electronpusher
Posts: 43
Joined: Sun Jun 25, 2017 3:11 am

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

Sat Sep 22, 2018 10:50 pm

Additionally, I had a look at the riser board, there is no way to mount the caps on there, however I was thinking of designing a new riser board that will accept through the hole caps, thus making future repairs easier. Basically you would remove the potting once, replace the riser or through the hole caps that were there with the new riser, and solder the caps to the new riser board that supports through the hole caps. Any future replacement of the caps would only require the damaged ones desoldered and new caps soldered in, bypassing the need to remove the waffle plate.

Thoughts?

coulomb
Posts: 103
Joined: Sun Jun 10, 2018 8:32 pm
Location: Brisbane, Australia

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

Sat Sep 22, 2018 11:14 pm

I think you'd want to re-pot the (new) vertical PCB, so I don't see much advantage unless the capacitors were up high out of the main potting. The extra lead length might introduce too much inductance. Though the existing PCB would have nearly as much inductance.

Perhaps really thick tracks, perhaps made from double thickness copper, would be equivalent. I'd want to secure the capacitors to the vertical PCB though.

electronpusher
Posts: 43
Joined: Sun Jun 25, 2017 3:11 am

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

Sat Sep 22, 2018 11:31 pm

coulomb wrote:I think you'd want to re-pot the (new) vertical PCB, so I don't see much advantage unless the capacitors were up high out of the main potting. The extra lead length might introduce too much inductance. Though the existing PCB would have nearly as much inductance.

Perhaps really thick tracks, perhaps made from double thickness copper, would be equivalent. I'd want to secure the capacitors to the vertical PCB though.


True, but I figured it would not be any worse that what was already there, and would make future repairs easier. I would definitely repot it if I put in a riser. I was thinking of designing and sending for a professionally produced PCB with screen printing, not something I etched myself.

electronpusher
Posts: 43
Joined: Sun Jun 25, 2017 3:11 am

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

Sat Sep 22, 2018 11:40 pm

Ok, removed the potting around the riser, and had a go with some solder wick to remove the riser board, without success. I think the waffle has to come off. Thoughts? Any suggestions on how to remove the riser without removing the waffle?

If the waffle has to come off, I will take it to uni where I have access to a re-work station, something I do not possess.

BTW, I am video recording everything I am doing, so that we can create a how to repair video. :)

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skylogger
Posts: 65
Joined: Sun Dec 14, 2014 3:54 am

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

Sun Sep 23, 2018 2:56 am

Electronpusher: Probably the reason you are having difficulty with desoldering the riser PCB is that you have to remove solder in 8 places, not just 4. Out of each of the 4 holes coming out of the main PCB, there are 8 pins, 2 pins come out of each hole. One pin solders on top side of riser PCB and one pin solders to bottom side of riser PCB. Since the riser PCB was so badly damaged, I didn't have to baby it too much. You could even use wire cutters to chew at the riser pcb leaving just small sections tied to the pins, allowing to flex and torque them a bit to get the pins to free/desolder from the PCB one at a time. Then you will end with two pins coming out of each main PCB hold forming a fork. It is easy
to resolder a replacement through hole cap lead by lead forming and running the lead between the two pins of the fork then wraping it around. I just made sure I did not over heat the pins so they did not fall back down the hole when joining the new cap leads.

If you use KIEV's schematic of the waffle pins, you can use an ohm meter in diode check mode, you can check out 90% of the semi's on the waffle. If you run through the 2 x 4.7R resistor and relay check in the doghouse, you might run across same problem that I had.

electronpusher
Posts: 43
Joined: Sun Jun 25, 2017 3:11 am

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

Sun Sep 23, 2018 3:18 am

Thanks @skylogger for the info.

I was hoping to save the riser, but I should be able to take the measurements I want off it first, before cutting it up for removal.

Finished up for the night, but tomorrow night I'll give it a go, and also check the semi's on the waffle and relay.

Still waiting on that fuse from Mitsu so I am not in too much of a hurry right now, I intend to order the solar fuse/holder tomorrow for testing, as I do not want to blow the 4 week wait Mitsu OEM fuse while testing the repairs.

Thanks for all the help.

ChristopheFR
Posts: 8
Joined: Sat Aug 11, 2018 1:08 am

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

Mon Sep 24, 2018 9:35 am

Hello tout le monde,

I took pictures this week-end.
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We see traces on the cover, I think it is not due to a short circuit, but just a significant heating of the material just below.

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1 of the three capacitors is inflated on the top. Are the other two still in good condition?Do you think it is better to change the 3 pieces?

