My Sharp LC-45GX6U gives only a white screen when I turn it on.

I got some additional information that I expect will not change your recommendation but I would appreciate it if you could confirm. I tried the "K" test on the monitor again. When the input and vol buttons are held in, the on/off switch will not turn off the monitor, it must be unplugged to turn it off. The on/off switch will control the monitor if the "K" test is not performed. Also, the AVC unit does not turn on if there are no cables in the output ports. I expect this is normal. Finally, to test the AVC unit, I tried using a DVI cable on the AVC unit output, but the wide pin on the DVI cable was too wide for the output fitting on the AVC unit. Is there more than one type of DVI connector? I got some additional information that I expect will not change your recommendation but I would appreciate it if you could confirm. I tried the "K" test on the monitor again. When the input and vol buttons are held in, the on/off switch will not turn off the monitor, it must be unplugged to turn it off. The on/off switch will control the monitor if the "K" test is not performed. Also, the AVC unit does not turn on if there are no cables in the output ports. I expect this is normal. Finally, to test the AVC unit, I tried using a DVI cable on the AVC unit output, but the wide pin on the DVI cable was too wide for the output fitting on the AVC unit. Is there more than one type of DVI connector?

Here is test mode procedure for this model...
1- Unplug the AC cord with the monitor power SW "ON".
2- While holding down the "VOL + " and "V CH" keys at a time, plug in the monitor AC cord. The unit starts up in the "monitor process mode".
Page 1 of the "Monitor adjustment mode" appears.
(The same displays appear on the left and right sides of the screen.)
* To exit the adjustment process mode, turn off the power.
Monitor should show test pattern.
Do not change any value if you get service/test menu display to avoid any wrong input.
Regarding testing AVC monitor output, please connect usual AV cable as mentioned in below image monitor output jacks and plug it in any other tv to get AVC output.
Thanks.





Here is test mode procedure for this model...
1- Unplug the AC cord with the monitor power SW "ON".
2- While holding down the "VOL + " and "V CH" keys at a time, plug in the monitor AC cord. The unit starts up in the "monitor process mode".
Page 1 of the "Monitor adjustment mode" appears.
(The same displays appear on the left and right sides of the screen.)
* To exit the adjustment process mode, turn off the power.
Monitor should show test pattern.
Do not change any value if you get service/test menu display to avoid any wrong input.
Regarding testing AVC monitor output, please connect usual AV cable as mentioned in below image monitor output jacks and plug it in any other tv to get AVC output.
Thanks.

Tried the test procedure on the monitor, vol and ch buttons, got a couple of "K"'s and some arrows. When I turned the power off the monitor went off, no test pattern.

I also tried the AVC with a monitor cable in the video and one of the audio outputs. I got no response from the AVC except for a click when plugged in and a second click. Also got a relay type click when the power button was pressed on the AVC.


Does this sound like an AVC DV/DV board problem?
If so, the board will be very hard to find. Tried the test procedure on the monitor, vol and ch buttons, got a couple of "K"'s and some arrows. When I turned the power off the monitor went off, no test pattern. I also tried the AVC with a monitor cable in the video and one of the audio outputs. I got no response from the AVC except for a click when plugged in and a second click. Also got a relay type click when the power button was pressed on the AVC. Does this sound like an AVC DV/DV board problem? If so, the board will be very hard to find.

If tv showed K during test then it seems every thing is fine and AVC would be defective, please attach AVC with tv and turn it On, if it remains On then check monitor output of AVC by attaching any other tv in above mentioned monitor output jacks of AVC to get audio-video.
Yes, dc-dc for AVC seems difficult to find out.
Thanks.
If tv showed K during test then it seems every thing is fine and AVC would be defective, please attach AVC with tv and turn it On, if it remains On then check monitor output of AVC by attaching any other tv in above mentioned monitor output jacks of AVC to get audio-video.
Yes, dc-dc for AVC seems difficult to find out.
Thanks.

When turned on the monitor gives a white screen with AVC attached. The remote will switch the monitor on and off, but no other functions. The AVC indicator lights do not turn on only the click from the AVC relay. There is no output from the AVC video jack when another TV is hooked to the video output on the AVC.

Since replacing the AVC DC/DC card may not be possible, is repair of the AVC DC/DC card possible? None of the components on the card show obvious defects (no leakage or burn marks). When turned on the monitor gives a white screen with AVC attached. The remote will switch the monitor on and off, but no other functions. The AVC indicator lights do not turn on only the click from the AVC relay. There is no output from the AVC video jack when another TV is hooked to the video output on the AVC. Since replacing the AVC DC/DC card may not be possible, is repair of the AVC DC/DC card possible? None of the components on the card show obvious defects (no leakage or burn marks).

DC-DC converter board in AVC can be repaired on component level and it requires good knowledge of electronics, schematics/ service manual copy of AVC/TV and proper tools. A good technician can repair that dc-dc board on component level.

