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Need help with a Wacom Cintiq 21UX monitor (Reverse polarity applied) - SOLVED

oh...hehe :) Yeah, just did that, measured that transistor and every other transistor that I could find and all of them give out some reading or another on two pairs of their three legs (I only measured a pair, didnt measure all the combinations on three legs), none of them are 0 ohms.

Quick Questions, whats the best way to desolder and solder that small IC, with a soldering iron or a hot air gun?

Thanks
 
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(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Whether those transistors are OK or not depends on

a) whether they're transistors or not
b) what sort of transistor they are
c) what the readings are
d) whether or not there are components in the circuit that interfere with your measurements

So, in short, you're really told us nothing.

The best way to remove a small surface mount chip is with a hot air rework tool. You simply heat it up, the solder melts, and you lift it away with some tweeezers.

A rework tool differs from a hot air gun in that the temperature of the hot air is controlled in much the same way that the temperature of a temperature controlled soldering iron is.
 
You need to include the middle unconnected pin in the measurement too, it's the same terminal that acts as a heatsink, being soldered to the board.
The measurements might not tell us everything but in this case it's vital that the switching power transistor at least is not shorted or else 12V would get out on the 5V.

I'd worry about the hot air desoldering & blowing away the small parts around the IC but I've never used pro hot air tools so I really can't tell how easily that might happen.
I'd just cut off its pins first and then desolder the pins from the board (using a wick/braid).
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
If you use a small air jet and appropriate air velocity, it's actually really hard to affect components that are even quite close by.

In any case, the solder has surprising surface tension and even if melted the components are unlikely to move.

However, I don't think I'd want to desolder that as my *first* experience with a rework tool.
 

davenn

Moderator
Hello again,
I took the measurements, it can be seen on the attached image. All the measurements are off the V type and (NC) means Not Connected.
The power coming in consists of two black and two white wires. Both of them carry 12V.
I have not measured the power this draws, how should I go about doing that the healthy way?
Thanks.

View attachment 1200

Just for you interest and learning :)

in that pic and the centre pins of those 2 devices that you have labelled as NC
these are actually connected and are part of the TAB which you will see soldered on the other end of the device
the first one Im picking is possibly a 8V reg you have 12V in and 8V out
the lower one is prob also a reg but interesting that you have basically 12V on each side
maybe its internally short cct'ed

wonder of you can read the markings on either of those 3 pin devices ???

Dave
 
Hello all,

Thanks for the replies and I am sorry if I am not helping very much but, I am trying and I can only do so much and pretty much only do what you request of me with my knowledge in this field.

I wrote down every part that seemed like a transistor or a regulator and gave them numbers so it will be easier for you guys to communicate with me.

Thanks.
IMAG0017.jpg
IMAG0017_BACK.jpg
 
First of all...its done and working!!! yay! :D

I would like to thank everyone who helped in this forum and Im really glad that it exist for people like me!

Short explanation of what Ive done:

I ordered the AIC1578PS part numbered piece from ebay and it came from Hong Kong yesterday (thats why I was not active on the thread).

I had a heat gun lying around and with that I watched some videos on Youtube about heat gun desoldering and soldering of ICs, analyzed and synthesized what I saw there and applied it to the IC on the board and voila! it came loose and then soldered the new one on.

I tested the device and it worked, put it back together and called my professor (who the device belongs to) and everyone was happy.

The device is a Wacom Cintiq 21UX

The repair center asked a price of 1600 euros to fix it and with help and direction from this forum it was fixed for 9 bucks :cool:

Here are the last two pictures of the new part and the working conditions, heh!

Thanks!

DSC_3263.jpg
DSC_3264.jpg
 
Last edited:

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
First of all...its done and working!!! yay! :D

Congratulations. But I really think you dodged a bullet with that one.

I had a heat gun lying around and with that I watched some videos on Youtube about heat gun desoldering and soldering of ICs, analyzed and synthesized what I saw there and applied it to the IC on the board and voila! it came loose and then soldered the new one on.

Do you mean a real surface mount rework tool, or one of those heat guns used for stripping paint? (Or something else)

The job looks very well done, so whatever method you used, it was clearly effective.

It would be interesting hearing your explanation of how you did it. It also may be useful for other beginners who may find themselves in your position.

I tested the device and it worked, put it back together and called my professor (who the device belongs to) and everyone was happy.

Let me guess, he was a little peeved when it was broken? :eek:

The device is a Wacom Cintiq 21UX

The repair center asked a price of 1600 euros to fix it and with help and direction from this forum it was fixed for 9 bucks :cool:

Looks like 1600 euro could buy a new one.

Did you tell them the power connection had been reversed? If so, they were probably allowing for the worst case scenario.

Here are the last two pictures of the new part and the working conditions, heh!

As I said earlier, I think you dodged a bullet. It is so easy for reversed power connections to destroy stuff. In your case, it seems to have killed the switchmode controller, and left everything else untouched.

Considering they ask 1600 euro to fix this, do you think a couple of cents to prevent reverse polarity damaging the board would be a waste? (Not a question for you, but for them)
 
Hey! No problem, of course I can explain what I did for other amateurs like me but, I am sure its not the best way to do it.

Please read all of it as I explain some stuff towards the end.

What I used:

I used a semi-pro grade stripping heat gun, SKIL brand to be specific with a smaller attachment head. Although the brand doesn't matter (as long as quality is preserved), what matters are two things:

1. Heat-control: It allows you to set the heat, not exactly but, to some degree.
2. Heat-check: it makes sure that the heat coming out is consistent and that it doesn't burn out the gun itself.

Also used a 6 inch - 150mm tweezer and some soldering flux.


