# The 12 vdc to AC MSW power inverter I fixed, a desktop PC has troubles seemingly running using it.

#### sdowney717

Joined Jul 18, 2012
648
Everything else seems ok with it, the LED TV works, TV signal amp works, my phone charger works.
The computer though it boots up, the GPS wont find satellites, and running program opencpn goes me error like jack server not running.
And then the PC refused to boot up at all, so I disconnected all the internal cables and hooked it all up, then it was booting again off this MSW inverter.
Sometimes the LCD monitor has vertical lines appearing which goes away if you move the window.

I was wondering if the thing is putting out electrical noise?
Would a better newer ATX power supply be a solution?
I thought switching power supplies were not compromised by MSW inverters?

If I run the PC off the generator or off the Minuteman UPS inverter, it works fine with no issues at all.

#### Hypatia's Protege

Joined Mar 1, 2015
3,223
The computer though it boots up, the GPS wont find satellites
Even DS signals are liable to interference...

I was wondering if the thing is putting out electrical noise?
Taken with the observation above I'd say it's generating broad band noise... (have you had a look at the waveform following repair?)

Would a better newer ATX power supply be a solution?
IWHT it obvious that a better power source is the solution...

@sdowney717

Just my $.02 Equipment is more expensive than quality power inverters -- So why fool about with MSW inverters at all -- Let alone 'rehabilitated' units??? With constructive intent HP Last edited: Thread Starter #### sdowney717 Joined Jul 18, 2012 648 Even DS signals are liable to interference... Taken with the observation above I'd say it's generating broad band noise... (have you had a look at the waveform following repair?) IWHT it obvious that a better power source is the solution... @sdowney717 Just my$.02
Equipment is more expensive than quality power inverters -- So why fool about with MSW inverters at all -- Let alone 'rehabilitated' units???

With constructive intent
HP
If I have both inverters on, the 3000 watt MSW and the smallish 200 watt minuteman UPS with the ATX nav computer running off the Minuteman UPS and it works fine, then it would not be RF type noise, but noise coming out on the power line from the inverter. Anyway, that is my next test, and I think it will pass that one ok. I watched a youtube video where an MSW inverter was very noisy RF wise.

I have the MSW for convenience sake say if the generator fails for running the AC electric windlass, the AC fridge, the AC Princess stove with oven, and all AC lights and the TV, etc.... Just makes me wonder why the ATX PC is having odd issues with it?
It is also nice to not run the gen when the main engines are running, less gas usage. A fridge pretty much runs all the time, so needs power all the time which the 3000 watt inverter does fine with it. It is also quieter. We did an overnighter and I was able to leave the 3000 watt inverter on all night powering the fridge and lights, etc... which was nice and quiet.

I dont have a scope to view the output waveform, would be nice.
If I cant figure it out, I might wire the ATX navigation PC simply to run off either the gen or the Minuteman UPS and not the 3000 watt MSW inverter. That means both inverters could be running at same time, which to me is wasteful of DC power.

I am wondering if the ATX power supply, maybe they make better ones that can deal with noisy power? The LED TV has no troubles and that is pretty sophisticated electronically. The ATX power supply is an old one from the 90's era made by Compaq about 250 watts.

To find out, I could take my household desktop ATX new PS out to the boat and see if it works with the MSW 3000 watt inverter.

Last edited:

#### sdowney717

Joined Jul 18, 2012
648
Well I have good news.
I put in a modern 300 watt SATA type ATX power supply and it works fine off the 3000 watt inverter. Got power supply free from a donated Emachines that the school was disposing of.
So the real old Compaq PS cant handle dirty MSW power wave. Maybe some noise passes onto the output.

#### Hypatia's Protege

Joined Mar 1, 2015
3,223
Well I have good news.
I put in a modern 300 watt SATA type ATX power supply and it works fine off the 3000 watt inverter. Got power supply free from a donated Emachines that the school was disposing of.
So the real old Compaq PS cant handle dirty MSW power wave. Maybe some noise passes onto the output.
Again - why fool around with noisy MSW inverters? -- The fact that such are incompatible with some equipment strongly suggests same are unreliable - even abusive - to most electronic loads! - I'm bound to say your penchant for fruitlessly 'sailing close to the wind' is as inexplicable as your (attempted) use of these fora to stroke your conformation bias is annoying! --- That said; I will happily assist you at such time as I feel your posts are more than assertion of preconception framed as inquiy...

FWIW I would regard a direct response to my first sentence of this post as a move in a constructive direction

Respectfully
HP

#### sdowney717

Joined Jul 18, 2012
648
Why fool with a noisy MSW inverter?
Cause it works ok. Especially now that the computer works ok now.
As long as the microwave, anchor winch, LED TV, computer, flourescent lights, led lights, phone chargers, fridge, GFCI breakers, electric stove, oven, vacuum cleaner, fans are all working, even though not as perfection as with sine wave power, that is ok by me. Life is fraught with compromises.

Perhaps the newer power supply was designed with the idea someone would use a dirty power source from an MSW inverter, while the oid Compaq PS, they did not care at that time. Maybe electrical designers now consider people might use MSW inverter to power the AC stuff they make.

Besides all that, I put some effort into the repair, even fixing it twice with new mosfets and mosfet drivers and want to enjoy the fruit of my labor. I was very happy to see it come back really from the dead, twice. Both times it fried trying to start my heat pump, so I locked that out with a relay so it can never start off inverter again.

Last edited:

#### Hypatia's Protege

Joined Mar 1, 2015
3,223
Cause it works ok. Especially now that the computer works ok now.
But does it? Only time will tell -- It hardly seems worth the risk to equipment reliability/integrity --- especially in light of the perils attending inopportune failure in your installation... (i.e. loss of communication/navigation facilities, etc...)

Besides all that, I put some effort into the repair, even fixing it twice with new mosfets and mosfet drivers and want to enjoy the fruit of my labor. I was very happy to see it come back really from the dead, twice.
I can understand that -- Even so, you could restrict their use to 'low stakes'/low sensitivity loads -- Dependable operation of sensitive, application critical, data processing and communications gear demands a clean, unequivocally reliable power source! -- Safety of life and valuable property does not brook 'compromises'...

Best regards
HP