oh shit but i have 2.6V on curent sense pin3
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Welder not turning on - Learning
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Originally posted by CapLeaker View PostThese two resistors would have to be very low ohm readings. I read brown, black, silver and red = 0.1 ohm, 2% to me and are 5w carbon film resistors.
i think c204 is the same as c208.
I mean I totally trusts you 😄 just want to know
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The size of the SMD cap is the same. Knowing that and part of the circuit, you can figure out a “range” on what voltage / capacitance the SMD capacitor was. Just download a SMD cap spec sheet from a good manufacturer and you will notice that besides the length and width, the height will change due to rating. So check the thickness of the bad SMD cap with the other one. On the pic they look the same.
Dont trust me too much, as I only can see whatever pictures you provide or info you give. Changing these 1 Ohm resistors for 0.1 Ohm won't make a difference.
C204 is a part of a “rc filter” that suppresses transients (spikes). It is a small value cap something like 0.0001uF (that is 1000pF). Could be even a bit lower at 100pf…
Like I said, this cap function is only there to suppress “transients or noise” on the sense pin. Does it have to be there? Yes, but at the same time it isn't extremely critical either.
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Originally posted by CapLeaker View PostThe size of the SMD cap is the same. Knowing that and part of the circuit, you can figure out a “range” on what voltage / capacitance the SMD capacitor was. Just download a SMD cap spec sheet from a good manufacturer and you will notice that besides the length and width, the height will change due to rating. So check the thickness of the bad SMD cap with the other one. On the pic they look the same
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All of these hadCAPs POOF
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Originally posted by CapLeaker View PostThe size of the SMD cap is the same. Knowing that and part of the circuit, you can figure out a “range” on what voltage / capacitance the SMD capacitor was. Just download a SMD cap spec sheet from a good manufacturer and you will notice that besides the length and width, the height will change due to rating. So check the thickness of the bad SMD cap with the other one. On the pic they look the same.
Dont trust me too much, as I only can see whatever pictures you provide or info you give. Changing these 1 Ohm resistors for 0.1 Ohm won't make a difference.
C204 is a part of a “rc filter” that suppresses transients (spikes). It is a small value cap something like 0.0001uF (that is 1000pF). Could be even a bit lower at 100pf…
Like I said, this cap function is only there to suppress “transients or noise” on the sense pin. Does it have to be there? Yes, but at the same time it isn't extremely critical either.
I measured C208 and it's 9.42nF so my guess is 10nF for both C208 and C204
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Update:
I bought 1Ohm 1W +/-5% resistors and its not working it looks like the resistance is too big, if i short the resistor to GND screw-hole it runs. Any thoughts?
Btw from my perspective C204 looks like C205 by the size. C208 is way thinner.
C205 is 97nF (measuring de-soldered) what do you think ?2 Photos
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The resistors are fine. Not sure right now what to think on why it isn't triggering as it supposed to. I do know that there are a few caps where we are guessing, since the size gives usually a choice of 3 or 4 capacitance values assuming they are 50V rated. Close, but yet so far…
Sometimes on these Chinese welders and plasma cutters there is a part of one circuit on one board and the other part on a different board. That happened to me on a plasma cutter I repaired a while back.Last edited by CapLeaker; 06-17-2024, 03:42 PM.
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