OBC Charger Repair

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Dec 24, 2021

At first I want to say that I really appreciate the help & support from you all in this forum, without the "Troubleshoot with OBC" thread I would have never come that far.

I have an Mitsubishi IMiev Gen 2 I think, with the OBC charger Gen 2 with the snubber caps directly on the main pcb in the doghouse.

At first the 2 power resistors in the doghouse were open circuit so i replaced them with new ones with the value I have read in the OBC thread, 4.7Ohm / 9Watt.

Because I already had desoldered the waffelplatte I also replaced the snubber caps with 2 new ones, rated at 3kV with 1nF of capacity.

By supplying +5V to the Anode & Cathode of C301, with + & - the right way, I got the relay working & measured around 0.4 Ohm between the white N blade contact coming down from the top board & the N connection points of the waffle plate on the upper left side of the board, like explained in the OBC thread. When the relay was not activated I measured around 10.4 Ohms of resistance between these two points, which is in spec right?

But never the less the OBC is still not working, at least the DC/DC works fine.

So maybe there are other things/values that I can check/measure to identify the problem or at least narrow it down.

Thanks a lot in advance, you all helped me a lot with the infos i got from the OBC thread.

Have a nice Christmas & relaxing holidays

kind regards
Sounds like you have made a good start to getting it repaired.

What happens when you try to charge, e.g. relays and contactor noise, fan noise, EVSE engages it's AC relay, lights on the dash, does it try to start if so for how long, or just do nothing, etc? Any and all observations are good information to troubleshoot.

On page 1 of the Troubleshooting thread there is a link to the "diode drops in the waffle plate"--do a search for that and use the diode check function of your multimeter to check if it is okay or damaged. It can be done in the car but all the faston tab connectors have to be removed.

Enjoy your Christmas too.
Hey Kiev,

Thanks for the quick answer.

When I now plug in the charging cable I hear the relay and contactor noise, I also measure the 230V AC on the Top PCB screw connectors.
The indicator light on the box of the charging cable turns orange but then after 2-3 seconds it turns of, also the AC Input Voltage on the top board goes to 0. No fan starts working, only the relay and contactor noise is hearable. Thats the case right now after the attempted repair.

At first, when the second power resistor in the doghouse was still open circuit, the relay and contactor noise & the fan short run was hearable after pluging in, but not anymore.

Additionally I have to say unfortunately I ripped of the connector on the bottom board of the ribbon cable so I had to resolder int completely.
Thanks to your information about the pinout here in this forum I got it right, after double & cross checking every of the 50 pins.

Honestly I also made another mistake by interchanging the blade connections on the bottom board on the upper left side, the Connector X2 was connected correct with the blue cable, but the pink one was there were the orange one with the blue ring should have been.
The Orange one withe blue ring was at the terminal of the pink one & the orange one with the red ring was at least also correct.
Hopefully I got it right all right like it really was at first.

Now all are correctly connected & the DC/DC is running, hopefully this interchanging of cables to the wrong blade conectors did not any damage down the line, what do you think?

The only question right know regarding the correct connection of the cables to the blade connectors are the 2 black cables on the upper left of the bottom board, FG2 & FG3, when I remember it right. They are directly connected to the DC output of the charger / input of the battery.
Because i was not sure which way they should have been connected I interchanged them to, but without any noticeable change of behaviour of the charger.

At the end I also tried to measure the output voltage of the charger at the big orange connector after plugging in, but nothing, 0V.
On the other hand I measure around 350V at the other side of this connector, going to the battery, after plugging in, but only for a short time, then the relay / contactor opened again.

Hopefully all this information is a lead in some direction to localize the assembly group / component who is responsible for the charger not being able to work properly.

Thanks a lot in Advance.

kind regards
Did you ever check the diode drops in the waffle plate?

After the misconnection of the faston tabs you should check the waffle plate diode drops to see if it is damaged.

Post 3 on page 1 of the Troubleshooting thread has a schematic of the waffle plate; post 2 has a link to the diode drops in the waffle plate.

