1500w pure sine inverter repair

[(unknown)]

Hello, I'm new to the group, I recently purchased an inverter from ebay which was dead on arrival. I traced the fault to components q29 and ic5. The inverter is similar to the Aims 24v 1500w pure sign but mine is in a light blue case, I believe the origin is Taiwan. Can anyone help me identify these parts? The board (bottom) says G-150SP Rev:E. I will try to post pics when I found out how.Many thanks.

[dinges]

I was going to ask what part numbers are on both components, but since you seem so sure that the fault is in these components, you probably know enough about electronics that you would post these numbers if they were printed on them.

Some detailed pictures might be nice (of the components). At the moment, I'm guessing (!) the IC is an opamp (8 pin DIL) and the TO-220 'thing' either a bipolar transistor or FET. Guessing, that is. Could also be a voltage regulator (7805/12 etc).

At first I thought the TO-220 component (on the right) was messed with (thermal grease present) but looks good enough. The board under it though seems a bit, ehm, smoked.

Also have a good look at any elco's in the vicinity; in me experience, they're extremely unreliable.

Can't help you any further than this, hope others can.

Peter.

[(unknown)]

Hi Peter, Thanks for the mail. I know that IC5 is the switch mode psu controller and q29 is a n channel to220 fet.Both are part of the units internal power supply but the fet was too smoked to identify the part number and the ic had it's numbers ground off. I was hoping someone with a similar inverter unit may be able to peek at theirs for me (unless their part numbers are grounded off too)

[dinges]

For the FET I personally would risk using a general-purpose FET with 'good' ratings, especially if it's only used as an auxiliary/internal powersupply. Best ofcourse would be original replacement. Like said, hope others can help.

As far as switchmode PSU controllers go; there can't be that many of them in DIL-8 case. Should all else fail, I'd search the net for datasheets on such ICs and compare the example schematics with the one in your inverter.

In my experience, designers are usually lazy and take the easy road: copying circuits from the IC manufacturers datasheets. There's no salary-bonus for originality. (Then again, why re-invent the wheel)

A wild guess that springs into mind for the IC: UC3852 (by Unitrode).

http://focus.ti.com/docs/prod/folders/print/uc3852.html

BTW, people who ground partnr's of ICs should have their <insert bodypart> cut off, IMO.

The joys of reverse engineering....

Peter.

[ghurd]

Many brands and sizes use the IRF44 mosfet, often in banks.

G-

[jimjjnn]

My last career was the same.

The company I worked for had the mfgr put on numbers specific to my company. If the mfgr wouldn't put company numbers on, my company would grind mfgr's numbers off with a moto-tool. A lot of parts were ruined due to the person with the moto would grind into the part too deep.

Had a lot of IC's and transistors to replace. Guess I can't complain tho, as it was overtime for me.

[johnlm]

I understand the logic and likely several reasons for having your own inhouse part number put on ICs but what is the logic in grinding off the OEMs part number and logo?  Is it soley to prevent others from  easily copying the design or to make it difficult for anything but factory repair?  Either way is seems pretty odd.  

John

[jimjjnn]

John, you got it right. My company wanted the profit on repairs.

[SamoaPower]

Yep, sure looks like an Aims.

Sorry I can't help as my numbers are ground off too.

[oztules]

Looks like the only way forward will to be to reverse engineer the pin outs of the pwn chip,

post a rough out of the circuit. The rc freq circuit should identify the osc pin, vin and earth should be obvious, pulse out should be identifiable (assume off to the switching smoked fet) and this four or five pin designations will be a good start to eliminate those dip 8's that aren't the ones, and those that are.

The more pins that you can identify, the closer the end game.. Last time I suffered this silliness, was with a  ka3846. The topology will help give some clue (in my case it was pushpull....  numbers were ground off on this and the lm324 next to it...odd vcc pin gave a clue for the  324).

best of luck

.......oztules

ps the fets a fet. electro's around it may give clue to voltage range.

[dinges]

I cannot see ANY logic in it. Apart from motives of having repairs made in your own shop.

As long as customers implicitly say they don't mind that the equipment they buy is intentionally made difficult to repair, I guess we're just rewarding the companies that do this.

