In this post we will try to learn how to diagnose and repair an inverter, by comprehensively learning the various stages of an inverter, and how a basic inverter functions.
Before I have explained how to repair an inverter it would be important for you to first get fully informed regarding the basic functioning of an inverter and its stages. In the following content I have explained regarding the important aspects of an inverter.
Stages of an Inverter
As the name suggests DC to AC inverter is an electronic device which is able to "invert" a DC potential normally derived from a lead-acid battery into a stepped-up AC potential. The output from an inverter are normally quite comparable to the voltage that is found in our domestic AC Mains outlets.
Repairing sophisticated inverters are not easy due to their many involved complex stages and requires expertise in the field. Inverters which provide sine wave outputs or the ones which use PWM technology to generate modified sine wave can be difficult to diagnose and troubleshoot for the folks who are relatively new to electronics.
However, simpler inverter designs that involve basic operating principles can be repaired even by a person who is not specifically an expert with electronics.
Before we move into the fault finding details it would be important to discuss how does an inverter work and the different stages normally an inverter may comprise:
An inverter in its most basic form may be divided into three fundamental stages viz. oscillator, driver and the transformer output stage.
Oscillator:
This stage is basically responsible for the generation of oscillating pulses either through an IC circuit or a transistorized circuit.
These oscillations are basically the productions of alternate battery positive and negative (ground) voltage peaks with a particular specified frequency (number of positive peaks per second.) Such oscillations are generally in the form of square pillars and are termed as square waves, and the inverters operating with such oscillators are called square wave inverters.
The above generated square wave pulses though are too weak and can never be utilized to drive high current output transformers. Therefore these pulses are fed to the next amplifier stage for the required task.
For info on Inverter oscillators you can also refer to the complete tutorial which explains how to design an Inverter from the scratch
Booster or Amplifier (Driver):
Here the received oscillating frequency is suitably amplified to high current levels using either power transistors or Mosfets.
Though the boosted response is an AC, it is still at the battery supply voltage level and therefore cannot be used to operate electrical appliances which work at higher voltage AC potentials.
The amplified voltage is therefore finally applied to the output transformer secondary winding.
Output Power Transformer:
We all know how a transformer works; in AC/DC power supplies it is normally used to step-down the applied input mains AC to the lower specified AC levels through magnetic induction of its two windings.
In inverters a transformer is used for similar purpose but with just opposite orientation, i.e. here the low level AC from the above discussed electronic stages is applied to the secondary windings resulting in an induced stepped up voltage across the primary winding of the transformer.
This voltage is finally utilized for powering the various household electrical gadgets like lights, fans, mixers, soldering irons etc.
Basic Principle of Operation of an Inverter
The above diagram shows the most fundamental design of an inverter, the working principle becomes the back bone for all conventional inverter designs, from the simplest to the most sophisticated ones.
The functioning of the shown design may be understood from the following points:
1) The positive from the battery powers the oscillator IC (Vcc pin), and also the center tap of the transformer.
2) The oscillator IC when powered starts producing alternately switching Hi/lo pulses across its output pins PinA and PinB, at some given frequency rate, mostly at 50Hz, or 60Hz depending as per the country specs.
3) These pinouts can be seen connected with the relevant power devices #1, and #2, which could be mosfets or power BJTs.
3) At any instant when PinA is high, and PinB is low, the Power Device#1 is in the conducting mode, while Power Device#2 is held switched OFF.
4) This situation connects the upper tap of the transformer to ground via the power device#1, which in turn causes the battery positive to pass through upper half of the transformer, energizing this section of the transformer.
5) Identically, in the next instant when the pinB is high and PinA is low, the lower primary winding of the transformer becomes activated.
6) This cycle repeats continuously causing a push-pull high current conduction across the two halves of the transformer winding.
7) The above action within the transformer secondary causes an equivalent amount of voltage and current to switch across the secondary by means of magnetic induction, resulting in the production of the required 220V or the 120V AC across the secondary winding of the transformer, as indicated in the diagram.
DC to AC Inverter, Repairing Tips
In the above explanation a couple of things become very critical for obtaining correct results from an inverter.
1) First, the generation of the oscillations, due to which the power MOSFETs are switched ON/OFF, initiating the process of electromagnetic voltage induction across the primary/secondary winding of the transformer. Since the MOSFETs switch the primary of the transformer in a push-pull manner, this induces an alternating 220V or 120V AC across the secondary of the transformer.
