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Power transistor identification

dsgohio

Mar 21, 2021
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I have a one man hobby machine shop. I bought a Sowon 3Kw induction heater used to heat up shrink fit tool holders. Bought it used - it does not work. Can't afford a new one. Unit blows 15 amp fuses when trying to heat the tool holder.

I am pretty good at building and fixing my own electronic gizmos - not so good at fixing other peoples circuits. Took the unit apart, removed the circuit board. Everything is on one board that is mounted to a large heat sink. There is no visible damage. First I checked the bridge rectifier - it is good. Next I did resistance checks on the 2 power transistors. I got: 0/0 ohms and 2.2/2.2 ohms and 2.2/2.2 ohms. I'm thinking 0 ohms is not good unless there is a transformer in parallel somewhere. I have not the traces yet. Sadly, the numbers on the transistors as well as the numbers on 4 ic's are ground off. I have no clue how to identify the transistors or the ic's. Any ideas??

I can only add a closeup picture of the transistors. No matter how I try adding a picture of the whole board always gives me an error...

Thanks, David5.jpg
 

dsgohio

Mar 21, 2021
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resized the board picture...
 

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bertus

Moderator
Nov 8, 2019
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Hello,

It could well be that the manufacturer obscurified the parts, so they must carry out the repair and can charge you for the repair.
We can not tell you anything without knowing the numbers.

Bertus
 

dsgohio

Mar 21, 2021
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I have searched the best I could for any info on "Sowon induction heater" No luck finding anything so far.
 

Bluejets

Oct 5, 2014
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I would expect a damaged device such as this to show some sign.

Removal will be the only option BUT you may do more damage to the pcb than you expect in getting them out.
 

WHONOES

May 20, 2017
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The best way to get those transistors off of the board is to cut the legs close to the transistors then with the aid of a pair of tweezers and a very hot solder iron, the legs can be removed without causing any / much damage. If you don't have a good solder sucker or solder wick then the holes may be cleared using a twist drill that is smaller than the holes. DO NOT try this with the drill bit in an electric drill of any description. Ideally, use a pin vice and rotate the drill by hand.
It may also help to re - solder the joints after cutting the legs and before removal. Also, if you can adjust the temperature of your solder iron, set it to 390 - 400deg C.
 

dsgohio

Mar 21, 2021
6
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A quick update. I removed the power MOS transistors. I have a vacuum de-solder station. It works GREAT! Did some research on how to build a induction heater. Found one that uses the FDH44N50 N channel power MOS transistor. The transistor "looks" identical to mine and has specs that seem reasonable. Tested the transistors - one is bad for sure - the other might be bad (gate does not seem to function) the other is shorted - this would blow the fuse. Ordered new transistors. Waiting for delivery. "Might" fix the litter bugger...
 

dsgohio

Mar 21, 2021
6
Joined
Mar 21, 2021
Messages
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The best way to get those transistors off of the board is to cut the legs close to the transistors then with the aid of a pair of tweezers and a very hot solder iron, the legs can be removed without causing any / much damage. If you don't have a good solder sucker or solder wick then the holes may be cleared using a twist drill that is smaller than the holes. DO NOT try this with the drill bit in an electric drill of any description. Ideally, use a pin vice and rotate the drill by hand.
It may also help to re - solder the joints after cutting the legs and before removal. Also, if you can adjust the temperature of your solder iron, set it to 390 - 400deg C.
 

dsgohio

Mar 21, 2021
6
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Mar 21, 2021
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Thanks for the input. I used my vacuum de-solder station. It worked great...
 

Martaine2005

May 12, 2015
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Those vacuum solder suckers are great.
I had to practice for a while as I pulled a few solder pads at first.

Martin
 

Bluejets

Oct 5, 2014
5,881
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Oct 5, 2014
Messages
5,881
A quick update. I removed the power MOS transistors. I have a vacuum de-solder station. It works GREAT! Did some research on how to build a induction heater. Found one that uses the FDH44N50 N channel power MOS transistor. The transistor "looks" identical to mine and has specs that seem reasonable. Tested the transistors - one is bad for sure - the other might be bad (gate does not seem to function) the other is shorted - this would blow the fuse. Ordered new transistors. Waiting for delivery. "Might" fix the litter bugger...

Best way to identify many unknowns is to get yourself a component tester.
Worth around AU$25 on Ebay or similar.
Possible to compare with known good component and also verify faulty part.
 

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WHONOES

May 20, 2017
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Have tried them all over the last 50 years or so. Never liked the hot vacuum sucker as it could cause a lot of damage very quickly, nor the hot air devices for use with SMD parts.
 

twayne

Dec 16, 2021
2
Joined
Dec 16, 2021
Messages
2
A quick update. I removed the power MOS transistors. I have a vacuum de-solder station. It works GREAT! Did some research on how to build a induction heater. Found one that uses the FDH44N50 N channel power MOS transistor. The transistor "looks" identical to mine and has specs that seem reasonable. Tested the transistors - one is bad for sure - the other might be bad (gate does not seem to function) the other is shorted - this would blow the fuse. Ordered new transistors. Waiting for delivery. "Might" fix the litter bugger...
 

twayne

Dec 16, 2021
2
Joined
Dec 16, 2021
Messages
2
Any luck with the repair? My unit has the identical problem. Changed the rectifier , Mine was shorted. now it powers up fine when the coil is not plugged in. i need to replace the transistors now but cannot find the parts.
 

Simon Mugo1

Mar 30, 2022
6
Joined
Mar 30, 2022
Messages
6
I have a one man hobby machine shop. I bought a Sowon 3Kw induction heater used to heat up shrink fit tool holders. Bought it used - it does not work. Can't afford a new one. Unit blows 15 amp fuses when trying to heat the tool holder.

I am pretty good at building and fixing my own electronic gizmos - not so good at fixing other peoples circuits. Took the unit apart, removed the circuit board. Everything is on one board that is mounted to a large heat sink. There is no visible damage. First I checked the bridge rectifier - it is good. Next I did resistance checks on the 2 power transistors. I got: 0/0 ohms and 2.2/2.2 ohms and 2.2/2.2 ohms. I'm thinking 0 ohms is not good unless there is a transformer in parallel somewhere. I have not the traces yet. Sadly, the numbers on the transistors as well as the numbers on 4 ic's are ground off. I have no clue how to identify the transistors or the ic's. Any ideas??

I can only add a closeup picture of the transistors. No matter how I try adding a picture of the whole board always gives me an error...

Thanks, DavidView attachment 51319
it would be more perfect if we get the whole picture including other components too. We need to master the circuitry in order to have a better decision and view of the same.
 
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