IMO, with current issues of 'corporate responsability', companies should strive to make their equipment serviceable and repairable. Also good for the environment. I'd expect at least the companies operating in this relatively 'green' market segment (RE) to behave like this.

But I won't hold my breath.

Peter.

[ghurd]

Could it be this is done to keep "You, Me, Us, & We" from attempting repairs on a dangerous device we don't understand?

OpAmps and 555's look close enough to my father-in-law.  As do 7805, 7924, and IRF540 TO-220's.

Maybe warrenty issues? I would not want to pay for repairs 'someone' made worse because they installed a IRF540 where a 7805 belongs.

(Almost famous quotes...

"If it fits, put it in there... My boy G- will fix it if it's not right!"

"It can't need any more parts than the one that exploded the first time!"

"It worked for a second, right before all the smoke and flames came out the little slots.  So it almost works. It'll only take you a minute to fix, if you know what you are doing."

"There was a funny hum from the breaker box, before all the lights went out, so it must be the electric company's fault."

"The transformer that came with it said 110. And that IS what comes out of the wall."

"What do you mean switches DON'T go in parallel with the light???"

"It just needed a LOT bigger fuse than it had in it. But now the LED doesn't even come on."

"Radio Shack will have one of those."

OK, I'll stop now...)

G-

[jimjjnn]

Ghurd,

Couldn't have said it better

[TomW]

G-;

Well said. I am always nervous when folks try to fix complex high power equipment from advice online. Dangerous business that will likely void any homeowners insurance you may have when [not if] it erupts in flames. They don't call them [F]ire [E]mitting [T]ransistors for nothing.

Always amazed that some people will put their lives and property in harms way to save a few bucks. I won't get into the burden of responsibility if you provide the advice they follow. Just too many aspects of common sense on repairs you cannot provide via internet osmosis and no real way to tell if the person on the other end has any clue what they are doing.

Anyway just had to agree with you.

Cheers.

TomW

[(unknown)]

Thanks to all those who have replied so far. I would like to make it clear that I'm NOT putting lives and property in harms way to save a few bucks.If I don't know what I'm doing then I seek help.

  My inverter is with an electronics engineer (thankfully my friend) as no inverter companies wanted to help,it is cheaper to buy a new unit than to post to America or Taiwan (I'm in the U.K.) I'm also a radio ham with some knowledge, but not enough, that's why I sought professional help. Thanks to those who have helped and not criticised. The engineer has replaced the said parts with a UC 3844 ic and a IRF 640 fet. The power supply is now running but the output voltages are low.Further investigation is under way. Any "helpful" comments would be appreciated. Thanks again.

[oztules]

Sorry Tomw

But I don't think enforced ignorance is the answer.

Not allowing or discouraging people from asking questions, or banning or censoring the answers is contrary to the life education of an individual.

Finding the balance between what is safe and what is not, is best left to the individual, benevolent dictatorship  is no better than dictatorship by any other name.

The freedom to test ones skills or satisfy ones curiosity is instrumental to learning and living an interesting and fulfilling life in general.

There will be instances where this may lead to a sticky end, but that is outweighed buy the gains of freedom of choice.

We know that driving a car is dangerous, having trucks on the same roads is even more dangerous, but we accept the risks.... why?

This applies to nearly everything, and with 60% of us obese or overweight, there is serious danger here, but we can still eat what we want. We shouldn't be allowed to. It will lead to heart attack or some other malaise, but we weigh the risks and make the decisions ourselves......far far more important than burning down the house....

I understand your viewpoint on this, but I feel that freedom to choose is worth any price, and Millions of lives have been and will be lost to maintain this creedo.

please let us choose, and be happy about it.

Sorry Tomw, just my thoughts...........oztules

ps. If he picks the wrong ic, it just wont work...it's at low potential. If he undersizes the fet, it'll just fail like the one before it...if he buggers it all up, he'll be no worse off for trying....he can still throw it away,.................. or just maybe, he knows what he is doing ( i think this is the case here), but just wants to know which pwm chip it is.....I've no doubt, once he has a pulse width going, he will bang in a fet of his choice and away he goes....It failed for some reason, and he will have to ascertain what that was before committing to full power.