The way I did it:

I used a small tweezer and held the part to be unsoldered so that the tweezer didn't get in the way of the heat gun and I wasn't going to burn myself from the heat bouncing back from the board. Holding the part with the tweezer, I lightly pulled on the tweezer so that the board was about 1/8" - 3mm up in the air. This way when the solder melted the part would separate and with the help of gravity the board would just fall a short distance to the table and nothing else would move. I held the heat-gun over the part, short of 2 inches - 4cm high and started waiting, in about 15-20 seconds, the part came loose in the tweezers and the board just fell 1/8" - 3mm and rested on the table. No other part was desoldered or had even moved.

After the part was off, I took the replacement part, dipped its legs in flux and put it back where the old part was, watching out for the direction marking circle on the IC. I had enough solder left on the board so that I didnt need to add any new solder and could just reheat the board and that would do it.

I pressed on the part with the tweezers, ever so lightly, just enough to make sure that as soon as the solder on the board melted it would catch on the legs of the new IC. I put the heat gun on the new part and waited, this time a little shorter as the board was already cooking from the last heating. In about 8-10 seconds, the part fell down, ever so slightly with the pressure of the tweezers, into the solder of the board and I saw the solder creep up the legs of the IC and knew that it was done. The board was plenty hot by this time, so had to wait to test it, but after a while I found out that it had worked just fine:)

What to watch out for:

Do not worry about the board getting hot as long as no discoloration occurs. If you see the green plastic (or other color) layer on top of your board turning yellow (or another color), that calls for concern so stop and let it cool down. It means either you're applying to much heat or too quickly. Other than that, the board will get pretty hot, but thats what happens when they originally make these parts in special ovens as well.

The setting that worked for me on the heat gun was medium. For first time users, the gun will seem to be pushing a lot of air, and it is, but no need to worry as the parts wont move from this airflow as it was mentioned before by Steve because of the surface tension of the solder.

The second thing to watch out for is the type of solder that was used by the manufacturer. The solder without lead is harder to melt and it take a little more time (seem way too long) for the heat gun to melt it. More and more companies are using lead-free solder nowadays for environmental reasons so more than likely thats what will happen when you experience it.

Its better to shield close by plastic parts, maybe with heat putty or even unsolder them if possible. The heat from the heat gun, even with a smaller diameter head, has a negative effect on nearby plastics, like sockets or the shrink-wrap plastics on the capacitors. It just melts them.

!!! Don't work on a wood or plastic tabletop for this repair. It will surely burn wood (not charcoal but will darken) and it will definitely melt or disfigure plastic as we are talking a high amount of hot air !!!

Thats it!

On to other topics, I definitely think a bullet was dodged but, it was the prof who dodged it actually, not me, as he would have ended up buying a new one :p

The retail price of the new unit where I am is 2500 Euro incl. TAX. So, that repair quote is beyond silly but, what they do apparently is that they don't fix problems as such as these, they just replace all the electronics boards that you see on the picture from my last post. So, its not technically repair, more like changing of parts is what they seem to quote for.

Hope this helps. Thanks!
 
That's an absolutely great writeup! Thanks!
I did a hot air repair once just like you describe and it also worked out nice (much to my surprise).
 
Hi There,
I'm considering an attempt to repair a Cintiq 21UX (DTK 2100) which is very similar to your Cintiq project. The person I'm buying the tablet from says that they "plugged it in and nothing worked, no power" and I'm wondering if it's something I might be able to tackle. The condition of the cintiq looks good, no signs of a fall or scratches. Which leads me to believe that it could be something similar to what you dealt with.

I was hoping you could give me a general idea of how much electronic knowledge I need to begin to troubleshoot this. In this thread it appears you have a solid knowledge of electronics. I am a COMPLETE novice in electronics, I'm an illustrator/animator but basically would love to fix and use a cintiq. My knowledge of electronics is basically that I can use a multimeter to check my house's electrical system and I know how to perform basic resistance checks. I have a steady hand and have done some soldering repairing jewelry.

Is this something I can tackle (at least troubleshoot) or do I need an electrical engineering degree? :)


Thanks for any guidance you can provide, and thanks for posting about your fix.

Alamont
 
Hello alamont,

First of all, my electronics knowledge is not much different from yours. I know what a resistor is, what a capacitor is what a diode is and what it does to some level but, thats about it. Knowing how to use a multimeter helps a lot of course but, that is not enough to solve a problem on these kinds of complex boards. In this thread, to put it simply, I got lucky. So, the answer to that one is you don't have to know a lot of electronics, you just need to find the right people that know and ask them kindly and with respect, thats what I did here.

Truth be told, most of the troubleshooting was done by our dear friends (*steve*) and Resqueline, I merely did what they told me to do. Then I ordered the part that might have been the problem and we got lucky, the problem was solved.

I think you can do the job, especially if you follow my write-up, get the tools that I used and ask questions along the way. The only issue is, is your problem the same as mine was? The only way to find that out is by opening it up and checking for issues as I did. Good luck:)
 
Thanks for the response!

I'm really hoping to tackle this project. One thing I'm concerned about is the number of different issues the cintiq could have. The previous owner says that "they plugged it in using the wrong power brick and now it doesn't show any signs of life." So my question is really about what possible things have gotten burned or broken. Is it likely that most or all of the electronics got fried or (as in the case on this thread) only one chip was fried. Also since this is a monitor/tablet could the wrong power source blow the screens bulbs or fry the stylus sensor?

I know it could be a wide range of problems but I'm wondering from an electronic standpoint, if this device is overpowered, what type of protection does the device have built in to prevent all of it's components from being destroyed? In other words (within reason) what are the likely culprits here?

Thanks
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
alamont, I think you should start a new thread. My input would be almost identical to that which I gave byazici.

In brief, you may have damaged anything between nothing and everything, and some photos would help.
 
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