2) The second important factor is the frequency of the oscillations, which is fixed as per the country’s specifications, for example countries that supply 230 V, generally have a working frequency of 50 Hz, in other countries where 120 V is specified mostly work at 60 Hz frequency.
3) Sophisticated electronic gadgets like TV sets, DVD players, computers etc. are never recommended to be operated with square wave inverters. The sharp rise and fall of the square waves are just not suitable for such applications.
4) However there are ways through more complex electronic circuits for modifying the square waves so that they become more favorable with the above discussed electronic equipment.
Inverters using further complex circuits are able to produce waveforms almost identical to the waveforms available at our domestic mains AC outlets.
How to Repair an Inverter
Once you get well versed with the different stages normally incorporated in an inverter unit as explained above, troubleshooting becomes relatively easy. The following tips will illustrate how to repair DC to AC inverter:
Inverter is “Dead”:
If your inverter is dead, do preliminary investigations such as checking battery voltage and connections, checking for a blown fuse, lose connections etc. If all these are OK, open the inverter outer cover and do the following steps:
1) Locate the oscillator section; disconnect its output from its MOSFET stage and using a frequency meter confirm whether or not it is generating the required frequency. Normally, for a 220V inverter this frequency will be 50 Hz, and for 120V inverter this will be 60 Hz. If your meter reads no frequency or a stable DC, it may indicate a possible fault with this oscillator stage. Check its IC and the associated components for the remedy.
2) In case you find the oscillator stage working fine, go for the next stage i.e. the current amplifier stage (power MOSFET). Isolate the MOSFETS from the transformer and check each device using a digital multimeter. Remember that you may have to completely remove the MOSFET or the BJT from the board while testing them with your DMM. If you find a particular device to be faulty, replace it with a new one, and check the response by switching ON the inverter. Preferably connect a high wattage DC bulb in series with the battery while testing the response, just to be on the safer side and prevent any undue damage to the battery
3) Occasionally, transformers can also become the major cause for a malfunction. You can check for an open winding or a loose internal connection in the associated transformer. If you find it to be suspicious, immediately change it with a new one.
Although it won't be that easy to learn everything about how to repair DC to AC inverter from this chapter itself, but definitely things will start "cooking" as you delve into the procedure through relentless practice, and some trial and error.
Still have doubts...feel free to post your specific questions here.
Hello Swagtam, Where I am located it is nigh on impossible to find technicians that will repair inverters and invariably those that can charge more than the inverter is worth to fix. This really leaves little choice for owners but to either replace failed units out with warranty periods with new or attempt to self repair. Failures seem common and replacing every few years is not sustainable economically or otherwise. I can repair basic electrical items but the complexity of these systems is far beyond my current skill. How would one go about learning to repair these complex devices?
Hello Mike,
I understand your problem, however, repairing a commercial inverter might not be easy for any newcomer, or even for an expert if a proper schematic is not available. Because all commercial inverters are build using unique ICs, PWM control stages, MOSFETs or IGBT driver stages, which can be quite challenging to troubleshoot.
Learning how to repair a commercial inverter might take a lot of time and might require many practical sessions, under an expert guidance.
However, if you learn how to build your own inverter then definitely it is possible to ensure a long life for the unit and also you can repair it if anything goes wrong anytime. This appears to be a much easier option.
Hi swagtam
Thanks for your valuable advice in electronic circuit problems and solutions.
As adviced, I changed the gate resistor and fix the burnt drive and the inverter now works OK.
But I observed something strange, while the inverter is on the transformer is humming, which is not normal.
The inverter actually go damage from emf feedback which vibrated the transformer for a while before the pcb damage. Now the output is OK and inverter is working but with a noticeable humming sound. I have not yet tested it on load appliance yet.
Please what’s your advice. I suspect the transformer is partially damaged previously?
Awaiting your reply ASAP.
Thanks
Thanks Daniel,
A humming sound in an inverter transformer might indicate an overload, an overcurrent, an internal short circuit or a high frequency input. Any one of these issues could result in a humming sound or any form of sound in a transformer.
Let me know if you have any further doubts.
Thank swagtam
Firstly before mounting the pcb, I tested the transformer on power to see if it works good, it did produce output of 24v from 220v but with huge humming vibration sound and shaking the lights in the house in a short seconds of test. So I perceive the transformer is shorted inside due to the feedback it received that caused the initial damage.
Before your reply I decided to test the inverter with a 60w bulb and it keeps cutting the battery fuse several times, so I decided to fuse the battery with big Guage to know why, on sw on this time, the inverter goes up in flames with a bang, the side mosfet undamaged initially are now burnt. Jus one side of the H-bridge.
