Accurate Tools Pure Sine Inverter Review and Repair - Part 4/4

An attempt at an Inverter Review results in a repair video. I first open up the inverter to show the construction quality, then I load it down until it fails, then I attempt to repair it.

[@jackt6112]

Thanks for the review. A long time ago I pestered you to do a review on Accurate Tools Pure Sine Inverter but some time later I just tried one. It was smaller than the 1500 watts, as I recall it was 600 watts. When I received it, it had something loose inside of it that I could hear travel from one end to the other when I tipped it. I called the vendor and talked to him about opening it. I did. It was a nut. I put it back and tightened the screw. I planned to put it under the passenger seat so I ran the wires into the car to do that. It fired up fine. It was summer time and I was in shorts sitting in the driver's seat with my M6600 Mobile Workstation laptop on my legs. It felt like when you stick your tongue on the top of a 9V battery only across the entire top of my legs. The touchpad also didn't work. My phone touch interface also didn't work. Grounding the case to the body makes no difference. Next, I moved it just under the hood on the driver's side next to the firewall with the hood and driver's door open. From there everything worked perfectly but there was no place to put it there, and probably not a good place due to the engine heat. I contacted the vendor and he resisted me sending it back. They finally did take it back since I had to fix it to use it in the first place. The Tiger Claw 1500 that you had reviewed was pretty big to be able to hide anywhere and I was concerned it may have the same issue. Then I started studying the ratings for electrical interference. Samlex was the only impressive one, but it was expensive. I called them and talked with a real engineer who explained the ratings and how that it is not simple nor cheap to engineer ones with low EMI and sent me some engineering tests and graphs. He also explained to me the difference between the different pure sine wave model lines and why the cost difference between them. He explained also how to over-spec based on the load for sine wave purposes.. I never bought a Samlex and ended up with a 320 watt modified sine wave that fits into a hidden compartment inside of my center console that already had a cigarette lighter outlet down inside of it for some reason. However, I learned that the socket would not run my M6600 with 220 watt power supply for long without the voltage dropping below the minimum and the inverter kicking out after a short time. The problem was once the charge edge was off the battery, plus the voltage drop in the wire, meant the only way I can use it for any length of time was to keep the engine running. It would probably work fine with a lower powered laptop too. My M6700 has the nVidia card in it, so it can shut itself down and use the Intel processor video and run a long time so I don't use the inverter hardly ever anymore.

[@GoingOffGrid101]

nice review/ repair, really like these videos thanks.

[@michaeld8975]

Using the light bar as a stealth heater very clever. I see what you did there.

[@ghengiscrayon]

As usual, great to see the process. You have a number of great great new tools! Is the heat sensor and oscilloscope voltmeter new? Love to help you with your work. Get in touch if so.

[@NakedMachinist]

Great series of videos on this inverter. I wish I would have found this before purchasing mine. I bought mine as an 'open box' item from eBay, in working condition for the same price as you. I'm almost scared to open it up and see what disaster I may find. It should be arriving today. I may remove the guts and design a new box for improved cooling. With the oscilloscope, What is the time duration of the flats on the peak of the sign wave? Thanks for sharing.

[@johnnyjimj]

Thank you for these very, very helpful videos! The IRF1404s blew on my inverter as well, and on the one I had before and I am suspecting it's because of a too low DSS for causing it. None of the fets exhibit any visual signs of damage but out of the 8 I had in the two inverters, 6 were open between source and drain. Can you suggest a FET to replace the IRF1404 with identical specs but higher DSS? Thanks in advance for your help!

[@JOHNDANIEL1]

K24, I started putting a item I designed into use on modified sign inverters. Using HAM radio knowledge I made a old school coil out of a 8" window weight and wire. The result has been much better, not so square wave that seems not to cause so much heat in motors. Have you tried this approach.

[@jockosboy17]

Very interesting video. Did you notice if the sine wave deteriorates while the unit is under load? Also what pure sine wave inverter would you recommend with a budget in mind. Looking for one to use in a camper while off grid. Thanks!! I gave your video a thumbs up!!

[@EverH0p3]

4 yrs on and I got excellent value out of this series. I have almost the same visually except its call Power Meg by Jinghen, 1400w, 240V out and quality of manufacture is worse by far. Oh and it only puts out 185v. This one has 6 transformers so I suspect one bank is not chooching. Thanks for the effort.

