inverter startup prob~!

bulgogi777 · 09-01-2004, 01:36 PM

Ok, I need all the EE gurus out there to help me figure this one out~!

I currently use an inverter to power my PC. I wanted to have the PC automatically boot when I flipped the inverter switch, so I wired up this circuit:

connected this to a relay that shorted my on/off motherboard pins.

Now, my fused 12v source was coming from my stereo wiring harness... it's basically an unswitched 12v source. Now I realized that my switched source had to be triggered from my inverter. The first time I tried wiring this up I found that I had 12v across the actual switch connection of the inverter. So I simply soldered a wire to the "off" lead on my inverter switch. (by the way, my grounds go to the ground wire coming from my harness as well) This setup actually worked for a couple times, and then the problems began.

The next morning I flipped the inverter switch, and the computer seemed to come on, and nothing came up on my monitor... it just kept flashing "no vga signal" and I realized that my computer was powered up but nothing was happening (it was not going to windows). I tried flipping the inverter switch a couple more times with the same result, and then, poof! my inverter fried.

I grudgingly bucked up and bought a new inverter (same model), and went for a second try.

I thought that the problem might lie in the fact that I was pulling a 12v source out of the inverter in a place that the inverter didn't like. SO, this time, instead of pulling the 12v from the switch, I plugged in a transformer that supplied a 12v output, and used that as my switched 12v source. Oh, and I did change the switched sources ground (the ground on the right side of the above diagram) to the ground wire off of the transformer. Again, everything seemed to be working, and today, I flipped the switch and the bad bad bad flashing "no vga signal" came on again. I immediately switched off, and unplugged the transformer from the inverter outlet. Luckily my inverter is still working.

If you have any insight to the source of the problem (and you've actually made it through this novel) please please please post, thank you~!

bulgogi777 · 09-01-2004, 02:59 PM

bump, bu-bump bump

SAScooby · 09-01-2004, 03:05 PM

to get the pc to start up set your bios "resume when power returns" or whatever your bios calls it and as soon as the pc senses the power supply has voltage it will start up !

to shutdown you have a few choices (the dummy ups interface comes to mind)

bulgogi777 · 09-01-2004, 03:11 PM

aahhh... I thought that option was to start if power had been cut and you didn't shutdown properly... anyways, I'll have to double check if my bios supports that feature. If not though, any thoughts on what could be causing my problem with the current setup?

bulgogi777 · 09-02-2004, 12:10 AM

I think some really bad mojo is going on with my inverter setup... Is it possible that my inverter doesn't like to start outputting juice IMMEDIATELY after it starts?

I thought my problem lied in the fact that I was wiring something wrong... But I just switched my PC to pwr on after fail, flipped the inverter switch, and the same bad thing happened: computer "powers on" and nothing shows up on screen.

And to test it, I hooked up my PC to my house AC outlet, and switched the bios setting back to off. Hooked back up to my inverter, turned it on, then hit the power switch, and voila, computer functions like normal.

So again, maybe my inverter can't immediately power stuff on turn on?? Has anyone experienced this kind of thing?

bulgogi777 · 09-02-2004, 08:53 AM

I just realized this is a lot of me talking to me

Seriously though, any inputs, please?

Ricky327 · 09-02-2004, 09:16 AM

I just realized this is a lot of me talking to me

I heard thats the beginning of CarPC madness. If you read the FAQ Im sure its mentioned there somewhere

Ricky327 · 09-02-2004, 09:31 AM

Im abit confused what you done there.

You said you connected the circuit to short the motherboard on/off pins?

How come you are feeding +12V into it? If you feed +12V into those pins you will blow something in the motherboard. I get an impressions thats what has happened.

Why not try to test the PC indoors? then atleast you can know if the PC is still ok.

You can try to just use a normal power button for the PC for testing.

Laidback · 09-02-2004, 09:34 AM

Quote: Originally Posted by Ricky327

Im abit confused what you done there.

You said you connected the circuit to short the motherboard on/off pins?

How come you are feeding +12V into it? If you feed +12V into those pins you will blow something in the motherboard. I get an impressions thats what has happened.

Why not try to test the PC indoors? then atleast you can know if the PC is still ok.

You can try to just use a normal power button for the PC for testing.

The momentary output from the relay above triggers another relay to short the pins...I think

bulgogi777 · 09-02-2004, 09:58 AM

Laidback that is correct. And I have tested the PC using my houses AC power, and it works fine.

Thanks to SAScooby I found out that I could forego the relay circuit I built and just use the Power on after fail option in the bios. However, my system reacts the same way as to the startup circuit that I built initially. So I did the following:

Scenario 1 - I set it to enable the Pwr on after fail. Run it off the inverter. Result: I get the problem stated above, the PC runs (has pwr), but nothing comes up on the screen.

Scenario 2 - I use the AC from my house. Still has the same bios setting enabled. PC runs fine.

Scenario 3 - I turn off the Pwr On after fail. Run it off the inverter. Manually turn on the PC via shorting the motherboard turnon pins. PC runs fine.

This is why I'm thinking that my inverter can't handle immediate power? Immediate meaning giving electricity the moment the switch is flipped. I only seem to get my problem if I have some sort of automatic startup which occurs the moment I flip the inverter switch on. Very very frustrating...

gizmomkr · 09-02-2004, 10:10 AM

I didnt take time to read through the circuit, but it sounds a little wacked.... anyway.

I have a VIA EPIA M10000 and I have noticed with this mb that with the use of an inverter, the pc can "start" disks spinn, screen flickers, and then nothing. but everything stays running. , fans and all. The unit alwys runs fine in the house, and even seems to run fine in the house on the inverter.

I saw some very strange activity like this on my old setup using a fullsize mb and inverter - When running off inverter, every couple of boots, the VGA display would revert to 256 color, and go through "Detecting new hardware wizzard" As soon as I switched to a DC--DC PSU all the problems went away.

I think a lot of has to do with the difference in ground potential between the devices in the system - take a volt meter and check for voltage between -12v rail of computer PSU and ground of car chassis - Voltage present here is a bad thing, and can occure because of the inversion process. I.E. the comon ground between chassis and computer PSU.

With a DC - DC PSU this is a true comon ground, and there is no voltage potential present here.

Simply put - I think the dirty ground ****es off the PC.

bulgogi777 · 09-02-2004, 10:30 AM

Yes, it is true that the inversion process is not the most efficient or "cleanest", but my computer runs fine. So long as I don't have any type of startup function (via built circuit or bios setting). This is what I find to be so confusing

bulgogi777 · 09-02-2004, 10:37 AM

Hmm... I'm thinking if my problems truely lie in the fact that my inverter can't handle immediate power, is there something I could put between my PSU's power plug and the inverter to delay the PSU from receiving power for a second or two?

Laidback · 09-02-2004, 11:30 AM

Quote: Originally Posted by bulgogi777

Hmm... I'm thinking if my problems truely lie in the fact that my inverter can't handle immediate power, is there something I could put between my PSU's power plug and the inverter to delay the PSU from receiving power for a second or two?

A relay?

bulgogi777 · 09-02-2004, 02:16 PM

Quote:

A relay?

nice...

actually... I'm pretty sure now that there's some sort of warm up time on my inverter. If my PSU tries to pull current too early after the inverter is turned on, it goes into some crazy non-working mode. So here's the plan:

1. plug in a spare wall outlet transformer that outputs 5v DC in the other outlet on my inverter.

2. Sent that 5v to a 555 timer circuit which triggers a relay

which would allow current to then flow to my PSU 2 seconds after I flip the inverter switch.

What do you guys think of this plan of action?