Obviously the transformer is short inside.
What do you think? It’s a whole lot of waste.
Tired.
You are right Daniel, that confirms your inverter transformer has gone bad, or maybe its winding is internally shorted which is causing it to draw huge amount of current from the battery.
When the fuse burned that was a clear enough warning that something is seriously wrong with the circuit, in your case the transformer, you shouldn’t have replaced it with a thicker wire, instead looked into the issue further.
Anyway, in the existing situation you can try replacing the transformer with a new one and also the mosfets and check how it goes.
Hi swagtam
Guess you doing pretty good? How are you doing in your job and tech world?
Jus wanted to ask this question. What is the best way to avoid feedback from entering inverters? We discovered this is the biggest and most common problems affecting and damaging inverters globally. Feedback from lightning strike and wrong actions from grid or consumers faulty or reversal connection otherwise they do pretty good without these interference. Essentially a live/hot current on N-line is the root cause.
What is the best protection method if any?
I though earthing could be of help but I discovered it does not in all situations.
Thanks 👍
Thank you Daniel, I am good!
Although I do not have any expertise in the field of feedback protection, i guess if the Earthing is made highly efficient, it can solve the majority of these issues.
Another device which can be used to eliminate these hazards are SPDs.
Additionally, high power MOVs can also be tried as a possible remedy.
Hi swagtam
Thanks for sharing this. This has actually helped save many inverters but some are not so lucky due to poor earthing.
Thank you 🤗 million.
You are welcome Daniel, Yes that’s right!!
Greetings.
I connected my inverter to my local DB without a changeover switch while there was power outage, when the main power (Grid) 220v returned, it blew my inverter (Capacitors). I tried replacing them but they keep blowing. What can be the problem, what need to be replaced? The inverter is a Chinese made (pure sine wave): CHANGI CJ-3000Q 24Vdc – 220Vac 3000 Watts. Please help.
Kind regards
Joseph
I suspect that the reverse current from the transformer might have burned not only the capacitors but the MOSFETS also.
The situation needs a deeper investigation into the motherboard of the inverter.
Hello,
Can you repair the circuit board for me please? How much will you charge me and where are you located?(for courier reason).
Thank you.
Hi, sorry, repairing a board practically may not be possible for me.
Ohk, no problem and thank you for your time and responses.
Hi, don’t exactly know how it happened, but there was some sort of a short working through the earth wire, which burned off the earth wire internally. This is on a 2kw digimark inverter. The unit is now faulty. What else could have blown in this case, any idea? In your opinion, is it worth sending this inverter in for repairs?
If the earth wire is burned it means the LIVE wire has somehow short circuited with the body of the inverter. Hopefully if the LIVE is directly shorted with the body then no parts could be damaged however if the short has happened through the circuit board then most probably a serious fault might have taken place on the circuit board.
I think what happened was that the borehole pump acted as a generator, and I plugged it out and put the plug on the ground, where one of the plug terminals then must have touched the ground strap. Because there is a second bore hole pump sharing a level switch, I am thinking that this is how the current then found a route through the circuit board. Do you reckon it may be repairable?
Yes, in that case it is repairable, according to me.
Thanks for the info
I accidentally shorted the battery cables that feed my psw inverter. It is dead. Any chance of bringing it back? The owners manual says it is protected from shorts.
If you shorted the battery cables then it is the battery which is supposed to get damaged, not the inverter. Please replace the cables and check the inverter again, it should be working fine.
If the inverter output is blinking when on load what is the solution
We bought an invetor which we just run the 2 tv on and wifi. Been working fine for months. My daughter plugged the wrong plugs in today s heater . We sat for an hour and the next minute a massive trip sound and all was dark. Is the invertor fixable. My husband is furious as it was so expensive.
If the trip sound was like an explosion then something might have burned inside. It will need to be checked practically to know the exact fault.
Pls I have a blue Gate inverter 2kva..it is not powering up.I have checked all the mosfets they seem to be ok from my DMM reading,what could be the likely issue here
Please check the fuses, if it is OK then check whether the battery supply is reaching the circuit board or not, then check whether oscillator section is working or not.
What happen when a transformer is giving heat
It means either there is an over voltage or an over load connected with the transformer.
