800 w Modified Sine wave Inverter Fault Light and No AC output

Discussion in 'General Electronics Chat' started by EcoRabbit, Jan 24, 2015.

  1. EcoRabbit

    Thread Starter New Member

    Jan 24, 2015
    4
    0
    Hi All

    New Member with something which I'm sure you will all be able to help with. I have an 800 w (2000w Surge) Modified Sine wave DC-AC inverter (Jaycar) that I mounted in a trailer towed behind my car. Have 1 x 120 w Solar Panel on a Frame above the trailer feeding into a Lead acid Deep cycle battery via appropriate charge controller. This was all powering my Waeco Car Fridge as a trial. All worked fine in the back yard and for a while while mounted in the trailer - then after traversing a dirt road approx 200 km long - no A/c current. I Know I could have run the fridge it straight 12 v with no inverter but I thought I would give it a go cause you don't learn unless you try thing out.

    So My theories are :
    • Vibration has caused the fault light to come on and somehow blown the driver circuits ??
    • Earthing / shorting Issues with the mounting of the unit direct to the body of the steel trailer with not insulation ? ( I had not run an earth wire from the Inverter to the Chassis of the vehicle or trailer
    • Dust problems ?
    So I had nothing - Just the Power and Fault lights. Being an inquisitive soul I thought I would pull the back off (as you are warned that you are not supposed to do) so I could observe and learn. No Fans working - nothing.

    Then like a dunce at some point I accidentally reversed the Polarity. Now Power and Fault lights still work, strangely the cooling fans work now too as soon as you connect power and switch on. Audible alarm now no longer works ( I suspect I have finished off the Driver circuitry if this had not happened already before !)

    I am just wondering what went wrong in the first place to cause the whole thing to shut down and fault ? All Fuses test out fine (still)

    Any Suggestions as to initial cause of Failure would be gratefully received as I am inquisitive but highly inexperienced. No doubt I will be Buying another inverter but I would like to learn from my mistakes and not kill another one.

    Thanks

    EcoRabbit
     
  2. wayneh

    Expert

    Sep 9, 2010
    12,154
    3,060
    Some photos of the innards might help.

    It's possible that extreme mechanical forces damaged a connection, a solder joint, a relay, cracked a PCB, and so on. Pure speculation at this point.
     
  3. tom_s

    Member

    Jun 27, 2014
    285
    333
    recently bought a 600w MSW inverter from aldi, unit worked first time i plugged it in (running a standard 40w floor standing fan), ran it for a few hours ok.

    following day, powered it up again, then died. actually the unit was ok, the cables connecting to the battery clamps were poorly crimped (not soldered, are now). if under warranty i'd be taking it back to jaycar and tell them it failed.
     
  4. EcoRabbit

    Thread Starter New Member

    Jan 24, 2015
    4
    0
    Hi wayneh,

    Thanks for getting back to me. I have attached photos - tried to take them from a few different angles to hopefully reveal what may be the cause of the problem. I am thinking that I have an internal electrical issue as leads are conducting fine and work fine on another (smaller) inverter I have. I don't know if you are able to download and annotate these pictures with which parts of the aparatus are which and do what. I have had a read of the following document which reveals that due to power conversion efficiencies it is highly unlikely that there would be a diode protecting the polarity for when I reversed it - and fuses are fine so something else has gone - but before that what went is the moot point. http://www.jaycar.com.au/images_uploaded/inverter.pdf
    I hope the resolution on the photos is sufficient for your to examine for damage. Please don't adversely inconvenience yourself on my behalf if you have better things to do . I appreciate the support of this forum but don't want to put you out !

    Cheers EcoRabbit
    Inverter 1 of 5.jpeg Inverter 1 of 5.jpeg Inverter 2 of 5.jpeg Inverter 3 of 5.jpeg Inverter 4 of 5.jpeg Inverter 5 of 5.jpeg
     
  5. EcoRabbit

    Thread Starter New Member

    Jan 24, 2015
    4
    0

    Hi Tom s

    Thanks for that. I will be back at Jaycar asking if I have done anything wrong but don't have high expectations of recourse. I bought the Inverter more than a year ago and haven't had the time to use it until recently - So despite being more than a year old it has done virtually no work. I have checked the Cables (thanks for your suggestion) and they are working fine on another inverter so I have been able to eliminate that as the fault. I am glad you were able to get yours working again with a fairly simple fix ! Out of Curiosity , with your poorly crimped cables did they run hot or show any signs of burning that you we able to notice before not working ?
     
  6. wayneh

    Expert

    Sep 9, 2010
    12,154
    3,060
    Nothing obvious jumps out. :(
     
  7. Evil Lurker

    Member

    Aug 25, 2011
    117
    23
    R77 is blown. One or more of the switching transistors is likely nuked.
     
  8. wayneh

    Expert

    Sep 9, 2010
    12,154
    3,060
    Darn, missed it. I was looking for mechanical damage.

    Good catch, that'a a big clue.
     
  9. cmartinez

    AAC Fanatic!

    Jan 17, 2007
    3,574
    2,545
    Wow... you're quite a good observer... I'd also suggest a picture of the underside of the board, see which traces were subjected to excessive heat.
     
  10. EcoRabbit

    Thread Starter New Member

    Jan 24, 2015
    4
    0
    I have attached a photo of the back side of the Printed Circuit Board - The Point of the screwdriver is pointing towards the back of where the R77 Resister mounts to the PCB . No obvious sign of charring or over heating I can see but I am not a trained observer.

    Can anyone point out / annotate where the Switching transistors are ? Feasability of testing these or better jsut to replace. ? I am assuming that it would be uneconomic to repair this as while I might be able to get a replacement Resister (R77) if I could work out it's value - getting the specs of the Switching transistor (s) would be more of a challenge.

    I am still at a loss as to whether the Blow resister and switching transistor is the primary or secondary damage (caused by me reversing polarity ?) Any input on this would be great.

    Thanks EcoRabbit.
     
  11. Evil Lurker

    Member

    Aug 25, 2011
    117
    23
    This device also has another problem... the capacitors are Fuhjyyu's. For those that don't know this company at once point was the poster child for unreliable, short lived, and altogether bad capacitors. I have lost court at the times I have seen computer PSU supplies and other devices become inoperable due to failed Fuhjyyu caps. In some cases they will vent and leak however many show no outward symptoms of failure and the only way to properly test them is to remove them from the PCB and connect them to an ESR meter. Basically if I am working on an electronic gadget and I find Fuhjyyu and a handful of other manufacturers capacitors (like CapXon, Sus'con, a few series by Samwha, Chengs/Changs/Chungs, in use I will replace each and every one of them on sight provided of course they are not mounted onto the PCB in such a manner that the removal process would subject the board to excessive risk of pad/track damage.
     
  12. Evil Lurker

    Member

    Aug 25, 2011
    117
    23
    Eewwww... there are a LOT of issues with the soldering on the bottom of the PCB. I'm going to try to attach an edited file to show what all is wrong and absent that I will just photobucket it.
     
Loading...