Stang70Fastback

So, I have my screen powered through the cigarette lighter, and my computer powered form the battery. I just finally got it installed and working this morning. It was awesome...

Went out, took the carputer inside, and opened it up to do two things:
1. I had to switch the usb connector to the case USB ports because they weren't working, so I assumed it was plugged in backwards (it didn't have the missing pin slot - they were all there, and the manual for the case just said to flip it if they didn't work.)
2. Added two more USB plugs.

I reinstalled the Carputer, and went to turn it on... nothing. I checked the fuse under the hood (15 Amp) and it turned out it was shot. Weird. I replaced it, computer went on for a split second, and then same thing. Very weird. I decided to put in a 20 Amp fuse, and started the computer - it seemed to work fine. Turned the key to accessory to turn on the screen, - and the screen came on for a second, made some crackling noises, and started smoking. OH ****. Turned everything off. So far, the carputer seems FINE. I haven't booted it with a screen yet, but everything spins up and it beeps (this is on a regular PC power supply plugged into the wall in the house.) The screen, however, is shot. I have no idea what happened. I called Xenarc and they said it was probably some chip component on the screen's board, and that they'd replace it for free. Fine, but is this all just coincidence? The fuse in the cigarette lighter plug for the screen is not burned up, so it didn't get a surge through that. The only other possibility then, other than the screen being defective is a surge through the VGA cable - which might be related to the computer wanting 5 more Amps through that fuse. However, I'd assume the PC would be shot if something like that happened, and yet it seems fine. Assuming then, that the screen was defective (though I got it on Christmas, and it worked fine up 'till now) what then caused my computer to draw an extra 5 amps out of nowhere? Does adding two USB cables make that much of a difference?

The only OTHER thing I can think of is the USB cables I used. They came with my Lian-Li all-in-one card reader, and I'm using them in reverse. Normally the 9-pin part plugs into the card reader, and the two USB plugs coming out of that go into your computer, making it an EXTERNAL card reader. I plugged the 9-pin part into a USB port on the mobo, and was going to get two female-female adapters so that I could use it to hook up two more USB devices. I cannot imagine that not being fine to do, but even if that DID cause massive problems, how is the computer still ok? Does anyone know what happened, or have any IDEAS??!?!?! This is so very disappointing - I've been working on this project for over three weeks now Thanks for any input you might have!

ARRAAAAGHHH!!!!

UPDATE: PC works fine. Using screen from desktop PC. Had a little hiccup starting it, but unplugged it and plugged it back in. Said CMOS error - reset to defaults. Then booted straight from hibernation mode to Centrafuse and works fine! So IDK what the whole fuse episode was. Just makes things even STRANGER. Guess maybe it WAS an odd coincidence?

pokki

Someting was definetly not right if you were blowing fuses and then smokign screens.

I'd never recomend increasing the fuse size above what is installed form the factory. You may well find that the fuse size is matched to the wire size and not the devices. This would mean that you have a greater chance of fire because the fuse may not blow on a short circuit.

As for what caused your problems I couldn't say without more info. However count yourself lucky you're getting a replacement screen.

Stang70Fastback

I did not replace the fuse in the power line to the screen. That's what's so odd. I guess I wasn't clear enough. The fuse I replaced was to the computer on my own wire. The fuse to the Xenarc monitor (in the cigarette lighter adapter) was left untouched, and was unaffected after the episode, which leads me to believe now that maybe it just WAS an internal failure. Still, it's just odd how this all happened at the same time. PLUS I'm afraid to try the computer in the car now, since it kept burning up the 15 Amp fuses and I have no idea why or what's going on.

pokki

What size wire did you use for your carpc? And what's the distance?
Also how much current is your PC power supply able to draw?

Stang70Fastback

I used 10 AWG, which is plenty lol (I'll never go that big again, that wire just doesn't BEND!!!) I'd say it's total length is no more than 15 feet from battery to fuse to switch in console to PSU hookup. It's an M3-ATX, which is rated at 125 W I think (more than enough.)

