the antenna itself. In this case, I'd be more worried about high voltages being induced in the long line between camera and receiver owing to incident EMI from nearby lightning hits.

I'm assuming that they've created a crowbar circuit, whereby the solid-state device shuts from V+ to ground with the intention of tripping the polyfuse whenever any sort of overvoltage condition occurs. This is most likely a seperate concept from any sort of lightning suppression- polyfuses are much too slow to deal with really sharp voltage spikes- they're more about saving you from failed switching regulators and whatnot.

And I can't speak to the gas tubes, assuming that's what they are. I've got zero experience dealing with them.


Regardless, I still don't think that any of those components are a primary causal factor here. If the sublimation on the CCD side of the board hadn't caused the solder under one of the tubes to melt, we wouldn't even be looking at them.

 

sorry wrong thread.

 

That 3 pin connector is Video, Ground, 12vDC from left to right.
The video pin has the surge arrestor to ground, then goes through what looks like a capacitor, then has the thyristor to ground, and then the trace goes off somewhere and gets lost.
The other surge arrestor is from 12V to ground IIRC.

Its interesting you mentioned the 24V AC Joe. Im wondering now if we accidentally sent him a 24V AC psu, and maybe some of the cameras are of a new batch and have had the rectifier and conditioning added to allow them to run on 24VAC, while the ones that failed were older and did not.

Either that or they dont have any reverse polarity protection and the customer blew up 5 of them before realizing what he was doing.

 

Megasquirt should include stickers which read
"I'm a squirter!" with every purchase.

 

So I'm installing a set of adjustable coilovers on my car, and it is not a fun job.

I have taken off and installed the wheels a dozen times so far to get the height in a ballpark range.

I have to set the ride height somewhere between 13-14 cm (5.1-5.5") at the front so my 215-45/16 KU36s won't rub.
I may get away with 12.5f 12.75r once everything settles.

And then, the sway bars.. RB54103 f, MSM 14 mm r. With homemade adjustable endlinks.

After all that stuff is dialed in, I will get the EDFC Active Pro, just because.
With the diversity of surfaces I drive on in this town, it will actually be pretty cool.
I hope.

 

Huh. I don't think I have ever removed wheels to adjust coilovers. Just lift the car high enough to unload the spring and reach in there and turn the rings.

 

Ready for Shuiend to come pick up...

 

Wish I could fit all my spare parts in a Miata trunk

 

Brain, how much did you put in the air box?

 

It's empty but I found more parts to toss in...

 

Where's the reset button? I need it...

 

A boy plays Super Mario Brothers for the first time on a Wii.

He cannot grasp the fundamental concept that the controller is supposed to be held in what I have long considered to be the "normal" manner, that is, with both hands, in the landscape orientation, and that input into the game is entirely by way of pressing buttons, with the orientation and movement of the controller unregistered.

This concept is entirely foreign to him, and he is completely unable to control Mario.

#IFeelOld

 

This should help:

 

We had family over on Sunday and I gave my nephew my original Game Boy to play with when he started getting bored. He told me he thought the screen was going out because it was dark and he had to sit near the window to see anything.

Also, when one of the games didn't load correctly, he told me it probably had scratches on it. He was rather impressed to find that blowing into the cartridge and reseating it fixed the problem.

 

The process of researching babysitters for my 21 month old son has inadvertently shown me the most efficient means to find attractive, articulate, educated, and (often) available young women of all ages.

no it's true. www.urbansitter.com

 

 

Quite true.

The majority of the girls at my boy's daycare are the same way. Yoga pants are the typical attire.

 

All my female employees wear yoga pants/leggings fairly often at the bakery...makes for a very pleasant & potentially dangerous day of work, if I let my eyes unconsciously slip.