Re: Lincoln Electric LE31MP welder not turning on
Good idea, thanks.
Good idea, thanks.
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Re: Lincoln Electric LE31MP welder not turning on
I did not find anything that way either.
It's kind of scarry to work on this, with all those 3 fans spinning at max rpm.
That 27k big resistor's value start increasing quite fast, so I can't keep it on only for a few seconds at a time.
If I'm looking at a UC3842 diagram, pin #7 is the Vcc, which is 14.5V for me and the output #6 shows 5.5V.
At which pin can I check if it's oscillating at the right frequency? At pin #4 I'm getting 55.99Hz and it seems like it is on and off.Comment
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Re: Lincoln Electric LE31MP welder not turning on
Depending on the output power, switched mode power supplies (SMPS) operate in the frequency range from about 10 kHz up to the MHz range.
maybe a shorted diode letting line frequency throughComment
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Re: Lincoln Electric LE31MP welder not turning on
It may very well be, what is happening here, but which one?Comment
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Re: Lincoln Electric LE31MP welder not turning on
what chip is it ? need the datasheet .Comment
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Re: Lincoln Electric LE31MP welder not turning on
Uc3842Comment
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Re: Lincoln Electric LE31MP welder not turning on
https://www.ti.com/product/UC3842
plenty to read through .
i skip read it and it appears frequency is set with a resistor and capacitor so that needs looking at .Comment
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Re: Lincoln Electric LE31MP welder not turning on
Sorry about not getting back sooner.
This IC needs 16V to start oscillating, and I'm getting only 15.5V.
Most likely that is the issue.
The question is, which component causing this drop.
There are 3x56K resistors in series after the diode bridge and from there it is already 15.5V.
I'm attaching a generic schematic of the UC3842 IC.
Before pin #7 there is a 56K resistor. On my welder I have 3x56K resistors.Attached FilesComment
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Re: Lincoln Electric LE31MP welder not turning on
“I'm attaching a generic schematic of the UC3842 IC.”
If you can find the right diagram for the welder that you have would help
What else does not match the welder circuit that you
There components that generate the low voltage to start the circuit I would agree with you that something is keeping it from getting the high voltage to start
Take a picture of the board in question so we can see what type of circuit configuration that you haveLast edited by sam_sam_sam; 11-06-2023, 05:31 AM.Comment
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Re: Lincoln Electric LE31MP welder not turning on
Unfortunately I can't find any schematic for this welder.
I have posted pictures already.Comment
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Hi all,
I have this electric tin opener and the part that moves the can round (1st picture), doesn't move, I can hear the motor turning, but no movement, there's something rattling inside, so presume a piece of plastic has broken, or come loose.
Took the bottom plate off, but left with this (3rd picture), any ideas how to get inside?
Thanks.... -
Hello everyone, I recently found this badcaps site and super Learn Electronics Repair youtube channel. And I wanted to learn how to troubleshoot power supplies and VGA cards and how to practice soldering, since I already have a properly defective piece of them. I am currently trying to solve two problems:
I have a Gigabyte GV-RX460WF2OC-4GD type card. I managed to find the faulty MOSfet (AON6414A) on it, which I replaced. The card starts up, but after about half a minute, the MOSfet in the same position will be shorted again. Is it possible that the PWM controller driving the MOSfet... -
Hello everyone
I attach a schematic and teardown photos for the DoCreate DHJ567 handheld spot welder. I bought this welder for temporary use while my supercapacitor welder was waiting for replacement parts. It cost only £24, though there is a screenless version available for £17.
Performance: The absolute maximum it can handle appears to be 0.15mm of pure nickel. Reliability was not great - welds were very inconsistent, ranging from weak attachment to burning through the strip. However, I was able to build a 5S2P pack without losing any cells. It's a bit difficult getting... -
Hello people. I trying to repair my welding machine oerlikon citomig 180mp hpf and there is a little board with blown stuff.The problem is i cant identify the value of the blown resistor and diode. Any suggestion? -
Hey guys,
i have a asus motherboard here and as the title says after the first mosfet (in the picture) there is nothing more than 3.15v.
I injected 19v and max. 1 amp at the charging port and there is not voltage drop or smth. It's just taking 19v and 1 milliamp.
Then i tried to inject 19v and max 1amp after the current sensor and there it first takes 19v and 4 milliamps and after 2 seconds it is taking nothing (no current).
I measured on the coils on board everything seems fine. Also the main power rail is not shorted (infinite resistance).
Now i thought something...
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