coulomb
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Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Sat Jun 20, 2020 5:06 am

I guess there is a lesson to be learned from this repair. If you choose to replace the capacitors without removing the lower board from the Waffle Plate™, you risk leaving some soot on the top of the Waffle Plate™. I'd say the devices themselves would be fine; that potting mix and the epoxy of the devices should prevent any problems of flash-over to other parts or to the presumed PCB below.

But some soot might end up near the pins from the Waffle Plate™ to the lower board. It would be worth attempting to clean that area as best you can around the pins where they exit the Waffle Plate™.

You may also have to clean the bottom of the top board, but that should be easy, and not removing the lower board has no impact on that. I imagine that most of the soot goes up not down, so if the top board is pretty clean, then the Waffle Plate™ pins are likely to be even cleaner.

318iEV
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Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Sat Jun 20, 2020 8:08 pm

I’m located in NZ, plus this iMiEV was imported from Japan so sadly nothing’s under warranty.

Luckily there are no soot/burn marks anywhere in the OBC apart from right next to the failed snubber, and after peeping between the gaps the waffle plate doesn’t show any visible signs of failure.
I have replaced the two snubbers with 3kv ones and am currently waiting for the replacement LE105 cap, transient surge absorbers and 20A fuse.

From what I’ve seen there is also a relay that can fail too though I’m not too sure where on the board to test it from, any help would be appreciated.

Thanks

kiev
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Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Sun Jun 21, 2020 7:01 am

@ coulomb, Thanks for hosting those pictures.

All that soot and molten metal [pic# 21]looks to me that the OBC was operating with a split snubber [pic# 11] that was arcing and eroding over some length of time. Look at the size of that gap! That looks like arc erosion has just eaten out the dielectric material and spread it inside the box. [edit, couldn't think of the word in the early morning]

There appears to have been burn marks [pic# 08] around some of the solder joint thru holes? don't know if that is from arcing or solder removal.

And the metal spheres and soot on the waffle plate looks like there may have been arcing between the un-cut or extra-long leads at the solder joint of the snubber cap [pic# 25]. i'm assuming they just cleaned the waffle plate and didn't replace anything in it. It's amazing that some FET or diode wasn't damaged in the plate.

The strangest picture is lucky [# 13] where it is showing soot on the backside of the AC line input covers and the decoupling capacitor at the card edge. It also shows a side view of the snubber to see the huge gap between the electrodes.

The story of these pictures appears to me that the OBC was still operating in a degraded condition with a broken snubber up until some time later when the MCU fuse broke.

Most other failure pictures have shown a snubber that is just cracked open a bit with a small amount of residue; these would be failed snubbers due the MCU fuse breaking first.
Last edited by kiev on Sun Jun 21, 2020 5:04 pm, edited 1 time in total.
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kiev
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Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Sun Jun 21, 2020 7:26 am

@318 , for testing the AC input relay.

Here is a link with a good picture of D301 which is a good point to apply 4.5V with a 200mA current limited power supply. i wouldn't connect a battery without current limiting and do be careful of the polarity.
viewtopic.php?f=23&t=4079&p=37548&hilit=relay#p37548


You can measure the resistance between the White Faston tab and the "Neutral" on the waffle plate solder joints as you activate the relay: ~10R when Open and shorted when Closed.
viewtopic.php?f=23&t=4079&start=30#p36735
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coulomb
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Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Sun Jun 21, 2020 4:29 pm

kiev wrote:All that soot and molten metal [pic# 21]looks to me that the OBC was operating with a split snubber [pic# 11] that was arcing and eroding over some length of time.

Look at the size of that gap! That looks like arc erosion has just eaten out the guts and spread it inside the box.

I agree, and was thinking similar thoughts, but not in as much detail.

Perhaps one capacitor failed first, and unusually failed not shorted but medium impedance. Operating at pack voltage, it would get hot. Amazingly, it stayed that way, eventually boiling its contents and depositing it on the PCB above and on surrounding components. The medium impedance was not enough to blow the MCU fuse.

I find it harder to explain the soot or more likely metal deposited on the waffle plate. Perhaps as you suggest @Kiev, there was arcing under the board as a result of extra long pigtails. Maybe arcing under the board happened first, heating the capacitor above and tipping it towards failure.

