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Thread: Look for schematic/service manual - Invertek optidrive E3 VFD

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    Default Looking for schematic/service manual - Invertek optidrive E3 VFD

    As per title, chasing anything to do with these variable frequency drives



Look Here ->
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    Quote Originally Posted by wotnot View Post
    As per title, chasing anything to do with these variable frequency drives
    Iíll assume youíve been here

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    Quote Originally Posted by Gitch View Post
    Iíll assume youíve been here
    You assume correctly, but nothing there of help =)

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    Found a couple of Manuals for the unit.. may not be of any use to you.... Here's hoping






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    Quote Originally Posted by snacker View Post
    Found a couple of Manuals for the unit.. may not be of any use to you.... Here's hoping






    Thanks for trying, but no cigar for you =) Typically I've found 'hope' to be essentially useless in the real world of electronics ; it's more of a human sentiment...ie; I hope I can fix this

    I'm not expecting anyone to be able to share schematic/service manual for these, just because they're expensive industrial units, and that being the case they tend to keep it in-house and tight to their chest, but it never hurts to ask =)

    Anyhow, I picked up the job as in the past I've worked on VFDs, but customer complaint is: "It doesn't work" ; sent instructions to a mate on site, to check it's getting mains AC, and to check the 24vdc service power appears where it should on the terminal block -- it measured roughly 2vdc. M'kay, pull the unit and I'll see what's going on ; easier said than done. The VFD tech has come a long way since I worked on the things.

    Remove 2 screws holding blue plastic terminal and remove it -- this gives access to 2 screws on inside of case at the bottom -- remove those and the 4 screws holding the outer case.

    Lift up the case carefully, and disconnect wires from terminal block & DIL header....upon doing so I caught a whiff of burnies..






    Aim of the game here at this stage is to remove the controller board and ascertain where the 24vdc is instantiated from, but these units are assembled using the big hole and PCB finger method, which one PCB attached to another at right angles...this, in an onion, layer upon layer with some screws inbetween. I just quickly sop up any excess solder at the connection joints with solder wick, then flood the joints with low-melt solder and gently wiggle the boards apart, works a treat without risking track damage.





    I've no idea what that hicky hybrid is top right, but it looks like -everything- is in there, and I'm pretty sure there's another MCU on the bottom board controlling it, and the controller board controls this controller. Meep. There's one heatsink block the width of the board, 2 screws clamping the hybrid IGBT module, single screw lower left clamping full wave bridge rectifier


    The bulk caps & filters are on another board soldered into the lower mainboard...all of it has to come out to get to the lower (main) PCB...




    Chip markings don't help much...



    IDL I<diamond symbol> 0E3
    GH250 98
    CHN GH 548




    The SOIC-8 between the relay & MCU here, is a TS78L24 -- it's output goes to the 24v user output on the terminal block, and also directly to a pair of pins on the unidentified MCU chip. I buzz all around it, everything seems 'sane' with no obvious faults. The input side of the 78L24 goes to the center PCB finger, ground is rightmost finger -- I can inject 24v on user terminal (and/or 28v on input side) to see if this board still works ; it seems reasonably autonomous and should spitout a bunch of error codes related to it not being connected to the VFD controller =)

    However I'm not seeing anything obvious here ~ I know what I smelt lifting the cover ; I test this board later, and now go back down the trail ; where's the 78L24 getting it's DC supply from? Turns out it's here;



    Upper SMD cap and diodes got to the controller board, lower SMD cap and friends feed the 12vdc fan circuit...m'kay, what's going on here...ah-ha, wee yellow taped tranny is standby/control power, and that power-rail has a really low resistance...something's wrong here ; turn out this is also the power-rail for the VFD controller chip, and peering down in there is see what looks like a bubble in the conformal coating ; time for the scalpel ;



    Ouch, it go boom. that's the smell I was looking for. What is it?...doesn't matter ; custom firmware, need replace the entire board as a part...price?...will let you know =^/

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    ...remove terminal board...




    Remove bulk caps/filter carrier board...




    ..and unbolt main PCB from heatsink....



    ...IC and bridge soldered to board upside-down -- if they don't want the old board I'll flip the hydrid IC to identify it out of curiosity...

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    Final bit of sleuthing & report on this day in the life on my (attempted) service workbench -- look at the image above bottom right, and the 5th and particularly 6th pins in from the left on the 'intelligent' IGBT module, and how they're slightly discoloured -- these are the control data lines going back to the chip that exploded -- looking more carefully, the interconnecting traces lead directly to the end of the chip that went boom ; these are supposedly the low voltage 'isolated' part of the IGBT. Get in a bit closer and have a look at those pins, to see if one can discern why they look like they do (ftr, the area between the bridge and igbt is for the motor braking resistor on VFD models with that option) ;





    That there is some damn interesting damage for the isolated side of an IGBT =) You would think that if the ~360vdc suddenly appeared there as a surprise, it would've blown the thin traces leading back to the cratered IC clean off the PCB...unless of course, all 11 pins found the HV all at the same time...fits the physical damage I guess. Thus, most likely cause of fault was IGBT failure, which blew controller chip.

    The model itself has been superseded, and while Invertek don't have any main power PCB as parts on shelf, they will make them for you on order, but lead time exceeds need for a working VFD at the moment, so for now the fix is "buy a new unit", and they'll get back to us with a quote for a new board to be made. So, as promised, flip them chips...



    M'kay, now we know who you are, lets grab the datasheet and have a read, to find out how this beastie works ->

    Okay, I'm looking for it's logic supply...15vdc (makes sense, see below)...and which actual pins look like they copped a hottie...pin14, 15...which is gating UL from MCU and COM respectively, and there's more than a few ways pin3(P) HV power could've found the darkside to the isolated domain...but no smoking gun yet. Years back, we figured out more often than not, IGBT failures are due to bad drive timing...(years ago, the gate driver circuitry was all in discretes, not builtin like these things), and I keep on reading and get down to the typical application circuit & description, and see...

    3rd Notes

    1) To avoid malfunction, the wiring of each input must be as short as possible (less than 2-3cm) ...oh really?...I'll believe you Mr Fairchild, perhaps your design malfunctioned here because of..



    You can see the data input lines coming from the vias on the left and traveling all the way to the IGBT interface ... distance?... 10centimeters....and running right beside the phase current sense circuit, and another 3cm on topside of the board to the MCU itself....sigh...when something blows up for no good reason, it's usually for a good reason =) As I couldn't find any schematics, I had to answer my own original question -- how/where was the 78L24 vreg getting it's power from...



    The square IC in the foreground is a THY286KG 'TinySwitch' offline switcher (). It drives the transformer, which has multiple output windings for the required voltage rails (6/12/24vac at a guess). The curious looking R13 is an inrush limiting resistor ()

    Finally, inside sticker ID



    Boxed & shelved pending owner's decision of replacement board cost + my time being economical or not.
    Last edited by wotnot; 16-10-21 at 07:47 PM.

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