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Old 01-16-2017, 07:08 PM   #1
Aeridyne
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Default Six Acer V173 LCD monitor all with same problem, only display Win 98 640res

I get the second flash to black issue on these mostly.

These are all Acer model V173 monitors. They all basically do the same thing, or I can't recall but a few might not power up at all. If important I can plug each of them in again and double check.

On the two that I've been focusing on, they do the same thing. One had one clearly going bad cap, the other one's power board looked totally fine. I replaced all but the two smallest on the board that had the one bad one on it. And on the other I did the one big cap anyway. (I then tested the removed cap that looked fine on the 2nd board with cap function on a matco meter I have and it was actually fine.)

Doing any of the caps has made no difference. I removed the two smallest from one of the boards, the only two I didn't do on the one board that I did all the others, and I tested them with the cap function and they were good too. So I have one board that has been mostly recapped and the ones I didn't replace test good when removed. (So basically, all caps on both boards are either new, or verified good.)

When turned on, if not connected to a VGA source, they will come on with the ACER logo fine, lamps light right up, and then show a "no signal" box. Then go dark. The light goes from blue to amber at this point.

If connected to a source when turned on, or simply connected to a source after turned on, the light will go blue, but nothing will come up on screen. If the VGA is then disconnected from the computer, it will again light up and show the "no signal" box, then go dark again. And by dark, the back lights are off.

The curious exception to this, is if I connect one to a Windows 98 system set to 640x480 display. They will usually display this. Not always but usually. I can disconnect and reconnect the VGA and it will usually come up and display and stay on. Not always, usually. I've gotten one to display an XP system and stay on once, and flash quickly a few times, but almost always it does nothing.

I'm stumped on these. Usually I can do re-caps but these seem to be a different animal. I have also tried swapping out the ccfls one at a time from other monitors and a laptop monitor. Pretty much same behavior, also visually inspected bulbs and they look 100% good on the ends. Also, obviously capable of staying on since they can display the 98 system usually, they just don't seem to want to stay on for some odd reason on anything else.

(BTW, behavior is the same whether I have the actual LCD panel connected to the VGA board via the ribbon cable or not)

I don't know how to check much else but I did check a few other things,

Each of these I put black lead on fat tab, and the readings are left to right as if fat tab is up.

(numbers on these two components U501 & U502 are; Nikos P2504BDG QN19K0501)
U502 (transistor?) - (not lit) 16.7v / 0 / 16.7 : (lit) 5.7 / 0 / 7
U501 (transistor?) - (not lit) 0 / 0 / 0 : (lit) 5.34 / 0 / 7.09

U101 (on VGA board, looks like 1117 series 3.3V) lit or not lit same = 3.2 / 0 / 1.8

There are three other "IC" (I think they are?) on the board.

(IC803)
A1
AS431A
A0814

(Q801)
C1815
GR8E

(IC801)
0823
817B

I also have two other Acer monitors, AL1706b, one dead as a doornail, and the other comes on sometimes and will display but has wavy picture. I will save those for after these I suppose, thought it worth mentioning though because they have very similar power boards, and also did not physically appear to have any caps bad, but still don't work right.

Any and all help much appreciated. I was tempted to just recycle these and say screw it, opting to fix only easily cap replaced ones, but I've spent the last two days trying to fiddle with these already and trying to learn about voltage regulators and such so at this point I'm not prone to giving up on them until I figure it out! But I fear I will never get there without the knowledge of others. I will try to post a few pics of the boards.
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File Type: jpg DSCN7336.jpg (705.4 KB, 7 views)

Last edited by Aeridyne; 01-16-2017 at 07:11 PM..
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Old 01-16-2017, 07:23 PM   #2
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Default Re: Six Acer V173 LCD monitor all with same problem, only display Win 98 640res

what is the history of them in as much detail as possible ?
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Old 01-16-2017, 07:24 PM   #3
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Default Re: Six Acer V173 LCD monitor all with same problem, only display Win 98 640res

"When turned on, if not connected to a VGA source, they will come on with the ACER logo fine, lamps light right up, and then show a "no signal" box. Then go dark. The light goes from blue to amber at this point. " It will go into standby it it thinks there is no Video signal receive from the PC, that is normal which you see 'NO SIGNAL" on the screen.
Something on the logic board is not working properly at high res mode, it is not detecting the signal.
If the power lights stays blue but no backlights, then you need to see if the main board is sending the BL-ON to turn on the backlights circuit or not.
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Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956

Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999

Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl

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http://s807.photobucket.com/user/budm/library/

TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809

Last edited by budm; 01-16-2017 at 07:25 PM..
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Old 01-16-2017, 07:26 PM   #4
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Default Re: Six Acer V173 LCD monitor all with same problem, only display Win 98 640res

ah i got it now ..resolution is too high from the source .. use a working monitor first and turn down to minimum .. try again .then set resolution ...
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Old 01-16-2017, 08:38 PM   #5
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Default Re: Six Acer V173 LCD monitor all with same problem, only display Win 98 640res

