Chinese plasma cutter CUT-50 - Page 1
Forum section: electronics / general

author: gaminn
author_rank: Frequent Contributor
timestamp: December 11, 2019, 02:20:02 pm
content: Hi,I purchased this cheap chinese plasma cutter CUT50 (50 amp):https://www.ebay.com/itm/Plasmaschneider-CUT-50-HF-Inverter-Plasmaschneidger%C3%A4t-bis-10-mm-230V-50Amp/202737585934I opened this thing to check whether there is actually anything inside the box.I can see two (dirty) boards named: CUT35-2A2 and CUT35-1A2 which triggered alarm: Did I buy CUT35 (35 amp) plasma cutter nicely packed in a CUT50 enclosure?On one board there are two pairs (total 4 pieces) of dual 15/30 A diodeshttps://www.onsemi.com/pub/Collateral/MUR3020PT-D.PDFEach pair is connected in parallel so they should handle 60 A.On the second board there are two pairs of 23 A mosfetshttp://www.unisonic.com.tw/datasheet/23N50E.pdf. Each pair is connected in parallel to handle double of the current.So, maybe, the components could handle declared current, but I'm still unsure whether this is really CUT50 plasma cutter. Can anyone confirm/comment?

author: ace1903
author_rank: Regular Contributor
timestamp: December 11, 2019, 04:07:56 pm
content: No idea about power rating but will ask one noob question.How plasma is ignited? Can not see HF transformer on pictures?

author: gaminn
author_rank: Frequent Contributor
timestamp: December 11, 2019, 04:10:41 pm
content: You have to touch the metal to ignite it. There is also a place on pcb where this HF transformer goes (but it is not assembled).

author: TERRA Operative
author_rank: Super Contributor
timestamp: December 12, 2019, 11:14:53 am
content: Hmm, been a few years since I used to repair this stuff...It looks about right, you'll probably find there are a few missing transistors etc in the Cut-30.Often they would do that for the lower spec models, customers never used to complain when we replaced a lower spec board with a higher spec one.The boards were so cheap, it was easier to just keep the higher rated ones in stock than the whole range..Incase you don't already know, you'll need to install an oil seperator, dessicant dryer and dust filter (preferably in that order) to make the air supply as clean and dry as possible.If the air is dirty or wet/oily in any way, you'll eat cutting tips and have inconsistent cut quality.

author: gaminn
author_rank: Frequent Contributor
timestamp: December 12, 2019, 03:39:30 pm
content: I'm returning this plasma cutter. Did you notice that AWG14 output cables inside this CUT50? Not sure if it is visible. How much current can they handle, 5 A?Everywhere on Youtube you can see CUT50 has 3 or 4 times more mosfets/diodes inside. I'm not saying more mosfets = better plasma cutter, but with this plasma it is clearly visible they are cheating buyers.FYI any CUT-50 that has item location "Jenec, Czech Republic" will be this garbage.

author: gaminn
author_rank: Frequent Contributor
timestamp: December 13, 2019, 07:57:35 pm
content: So, before I return the unit, I tried to cut 8 mm steel. It cuts, but really slowly.I measured current via UT210E clamp meter (100 A DC range) on + wire off the unit - max reading I was able to get was 25 A on meter when the plasma cutter was set on 50 amps. Should I believe my clamp meter? On lower DC ranges it is quite accurate (+- 2 %).

author: TERRA Operative
author_rank: Super Contributor
timestamp: December 14, 2019, 07:06:36 am
content: It's probably an extremely optimistic 50A, or an outright lie.... I'd trust the DC clamp meter over the seller trying to maximise profit on cheap welding gear.