[@powerpop23]

Hi Knurgnar! I have another theory why this inverter failed. In the first Video of this series it seems that two of the input FETs are not mounted to the Heatsink properly: The bracket is really off to one side, and it even seems the metal tabs are lifted off the heatsink a little at the other side. One of those FETs is the one that smoked. Really heating it up an then surge testing it might have then just pushed that FET over the edge. Keep up the great videos!

[@knurlgnar24]

Your theory could be the case. The brackets supplied by the manufacturer were not long enough to properly clamp the FETs to the heatsinks which made properly assembling it difficult. I re-assembled it better than it was out of the factory even bending the brackets and FETs to make them clamp better but it still wasn't all that great. I do think they were heatsinked well enough but it definitely wasn't as good as I'd have liked if it was something I designed.

[@523panda]

Can you tell me what type and model that multi - meter -oscilloscope is. That is a cool combo. Where can it be found if still available?

[@theoldwizard998]

A larger fan, which would require a larger housing ($$$) would certainly help. I am surprised the output voltage regulation is so poor. Do you think this is because the boost stage is not making adequate voltage, possibly because the transformer are loosing efficiency due to heat ?

[@aterack833]

on average inverters put out 80% of their rated capacity most put out rated for 5 minutes and double rated for less than a second up to around 10 seconds usually determined by the capacitor capacity, run a higher farad cap and get a longer surge (no guarantee)

[@Escape3000]

So what is the best Pure-Sine Wave Inverter DC 12v to ac 120v between 800w and 1000w?

[@chikiguites]

The same mosfet FB4310Z blow out... well similar, i mean in the same posision, i changed all of them but still blowing the fuse 20 amp in the last line, I have three transforms, the firt two are oK, could you help me? I suspec from the diod or the brige?

[@1101rcampana]

Thanks for the video, I am researching an issue with my AT3000... I won't run anything and it shows a load when you first turn it on , even though nothing is plugged in... Any idea where I should start to look internally?

[@Hammerjockeyrepair]

I have one of these and regret buying it!. At 1000 watts, it drops to 90 volts, at 1500 watts it shuts down

[@yourGAcousin]

Thanks for the video. I actually purchased a larger version of this at 5K/10K pure for my toy hauler. I ran it for 10 minutes and it was great and then all of the sudden it died. Nothing, won't turn on, nothing. Two fuses continue to blow every time I attach it to the batteries. I can'f find a schematic that tells me which resistor that might be attached. Yes, I am a novice. More to the point, I'm just desperate to get this expensive boat anchor to produce power. Any thoughts on where I might find the issue?

[@DMAN22yeah]

shorted fet

[@donovanpl]

Knurlnar24 How about showing some repairs of grid tie inverters?

[@stephengrant2677]

I have one of those in the 2500 watt model. I works fine but it started shutting down at 12 volts instead of 10.5 - 9.7. This is on one battery starting on 13.10v. I could run several hours before with 100 watt bulbs on a string, now only 1/2 hour. What do you think about this?

[@stephengrant2677]

Stephen Grant Is there a way to step down 24v to say 14v for this inverter

[@FDM33510]

Greetings, Knurlgnar. As a layman, I have learned a tremendous amount from your vids. Even on the mini fridge efficiency improvement. Who would have known? Anyways, I do have a few questions, if you will. Are you familiar with Vector Inverters? Black and Decker bought them out back in 2006.... I have a 3000 Watt Modified Sine Wave that is about 8 years old. I had it installed on my boat, and rarely ever used it. Model # VEC051M. It is the Marine version, so the board is coated and it still runs fine. Are the internals of decent quality in them? Have you ever experimented with Sine Wave Filters? I see a few random videos on it, but they are more for big industry. But, I do see Sine Wave Filters on eBay, and just wondering of I could use one with my current inverter to help clean things up a bit. I am in the beginning stages of building either a bugin or bugout solar power rig, but this is obviously an integral part of it.....I know temporary use won’t really damage my appliances and whatnot, but down the road I am going to put it all into a fifth wheel and use solar. Albeit, I will set most all of it up as 12 volt. What say you? I saw your Samlex 3000 video, I can’t believe how much it took to get it to shut down. Impressive!!

[@knurlgnar24]

If it's been on your boat, used or unused, for that long and is still working then I'd say keep using it! Newer products are increasingly cost driven so you need to pay more and more to get good marine quality these days. Not sure on the quality though. As for filtering a MSW you can reduce some of the EMI interference as for radios and such, but it will do nothing to convert the waveform to pure sine. For that you need a pure sine inverter. No transformer or filter circuit is going to do anything except waste power and potentially overheat.