My daughter turned on the utility supply on in the DB board before she disconnected the inverter. I’ve replaced the blown fuses and the inverter now turns on but does not supply any AC power. The fault light is not on
The utility supply could be completely destroyed the MOSFETs and other valuable devices of the inverter according to my knowledge, since the utility AC across the transformer primary might have caused an AC to be generated at the secondary of the transformer damaging the devices.
I notice the inverters are grounded in the refrigerators and the refrigerators have a ground. I’m getting 43 volt intermittent reading from the refrigerator ground to earth ground. Do these inverters use the unit ground as a French ground while the unit runs and creating this reading? I have checked the house wiring, it’s OK and this fridge is on it’s own circuit. Thanks for any in-put you may have.
Sorry, I have no idea about this situation, hope somebody else in this forum will be able to throw some light on this.
Good day,got a 300w Goldstone invertor/charger.fuse was blown.somebody tampered with switch wires inorder to fix it…how should the Invertor or Charge wires be connected?
Sorry, I have never opened a Goldstone inverter so solving your query can be difficult.
Power drive 1500. Normal voltage at rest. Loaded with water pump (5.5 amps) output voltage goes to 135.
Dear Swagatam,
My inverter has a continuous beep with code 7 indicating that it is an overload fault. But nothing is connected to it. Could there be an internal overload? The fan is working well.
Any suggestions to what I should look for?
Hi Claudius,
Error 7 might indicate an internal temperature sensor failure. But you are saying that the fan is working alright. So it may be difficult to judge the fault without a practical check.
If you think it is due to overload, you can refer to this article:
https://sakopower.com/wp-content/uploads/2022/03/How-to-check-error-code-07.pdf
Hello , I have a doxin 3000w which is coming on but the fault light comes up then goes out but no HV. MOSFETs and all of the usual suspects are ok. Any advice? Thanks for your time.
Hello, further practical tests will be needed to identify the fault, it cannot be judged without testing.
Can one convert an inverter to a normal ac?
I have a Chicago elec 2000/4000 inverter. The problem is:. Turns on and I push trigger on jigsaw. It runs for as long as I hold trigger. Once let go of trigger alarm sounds and voltmeter on front completely lights up passed 15v dc. Turn off and then back on can use again untill I let go of trigger
Sorry, no ideas! I do not have sufficient information regarding Chicago elec 2000/4000 inverter specifications and working!
Thanks for your time. Great site.
My pleasure!
Thanks for posting such an excellent article. It helped me a lot and I love the subject matter.
Very nice explanation..Thanks
Hello Swagatam , I have a 4000w inverter that I tapped into the 120v on my sailboat. It worked just fine. The line that I tapped into also runs to the shore power, so I disconnected the shore power from the boat. So when I wanted to run the inverter I would make sure that the shore power was not connected. I didn’t have the inverter turned on one day and went to plug the shore power in. I didn’t get any power, so I unplugged the shore power and went to turn the inverter on. The display came up but it didn’t show the AC voltage rising up to 120v. It just shows oo volts. Then an alarm sounds and I get a VDC overvoltage on the display. I removed the casing and found a bad cap(3300uf 35v), I replaced the cap, hoping that may have been it, it wasn’t. The overvoltage still comes on,with no AC voltage. Can you to the best of your ability let me know what you believe may be at fault.i looked the two boards over pretty close and could not fine anything burnt or singed or discolored. Thank you so very much, I’m very happy to have found your site and have bookmarked it. Thank you again, Richard.
Thank you Richard,
From your explanations what I understand is, the shore power and the inverter both are used to supply 120 V to the sailboat. So I am wondering how the problem occurred? Was it due to shore power entering the inverter 120 V socket while both were connected to the same line? I am not able to figure out this aspect.
You also said the display is showing over voltage. From where is this over voltage occurring, is it from the battery DC side or the 120 V AC side of the inverter transformer?
So the above doubts will need to be first clarified before we understand the actual issue with the inverter. I am glad you found this site useful. I hope your problem will be solved soon.
Hello Swagatam, yes, the inverter was connected at the sc terminal block to to house wiring, which continues to the shore power socket(both are 120v). The inverter was turned off,so when I plugged the shore power in, it had to have 120v at the terminal blocks on the front of the inverter. As for the display, the VDC overvoltage must be coming from the batteries12v.thats the only thing connected. There is nothing connected to the ac side, no wires or plugs.
Thank you Richard, could there have been a possibility of the 120 V from the shore power entering the inverter 120 V side? In that case the power devices of the inverter could have easily blown off.
