Need help with my 900G

[PlainBill]

Re: Need help with my 900G

PlainBill
well I replaced the defective zener, brown green green, with the only one I could find, red red green, attached to one of my used circuit boards.
I am typing this post using the monitor that has been down for weeks.
THANK YOU, THANK YOU, THANK YOU and to all the others that worked patiently with me through this.
Now I just need to figure out why I have a horizontal line across the middle of the screen. Go figure. LOL
Do you have any ideas what could be causing this? Is it because I used a different zener?

What is the voltage across that zener (measure it). If the input voltage to the inverter controller is too high you could damage it.

As far as the line across the screen, I AM good, but even with my new eyes I can't see that far.

PlainBill

[oldmanjohnson]

Re: Need help with my 900G

Well I spoke too soon. About an hour after I said it was gone it came back. Now it hasn't gone away again all day.
It's the craziest thing in that it looks like a piece of thread stretched across the surface of the screen. When I put the mouse pointer on it, it's actually under the line. It's weird looking 3 dimensional. LOL

[oldmanjohnson]

Re: Need help with my 900G

PlainBill
Okay I will put this thing back on the bench and check that voltage and get back to you.

[oldmanjohnson]

Re: Need help with my 900G

PlainBill
I checked the voltage across the zener and it's 11.54. Then I turned the house inside out looking for one of a lower rating and came up empty handed. I guess I will just have to take my chances with it and order what I need. I do have another ccfl chip just in case.
Should that voltage properly read 7.5 if I have the correct zener?

[PlainBill]

Re: Need help with my 900G

PlainBill
I checked the voltage across the zener and it's 11.54. Then I turned the house inside out looking for one of a lower rating and came up empty handed. I guess I will just have to take my chances with it and order what I need. I do have another ccfl chip just in case.
Should that voltage properly read 7.5 if I have the correct zener?

I would think so. Upon further review, the important voltage is the voltage at pin 10 of the inverter controller. The zener you used is rated for 15V, the supply to the inverter is below that.

By all means, take your chances. It's not that often I meet someone who looks forward to replacing an SMD device twice.

PlainBill

[oldmanjohnson]

Re: Need help with my 900G

Does anyone here know where I can find a schematic for a 20" Astar LCD TV?
A friend of my daughter gave it to me and the only thing wrong with it is no sound.
I opened it up and can't see anything obvious so I need to do some tracing.

[PlainBill]

Re: Need help with my 900G

Does anyone here know where I can find a schematic for a 20" Astar LCD TV?
A friend of my daughter gave it to me and the only thing wrong with it is no sound.
I opened it up and can't see anything obvious so I need to do some tracing.

From another source, a list of possible sources of documentation.

<http://kythuatvitinh.com/forum.php>

<http://www.eserviceinfo.com>

http://www.bitsavers.org/pdf/

http://128.238.9.201/~kurt/manuals/manuals/

http://www.ko4bb.com/

www.elektrotanya.com

http://english.electronica-pt.com/

http://www.4shared.com/dir/7126951/4..._INVERTER.html

Information is provided As-IS, no warranty at this price.

PlainBill

[oldmanjohnson]

Re: Need help with my 900G

PlainBill
Thank you for all that info. I will have to spend some time now going through it.
I truly appreciate your assistance.

[oldmanjohnson]

Re: Need help with my 900G

PlainBill
well my ccfl survived the high voltage zener. Got the 7.5's in yesterday and now have the correct zener in place.

Also I have been looking through each of the links you posted for the schematic for the Astar LTV-20pw tv and haven't been able to find one. So I started accumulating the data sheets for the chips on the board that are in the vicinity of anything related to sound. It looks like every component in the 400's is related to sound somehow. I checked voltages in and out at the sound and amp chips and they are correct. So I'm guessing the holdup is somewhere between the rca inputs and the sound chip. Do you think I'm following a logical course of action?

[PlainBill]

Re: Need help with my 900G

PlainBill
well my ccfl survived the high voltage zener. Got the 7.5's in yesterday and now have the correct zener in place.

Also I have been looking through each of the links you posted for the schematic for the Astar LTV-20pw tv and haven't been able to find one. So I started accumulating the data sheets for the chips on the board that are in the vicinity of anything related to sound. It looks like every component in the 400's is related to sound somehow. I checked voltages in and out at the sound and amp chips and they are correct. So I'm guessing the holdup is somewhere between the rca inputs and the sound chip. Do you think I'm following a logical course of action?

Almost absolutely. One thing I would point out is that every LCD monitor with speakers that I have ever seen has an electonic volume control and possibly mute control.

PlainBill

[oldmanjohnson]

Re: Need help with my 900G

PlainBill
okay I will see if I can figure out how to check those circuits.
Thanks

[PlainBill]

Re: Need help with my 900G

PlainBill
okay I will see if I can figure out how to check those circuits.
Thanks

On my monitor the Up and Down arrows function as volume up and volume down when the OSD is off. If the Astar controls don't function that way go to the menu screen on the monitor. There may be a screen to adjust the volume.

The actual volume adjustment takes place on the amplifier chip.

PlainBill