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The two resistors 4.7 ohm seem in good condition, there is no trace of burn.
Ditto for the two blue capacitors

So I relized the “skylogger test" for the resistance of 4.7ohm
Is this a correct connection for my ohmmeter (green wires)?
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and there, result: my ohmmeter reads 0L, no resistance.
Is it the larger resistor that fused? due to overcurrent or overvoltage? No apparent damage on this resistors!

Skylogger, do you think for the second test with 5 volts on the terminals of diode D301, that a 4.5volt battery like this one is enough to carry out the test? Is this correct for the wire connections?
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what do you think of this failure? A problem due to a storm? A problem due to the capacitor that has inflated?

reminder: my dc-dc charger for the auxiliary battery still works, and I changed the auxiliary battery in 2015 when it lost power

coulomb
Posts: 103
Joined: Sun Jun 10, 2018 8:32 pm
Location: Brisbane, Australia

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

Mon Sep 24, 2018 4:32 pm

ChristopheFR wrote: We see traces on the cover, I think it is not due to a short circuit, but just a significant heating of the material just below.

It looks like this discoloration is common, sadly.

1 of the three capacitors is inflated on the top. Are the other two still in good condition?Do you think it is better to change the 3 pieces?

Difficult to see in your photo. Presuming that one really is bad, then yes I would replace all three.

The two resistors 4.7 ohm seem in good condition, there is no trace of burn.
Ditto for the two blue capacitors

Yes, unlike many charrgers so far. But the 4.7 Ω resistors may still be bad, see below.

Is this a correct connection for my ohmmeter (green wires)?

It looks right to me, but others please chime in.

and there, result: my ohmmeter reads 0L, no resistance.

Actually, "OL" represents OverLoad, which is infinite resistance, i.e. zero conductivity. Either one of the 4.7 Ω resistors is open circuit, or the test isn't valid. Energising the relay will hopefully show which.

Is it the larger resistor that fused?

They are in series. So it's not possible to tell which one failed, or possibly both.

due to overcurrent or overvoltage? No apparent damage on this resistors!

It's certainly unusual. Unless the resistors somehow saw 240 V across them; in that case, the fuse inside one of them would blow quickly, before the resistors overheated and discolored.

Skylogger, do you think for the second test with 5 volts on the terminals of diode D301, that a 4.5volt battery like this one is enough to carry out the test?

That battery should be fine.

Is this correct for the wire connections?

NO! The stripe (on the diode and also on the silk screen overlay of the printed circuit board) is for the cathode of the diode, which is the negative end if you want the diode to conduct. But in this case, with no current limiting, we don't want the diode to conduct, except briefly as the power is removed from the coil. This gives a path for the current to continue flowing after the battery is disconnected, so there isn't a large voltage spike that could damage the other electronics (though the other electronics on the upper board should be disconnected for this test). [ Edit: so you need to reverse the battery compared to your photo; battery positive to stripe on diode; battery negative to non-stripe end of diode. ]

With the relay energized, you should see much less resistance across your green wires, reading "0.0" or perhaps "0.2" due to the resistance of the multimeter leads and green wires.

If you don't see this, and it remains at "OL", then either one of your resistors is open circuit and the relay contacts are open circuit as well, or your green wires aren't right. Another possibility is blown PCB tracks or badly soldered quick connects (etc), but these seem very unlikely.

what do you think of this failure? A problem due to a storm?

I think it's too early to tell.

A problem due to the capacitor that has inflated?

I don't think so. Those three large capacitors only work at 100 or 120 Hz, not at several kilohertz switching frequency. So they can degrade a little and still perform adequately. If they went low capacitance, there would be higher than normal 100 or 120 Hz ripple on the ~400 V DC bus, but I don't see that causing the pre-charge resistors to open circuit.
Last edited by coulomb on Mon Sep 24, 2018 10:27 pm, edited 1 time in total.

redcane
Posts: 14
Joined: Sat Aug 18, 2018 2:21 am

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

Mon Sep 24, 2018 8:54 pm

An update on failure #14 - our charger was replaced as a recall in January 2017, so it's been in service less than 2 years. It's dated 2015 manufacture.

kiev
Posts: 777
Joined: Sun May 03, 2015 7:15 am
Location: The Heart o' Dixie
Contact: Website

snubber cap options

Mon Sep 24, 2018 10:00 pm

The blue 1000pF snubber caps are rated 2kV and are ~9.3mm diameter. i have a bag full of some 3kV @ 12.0mm, and 6kV @ 17.3mm, that would provide a bit of HV margin--will make these available in a repair kit if you can't find a local source.

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kiev = kenny's innovative electric vehicle

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