Re: VisionQuest LVQ40HLA black screen, backlights work
Update:
I did some searching and couldn't come up with an identical t-con board. Nothing to lose I thought, so I bought some no-clean liquid flux and baked the board. Still lying face down on the ground but propped up enough that I could peek under it, I hooked the board back up and what do you know, a nice pretty blue screen. I hooked up my SNES and sure enough, it was alive again!
So I took the steel components to work and cut clearance holes for a heatsink over the Altera chip with my yag laser....
SBlackfoot
Member
Last Activity: 11-14-2018, 06:32 AM
Joined: 04-20-2012
Location: Hamilton, Ontario
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Re: VisionQuest LVQ40HLA black screen, backlights work
Any more suggestions? :-)Leave a comment:
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Re: VisionQuest LVQ40HLA black screen, backlights work
I'm happy to try anything you suggest. :^) Just trying to educate myself in the process.
I tried with each of the cables to the panel disconnected, one at a time. No change in behaviour at all. Still working backlights with nothing on screen.Leave a comment:
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Re: VisionQuest LVQ40HLA black screen, backlights work
You mean the two flat cables from the t-con board to the panel? I can disconnect one at a time and see what happens, but if the panel is doing nothing with both connected...
The set did come to life a few times after doing the caps before post #1 but that was a couple of weeks ago now. Nothing since then aside from the backlights and all I've really done is removed and reinstalled things.Leave a comment:
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Re: VisionQuest LVQ40HLA black screen, backlights work
11.7v on either side of the SMD fuse on the t-con board. It's getting power... Time to bake my t-con? lolLeave a comment:
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Re: VisionQuest LVQ40HLA black screen, backlights work
Ah shoot, you're right... Guess I'm still hoping for an easy fix. I'll check the fuse on the t-con board.Leave a comment:
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Re: VisionQuest LVQ40HLA black screen, backlights work
I have yet to check for power at the t-con board, I figured it might be a good idea to take some readings on the power supply before I stripped the set down again.
Checks were done with the power off but plugged in, then with the power on, backlights lit, but no picture on screen. I left off the grounds because they're all zero, as expected.
_________Off_____On
+24v______0____24.5v
+24v______0____24.5v
+24v______0____24.5v
+24v______0____24.5v
+12v______0____12.42v...Leave a comment:
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Re: VisionQuest LVQ40HLA black screen, backlights work
I can try, bit the t-con board is pretty buried and inaccessible when everything is hooked up. And it has been somewhat intermittent, although more off than on.Leave a comment:
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Re: VisionQuest LVQ40HLA black screen, backlights work
Any ideas, guys? This thing is apart on the floor in my shop. ;^)Leave a comment:
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VisionQuest LVQ40HLA black screen, backlights work
Hi guys! You gentlemen helped me with a monitor a while ago, I was hoping that you might be willing to lend your wisdom one more time.
I picked up a non-working VisionQuest LVQ40HLA recently. When plugged in the red light comes on as normal. When I press the power button nothing happens. Press again, nothing. A third time, the light turns green and the backlights come on and stay on for five or ten minutes, nothing on screen. As long as it hasn't been unplugged it'll turn on and off with one press afterwards. Then things get weird...
I opened it up which was a... -
Re: Proview PL926Wbi, no power
By "new" heat gun, I mean a gift from last Christmas that I used for the first time. lol I'm sure it's fine. I'm sure they all smoke a little the first time they're fired up. The next attempt will be outside though. lolLeave a comment:
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Re: Proview PL926Wbi, no power
See you guys are amazing... I used some insulating wool to protect the surrounding board and replaced that voltage regulator. I managed to set off the smoke detector (new heat gun was smokey) and melt part of the connector to the inverter board, but when all is said and done she fired right up. It has been running for about ten minutes now without a complaint.
I really appreciate all of the help. If I ever get the chance I'd love to buy you guys a beer. lolLeave a comment:
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Re: Viewsonic VG920 2 seconds...
Just thinking that it's probably not worth it to spend $25 on a panel that I could probably replace outright on Kijiji for $30. I mean, I'd love to get it working but if it just doesn't add up...
Do the transformers need to be a specific pair, or will any matching pair do? Wondering if I could salvage transformers from a totally different board just to play around. Do my old ones look totally out of spec? They still seem fairly close in range to each other to me, and I didn't see any open circuits.Leave a comment:
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Re: Viewsonic VG920 2 seconds...
I think I'll have to keep an eye out for a spare on eBay or something. It's just a 19" monitor, it's really not worth it for me to sink any significant money into it.Leave a comment:
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Re: Viewsonic VG920 2 seconds...
Yeah I did the add-more-solder trick too, it seems necessary to get the old solder flowing. I had way more success this time than the last time I tried. It seems to be a lot tougher when the leads sticking through the board are folded over instead of sticking straight through.
The number on the transformer looks like 80GL17T-28-DN. It's awfully tough to read it's so small.Leave a comment:
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Re: Viewsonic VG920 2 seconds...
Sorry abot the delay, I'm not as confident in my soldering skills as you guys. Removing parts, no problem. Removing without cooking 'em, that I'm not so sure about. lol
On my 2000k ohm scale all four ballast caps show open circuits. I then swapped the transformers (wow that little suction pen worked good!) and the dimmer lamps did indeed follow the transformer, now it's the bottom set that aren't very bright.
So logically, replace the transformer. I do get a slight whine out of the board though when it is plugged in,...Leave a comment:
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Re: Viewsonic VG920 2 seconds...
While still soldered to the board, the top transformer gets on it's windings:
output side: 2.38k ohm
input side: 449 ohm, 1.2 ohm
And on the bottom I get:
output side: 2.32k ohm
input side: 449 ohm, 1.2 ohm
In my mind that's fairly close but I am the rookie in the room. I can edit the pics to show where I tested if it helps. How would I go about checking the balast caps?
Leave a comment:
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Viewsonic VG920 2 seconds...
While waiting for a regulator for my Proview I decided to take apart my Viewsonic with the usual two seconds to black issue. Now that my regulator has arrived, I'd like to get this Viewsonic off of my work table.
It's a Viewsonic VG920 with the usual problem. I looked it over and saw no evidence of bad components that I could find. The caps all looked normal physically, the transformers don't show an open circuit and are pretty close in resistance to eachother (once I figured out the pinout, they're sideways!). A few of the caps were Rubycon which surprised me.
I... -
Re: Proview PL926Wbi, no power
18 days later and my cheapo regularots have arrived. On my birthday no less! lol When I get a chance I'll break out the heat gun and try to get the old one off. It probably won't be until next week though. I have a basement to tear apart. *sigh*Leave a comment:
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Re: Proview PL926Wbi, no power
lol I thought even five was overkill...
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