Blown power supply dy10 for reci laser 80w

Hi everybody,
I bought a chinese laser machine lxj1390 and just while doing the first test cutting a 3mm of acrylic for two minutes i heard a pop and the laser stops emitting. I checked the laser power supply, and i found that the fuse is burnt. I changed it with piece of aluminum foil just to test thinking that the problem is in the fuse( a spare fuse was not available). As soon as i released the emergency switch a loud pop electric sound like arcing. So i push the emmergency swith immediately. I inspected the laser power supply and two transistors 2sc2625 were blown and maybe a 0.22ohm resistor. The ampermeter doesn't exceed the 10ma before the problem.
Please did someone face such a problem and what might be the cause for the power supply to be blown.
Best regards and thx in advance

Shreifali,

There is a reason for a fuse to be where it is and a reason the fuse blew in the first place. Replacing it with wire or aluminum foil causes the break to be overlooked so that the voltage goes straight through and what ever is causing the blown fuse will only get hotter and hotter until it sparks and blows other components or starts a fire. Find out what is blowing the fuse and fix that problem first. You should purchase a set of fuses to have as spares just in case something like this happens again. :\

If you can't figure out the cause, feel free to send in your equipment in to us for evaluation. The evaluations are free so it won't cost anything for us to look at. Just shoot me an email and I'll give you my info. My email is [email protected]

thx ies for your reply,
i live outside US so sending the power supply to you will cost me more than a hundred USD for shipping:).
please may you tell me what might be the possible causes to check them myself.
and thanks a lot.
best regards

We'd have to evaluate it to know.

Do you have a part number for the power supply?

Hi again and really thx for your replies.
The part number is HY-DY10.
I will send some pictures of the blown 2sc2625 transistors.

Those are the push-pull transistors on the front end of the flyback to make the HV for the laser tube. If they blew, it's likely the power supply is bad due to a shorted flyback transformer or a broken bridge rectifier on the front end. The other case is if a 110V rated power supply was used on 220V, that could probably kill them too - but otherwise they are big old beasts that will take a lot more abuse than 5 seconds of proper operation. From your description, I doubt this is something you could have caused.. Even by shorting the HV line you will not kill the frontend of the flyback. I would get in touch with the seller and tell them they sent you a dud power supply.

Do you want to try to debug it yourself? I can walk you through it if you want to post some pictures of the pcb. Sometimes (if the transformer is OK) this type of failure could be an easy fix. Me, I'd still complain to get a new PSU and then try to fix the bum unit someday in my spare time.

Hi, i ordered a new one but i am affraid of the possibility of that the cause that burned the old one is still there.
By the way when the fuse was blown the first time the machine mechanics keeped working, only the laser is stopped, and when i changed the fuse by an aluminum foil piece
The trqnsistors exploded. I think the transformers are working ok. But anyway i will send you the pcb pictures tomorrow.
Really thx for your help qll of you

There is a transformer inside the power supply to make the HV. That's the one that may have a problem, not one outside.

I think your new supply will take care of everything, but yes - if you can post pictures I'll still try to help point out what could be wrong.

hi again, here are attached the pcb and board pictures.

Wow. Same "accident" here today. Is it safe to open the power supply? No high voltage anywhere when disconnected? I would like to check what component was burnt.

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Quote:

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Originally Posted by manolohpm

Wow. Same "accident" here today. Is it safe to open the power supply? No high voltage anywhere when disconnected?

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There are large capacitors inside which stay charged for a few minutes after you unplug the power supply. After 10 minutes or so it should be safe to open and touch. Keep in mind that bad components do not always look burnt on the outside.

Great, thank you.

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I only found the fuse burnt. I'll place a new one tomorrow and test if it burns again.

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Hi, finally I changed the complete PSU. Had to calibrate it because it gave 34 mA when connected.

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Quote:

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Originally Posted by manolohpm

I only found the fuse burnt. I'll place a new one tomorrow and test if it burns again.

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Whenever you see a blown line fuse inside a power supply, there is a 99.9% chance that it blew for a good reason. Replacing it without checking other components will only get you another blown fuse. (And replacing it with a piece of wire will get you some sparks and smoke.)

Hello,
I have a similar problem with 2 PSUs i am using. They are standard chinese 36v psus from ebay. On the back of the board there are 3 2sc3320 tranzistors that are coninously burning. It happens randomly after 5-15 minutes of usage even withou having high temperature. I have resoldered them 3 times so far and have no idea what is causing the problem. If something was connected wrong they should burn imediatly, right? They are rated to 500v and 15A while unit produces 36v with 10A.
Does any one have a clue what could be wrong? I am wondering if replacing them to 2sc5302 (more powerfull) could cause damage to some other board's component?

Where do you buy those transistors - a reputable source or Ali Express? It is possible that you got some counterfeit ones.

2SC5302 has worse parameters than 2SC3320 (apart from the maximum voltage which should not matter in your situation).

Actually I brought an example to local electronic component store and they didn't have 2sc3320 so I have ordered lot in ebay. from china.
What parameter is important in this case?

Unfortunately I am not very familiar with these guys, however higher numbers makes impression that part is more capable and reliable.
here are few examples that are available in stock and numbers seem to be high enough to replace original part. CitizenOfDreams, could you please advise which one could be the best replacement?
2SC5696 NPN 1600V 12A 85W 0.3us
2SC5242 NPN 230V 15A 130W 30MHz
2SC3263 NPN 230V 15A 130W
2SC5144 NPN 1700V 20A 200W
2SC3856 NPN 200V 15A 130W 20MHz

Thanks for your help!

None of the transistors on your list are particularly suitable for your power supplies. 2SC5242, 3263 and 3856 are low voltage transistors that will not withstand the line voltage. 2SC5696 and 5144 are old school horizontal deflection transistors for tube TVs. They are quite a bit slower and have higher saturation voltage compared to the original 2SC3320. Plus, at least one of them has a built-in resistor between the base and the emitter. You could try 2SC5144, but I cannot guarantee it would work.