Finally, the second capacitor failed, and as is far more common, it failed shorted, blowing the MCU fuse and alerting the owner that there was a problem. Perhaps it was affected by the same heat that fried the first one, but failed later as it was further away from the source of the heat (either the arcing below the board, the first capacitor failing medium impedance, or both).

> And the metal spheres and soot on the waffle plate looks like there may have been arcing between the un-cut or extra-long leads at the solder joint of the snubber cap [pic# 25].
Well spotted, I didn't notice the metal spheres. It seems unlikely to me that extra long pigtails would be present from the factory; it depends on how they buy the capacitors. So this might have resulted from a botched repair job. Possibly performed from above, so there was no opportunity to do the obvious tidying up, including clipping the pigtails. The metal spheres might even be solder, resulting from inserting and soldering from above.

BTW, the numbering of the pictures was just my way of keeping track of them when reordering them. The numbers are actually in front of the img tags, so refer to the image to the right or below. But no matter, I'm glad that they served another purpose.

Edit: the numbers indicate the order of the original images. Pity it's now such a pain to find a particular image (use search I guess).

zetafunction
Posts: 11
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Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Fri Jul 31, 2020 4:44 pm

Hello,

I own a 2011 Citroën C-Zero which does not charge anymore at 220VAC. Fast charging does work. When I connect the 220V charger, it tries to charge and after 5 seconds it stops. The OBC Error codes are 39 and 42.

I opened the OBC unit up and took out both boards, everything looks fine. I double checked under the microscope and could not see anything wrong. However I did not desolder the backplate of the second board yet.

Can you please give me any advise on what to check first? Thank you very much!

kiev
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Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Fri Jul 31, 2020 6:04 pm

Howdy zeta,

If you can somehow share the pictures then we can look to see if there is something abnormal.

Your OBC codes indicate 2 different problems on opposite sides of the board.

OBC 39 is Power factor correction (PFC) circuit output voltage abnormal; the PFC boost is done after the rectification of the input AC voltage and is in the vicinity of the 3 large capacitors on the bottom board. The control ic IC312 for the PFC is on the bottom side of the board, so i would recommend to check all the diode drops in the waffle plate first to rule out a major semiconductor failure.

OBC 42 is Output current sensor zero-point abnormal; this is telling me that there is a bias voltage or bad feedback in an op amp circuit. The output should be zero when no current is flowing on the output, but it is reading some voltage that is interpreted as a current in the sensing circuit. This is located in the vicinity of the single large capacitor, resistor R232, and a high voltage isolation slot cut out in the bottom board.

The one thing in common is that both of these signals are sent to the top board for reading by the main controller chip, and they may share the same low voltage power supply. Which means the issue could be on the top board digital section. So closely inspect both sides of the top board looking for scorch marks or puffy capacitors.
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zetafunction
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Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Fri Jul 31, 2020 7:32 pm

Thank you for your fast answer!

You can find all the pictures of the boards here: https://imgur.com/a/zUoyObd

I just checked the board again and I can not spot anything burn marks or damaged parts. Then I checked all of the diodes I could reach with the diode setting of my multimeter. Diode D301 has a drop of 0.0925V on both sides, is this normal?

kiev
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Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Fri Jul 31, 2020 7:58 pm

D301 is the freewheeling diode for the coil on the AC input relay inside the potted region. It should read about 60 Ohms and will cause the diode drop to read like you did.

F701 is a fuse on the top board, likely okay but doesn't hurt to check.

The diodes i am worried about are inside the waffle plate with the big heatsink soldered to the bottom board. There is a diagram with the voltage drops that you can measure on the solder joints on page 45, but there are some good pictures of the plate and underneath the board on the previous page of this thread.

latest schematic of waffle plate is here:
https://drive.google.com/file/d/1tHilCx ... OVV85/view
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zetafunction
Posts: 11
Joined: Fri Jul 31, 2020 4:26 pm

Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Fri Jul 31, 2020 9:32 pm

I just checked all diodes with your great schematic and they seem to be fine. I also checked F701.

What should I consider doing next?

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