Bongofish
September 24, 2018, 09:12:35 PM *
Welcome, Guest. Please login or register.

Login with username, password and session length
News: You can attach photos hosted by the forum rather than using an external image hosting site, this means they will stay forever and not disappear after a year or two.
 
   Home   Help Search Login Register  
Pages: 1 2 [3] 4
  Print  
Author Topic: Chingwa's Build Log  (Read 26878 times)
Drewid
Administrator
Hero Member
*****
Posts: 2289


wielder of electric crayons


View Profile
« Reply #30 on: December 13, 2006, 02:08:42 PM »

Extending the wiring for those may be a problem.  It would be worth doing it in such a way that you can change it back if it doesn't work. :'(  I've heard it might lose brightness, though technically I can't really see why that would be.  I certainly did on one I tried, but it may have been my crap soldering.

You could always be the first to try an LED strip instead.   Lose a lot of heat problems at the same time.

As to extra shielding, some sort of earthed cage round the LCD boards may help, or maybe it could be something as simple as the positioning of the power supply.


And I've found my penpartner pen PM me if you are interested.

« Last Edit: December 13, 2006, 02:10:22 PM by Drewid » Logged

Games work site:  Drewnorthcott.co.uk
Personal site: Bongofish.co.uk
r3d373
New Poster
*
Posts: 29


View Profile
« Reply #31 on: December 13, 2006, 07:30:21 PM »

I bought a some alu tape from a Halfords, for sheilding where needed. Seems to be pretty much the same stuff used already in monitors.
It was £5 for a 10 meter x 50mm roll ($9.80, 32ft x 2" approx).
Might be useful to get some for temporary shielding to work out bugs.
Logged
Drewid
Administrator
Hero Member
*****
Posts: 2289


wielder of electric crayons


View Profile
« Reply #32 on: December 13, 2006, 09:29:34 PM »

Good idea, stick it in the tips thread.
Logged

Games work site:  Drewnorthcott.co.uk
Personal site: Bongofish.co.uk
chingwa
Jr. Member
**
Posts: 34


View Profile
« Reply #33 on: December 14, 2006, 04:18:30 AM »

Now I'm really paranoid about extending the backlight wires!  I wish there was another way around it but there isn't.  They HAVE to be extended.  I'll see if I can find wiring of the same rating online somewhere, and just hope for the best.  Probably heat shrinking the wires would work better than just electric taping them?  The aluminum tape seems like a good idea, I'll have to get some of that stuff.  I also plan on building at least a partial metal enclosure for the monitor component boards.

I was at the hardware store today picking up some stuff for my custom case.  I'll need to order a few parts online though.  I also ordered felt tip nibs off of Wacom's site.  $5. free shipping Cheesy

Logged
Drewid
Administrator
Hero Member
*****
Posts: 2289


wielder of electric crayons


View Profile
« Reply #34 on: December 14, 2006, 08:29:07 AM »

Internal power supply horror!  Embarrassed   I feel really bad about this, it was one of the things I checked for when looking for monitors. I'll have to make it clear on the main site.

It should be possible to shield that,  but it adds a chunk of complication.  Is it a seperate board? Could you shift it external to your main case or shield it seperately?

If not then the board that its on could be shielded.

edit - I've been doing some reading,  the shielding will lessen (not stop entirely) magnetic effects, but should stop electrical effects,  lets hope it's mainly electrical.  The shield will need to have ventilation holes but as a test you could get away without.

It might be easier to get an external supply, then figure out an insert point on the board, then cut connections to the onboard supply, or remove it.   Actually there would probably be a single very obvious point to do that.   

« Last Edit: December 14, 2006, 10:19:37 AM by Drewid » Logged

Games work site:  Drewnorthcott.co.uk
Personal site: Bongofish.co.uk
chingwa
Jr. Member
**
Posts: 34


View Profile
« Reply #35 on: December 14, 2006, 02:09:54 PM »

Hmm.  I'll be trying another test in the next day or so, this time with a metal shield.  What you're saying about connecting an external power supply directly to the video board is intriguing... not only would it solve my interference problem but also would help me cut down on the width of the board.  I have no electrical/soldering experience to do that though.  unfortunately I think shielding is my best bet here.  Well, live and learn,
Logged
Drewid
Administrator
Hero Member
*****
Posts: 2289


wielder of electric crayons


View Profile
« Reply #36 on: December 14, 2006, 02:38:08 PM »

How are you going to earth the shield for the test?
Logged

Games work site:  Drewnorthcott.co.uk
Personal site: Bongofish.co.uk
Drewid
Administrator
Hero Member
*****
Posts: 2289


wielder of electric crayons


View Profile
« Reply #37 on: December 14, 2006, 03:52:31 PM »

Also have you tried it without the inverter plugged in?
Logged

Games work site:  Drewnorthcott.co.uk
Personal site: Bongofish.co.uk
chingwa
Jr. Member
**
Posts: 34


View Profile
« Reply #38 on: December 14, 2006, 08:31:24 PM »

I had planned on using the metal back-cage tat had come with the monitor originally, but orienting it so the metal forms a shield between the electronics and the sensor... I'm hoping I should get enough of an idea just from a test if this is what's needed to address the problem.

