Troubleshooting and repair for On-board Charger (OBC)

[kiev]

duh i wasn't thinking right about losing a pin vs connector, or the great desoldering job. i could try to remove one from a damaged board but don't know if i could do it that well.

The missing pin looks to be pin 41, which is used in the current feedback circuit. See the bottom half of this post for previous notes and discussion with schematic:
CN1 Pin 41 Current Sense

[ZsoZso]

Thanks for the great info guys!

The mystery of the desoldering is interesting indeed. My guess is that it was never soldered in the first place -- sloppy manufacturing job ?
I can push the connector back onto the 2 metal clips at the end, then it is held firmly in place with the pins making contact, so I guess that's how it was working for all these years without soldering.

I started ordering parts: snubber capacitors, a replacement connector, 0HEV020.ZXISO fuse in MCU.
However it looks like the fuse F102 inside the OBC might be dead too:


Do you guys know what are the specs or part number for that one ?

Thanks a lot again!

[kiev]

thanks for the update.

This is a first time (i think) that we have ever seen F102 blown, which has always puzzled me.

There may be a post in this thread with the fuse info, can look for it later tonight.

[ZsoZso]

Correction, the F102 is not blown, checked with an ohm meter and it shows near-zero resistance.
The fuse inside the MCU is blown, but I got the replacement for that already.

The connector I got to replace the NC1 is not an exact match (different plastic cover shape, not compatible with the black connector insert).
To make this work I would need to cut off the black connector and fit the cables into the new one.

The missing pin is actually 42 not 41. There is 41 existing pins on one side and 8 on the other, so the missing one is #42.
Do you know if there is any unused pin that I could take out and replace the missing pin-42 so I could salvage and re-use the old connector?
I would be more comfortable with that option, rather than trying to adapt the one I bought.

[coulomb]

Do you know if there is any unused pin that I could take out and replace the missing pin-42 so I could salvage and re-use the old connector?
I would be more comfortable with that option, rather than trying to adapt the one I bought.

I don't know, but an alternative would be to just run one wire separate to the ribbon for pin 42, preferably with a connector so you can separate the boards if needed.

[kiev]

i don't know of any unused pins in CN1 connector, but there are numerous pins to the ground plane that you could borrow from, i doubt it would affect any signals since these are not returns or current-carriers.

For example, pins 47-50 are all tied to the ground plane on both boards. Pin 50 seems like a good candidate to donate to the repair.

[ZsoZso]

Operation pin-swap completed. I also made (an ugly) solder-blob to connect 49-50 on the board if they are both ground to share.



Now it is getting dark, so I wait for tomorrow morning to put the board back into the car and test.

[ZsoZso]

I put it back together, also replaced the dead fuse in MCU and burned out capacitor:


Now, there is some improvement:
- no red 12V battery charge indicator error light
- no yellow drive unit error light when I turn it on

However, it is still not charging. The code reader shows only 1 error this time:
P1A12 - OBC abnormal stop

So the communication errors are gone.
I can also hear a click and the humming noise for a second when the charging cord is plugged in, but it stops quickly (normally the humming noise, probably coolant pump goes on longer). On the dash, the yellow drive unit error flashes up for a second at the same time (when charging cord is plugged in), but then it goes away.

Definitely a different behavior. Any suggestion what I should check next ?

[kiev]

Did you ever check the diode drops in the waffle plate? That was recommended as the first thing to check on the previous page.

Any discoloration or cracks in the white ceramic resistors or capacitor in the AC input section of the black potted area? Does the relay function okay and do you read ~10 Ohms thru the resistors?

Any metal splatter that might be shorting pins on the bottom of the control board?

Generally speaking i would want to replace both snubbers even if only one blew. They are a weak point of this OBC and at the top of the culprit list, most common to fail in addition to the ceramic resistors and AC capacitor mentioned above.

[ZsoZso]

Did you ever check the diode drops in the waffle plate? That was recommended as the first thing to check on the previous page.

How can I check that ?
Do I have to de-solder all those (many) connection points -- two rows on each side to remove the plate from the bottom board ?
The diodes are in between the heat sink and the bottom board, so can't really see them to determine if there is any burn signs.

Any discoloration or cracks in the white ceramic resistors or capacitor in the AC input section of the black potted area? Does the relay function okay and do you read ~10 Ohms thru the resistors?
Any metal splatter that might be shorting pins on the bottom of the control board?

The ceramic resistors look good, no cracks or discoloration. The relay seems to function fine (see more below).
I do not see any metal splatter either.

Generally speaking i would want to replace both snubbers even if only one blew. They are a weak point of this OBC and at the top of the culprit list, most common to fail in addition to the ceramic resistors and AC capacitor mentioned above.

After I replaced the second one too, I have seen improvement:
Now after I hear the click (relay?) it starts charging (can hear coolant pump going, EVSE indicates charging started) for about 8 seconds, then shuts off. Perhaps my new capacitors are not good enough ? They overheat?

I bought 2kV 1000pF ones, they are smaller physically than the originals.
I have now ordered bigger ones rated for 10kV which also have wider operating temperature range, they should arrive in a day or two, then I swap them out and try again.

Was the purpose of the black rubbery goo around them to help with cooling ? If yes, then perhaps I should get some to restore that function. What should I look for, what is the name of that material and any idea where I can buy from ?

Thanks a lot again!