Hopefully i got it right by drawing it on that existing schematic
Good news on the diodes then.

The FG wires are Frame Grounds and it doesn't matter which way those 2 wires are connected.

But cross wiring the Orange wires with the tape is a serious blunder; the X1 and X3 are the Positive side (Red) of the HV to the DCC and the MCU, and the X2 X4 are the Negative side (Blue). Hopefully fuse F102 has blown to protect the Output Filter. If the DCC is working to recharge the 12V while in READY then that is a good sign. Maybe the OBC never started up and put voltage on the Output with the wrong polarity.

Did you ring out the flat ribbon cable from board to board? It could be damaged, open circuit or shorted.
Hey Kiev,

Thanks a lot for your answer.
I ringed out every single pin of the ribbon cable to ensure correct connection & exclude any possible short circuit.

& yeah the DC/DC converter works fine if on Ready, so thats at least a good sign.

I will check fuse F102 if it is blown & if so replace it to check how it behaves when plugging in the charging cable.

I also have the impression the charger never really started up like you implied because I once measure the AC input voltage from the charging plug on the top board and it was 230V. After that I repeated the charging attempt & tried to measure the dc output voltage of the charger on the orange plug going to the main battery, but no dc voltage was measurable.

Great news regarding the FG wires & the diodes, that they are still good.

I will keep trying(;

Thanks a lot
Hey All,

I am still hoping to find a way to get the obc to work again.
Maybe somebody of you has an idea of how to approach the localisation of the faulty section/parts?

Plan b would be to use an external charger, like the Elcon PFC 2500 Battery Charger, which i have on spare.
The main question is how get this charger to work with the internal system / the vcu of the miev?
The Elcon has an CAN Interface so maybe there is a way to integrate it into the charging control system of the miev.

Thanks a lot in Advance

i think there may be a few posts of folks using an external charger. If the HVDC were connected to the terminals under the MCU cover (in the correct polarity), then charging might occur when the car is in READY. The car would consider this as a regen, so maybe it would need to be put into N.

The Elcon PFC with CAN allows you to set the voltage and current levels using a separate CAN buss connection and control to the Elcon, not the car. The commands are in the ELcon manual. There is a big thread on the 1.5kW TCCH/Elcon chargers in the diyelectriccar forum in which coulomb, piev and i reverse engineered the circuit boards and the firmware.

It might not hurt to recheck the diode drops in the waffle plate for the output side rectifier and the inspect/check the components of the output filter. With cross wired HVDC connections there may be some damage..?
Hey kiev

The diodes definitely seem to be fine.
I really dont know how to further approach the failure search of the obc, maybe you can give me a hint were else I could look/measure to get the error contained?

Thanks a lot in Advance.

Kind regards
Sometimes they just can't be repaired. There is much that we don't know about how they work. i have several units that resist all attempts to repair.

i've never considered what could happen if the HV output lines were cross-wired, so i don't know if that would cause a new fault, or if your original issue is still involved.

Probably time to replace the OBC with either a new or used unit, or try Plan B.
Thanks a lot for your answer kiev, I really appreciate your engagement regarding my attempt of the obc repair.

I was thinking about If maybe there is somebody out there who has experience & knowledge who could / would like to take a look at my obc pcb, ideally here in Europe, maybe even in Austria, Switzerland or Germany?

I am willing to pay adequately for every expense & effort for sure.

Otherwise I am trying plan B with the Elcon PFC Charger, to get the imiev charging again this way.

At least I am still able to drive by charging via Chademo, but the major downside is the cost.
My utility charges horrendously 12.50€ per 15min, with a battery in the 10s of kWhs range you get at least a reasonable amount of energy for that but with the imiev, maybe 4-5kWh per 15min depending on the SoC of the battery. 2.50€ per kWh is far to crazy especially because I pay only 0.20€ per kWh at home.

So I must figure something out beeing able to charge at home again, above all from an financial point of view.

Thanks a lot for your effort & time in Advance.

kind regards,