I guess what I'll do is use a voltmeter to make sure I'm getting 12V through the wires. If I am, and since the PC is working fine now on a different regular PSU, then if it doesn't work in the car, or freaks out again, it can only be my brand new M3-ATX, right? How many amps SHOULD that power supply pull? As I stated above, it was running fine with a 15 Amp fuse, and then all of a sudden, after I took it apart and plugged in some more USB ports (but didn't plug more things into it) it started asking for 20...

pokki

The specs i can find for the m3atx show 15 amp input, so yeah - if you're blowing 15 amp fuses then i'd get that powersupply and/or your wiring tested.

How'd you ground the PSU?

Stang70Fastback

It's grounded with one of those rings (forget what they're called) to a giant bolt that secures the front passenger seat to the chassis. Worked fine earlier. If it isn't grounded well, does that create power spikes? I'd imagine there just wouldn't be enough current to power it... or does a bad ground force it to draw more amperage to make up for it?

Even if it is a good ground, does the fact that it DID burn 15 Amp fuses mean its likely ruined or damaged? It did NOT burn up a 20 Amp... Thanks for trying to help me out with this.

I'm bringing the car to an aftermarket install place tomorrow to have some guy look at my EXTREMELY amateur wiring and see what he thinks of it before I do ANYTHING else with either the PC or my replacement screen.

pokki

Did you sand the paint back to raw metal? (sorry if these seem like silly questions, but I've seen many dodgy installs).


Correct, poor grounds leads to voltage drop, so the device draws more current to maintin it's required power which then increases the restance and leads to more voltage drop.


There definetly is a possibility it's still working fine (presuming it wasn't faulty).

Stang70Fastback

Yeah, this is sounding more and more like my fault (the computer problem anyway.) I did NOT sand it, but I figured the bolt screwing into the chassis would be enough (I guess I was wrong.) I'm STRONGLY thinking that this is the problem, but I'm gonna leave it as is and bring it to that guy tomorrow just to see ALL that he has to say about it before I touch anything. Still though, it's the same case of "it was working fine BEFORE, so why the hell after I unplug it and plug it back in would that suddenly become such an issue?"

But yeah, I'm willing to bet that was the issue. Just hope the PSU is alright! I shut the computer down before anything was damaged, so I'm willing to bet it's still okay (it was on for maybe 5-6 seconds???)

Just to be certain, since I know no spike of power got to the Xenarc through the power wire (fuse still intact), is there any way to smoke the thing like I did through the VGA cable? Or is it likely a VERY ODD coincidence?

pokki

A quick google of VGA pin outs shows they have a gound pin. There is a chance that because of your possible poor ground for the CarPC, it then tried to gound through the VGA pin, and thus through the screen. However this is well beyond my knowledge of PC, VGA and LCD screens.

Stang70Fastback

Well, today is my birthday, and earlier, uh, yesterday, we took my car to an audio specialist and my dad told me that he'd pay for them to redo the wiring CORRECTLY for my birthday, so although it would have been cool to do it myself, I think I'll feel better knowing I've got all the relays and such correctly installed and the wires correctly grounded. He DID say that it is possible for the computer to attempt to ground through the VGA cable, so that's probably what did it (whoopsey...) At least Xenarc was kind enough to send another!

Stang70Fastback

Well, I got all of the wiring done today, and it turns out that I think I fried the power supply with the bad ground. I guess it's a very touchy PSU because it didn't go over 20V and I definitely hit the power switch and turned it off before IT quit working... so IDK. The light on the motherboard doesn't even come on when I plug everything in. Sucks, cause tomorrow I'm driving 9 hours back to college and we got the screen overnighted back to us just so I'd be able to use the whole thing

loginfailed

Try running 1/0 AWG or bigger and you will wish you has some "hard to bend" 10 AWG.