 I don't see the big issue here.......

[dinges]

Fully agreed.

And if the IC-nr's were on that thing in the first place, it would make repair easier and safer. Not to mention how a schematic (gasp!) could help...

If liability is such an issue, we should stop giving advice to just anyone, not only where black-magic-electronics is concerned. A prop can strike very hard. A free running windgenny generates high voltages. A falling tower...

What if you had helped a guy by advice on how to size/build/install his windmill and it fails for some reason.

No matter whether a schematic or component print is present, people will often want to attempt a repair. And once in a while, those people are actually knowledgeable, know what they are doing and do care about their own safety and fire hazards.

As far as the less-well-informed people around; they will soon run out of money, if they continue replacing FETs with 7805s. They may also end up without a house, or their life.

Sometimes Darwin is very merciless to the individual... and a blessing to society.

Sorry. My emotions just got the better of me, I should know better.

Hope Solar gets the thing fully operational again. Guess I wasn't to far off with that Unitrode-IC. Be expecting the bill soon

Peter.

[dinges]

Oops..

In the heat of the moment I forgot:

What might have caused failure in the first place (FETs don't blow up out of themselves) could have to do with the feedback circuitry. I'd check any small elco's, diodes and semiconductors near that IC. But if your friend is an electrical engineer, he doesn't need me to tell (I hope... I have trouble suppressing a rant on the ignorance and idiocy of some engineers, which I'm ashamed to admit I'm one myself )

Low output could also mean that the auxiliary supply is overloaded, so perhaps trying to run it without a load (no load on the internal PSU, I mean) could be an option.

Curious: you sure that the UC3844 is correct? How did you find this out?

Peter.

[TomW]

dinges & oztules: Well, guys;

Excuse me for caring about safety.

Some folks [not anyone in particular on this thread] could not figure out pouring urine out of a boot if the instructions were written on the sole.

Now I will take my decades of commercial high power rf gear tuning, repair and installation and stand off to the side while he learns the hard way about cascade failure and how the part with the top blown off is probably just a symptom and not the cause, as he apparently has already discovered.

BTW, I did not eliminate this posting like I could have on the basis that its a dangerous activity. I left it in the hopes others would point out the folly of trying to remote troubleshoot undocumented devices for a person with [apparently] no clue on how it is built.

Opinions vary and I have a policy of not even trying to remote troubleshoot things unless I know the person on the other end has some experience so they don't waste their time and mine as well as their money.

Then again I have only been on this board a short while so my opinion is obviously less than valuable.

By your attitude I suspect you would prefer I just go away rather than express my opinion? That censorship blade cuts both ways you know.

Thank you, carry on and good luck.

Sorry to get off topic but I feel this is important to point out to those who may not understand why I made that comment.

T

[oztules]

Hi Tomw,

I hadn't seen that partial success had been achieved  when I wrote my screed. That Post must have appeared while I was scrivening my post.

It looks as though the man was experienced enough to make his own decisions as to his suitability for the task at hand.

 I am desperatly ashamed of using the censorship slur on you, as I had no idea I was talking to the censor.That would have been unintentionally hurtful to yourself and was not meant as a critique of your efforts. Sorry if your position coloured the reply.

"BTW, I did not eliminate this posting like I could have on the basis that its a dangerous activity. I left it in the hopes others would point out the folly of trying to remote troubleshoot undocumented devices for a person with [apparently] no clue on how it is built.".........ooops  I'm guessing that means that you are the moderator here?

Oh well..In for a penny in for a pound... off we go again....

"Then again I have only been on this board a short while so my opinion is obviously less than valuable.".........

no, you're opinions are valued and should be freely expressed, particularly if held strongly, but they are there to be challenged also, by those who are not of the same persuasion.

 Only by reasoned questioning of each others strongly held beliefs, can a path of moderation be followed successfully. Without dissent, no frame of reference is available to balance the equation..... and I guess balance is the goal in all instances.... even in rf propagation, and switchmode feedback.

If some of us push too far in one direction, it is essential that others bring balance to the argument, and push back to a reasonable position.

