This is what I meant, a linear pot with 0 - 100k will have 50k in the middle since it is...linear.
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zocoloco
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Last Activity: 12-23-2009, 05:41 AM
Joined: 08-27-2008
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Re: Help from pot tweakers needed!
This is what I meant, a linear pot with 0 - 100k will have 50k in the middle since it is...linear....
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Re: Help from pot tweakers needed!
Hmm, really? I thought that was the definition of linear...?
No no no, I would like to have 1 mA, but 10 mA would also do, if that would mean I could get a linear slope between the lowest and highest current.
Very nice tool, will save that page. Don't know exactly how to count, have to think it over....Leave a comment:
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Re: Help from pot tweakers needed!
Hm, well, thanx for the idea, but I believe this solution is a little more than I would like to invest into this project as far as parts and time goes. My solution also doesn't have to be that accurate, so if there is a easier solution, I will go for that....Leave a comment:
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Re: Help from pot tweakers needed!
Well that's what I also thought at first, but when you think it over, a linear pot means you have 5k in the middle, resulting in 9v/5000Ohm = 0,0018 = 1,8 mA. At 10k I would have 9/10000 = 0,9 mA. This is very logical once you get your mind clear, which took me quite some time. What I believe I would need is the behaviour of a reversed logarithmic pot.
Will it really? Hmm... Tried, after reading some guides on how to tweak pots with external resistors, to put 300 Ohm - 2.2 k in parallel with the pot. This changed the behaviour...Leave a comment:
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Help from pot tweakers needed!
Hi all,
I'm working on a small electronic project, where I want to deliver 1-~90 mA using a 9 V battery. To do this, I have chosen a linear 10k pot. My problem is, since this pot is linear, that the first 90% of turning the knob, hardly does anything, and the last 10% the current jumps up to 87 mA or so.
Since finding a reverse logarithmic pot (which I believe is what I actually would need), for all in this range of specs, is extremely difficult, I've been searching the internet for possible ways to tweak my pot to be a little less linear, and found a couple of pages... -
Re: Bad Viewsonic LCD monitor
No, I didn't, but it's not impossible that it gives the correct voltages. If you check the picture in my first post, you can see that the screen is working, it just has some intermittent glitches/stripes. I am more thinking that this "superhot" transistor or some other component in the PSU is damaged and therefore distorts the picture every now and then.
Of course, the problem could also lie somewhere else, what makes me wonder quite a lot is that the problem always comes on either the left or the right half...Last edited by zocoloco; 02-11-2009, 01:24 PM.Leave a comment:
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Re: Bad Viewsonic LCD monitor
Tried to reseat all connectors, without much success. I am tending more and more to believe that the problem lies within the power supply of the screen. The "white powder" is probably thermal paste that has "burst out" due to extreme heat on the transistor pointed out in my picture above. The only question is why it has become hot...
Found a spare power supply online for 30$. The shipping to Sweden, where I'm living, is 40$ though. Have to think about it a little, cause it might still be that the problem is in another...Leave a comment:
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Re: Bad Viewsonic LCD monitor
To me it looks like we have the exact same layout, the only thing with your pics is that they are taken from different angles, or? And that your big capacitor is hidden under some kind of plastic cover...Leave a comment:
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Re: Bad Viewsonic LCD monitor
I've looked a little more into this and it seems that the powder comes from the thermal paste applied to the transistor marked in the image below. Is this a normal reaction of thermal paste? Is it from heat, or what do you think?...Leave a comment:
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Re: Bad Viewsonic LCD monitor
Hi y'all again. Finally managed to open the thing up. Didn't see any obvious signs (for me that is) of what the problem could be. The only thing that struck me was this white powder in the power supply section, is this normal?
See attached pictures and let me know if you find anything weird on them.
Thx all!...Leave a comment:
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Re: Bad Viewsonic LCD monitor
Update:
Sometimes, when the screen flickers but is still watchable, when I play a movie (xvid), the movie is perfect, but the surrounding area is not. Is this a clue to you experienced lcd repair people?
Still didn't open it up though...
Edit: Can som Mod please move this thread to the appropriate section, just noticed I started the thread in the wrong one...thx!Leave a comment:
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Re: Bad Viewsonic LCD monitor
So you think the problem might be in the connection between the circuit boards and the panel?...Leave a comment:
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Re: Bad Viewsonic LCD monitor
and with pcbs you mean...the circuit boards inside the monitor?...Leave a comment:
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Bad Viewsonic LCD monitor
Hi all,
My Viewsonic VP201b monitor has recently started to mess with me, and I would like to get some advise what to check, since I believe there are lots of people who know LCDs more than me. I'm working with electronics, so the handling and possibly repairing should be no problem. I just need an idea where to start. Since I'm a little low on money, I would really need to fix the monitor, can't afford a new one at this point.
I have also tried desperately to find a service manual for the monitor without success. The viewsonic store has no in stock, and the net seems...
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