Mitsubishi Melservo MR-J2S-100A alarm: AL.E9

[Per Hansson]

Re: Mitsubishi Melservo MR-J2S-100A alarm: AL.E9

Exactly correct!
I even bought it at the local food market

[ChaosLegionnaire]

Re: Mitsubishi Melservo MR-J2S-100A alarm: AL.E9

nice... u used acetic acid? isnt that whats in vinegar?

[Per Hansson]

Re: Mitsubishi Melservo MR-J2S-100A alarm: AL.E9

Nice to see so many new members in this thread, welcome to Badcaps!

On that theme I present you the latest repair:
I was hoping for it to be an "easy" fix but for the first time was greeted with leaking SMD capacitors in this servo!
The electrolyte had started attacking the through hole vias and crystalline formations had formed on the negative legs.
I used acetic acid and it worked a treat, I did not photograph the acids process in the first two caps but after what I saw was ready on the next couple.
I made this little GIF showing the action, the board turned out great after the cleanup thankfully!
P.S: I attached several high resolution photos of the before/after process as well, oh, and the SMD caps measured around 80 to 140 in ESR!

[sam_sam_sam]

Re: Mitsubishi Melservo MR-J2S-100A alarm: AL.E9

I also had this same issue with my MR-J2S-100A on my cnc mill Y axis. Replaced that opto today and she is alive again. Thanks for posting all this!

If this is a drive that is over 10 years old I would highly recommend that you recap the switching power supply board at a minimum and also recommend that any capacitor under 100uf replace them

[sam_sam_sam]

Re: Mitsubishi Melservo MR-J2S-100A alarm: AL.E9

( these Servo drives are a pain in the ass to repair )

I have tried in the past to repair Servo drives that have a low buss voltage with limited success on some models it just replace all of the small value capacitor and that seems to fix the issue but not always the case

I have even replaced an IGBT module on one and never figured out what the problem was

With over current error message I have been more successful repairing this kind of fault

I have even repaired Servo drives that have priority controller boards this is even more channeling because if the controller board has issues it basically unrepairable but ( if the controller board still working) if you can find the same exact model then use the replacement drive with the original controller board and this dose work I have done this a few times before

[macona]

Re: Mitsubishi Melservo MR-J2S-100A alarm: AL.E9

Oh, and I thought I should add it does seem temp related, it was not until the shop got cold that this issue cropped up.

[macona]

Re: Mitsubishi Melservo MR-J2S-100A alarm: AL.E9

I also had this same issue with my MR-J2S-100A on my cnc mill Y axis. Replaced that opto today and she is alive again. Thanks for posting all this!

[bench22]

Re: Mitsubishi Melservo MR-J2S-100A alarm: AL.E9

Thanks! also fixed my servo with alarm 9.

[fazal kareem]

Re: Mitsubishi Melservo MR-J2S-100A alarm: AL.E9

IF Driver Shows
AL.E9 change ic chip 7800 80% solved
AL.24 change module 50% solved
but
AL.30 ?
AL.17 ?

[jae2020]

Re: Mitsubishi Melservo MR-J2S-100A alarm: AL.E9

Hi, these two caps came from a unit that otherwise is full of Nichicon caps:
Nichicon GQ, GU & PJ manufactured late 2001.
Got any idea what model they are? (See picture).

The 33uF cap has an ESR of 40 so it's in dire need of replacement
I could get it down to ca 5 by heating it with my iron, then matching the other cap...

I ordered the "A" version of the 7800 optocoupler linked above from Mouser, actually it was the only one in stock.
It worked a treat, the bus voltage reading is now correct

Thanks. I solved alarm E9 after replacing this IC.

[Per Hansson]

Re: Mitsubishi Melservo MR-J2S-100A alarm: AL.E9

The bus voltage depends on the incoming AC voltage.
If you measure 200VAC input then 280VDC bus voltage is normal.
Calculation: √2 x 200VAC = 282.8VDC.

If not and you believe you have a heat sensitive component then heat it up with a heatgun carefully and see if the voltage changes.
Or cool it down and see if the voltage changes.
This is the way I used to pinpoint that it was component O15 the HCPL-7800 that was the culprit as described here.
And yes, the servo might be sensitive to the value of the capacitor, especially capacitor C6.