[@mathew220220]

Mine is quite a bit definitely designed on the inside. Same inverter very different. Mine has 3 transformers for start

[@knurlgnar24]

It's likely they've changed their design over time. This is a pretty old video! The same principles apply though and the general architecture will be nearly identical even if it looks physically different.

[@Nomad8324]

Why not fix some of the other issues with build quality and see if it works better or would nothing you noted in the first video make any difference? IE missing resistors, not grounded, weird wiring, etc. I would be curious if they hadn't done such a sloppy job or no job at all on some parts if it would effect the usability and reliability of the unit.

[@douglasbenner4778]

Hello sir, I have enjoyed watching your repair videos. I have an Accurate Tools AT5000P 5000 Watt inverter. It worked very well for almost a year. Recently while we were gone it quit working. No front panel light, no 120 AC with solid 12 volt input. I have a well designed 12 volt battery configuration with controllers When I opened up the case I found the ribbon cable between the input board and the output board had gotten hot and melted the insulation. There is no other evidence of smoke or heat on the components. Both circuit boards and components look clean. Do you have any suggestions how to check things further. I have moderate knowledge and experience with electronics and computers. Any help would be very much appreciated as we live in Central America and the electricity here is very unreliable.

[@knurlgnar24]

That doesn't sound good, but it is probably still repairable. Most likely your output FET or FETs failed and took out the drivers (Assuming they run through that ribbon cable?) I would start by ohming out the FETs. There should be no shorts between pins. Often they fail shorted with no external signs of failure. If the FETs are shorted then you will have to make sure the resistors on the gate pins are functional, and the NPN/PNP gate drivers are functional. If it looks like high current went through them it is best to replace them regardless since those parts are inexpensive. If the damage made it all the way back to the driver IC that can be replaced as well, though things start getting more difficult if the damage went that far.

[@knurlgnar24]

A second note, if FETs are bad and you want to save some money you don't have to replace FETs that test good. Output FETs don't have to be completely matched so I usually don't replace ones that test good myself. I replace the bad ones and stress test it looking for hot spots. If it all seems OK then I consider it fixed.

[@suataydemir9144]

Hi, 3000 watt full sinus inverter fault light is on. When the inverter is turned on, a relay tripping sound is heard, then the fault light is on, what do you think could be the problem?

[@knurlgnar24]

I do not know what the relay tripping sound would be as very few inverters have relays, but assuming the sound you hear is a current surge due to a damaged components and the inverter subsequently protecting itself then I would guess it is a shorted FET or diode.

[@suataydemir9144]

@@knurlgnar24 Thanks for the valuable information. I will do as you say mosfet diyot

[@skyfly51]

Do you have any experience with the inverters Harbor Freight Tools sells?

[@stevenhardy8263]

Witch model do you want ? I'm pretty sure he thinks they are exceptable for the price . I have a Harbor Freight Tools Cen-tech 2000w-4000w peek, Item # 69662 For Sale still in the box. I just looked at it and its still in the original plastic, I don't remember even taking it out of the plastic .never hooked up . Cost $224.99+ tax 18 months ago . Its on sale this weeks ad $124.99+tax. I'll sell mine $50.00 +shipping . If your interested email me . [e-mail]. I need to buy a pure sine wave for my boat & the Tiger inverter has the same case & bolt holes etc. I'm not a lier,cheat or thief ! If i say its never been hooked up & still new in the box you can believe it. Sincerely sailersteve.

[@knurlgnar24]

Yep, that inverter Steven Hardy is selling is a pretty decent MSW inverter for the Harbor Freight price and at $50 it's a great deal. So long as you take advantage of their coupons Harbor Freight is a good source for reasonably priced mid-range consumer inverters, which is what most people are interested in. I've also used their 400W model if that is more in line with what you were interested in and it is a decent product too. Not great but a good value. Note that some of their older stuff was even better - if you can find some of their older units on eBay and don't mind the larger case size that could be good too.

[@TheDiceAreLoaded]

When charging a battery bank should I connect both the + and - to the same battery at one end OR connect the + to a battery at one end of the bank and the - to the battery at the opposite end? Which way is better? Does it even matter?

[@tarefoot]

If the batteries are 12 volt, you go + to + and - to - to keep 12 volts. If they are 6 volt batteries you go + to - to make 12 volts.

[@gridarmorfix]

Opposite terminals.

[@TheDiceAreLoaded]

steve p. Not what I was asking

[@TheDiceAreLoaded]

tarfoot not what I was asking

[@TheDiceAreLoaded]

I was asking the proper way to connect the charger; nothing about voltage or opposing terminals.