On a macro scale. it is interesting that in those countries where only one view of the universe prevails.... well you wouldn't want to live there, in those countries that have vibrant discussion of every little detail of the life universe and warts and all discussion of everything in all directions, we end up with a vibrant society, where differences make the whole thing balanced and livable.

"By your attitude I suspect you would prefer I just go away rather than express my opinion? That censorship blade cuts both ways you know."

....No ....I want you to hold to your opinion, and express it, because by doing so it lets others make a balanced decision as to their position on things. If I let you or you let me have the only opinion on any subject, how can a third party make a reasoned decision........we need both sides. ( even when we reckon the other blokes boot is wet and instructions are supplied.)

You are welcome to delete at any time anything I may say, for any reason. I should not and will not require a reason nor should I require justification. You have an unenviable job as moderator, and interests to protect which I am not privy too nor should I be....it's not my board.

Best of luck on your task.. fire at will

.........oztules

[ghurd]

Hey Peter!

Darwin is no longer in the US.  I wish he were.  I really really wish he was here.

A drunk fell down stairs I "own".  The stairs were deemed, in a court of law, 100% perfect.

Admittedly he was as drunk as a skunk, and not able to walk on level ground.

He was not injured. At all. He just fell down. No injuries. At all.

I do that when I'm drunk too.  But I never sued anyone.

My insurance company paid him US$18,000.

The metric thing again... Is that about 40.000 Euros?

Another time, a guy sued me, repeatedly, for branches falling in his swimming pool.

There was (apparently?) damage to his pool filter and the pump.

Go ahead, piss me off.  Yea, I did it.

I proceeded to remove about 8, 60 foot tall oaks from the North side of my property.  Being the South side of his property.

I was immediately sued for rendering his pool 'too hot and/or exposed to the sun' for normal use.

I was also sued for removale of the chips from the chain saws that somehow ruined his lawn.  Don't recall what they paid... a couple thousand US$?

Another time, a renter re-lighted the water heater.

Somehow he managed to burn his penis, making him unable to perform his 'duty'.

His crack-head girl friend managed to sue for 'personal' damages.

Think 30.000 Euros.

(how the heck is that even possible?  That building is a 4 family unit. Was he attempting to light a water heater naked?  

Could he hold a match to the thermocouple and have a back flame burn his do-hicky?

A school teacher would certainly be in jail for even suggesting it could happen)

Stupid people are givin huge amounts of money to procreate more stupid offspring.

Darwin fled the US.  He is in hiding.

Rich?  You want to add to this?

G-

[TomW]

Aww, shucks My only goal here is to keep this forum a viable and sane resource.  I am not much of a builder but I have the time and resources online to help out here on the forum. I am one of several and prefer to be anonymous in that role but it is certainly no secret to anyone thats been here awhile.

I have no problem with differing ideas and opinions but sometimes I see advice and information passed on here that is a bit scary from my perspective. Similar to how I would feel if i saw someone hand a loaded firearm to an uninformed novice.

The stuff we generally discuss here all have dangerous aspects. Batteries with toxic lead and harmful acid and the ability to melt most objects if shorted across the terminals.

Rotating mass on tall objects. inverters creating up to a couple hundred volts on the outputs which could kill you dead. To me it is serious business and if being the wet blanket and pointing it out once in awhile gets me some flak I can take it.

It sure seems perfectly acceptable to agree to disagree and to have varying views. The main point is to keep your eye on the prize which is spreading this disease.

Anyway, sorry to ramble off topic on your thread, solar. Good luck getting it working.

Cheers.

TomW

[vawtman]

Oz and Tom you guys are valuable resources to us.Alot of us fly a kite in a storm.So comments on the negative side should always be considered with the positive ones.One day they connect and BOOM either good,bad or ugly we move on.Thanks

[wpowokal]

And so say all of us.

allan down under

[elvin1949]

Outlaw insurance companies.

 Then the IDOITS in this world would have to work for a living.OH so would most of the attornies.

later

elvin

[finnsawyer]

While you're at it get rid of the building codes.  Since anyone that builds a house now has no way to manage the risk of loss, he should be allowed to build anything he wants up to what he can afford to lose in one catastrophic event such as a fire.  I can see all those one room and two room shacks now.  Yeah, who needs indoor plumbing anyway.  Build cheap so you can cover the loss.