[Alex-Signals]

Re: Mitsubishi Melservo MR-J2S-100A alarm: AL.E9

hi, I made the change of the caps, and the HCPL7800A, in the DC BUS marks me an output of 280 vcd, the equipment was already installed in the machine and I am still working.
Since I don't have 33uf caps, install some 47uf caps. they believe that for this reason I am giving a bus voltage of 280 vcd, the caps I use are low ESR

[sam_sam_sam]

Re: Mitsubishi Melservo MR-J2S-100A alarm: AL.E9

When I have done these drive before I have given them a recap and change the switching regulator ic chip and now when I do another one of these drive I will change the optic sensor and the surface mount capacitor as well

After reading your post

[Leopard]

Re: Mitsubishi Melservo MR-J2S-100A alarm: AL.E9

Hi, the ones I've seen have shown AL.E9 as first & only error AFAIK.
I work as a service technician, so I get called whenever the customers can't get the machines working again...
So far I've repaired quite a few of these and had 100% success so far, and no returns...
Actually I'm near Tampere sometimes for customers too (actually in Lempäälä) but not right now.

Thanks for the response. Nice to hear that the failure mode has been consistent.

We've luckily had spare units for the ones that have been acting up, but apparently this model is outdated and hard to get nowadays.

I'll order some optocouplers and will see if these can be brought back to life.

[sam_sam_sam]

Re: Mitsubishi Melservo MR-J2S-100A alarm: AL.E9

Thank you for this posting I also repair servo drives I have had switching power supply problems from bad capacitor to bad switching regulator IC chips but have not yet seen this problem

Thanks again for sharing this post

[Per Hansson]

Re: Mitsubishi Melservo MR-J2S-100A alarm: AL.E9

Hi, the ones I've seen have shown AL.E9 as first & only error AFAIK.
I work as a service technician, so I get called whenever the customers can't get the machines working again...
So far I've repaired quite a few of these and had 100% success so far, and no returns...
Actually I'm near Tampere sometimes for customers too (actually in Lempäälä) but not right now.

[Leopard]

Re: Mitsubishi Melservo MR-J2S-100A alarm: AL.E9

Hi Per,

Sorry about the thread necro, but anyway:


We are slowly starting to get failures of these Melservo units at work.

What were the initial error codes & symptoms?

We have two units which show AL.33 (overvoltage) and two units which had a hard time getting to a working state, initially showing AL.16 or AL.E9. Once they warmed up, they would work normally, but this took longer and longer as months passed.

[Per Hansson]

Re: Mitsubishi Melservo MR-J2S-100A alarm: AL.E9

Yea, in this case that's not really possible though.
The HCPL-7800 is not driven directly, as I mentioned it's a digital device with a DAC on both sides.
The advantages is that it's a very well behaved device.
It would still be possible to misuse it though, the DAC on each side requires a 5v supply, it's derived in this implementation from a 17v supply i think, with a zener diode to get it down to 5v.
But then the sense pins should ideally be driven with max +/- 200mV, it can operate up to +/- 2v but with reduced accuracy.
In not sure if the problem is there maybe: I could see how an overvoltage during motor breaking would increase the bus voltage for example...

[stj]

Re: Mitsubishi Melservo MR-J2S-100A alarm: AL.E9

opto failure used to be common, specially in philips tv's
people used to overdrive the led and the output dropped over time.

[Per Hansson]

Re: Mitsubishi Melservo MR-J2S-100A alarm: AL.E9

Yea Behemot it's a bit interesting failure mode.
Maybe it's being driven too hard or improperly in this implementation.
But due to where it's mounted it's not really very easy to test that.
And if it lasts another 15 years I'm happy

Of course a photocoupler has both a LED that will degrade, and also a phototransistor that will degrade.
The correlation is described in this article, that said I think a high-end device like this:
Which has a DAC on both the primary and secondary side will behave extremely well over it's lifetime.
So the failure could be caused by something different all together.
As a fun test I wired it up to 5v, and used simply the diode test mode on a meter to send it a signal.
I watched the output on a scope: it was a nice well-behaved waveform.
Then I heated it up and the waveform only became smaller, not distorted in any way.
So it's really a quite linear failure mode, at least it makes the troubleshooting much more convenient
Oh, and the second servo is now completed and seems to behave equally well too