# Seig sx2 board faults



## Alex george (May 23, 2019)

Hi guys.

I apologise if this isn't the right place for this and I'm certain there's a bunch of similar threads somewhere, but...

I recently popped a few IGBT transistors on my seig sx2 mill. Of course it's 3 months out of warranty, typical. I've been attempting to resoldered in replacement parts and I've got everything back in, now when I turn it on, I get the green power light illuminated and then when I turn the speed control up, I get intermittent flashing of the fault light. The orange light on the board flashes 2s on, 2s off. Nothing from the motor. I'm at my wit's end as I've tried much of what I can think of. Does anyone have any experience repairing these things? Or have advice on what to be looking for? Or can advise on how to replace the board?
Seig boards in Australia cost over $200...something I'd like to avoid.

Thanks for the help

Alex


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## tornitore45 (May 23, 2019)

From 50 years experience in power electronic but knowing noting about the specific item, when a power element fail it usually does "collateral damage". Sometime a power device failure is caused by a smaller component failure but that is rare.
Without a schematic and a scope is next to impossible to debug a power circuit, you are at the mercy of the elusive lady luck.


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## XD351 (May 23, 2019)

Does your owners manual mention anything with fault lights ? Can you post a few photos of the boards ( both sides and a few different angles ) ? I will have a look at the asusee site to see if they have any info .


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## XD351 (May 23, 2019)

Is this the board ?
I would check the fuse on there and also the rectifier , there are two boards- one is the motor driver and power supply and the small one is for the micro controller and if you do a web search on the numbers on each chip you should be able to get a data sheet to show what pins are for power . Check that the power to these chips is correct ( probably 5 volts but could be 3.3 volts ).
Please be careful playing with this thing as the majority of the main board is at mains potential and those big capacitors can hold a charge long after it has been switched off and it is capable of killing you.
On the main board  is there an led and is this the one that is flashing ?


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## Wizard69 (May 25, 2019)

Alex george said:


> Hi guys.
> 
> I apologise if this isn't the right place for this and I'm certain there's a bunch of similar threads somewhere, but...


I don’t believe there is a repair section so this will have to do.  


> I recently popped a few IGBT transistors on my seig sx2 mill. Of course it's 3 months out of warranty, typical.


Perfect timing on their part!   .   Yeah but know not funny to you.   


> I've been attempting to resoldered in replacement parts and I've got everything back in, now when I turn it on, I get the green power light illuminated and then when I turn the speed control up, I get intermittent flashing of the fault light. The orange light on the board flashes 2s on, 2s off.


As XD mentioned do realize that this is power circuitry and thus can literally kill you.  

The first thing that comes to mind is how did you determine which parts where bad?   That can be very difficult without the tools and knowledge to do so.   IGBT’s can be very reliable.  Often they can be destroyed by failures in other parts of the drive.   To get anywhere fast it really helps to have drive documentation and the diagnostic tools.  Without such tools it can take far longer.  




> Nothing from the motor. I'm at my wit's end as I've tried much of what I can think of. Does anyone have any experience repairing these things?


Most of my limited experience has been with older Fanuc drives for large AC servo motors.  However the basic idea is the same on most drives, you turn AC into DC and then convert it to some sort of variable AC power.    The general idea is well understood so I wouldn’t be surprised if a local repair shop wouldn’t be able to fix it.  The problem is it often is cheaper to buy a new board.  


> Or have advice on what to be looking for?


Well make sure your DC bus is proper to start with.  Then look for the driver transistors that drive the IGBTs.  This assumes that they are even using such transistors.  Ideally you would want an oscilloscope to find and track these signals.  

Without the right tools trying to repair boards like this turns into shotgunning lots of parts.  


> Or can advise on how to replace the board?


It all depends upon the type of motor you are running and how much documentation for that you have.  Depending upon the milk it might have a universal motor, a DC motor,  a brushless DC motor or an AC motor of some type.  Some of those motors use feed back devices that must integrate with the drive.  So we would at the very least need to know if it can take a simple retrofit drive or needs a more elaborate conversion.  


> Seig boards in Australia cost over $200...something I'd like to avoid.


That is actually pretty cheap.   


> Thanks for the help
> 
> Alex



I’m not sure this will help much but is the best I can offer from this distance.   Sometimes the repairs are obvious other times it takes a bit of sleuthing around.


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