The over voltage of the batteries is not supposed to affect the inverter working, it should be more related to an automatic battery charging cut off system.
With the battery fully charged the inverter should have no problems operating normally, since the battery is fully charged and ready to use.
It might be actually difficult to assess the exact fault without actually checking the device practically.
My inverter was dead. Make — microtech, ic used – cpj2m84g, Lm358ap, 83202IBZ, MOSFET Irfb7545 .I found all MOSFET, gate resistance 4.7ohms, capacitor 4700/50volt was defect. All these components replace. But no results found. What can I do after that? Kindly give your valuable suggestions.
In that case you may have to replace the entire motherboard, because there might be some ICs which are also blown. A microtech technician would be able to suggest better.
Good day
I had a lightning strike on my 24v 3KVA inverter. I opened it and found 2 x Mosfets blown with values on it as follows…ygw60n65f1. There are 4 of them in total. I want to try and replace them and see if it lives again. I see no other visible damage. Do you think it might work and what replacement part can I also get for that value mentioned as at first search I cant find that in my country
Thanx
Hi, Lightning strike can be extremely fatal to any electronic system. You can try changing the mentioned IGBTs and check the results. Your inverter might just stat working if you are lucky, however chances are that the damage could be even more serious and the internal ICs could have been also burned. You can start by replacing the IGBTs and see how it goes.
Those devices are actually IGBTs rated at 650 V, 60 A. You can also try any other equivalent IGBT with identical ratings
Nice teacher ,when I connect my 12dc batt the ac output measures 26volts help troubleshoot the problem ,I am learning so my inverter 300watts what can I measure with my dmm?
Hi, If your inverter is producing 26V instead of 220V then there can be some serious problems with your inverter, which can be verified only through a practically checking, it cannot be judged verbally.
I connected wrong polarity how to repair
Good day sir,I really enjoy your tutorial but pls help for formulae on mppt charge i.e how to rate it, controller thank you for building us
Thank you Olufemi,
MPPT calculations can be a quite complex, they cannot be explained through comments. If possible I will try to create a separate article on this.
I have inverix sin wave UPS 2000VA, 24 volts input, 220 volts output working okay condition.
I want to use this ups as solar invertor, I need hybrid one MPPT charge controller 80A .
I don’t need charging of batteries through UPS means not utility supply and save energy only charge controller charge batteries, can I do it how?
You will need a ready-made MPPT charger controller (80A) which you will need to connect with your solar panel. After this you can connect the output of the MPPT with your UPS inverter….that’s the basic set up you will need to implement.
Good day, I have a Problem with my ecco 1000 W inverter , it starts up but immediatly switches off. The battery is good , i have checked the fuses , they are fine , tests are done with out any load , The inverter pv charger is working and the AC charger is working , I do not get any error messages .
I do not know where to get spares for this inverter , i assume it is a china manufactured product. Can you give advise regards
If it is a Chinese product then getting its spare parts can be extremely difficult, since they mostly use their own specific parts manufactured in their own country. The issue could be due to over load or a short circuit somewhere in the circuit board. This fault can be diagnosed only by practically opening the unit and checking the stages individually.
Thanks so much sir this is really helpful. Please sir, I need DC to DC booster circuit, 3.7v to 12v and 5v. Thanks Sir
Hi Momoh, you can try the following concept. The coil can be wound over a 1 cm thick ferrite rod with 50 turns of 1 mm copper wire.
The mosfet must be replaced with a TIP31 transistor.
The zener diode can replaced with a 12V or 5 V zener diode.
https://www.homemade-circuits.com/wp-content/uploads/2022/06/laptop-battery-charger.jpg
Since April I have my new combined with charger power inverter 25A /5000 W /12V DC /220V/AC connected to the home circuit via manual change over switch. Because we are
experiencing heavy load shedding I am using it for three months non stop with no problem. But 2 days ago at the moment of restoration of the power from electrical supplier the MCB
breaker after the inverter output 220V tripped. Now charger is still working. When I switch to inverter the display for the battery voltage shows correct reading but voltage display shows
0V no 220V and ‘inverter indicator’ is flashing in red/green and it is sounding like relay on/off. Did not realize what actually is happened. The 220V output terminal normal reading was
L-N 220V, L-E 185V, N-E 50V. Now L-N 0V, L-E 0V, N-E 0V. Some more important details about connection I made in the beginning. I connected only Live and Neutral to the panel.
