# VFD Repair



## MikeFL (Apr 16, 2016)

If it's a 3 pin through hole IGBT desoldering with vacuum pressure would probably be easiest. If you don't have the tools for that you can use solder wick. 



Go on youtube and search for videos for "pcb rework" "desoldering" etc.


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## robinbd90 (Dec 8, 2018)

I tried u tube not found any good. Its compact module of 100A, 35 pin in total.


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## telsa (May 22, 2015)

Send it outside... to a bench tech.

If this is not your everyday cup of tea... you're sure to ruin everything.

This is not an object to learn on.


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## MDShunk (Jan 7, 2007)

telsa said:


> Send it outside... to a bench tech.
> 
> If this is not your everyday cup of tea... you're sure to ruin everything.
> 
> This is not an object to learn on.


Maybe it is? Who are you to say?


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## gpop (May 14, 2018)

put fresh solder on the tip of the iron (or use flux), Prime de-soldering pump. Touch the solder joint then pop the pump to remove the solder. Wipe solder iron on cleaning sponge, empty pump then repeat on every joint. 

Add pressure (gently pull it from the board) to the component and walk around the pins with the solder iron until it is free of the board. 

Good eye site and working quickly will avoid a lot of problems.


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## MikeFL (Apr 16, 2016)

robinbd90 said:


> I tried u tube not found any good. Its compact module of 100A, 35 pin in total.



YouTube has many videos on the subject. 



Poor man's way is to use a heat gun but it takes some learning. You're sure to ruin the entire board trying to learn with a heat gun on a 35 pin device.


Proper way is to use hot air soldering. Spend the money to purchase a hot air soldering system. Heat the pins evenly until you can remove the device with a pair of tweezers. 



After that you'll need a conventional soldering iron, flux pen and solder. 



There is an art to all of this. I strongly suggest you find someone experienced and have them do it. Otherwise you end up with ruining the entire board.


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## John Valdes (May 17, 2007)

Why not replace the entire board? 
What size is this control? The IGBT is on a heat sink, so how is it soldered? It is on a heat sink? Right?


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## Bird dog (Oct 27, 2015)

John Valdes said:


> Why not replace the entire board?
> What size is this control? The IGBT is on a heat sink, so how is it soldered? It is on a heat sink? Right?


IIRC some dielectric grease?


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## Cemo (Feb 5, 2011)

robinbd90 said:


> Do anyone have any hand on experience on changing IGBT module from PCB. I need to change one IGBT module from electronic PCB card of ACS850 vfd but can't able to desolder the damaged on. What type tools should is use? How to proceed? Any video tutorial would be very helpful.




IGBT packs have quite a thermal mass + they are mounted on a heat sink so you will need a powerful soldering iron and lots of patients. I would recommend at least a 70w iron and a chisel tip around 4mm wide and desolderind tool with 1.5-2.5mm hole. 
I use Hakko FM202 soldering iron with FM 2024-21 optional desoldering module, desoldering tool operates with compressed air. I use a small dedicated compressor set to about 70-80psi. This set up costs about $1300US without the compressor. 
Wet the pads with fresh solder first using the soldering iron than switch to desoldering iron and hit the trigger repeat as needed, make sure to clean the desoldering filter/catcher regularly there is a lot of solder on those pads ,it will clog quickly. 
Those parts are usually soldered on both side of the pcb so it is a tedious work allow lots of time. Using synthetic smt solder flux also helps oh dont forget to get a soldering fume fan. Good luck.


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## John Valdes (May 17, 2007)

In my experience the IGBT is installed onto the heat sink with screws.
You should be able to remove the screws and pry it up off the heat sink. Heat sink compound or pad and screws were how I remember they were secured.
Never needed to un-solder anything to replace the IGBT's or the diode bridge in front.
In fact I did not even have to remove the board.

The wires attached to the IGBT were on push on connectors.


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## EJPHI (May 7, 2008)

robinbd90 said:


> Do anyone have any hand on experience on changing IGBT module from PCB. I need to change one IGBT module from electronic PCB card of ACS850 vfd but can't able to desolder the damaged on. What type tools should is use? How to proceed? Any video tutorial would be very helpful.


Any chance you can check the offending module for short/open before replacing it?
If it is shorted internally, you can cut the drain or source lead then check resistance with an Ohmeter. This simple measurement will confirm that replacing the module is a good fix. Unless something else caused it to short out!!


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## John Valdes (May 17, 2007)

I would hope the OP would know before replacing anything, that it is indeed bad.
IGBT's and the diode bridge are easy to check with a meter.
In fact the drive manufacturers do publish how to do this. Pretty simple and straight forward.


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## paulengr (Oct 8, 2017)

Not true on checking IGBT. The diode test only measures shorted back diodes and diodes on the rectifier and SCRs if you have those. You can't test an open IGBT except with an oscilloscope and the diode test only works on 6 pulse drives. More pulses or neutral clamping make it impossible.

Some small drives have a power module called an IPM and those are easy to replace. But as you go up in power thermal management becomes critical. They get press fitted onto the heat sinks and it's hard to get the right tension without a computer controlled press. The heat sink grease is typically also not your typical heat sink grease. If you use that in a conductive path it will tear up the machined heat sink and burn up the new part. It requires electrical joint compound which is basically heat sink grease but without the zinc oxide particles.

The problem I've had with drive repairs is the people that do this are successful about 50-75% of the time. But even then if say A phase fails, B and C phases are the same age and will fail soon enough if the control board doesn't die first. So it usually turns into a never ending death spiral. Best to just accept under good conditions VFDs have a design life of 100,000 hours or 11 years. Cutler Hammer claims 500,000 MBTF hours but in practice they're not any better than everyone else that bases their numbers on a 10% failure rate.

Sent from my SM-T350 using Tapatalk


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