Pete, they came from a local school, they generally just set stuff aside when it does not work anymore and it goes to me, so I don't really have a detailed history of what they did before I got them. I did have a few of these same model, a few were white that did work, I no longer have them though. Wish I did, I'd have been swapping parts and praying most likely :P

Quote:
Originally Posted by budm View Post
"When turned on, if not connected to a VGA source, they will come on with the ACER logo fine, lamps light right up, and then show a "no signal" box. Then go dark. The light goes from blue to amber at this point. " It will go into standby it it thinks there is no Video signal receive from the PC, that is normal which you see 'NO SIGNAL" on the screen.
Something on the logic board is not working properly at high res mode, it is not detecting the signal.
If the power lights stays blue but no backlights, then you need to see if the main board is sending the BL-ON to turn on the backlights circuit or not.
I thought of this possibility, but I have no idea how to pursue how to test or potentially fix that particular issue. I'm kind of useless without specific direction beyond simply replacing caps. Trying to learn but haven't learned a lot yet. Should I post a picture of the VGA board to start down that road? I did test the only voltage regulator I could identify on it, the 1117 33 and it seemed fine. I don't know how to test anything else on it. There are two realtek chips on it & lots of other little stuff.

Last edited by Aeridyne; 01-16-2017 at 08:41 PM..
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Old 01-16-2017, 11:22 PM   #6
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Default Re: Six Acer V173 LCD monitor all with same problem, only display Win 98 640res

Oh, also Budm, just re-read your reply, blue light stays on, it thinks there is a signal, it just stays black though. Not sure what to do or how to do whatever I need to try next.

The only theory I had at this point was the really low res / low color mode somehow gets past something failed, but I really have no idea. (On the other hand it occurs to me that bios screens should be very low res & low color as well, and those do not display either.)

Last edited by Aeridyne; 01-16-2017 at 11:24 PM..
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Old 01-16-2017, 11:47 PM   #7
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Default Re: Six Acer V173 LCD monitor all with same problem, only display Win 98 640res

Another update, I went and got two more out from the basement and they seem mostly repeatable, but not exactly the same.

#3, I first hooked up to the 98 system at 640res, it displayed and stayed on. I then while still powered on, unhooked the VGA from the back of the 98 computer and hooked the monitor to a 7 computer, it stayed orange, as if not detecting the signal. I then pushed the power button twice turning it off and back on again and it then seemed to sense the signal, the power button going from amber to blue and staying blue but the screen stayed black and the backlights off.

#4 Did not display the 98 system at all, although it did stay blue, reconnecting it I saw a very brief flash then dark, again, nothing, then while connected I turned it off then on again while still connected to the 98 system and it came up and stayed on, display looked fine. Disconnect and hook to 7 system, led blue, screen black. Turning it off and back on while connected to the 7 system I saw a very brief flash of the screen and back to black. Led stays blue.
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Old 01-17-2017, 07:59 AM   #8
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Default Re: Six Acer V173 LCD monitor all with same problem, only display Win 98 640res

the resolution doesnt matter much, monitors will scale the input.
what does matter is frequency - dont set it lower than 60Hz or higher than 73Hz unless you know the monitor can handle it.
CRT monitors can handle much higher frequency's
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Old 01-17-2017, 09:28 AM   #9
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Default Re: Six Acer V173 LCD monitor all with same problem, only display Win 98 640res

Assuming that the screens are faultless (which might not uniform for the whole bunch ) , then , The best way to deal with some types of old LCDs in this case , is to force the computer into safe mode , uninstall the VGA driver , let it restart , so it goes on standard display , then reinstalling the VGA driver once again , which will let the system control and give what should be the best frequency and resolutions that those LCDs can support ..
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Old 01-17-2017, 10:09 AM   #10
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Default Re: Six Acer V173 LCD monitor all with same problem, only display Win 98 640res

User manual.
If Blue light is on then check if the BL-ON signal is present or not. what resolution does the win 7 computer is set to? Most monitor will put message such as " FORMAT NOT SUPPORTED" or "RESOLUTION NOT SUPPORTED" on the screen, but without backlights being on then you will not see the message.
Symptom of problem in the main board acting with resolution setting.
http://www.badcaps.net/forum/showthr...ghlight=HG281D
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Old 01-17-2017, 10:41 AM   #11
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Default Re: Six Acer V173 LCD monitor all with same problem, only display Win 98 640res

Thanks for the replies, I've checked the refresh rate and it does not seem to matter what it is set to. These monitors are not ancient, they are LCDs from about 08 and capable of max resolution 1280x1024 I believe, they should display just fine on a wide range of systems just like any other would. Win 7 auto adjusts to the display. I've had them hooked up to 4 different systems and the only one that will display is the 640 res most of the time, not always, sometimes have to turn it off and on to get that to display. And I feel that is a fluke and circumventing whatever the issue is. I can only access the menu when it is displaying the 640 system, no other time. I navigated the menu and "reset" but it made no difference. Something is broken on them, the other ones I had that did work that I no longer have would display Win 7 no problem at high resolutions. I would get one out at random, if it didn't work hooked up to the 7 system I set it aside and grabbed another one until I found one that worked, it was about every other, now I just have the ones that didn't work left. So I don't think its a matter of monkeying with settings or that they are old and need certain refresh etc, they are busted somehow. I just need to figure out exactly what and how to fix it. I know they aren't working right.