Earth one I left loose because our country earthing system is TN-C-S and Manufacturer strongly advice no bonding between N and E conductor to avoid burning of the inverter. This could
happen if I did connect Inverter Earth to the consumer panel, because TN-C-S system means Neutral and Earth are combined in a single conductor between the source of energy and the
point of supply and separated in the consumer’s panel. So the inverter wasn’t grounded (earthed). I have no circuit diagram of this inverter but saw on Internet many different and in any one
of them I noticed that all transformers, IC and mosfits are grounded, so what was my mistake. In the mean time after investigation I found that in my home panel at time of building the
house the electrical contractors connected Neutral direct to some of the appliances Stove, Geyser and Lights which do not required Earth Leakage, instead to interrupt it through the MCB
and then to connect to appliances. Any advice please. I’ll appreciate it.
Hi, as you will understand it can quite difficult to troubleshoot an inverter fault without having a practical look at it. It seems there is some malfunction in the changeover relay section but it can be diagnosed only after a thorough checking. Even with a circuit diagram it can be difficult to judge the fault. The fault can be checked only by opening the inverter and then testing the relevant circuit stages. You will have to contact the manufacturer and ask them to check the fault.
Thank you! Unfortunately the manufacturer is in China…
If it’s a Chinese inverter then it could almost impossible to repair it, since they use non-standard parts which are available only in their own country.
how can i reset my genus inverter 3.5kva that output was shot because of overload
Sorry, I have never used a genus inverter so have no Idea about it
Thank you for your help. I have prag 1.5kva invater if the is on it will supply power and bip for more than 5 times ît will stop biping after like 5min it start biping abnormal a triangle red light will indicate on the inverter if I off the inverter at that moment and on it will stii biping abnormal so I will have disconnect the inverter from the battery if I connect back to battery and on it will work like tha, after another few min it will start that abnormal biping again and supply will cut off. Pls what do I do? Thanks
It seems something is heating up inside the inverter like a mosfet or some other critical part which is causing the internal protection circuit to trip. You will have to show it a qualified engineers to get it diagnosed.
On the screen, fuse trip, the AC and DC does not supply . Once the inverter switch on, the alarm keep shouting continuously. Pls what is the cause and the way forward sir. Thanks
What does the alarm sound indicate on your inverter?
My inverter beeps continuously, when it is on it returns power to the input AC. So I can read 220v and both AC output and AC input.
It wasn’t always so. This started a few days ago.
What could be the problem?
It seems the AC/inverter relay changeover is not working. You will have to open the specific section of the inverter and check why the relay changeover is not working.
Good day my prag 1.5 kva will work for like 5min and started southinh and it will not supply again if I off it and the battery cable from the inverter to the battery and put it back it will still work for another 5min again and stated make the same noise?
It seems there’s something heating up inside the inverter which is causing an auto shut-off by the inverter internal protection circuitry. It will need to be diagnosed using a multimeter to locate the exact fault.
Please what could have damage my inverter being used with same load for 1year, came out with serious fire suddenly, just while on load, not connected with grid.
The fuse did not cut off.
Thanks
Where did the fire happen exactly?
Thanks for your reply, from the mosfets.
I discovered the transformer has bridged. Please I have some questions.
Is it possible for an inverter to work 24/7.
How can I avoid such occurrence?
Thanks
OK, it means the transformer winding burned due to overheating (overload) and bridged, creating a short circuit on the mosfets. This in turn caused the mosfets to catch fire.
You can definitely use the inverter 24/7 provided it is not working under overload conditions and getting over heated. Alternatively you can use a fan cooling for the transformer and the mosfets so that even with an occasional overload the transformer does not get over heated.
I have a little problem on repair pls I need to chat with someone pls
I can can help you with general tips about inverter repairing, however it can be difficult to suggest if it is about a specific inverter brand, since all inverter brands have their own personalized design, which is known only to their own engineers.
My inverter 3kw gold series . indication on screen fault #9 frequency problem . I want to repair in my own workshop how you can help me ? Need circuit diagram for this and related parts if required for this stage to remove fault. Please guide me thanks
This problem is specific to your inverter design, it can be difficult to get the circuit diagram of your inverter and troubleshoot the fault.
I have a 1200VA inverter, hooked up to a 12V 100AH Lithium Battery.
About 10 minutes after a power failure, the house’s lugs tripped at the mains. After investigation I found that the inverter was completely dead. Battery voltage still reads 13V, so seems good. When switching inverter between online only and battery backup mode, the LCD quickly flashes and goes off again.
I checked the fuses and they seem fine. All I can see wrong is two burnt resistors.
