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Old 02-10-2012, 07:33 PM
brujaja brujaja is offline
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Trying to repair a tattoo gun power supply-- help?

I was in the tattoo shop today, and just as he was finishing up, the tattooist said, "Do you smell something burning?" (I know, one of the top ten questions you don't want to hear from somebody performing your body modification.)

Long story short, he opened up the power supply box and sure enough, he let the smoke out. This guy doesn't know much about electronics, but he's a friend, and it's his livelihood, so I offered to help him out.

I took it to the only electronics shop in town; they told me that the part with the cracked housing and burned spot was most likely a voltage regulator, but that the damage had obscured the part number.

So I looked for diagrams online but there seems to be a lot of variation in the capacity of these things, so they all have different parts.

So, here are my questions:

1. I am assuming that it would be bad form to simply call the manufacturer and ask them for the part number?
It is a large equipment supplier in a populous part of a populous state, and I'm sure that 95% of their customers are not interested in repairing their equipment. (and unfortunately, the box itself has no model number or model name on it. So I wouldn't know how to find a specific diagram.)

2. I also have the power cable and adaptor for the box. It of course lists the output. (18V dc 3A negative to positive) Would that information indicate a specific enough voltage regulator? I don't know much about the increment ranges involved.

3. Right before the burning smell started, we heard some part of the equipment making a sound for all the world like an off-center belt in a small device. (a squeak at regular intervals, with sort of a rotary doppler sound to it.) I am assuming that this is probably something inside the gun, since the box has no moving parts. That means that probably something is dragging inside of it, and probably is what blew out the voltage regulator, right?

Thanks!
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  #2  
Old 02-10-2012, 10:41 PM
beowulff beowulff is offline
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Photos would help.
If it's a modern "switching" regulator, you're not going to fix it - they fail in too many obscure ways. It might be a lot easier to just find a cheap compatible power supply for the gun. Does the gun itself take 18V @ 3A? If so, that's an easy and cheap power supply to find.
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Old 02-10-2012, 10:51 PM
cornflakes cornflakes is offline
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1. I am assuming that it would be bad form to simply call the manufacturer and ask them for the part number?
It is a large equipment supplier in a populous part of a populous state, and I'm sure that 95% of their customers are not interested in repairing their equipment. (and unfortunately, the box itself has no model number or model name on it. So I wouldn't know how to find a specific diagram.)


It's not in bad form, and whether they have parts or part numbers will depend more on whether they are set up to provide parts. Do you have any information, either about the whole setup or about the component pieces. Can you post pics?

2. I also have the power cable and adaptor for the box. It of course lists the output. (18V dc 3A negative to positive) Would that information indicate a specific enough voltage regulator? I don't know much about the increment ranges involved.

I don't see why you couldn't get a voltage regulator and make it work. It might take a little work to make it look good though.

3. Right before the burning smell started, we heard some part of the equipment making a sound for all the world like an off-center belt in a small device. (a squeak at regular intervals, with sort of a rotary doppler sound to it.) I am assuming that this is probably something inside the gun, since the box has no moving parts. That means that probably something is dragging inside of it, and probably is what blew out the voltage regulator, right?

Something may have broken and loaded down the motor, and the added current required may have blown the supply.
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Old 02-10-2012, 11:06 PM
johnpost johnpost is online now
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the supply failing could have under drove the gun causing it to make sounds not ordinary.
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Old 02-10-2012, 11:09 PM
astro astro is offline
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Professional tattoo gun power supplies are around $20-$40 on ebay. It seems that it would barely be worth the time and gas to travel around town vs buying a new one. Just to have a tech breathe on it will be multiples of that cost. If the gun is jammed and burning out the PS that's another issue.

As a side note I'm stunned a professional tattoo artist would not have a backup gun (several even)

Last edited by astro; 02-10-2012 at 11:13 PM..
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Old 02-10-2012, 11:09 PM
Joey P Joey P is offline
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Just taking a quick look around online (Amazon and some other websites). These power supplies are ridiculously cheap. I can't imagine it could possible be worth attempting to fix them. That could be why you're having a hard time coming up with part numbers. They're probably designed to be thrown out when they stop working.
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Old 02-10-2012, 11:18 PM
brujaja brujaja is offline
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Hey, beowulff, thanks for answering. I was worried no one would.

Well you see, the power supply has no label of any kind outside or inside the housing. My friend assures me that the wall wort thing came from the manufacturer, along with the power supply. (together.) The box has one dial/knob that, oddly enough, has no dial stop -- it just keeps turning. I wonder if that's something to do with the reason it burned out; or, once the circuit is all the way open, does turning the knob more do nothing?

Anyway, I went and examined it more closely myself just now. The printing on the damaged component does appear to be black on black, but here's what I can see:

468AC
25761
P+

There do appear to be additional characters to the left of each of these lines, but they are obscured by the heat deformation and crack.

I know that this was a lower-end model in the $100 -- $200 range. The damaged part has its own tiny aluminum heat sink, like you might find on an older video card. (before they had their own built-in fans or water cooling)

It is located directly underneath the LED for the power switch.

Okay, I posted a few pics, but my phone takes pretty crappy pictures.

You can just barely see the round white burned spot.

If you need pictures of some other view, please let me know.

--And thanks again!
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Old 02-10-2012, 11:27 PM
brujaja brujaja is offline
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You know, I have a feeling this guy may not be doing the required maintenance you are supposed to do on your guns. (heh heh, all of them!) It may well have carbon buildup inside, causing a poor connection. I have just remembered that he said the power LED was blinking right before it happened.

<sigh> I dunno; it sounds like maybe I should send him an ebay link instead. Then again, if he can't pony up the $50, my sister may not get the tatt I prepaid as a birthday present for next week.
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  #9  
Old 02-11-2012, 08:05 AM
beowulff beowulff is offline
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My gut feeling is that the part on the heat sink is not a regulator - they are generally fully overload protected. It's probably a power transistor. If it burned out, It may well mean that some part of the control circuitry is shot also. You are going to need someone with electronics experience to look at this.
Also, it sounds like it's not really a power supply, but the speed control (?) for the gun - the power supply is another external box, right?
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  #10  
Old 02-11-2012, 02:20 PM
brujaja brujaja is offline
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Well, the device would appear to be commonly referred to as a "power supply," but you might be right. It has an on/off switch, a place where the wall wort plugs in, two holes which I presume are for the guns, and the dial. I did see an awesome article online about how to transform an old computer power supply into a tattoo gun power supply. (I love the internets!) Then again, people often refer to wall worts as "power supplies." You tell me.

Since you mentioned that the circuit board may be compromised, I looked it over more carefully with a magnifier and sure enough, there is a white burned spot on the circuit board as well. I think it's fried. And thank you all very much for your assistance. It is so cool to know that no matter how unusual or obscure my question may be, there is someone on the SDMB who knows the answer, or has a good guess.
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