However, and here's where my electronics in-experience shows (or perhaps it started to show a long time ago Cheesy ) what is an inverter?  I have 2 boards that came with the monitor, one is a power input which takes in power from the wall socket converts it, and channels it out to other compnents (the video board and the bulbs), and attached to that by a socket is the video board which has outputs for VGA and DVI and ribbon cables connecting to the LCD.  These are the only components and for me to do the test everything needs to be plugged in.

Oh yeah I just got some more stuff at the hardware store, including the metal foil tape.  I'll be playing around a bit with that as well.  I'll see if I can get some pics of the components when I get home from work.
Logged
Drewid
Administrator
Hero Member
*****
Posts: 2289


wielder of electric crayons


View Profile
« Reply #39 on: December 14, 2006, 11:47:27 PM »

I'm no expert but as I understand it it's something like this:

The inverter is the circuit that drives the bulbs. It takes the 12 volt DC input and turns in into a high voltage & low amperage AC current. An inverter can give you a jolt, but because of the low current it's not "dangerous".   Because it is generating AC it has the potential to create disturbances in the force I guess.   
On a number of monitors it's a separate board, and the screen will often still function with it unplugged.  (just makes it very very hard to see).   Sometimes an inverter will turn itself off if a bulb is damaged, as a self-protect thing.

Perhaps with an internal power supply you wouldn't need an inverter as such but could drive the bulbs from a tap on the mains supply transformer? (anyone ?)

You could try the screen with the bulbs unplugged  or away from the sensor board to see if that makes a difference.    If it does then you could ally tape the bulb cables then insulate over that  leaving a tag to earth the shielding. 

The test shield really ought to surround the offending board,  if makes electrical contact  with the foil on the back of the sensor then that will become part of the shielding as well.

I'm reasonably confident that shielding should work. I think the problem is probably something to do with an AC current, because of the way the jittering looks.
If the problem was a "magnetic force" effect then my tablet would suffer in the same way, because it's very difficult to shield magnetic forces.

Tell you what I've a friend who's an engineer, I'll see if I can get him to log on and have a look.
Logged

Games work site:  Drewnorthcott.co.uk
Personal site: Bongofish.co.uk
r3d373
New Poster
*
Posts: 29


View Profile
« Reply #40 on: December 15, 2006, 01:08:59 AM »

@Drewid. I wouldn't like to try to tap the voltage needed from the AC input transformer. As far as I know the voltage has to rectified before going into the bulbs.

@Chingwa. The power/inverter board and mainboard look very familiar to some of the Acer ones I've worked with. If you need any pinouts for the boards PM me the OEM part numbers and I'll see if they match up.

BTW. What frequency are you running the monitor at?
Logged
chingwa
Jr. Member
**
Posts: 34


View Profile
« Reply #41 on: December 15, 2006, 04:25:00 AM »

Thanks for the feedback guys.  I haven't had a chance to try the shielding yet, maybe I will tomorrow or over the weekend.  Here's a clearer picture of the display boards and where the outputs inputs for each are.  I'm not yet convinced I want to go in and start cutting up electronics or reattaching this to that... but if that ends up as my only option, thats what I'll have to do.

(the green board at the top is the tablet electronics... and has nothing to do with the display electronics)
Logged
Drewid
Administrator
Hero Member
*****
Posts: 2289


wielder of electric crayons


View Profile
« Reply #42 on: December 16, 2006, 12:12:22 AM »

Definitely that yellow sucka.   I was talking to my friend the engineer tonight, he confirmed the diagnosis.

The shield can be very very thin, (microns even) as long as it's earthed it should stop electrical effects, if it's a magnetic effect then it's a more difficult issue.
Logged

Games work site:  Drewnorthcott.co.uk
Personal site: Bongofish.co.uk
chingwa
Jr. Member
**
Posts: 34


View Profile
« Reply #43 on: December 16, 2006, 02:17:06 AM »

Thanks drew.  I'll have some time to play around this weekend and see if it works.  I figure I can earth the shield to one of those 2 metal heat shields... boy do those suckers get hot though.  Or do you guys think it's better to have a metal contact on the inside of the case and make contact with that?

Logged
Drewid
Administrator
Hero Member
*****
Posts: 2289


wielder of electric crayons


View Profile
« Reply #44 on: December 16, 2006, 12:24:47 PM »

It's entirely possible that the mounting bolt holes are also earth points, it's very common, which might make it easier.
Perhaps you could trace through the mains plug earth connection to see.


@ r3d373, ok, I thought an inverter went from DC >AC.  Does it get rectified again to get a higher voltage DC afterwards?
« Last Edit: December 16, 2006, 12:26:55 PM by Drewid » Logged

Games work site:  Drewnorthcott.co.uk
Personal site: Bongofish.co.uk
Pages: 1 2 [3] 4
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.21 | SMF © 2015, Simple Machines Valid XHTML 1.0! Valid CSS!