I am at the point of buying a new inverter, but I still want to try and have the damaged one inspected and fixed, if possible.
What would you advise I do? I have very limited electronics knowledge, and only a multimeter.
Burned resistors indicate towards a serious fault in the inverter. It could be either burned MOSFETs or a malfunctioning circuit stage in your inverter. It can be difficult to analyze the fault unless the inverter is opened and checked with a multimeter. If you are a newcomer to electronics then I would recommend calling a qualified technician, or buying a new inverter.
I have Solar Off Grid Inverter 3000Watt 24v working faultlesly for 3 years
Recently audible alarm came on solid and red led on solid indicating fault code 01 on display panel suggesting fans at fault to be replaced
Fans however are both running at full speed and definitely not faulty
Inverter still working fine all functions can be monitored on digital display and no sign of any malfunctions there
No indication of any component or heatsink running hot
I am familier with electronic troubleshooting and would appreciate some assistance to locate the fan sensing circuits since unable to obtain circuit diagram for this inverter
Thank you so much in anticipation
Willem
The sensing circuit for the fan may have a thermistor, or an IC such as LM35, or some other variant, since there are many types of heat sensing ICs available today. Mostly it could be a thermsitor.
Thank you so much for reply
Very much appreciated
God bless
Willem
My pleasure Willem!
All the LED of my NEXUS inverter keep blinking after like 15minutes of charging the battery, i always press the off/on button to stop it. And after awhile it will start blinking again…..what’s the solution?
What is the function of this LED? Is it for indicating full charge battery voltage?
I have a must 1.5 KV if you switch it on, wakes up for 2 seconds then cut off failing to run the tansformer
Hi I have a ginlong solar inverter that is chucking a fit, And I don’t have any idea where to start looking.
When powered on the inverter will freeze up after a few seconds, However the longer it’s left disconnected then the longer it will run for when powered back on.
After being disconnected for a week I can get it to run for about 1 -1 1/2 minutes.
When it freezes the screen remains on but none of the buttons to set the settings will operate.
Hopefully you may be able to point me in the right direction.
Thanks
Scott
Hi, It can be difficult to figure out the problem without checking it physically, since every inverter has their own specific circuit board. This problem seems to be specific to the inverter. Only the service technician will be able to solve it for you.
Hi Swagatam,
I have a 2500w inverter that works of a wall plug.
The charger light flashes continously even though the batteries are fully charged.
The fan does not kick in either.
When co nected to my wifi.only there is a continous beep and I noticed code 35 appears on the screen.
Please shed some light.
Hi Abel, Without a practical testing, it may be difficult to judge the fault that you are facing. I can only help with general inverter faults.
I am building a dspic inverter at home, system is working the problem I’m having is on setting the menu calibration and parameters. Getting to Ac In and Inverter Load settings , I was not enable to set in fact the figures are not changing , it remains 000v and 000watts. What could be the issues because I had already replace the Lm324
Sorry, I have no idea about it!
Hi Swagatam, I have a 24v 3000w/6000w pure sine wave inverter on my stand alone solar system, I installed a diy transfer switch to swap my pool pump between 240v Street supply and my Solar supply, It worked great for the first few times, but on the last attempt the pump was still ramping up as it switched from Solar to street supply, for a split second I think the two supplies connected (High current causing the contactor to arc internally) obviously the inverter came off second best, I want to try and repair the inverter. What I would like to know before I try is what componants would it have most likely damaged? Would it be the MOSFETs or the BJTs or both, or would it be a total write off.
Hi Andy, considering there could have been an instantaneous short circuit between the grid supply and the inverter supply output, chances are that the grid voltage might have entered the inverter transformer secondary and fried the mosfets, due to the reverse DC from the transformer across the drain/source of the mosfets. So the mosfets might need a thorough checking
Thanks for the reply, I’ll remove them at the weekend and test them all. I’ll update on how I go.
Thanks again ????
OK great! all the best to you!
hi, thanks for this article. I am currently trying to repair a 2000w inverter. No power seems to be getting to the output section. I have no voltages on the TC4420 driver chips or anything in that area. No fuses are blown and I seem to get 12v on them.