Budm - How do I check for BL-ON signal? Resolution set to 1024x768 @ 75Hz when connected to working monitor to check on the 7 system. Also tried 1024 @ 60Hz and made no difference.
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Old 01-17-2017, 10:55 AM   #12
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Default Re: Six Acer V173 LCD monitor all with same problem, only display Win 98 640res

I need STRAIGHT SHOT pictures (top and bottom side) of all the boards without the glares, and pictures showing how all the boards are connected together.
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Old 01-17-2017, 11:21 AM   #13
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Default Re: Six Acer V173 LCD monitor all with same problem, only display Win 98 640res

Having a tough time getting really good pictures, my camera isn't the best and it's really overcast today so outside is actually worse. I hope these will do. If not I can try again for whatever you need to see better.
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Old 01-17-2017, 11:30 AM   #14
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Default Re: Six Acer V173 LCD monitor all with same problem, only display Win 98 640res

http://www.badcaps.net/forum/attachm...2&d=1484673696
Power supply/Inverter board:
Pin 5: on/off = BL-ON. <1 VDC = Backlights OFF, >2.5 VDC = Backlights ON.
Pin 6: Brightness = Dim control signal.
So you should check the Voltages of all the pins (except GND) when you do have backlights and pictures on the screen and when you do not (but Blue Power is still on solid).
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Old 01-17-2017, 11:43 AM   #15
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Default Re: Six Acer V173 LCD monitor all with same problem, only display Win 98 640res

Quote:
Originally Posted by Aeridyne View Post
Thanks for the replies, I've checked the refresh rate and it does not seem to matter what it is set to. These monitors are not ancient, they are LCDs from about 08 and capable of max resolution 1280x1024 I believe, they should display just fine on a wide range of systems just like any other would. Win 7 auto adjusts to the display. I've had them hooked up to 4 different systems and the only one that will display is the 640 res most of the time, not always, sometimes have to turn it off and on to get that to display. And I feel that is a fluke and circumventing whatever the issue is. I can only access the menu when it is displaying the 640 system, no other time. I navigated the menu and "reset" but it made no difference. Something is broken on them, the other ones I had that did work that I no longer have would display Win 7 no problem at high resolutions. I would get one out at random, if it didn't work hooked up to the 7 system I set it aside and grabbed another one until I found one that worked, it was about every other, now I just have the ones that didn't work left. So I don't think its a matter of monkeying with settings or that they are old and need certain refresh etc, they are busted somehow. I just need to figure out exactly what and how to fix it. I know they aren't working right.

Budm - How do I check for BL-ON signal? Resolution set to 1024x768 @ 75Hz when connected to working monitor to check on the 7 system. Also tried 1024 @ 60Hz and made no difference.

I did such procedure some hundreds of times .. It shows on the windows 98 640*480 cause it's a low resolution available in any monitor or LCD . We may even call it a basic display .
Some types of LCDs only need to boot a computer , and then off and on them like three times and they'll catch the resolution and ignite the signal . Others need to press F8 while booting while screen is black , or shut down the computer repeatedly to force him go to safe mode ..

Tempering with probable good screens with some capacitors waking up after a long sleep needs a little patience ..The rest is up to you .
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Old 01-17-2017, 12:53 PM   #16
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Default Re: Six Acer V173 LCD monitor all with same problem, only display Win 98 640res

thanks Budm, I didn't even noticed that the power output from the power/inverter board to the vga board was labeled! Good eye!

Ok so the Pin 1 & 2 says 5V and they look good. Pin 6 looks reasonable and the pin 5 / BL-ON pin has nothing, the power led is blue, back lights are off.

pin 1 4.9
pin 2 4.9

pin 5 (bl-on) 0
pin 6 (brightness) 2.67
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Old 01-17-2017, 12:56 PM   #17
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Default Re: Six Acer V173 LCD monitor all with same problem, only display Win 98 640res

Its being a punk and won't display on the 98 system at the moment either, goes right back to black after 5 attempts to turn off/on. I can catch it while the lights are on briefly though and pin 5 shows 3V at that time.
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Old 01-17-2017, 12:57 PM   #18
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Default Re: Six Acer V173 LCD monitor all with same problem, only display Win 98 640res

Well, no BL-ON = No Backlights. That signal is generated by the main/logic board so main board troubleshooting will be next to find out why.
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Old 01-17-2017, 01:12 PM   #19
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Default Re: Six Acer V173 LCD monitor all with same problem, only display Win 98 640res

I see one regulator IC U101 on that main/logic board. What is the P/N on it and what DCV do you get on all 3 pins with ref to GND.
You can also try heating up that main board with hair dryer for a 22-3 minutes and then power up the monitor with running PC to see what happen.
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Old 01-17-2017, 01:19 PM   #20
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Default Re: Six Acer V173 LCD monitor all with same problem, only display Win 98 640res

U101 is
A1
AS1117L-33
B0815 D1

it measures, with black lead on top "fat" tab, from left to right
3.2V / 0 / 1.8
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