Hi, you will have to trace the voltage path and check whether it is reaching the oscillator stage or not. The oscillator stage would then feed the TC4420, so it is important that the oscillator section works
I purchased Vevor Pure Sine Wave Power Inverter 3500w 7000w 12vDC to120vAC. It operates fine when only small appliances are plugged in. When I plug in a 1500w heater, it will run 15-20 seconds and then show it is draining the batteries down to 40%. Immediately after shutting of the heater, the batteries show a full charge and everything works. Any ideas what the problem could be? Thanks
Can you please specify the Ah rating of your battery. To handle 1500 watts comfortably, a 12V lead acid battery must be rated at a minimum of 700 Ah, ideally this should be 1000 Ah. Only then it will be able to sustain the 1500 watt load for more many hours.
I have a power bright inverter 2300 did I accidentally reversed polarity or hooked up backwards and I heard something like a great big noise I’ve checked all the fuses any idea what might be wrong I called the company they said something about a glass fuse on the AC side that lights up and comes on but no power will come through the AC outlet thank you
If your inverter did not have a reverse polarity protection then most probably all your mosfets or IGBTs are blown. It is highly unlikely that the fuse would blow prior to the power devices. If it’s the fuse that blew first then you are lucky.
Must be the see it’s because I changed all the blade fuses thank you so much
No problem!
Thank you for your page. I have bookmarked it. You Provide many links I am sure will raise my knowledge of inverters and electronics. i sometimes wish to figure out the problem on my own and many hours days and months elapse so in my later years of life im going to save some life and ask. Thanks in advance for any information you wish to share.
This is a eco worthy solar hybrid inverter 3000 watts.intigrated has a pwm charger but when in service was only hooked up on the battery side and the solar terminals left bare. I only use it for the inverter.i use it in a mobile dog grooming vehicle. One day it was rainijg all day, usually the system remains active but due to the rains i shut it down. The nextvl morning was humid so when my wife went to plug in the ac the ground prong touched the already running inverter,displayed a mild discharge of electricity followed by inverter death. I by no means good at repairing broken electronics but i do have a good size pile of parts.i visually inspected the mosfets and notice a damaged one and replaced all 8 off the line.i reassembled the unit and still dead. When checking battery voltage i noticed it read 5 volts so i disconnected the positive and then batteries returned to 24. I checked continuity at the battery terminal it breifly beeped the reading rose in value then the meter read -1 open circuit so I reversed the leads and the count down to the beep then back up. So i decided to power the solar side and there was no battery fault. Battery and solar share a possitive common .when checking negative battery negative solar i get -22.7 when battery at 23.4 and open when pos pos checked.thats all i have for you on my puzzle. Im really excited about your links. I hope you wrote them because this basic tutorial on the stages of a inverter i grasped and I dont grasp much.im thinking a short at a capacitor. Thank you.
Thank you for bookmarking, and for the detailed explanation. It seems there’s been a serious short circuiting inside the inverter due to the accidental grid AC connection with the inverter. It is important to check whether only the MOSFET were fried or the oscillator section was also damaged?
Before replacing the MOSFETs you might want to check whether the oscillator section is alive or not and whether it is providing the required PWMs to the MOSFET stage?
Once this is confirmed only then the MOSFETs may be connected and checked for the response!
Hi, I mistakenly connected the inverter (2000w GMC pure) to ac while setup with the batteries and now there is no power output despite the lights at the top of the inverter working without the fault light kit up. The load bars that look like a bar chart are flashing. It does smell like I fried something inside. Can you advise me of the process to diagnose and where I could get parts of it’s likely to be able to be fixed? I live in Bolivia and it may be hard to find things here. So appreciate this info resource and the knowledge you are putting up
Hi, where did you connect the AC? Is the AC input for charging the battery, and is the inverter equipped with automatic changeover?
If the AC input was for charging the battery, then you have done nothing wrong?
Hello,
what can I do if my inverter is charging the connected battery very slowly. Is thee a setting for fast charging?
Thanks
Hello, if this issue has developed over time, then it may be due to a degraded battery condition. Try charging the battery externally with an initial high current, and then reduce it as it reaches 60% of its charge level. If it accepts the charge correctly and quickly, then your battery may be fine and the problem may be with the inverter charger.
My inverter output is supplying a very high voltage
The screen of my inverter is blank and I turned on my fridge in error causing it to malfunction I have tried resetting it but it’s still making a lot of noise please help.
It is an inverter specific fault which cannot be judged without checking it practically.
My DC power is 24 volt and battery is full, but My outback inverter it indicate error All the time why? But there is no any faults?
Either your battery is not full, or your inverter is showing an error reading. Check the battery externally with a heavy load and confirm whether the voltage stays normal or not….if yes then your inverter indicator circuit is malfunctioning.