DC-DC converter board in AVC can be repaired on component level and it requires good knowledge of electronics, schematics/ service manual copy of AVC/TV and proper tools. A good technician can repair that dc-dc board on component level.

Ok Guru, I have a challenge for you. Can you give me help with the DC inverter board? I have a service manual and I checked the voltages indicated on the schematics. Most voltages looked normal when the monitor was turned on. Most also went to 0 when a relay clicked about 2 seconds after the monitor was turned on. However, on one of the plugs, a 9V output was specified and I got 0 when the unit was both off and on. The 9V power was on a small plug with only 3 wires. The 9V signal goes to the power unit in the AVC so it looks like it is the culprit.

As a second option, I found an AVC unit for a Sharp HC-37HV6U. Can you tell me if it will work with my monitor? Is there a reasonable chance that it has the DC inverter card I need?

Thanks Ok Guru, I have a challenge for you. Can you give me help with the DC inverter board? I have a service manual and I checked the voltages indicated on the schematics. Most voltages looked normal when the monitor was turned on. Most also went to 0 when a relay clicked about 2 seconds after the monitor was turned on. However, on one of the plugs, a 9V output was specified and I got 0 when the unit was both off and on. The 9V power was on a small plug with only 3 wires. The 9V signal goes to the power unit in the AVC so it looks like it is the culprit. As a second option, I found an AVC unit for a Sharp HC-37HV6U. Can you tell me if it will work with my monitor? Is there a reasonable chance that it has the DC inverter card I need? Thanks

I hope AVC of HC-37HV6U will work with LC-45GX6U
Regarding missing 9V in Dc-DC board, please check power supply board for little pico fuse on 9V supply line.
I'll study schematics of power board to answer in details.
Thanks.
I hope AVC of HC-37HV6U will work with LC-45GX6U
Regarding missing 9V in Dc-DC board, please check power supply board for little pico fuse on 9V supply line.
I'll study schematics of power board to answer in details.
Thanks.

Thanks for the quick response. By the way, thanks also for checking on the test procedure for the monitor. Your correcting me on the test procedure on the monitor (the chn and vol buttons) saved lots of time and money. Now for the current problem -- I need to decide whether to purchase the HC-37HV6U AVC box for about $50. I need to have it shipped across the country, so I can't test it before buying it. I'll contact Sharp about the compatibility issue tomorrow. I have studied the schematic for the DC inverter board and I'm pretty certain that the 9V signal goes FROM the inverter board not TO it. I am assuming that the convention is to have inputs on the left and outputs on the right side of the schematics. The 9V circuit does not have any fuses (too bad). It does have several ferrite beads, several zenier diodes, transistors, diodes, capacitors, inductors and IC chips. Can you guess at what type of component would be most likely to fail? My next step will be to track the voltage across the schematic. One of the signals on the P1701 output connector is labeled "D-Pow". "Pow" I expect is power. This is an input signal to several of the transistors in the 9V circuit. What does D-Pow mean? Thanks for the quick response. By the way, thanks also for checking on the test procedure for the monitor. Your correcting me on the test procedure on the monitor (the chn and vol buttons) saved lots of time and money. Now for the current problem -- I need to decide whether to purchase the HC-37HV6U AVC box for about $50. I need to have it shipped across the country, so I can't test it before buying it. I'll contact Sharp about the compatibility issue tomorrow. I have studied the schematic for the DC inverter board and I'm pretty certain that the 9V signal goes FROM the inverter board not TO it. I am assuming that the convention is to have inputs on the left and outputs on the right side of the schematics. The 9V circuit does not have any fuses (too bad). It does have several ferrite beads, several zenier diodes, transistors, diodes, capacitors, inductors and IC chips. Can you guess at what type of component would be most likely to fail? My next step will be to track the voltage across the schematic. One of the signals on the P1701 output connector is labeled "D-Pow". "Pow" I expect is power. This is an input signal to several of the transistors in the 9V circuit. What does D-Pow mean?

I've been testing the DC inverter board. The 9V supply seems to be generated normally but then gets stopped by an IC chip (schematic #Q1709). This chip has has 8 pins, 4 labeled "D" are 9V inputs, 3 labeled "S" should be 9v outputs (but the output is low, about .3V), and one pin labeled "G" for gate. When the unit is off, the G pin as .3 V. When the AVC is turned on the G signal starts dropping to .1 V and then the relay kicks the power off and the voltage returns to .3V. I'm thinking the G pin is sending a signal back to another IC chips that senses failures, but I'm not sure. It looks to me like the G pin should send a signal to another IC chip that also as a "gate" pin -- the low level drifting signal looks like were he problem is . Guru, please comment, I think I'm close, but I need help. I've been testing the DC inverter board. The 9V supply seems to be generated normally but then gets stopped by an IC chip (schematic #Q1709). This chip has has 8 pins, 4 labeled "D" are 9V inputs, 3 labeled "S" should be 9v outputs (but the output is low, about .3V), and one pin labeled "G" for gate. When the unit is off, the G pin as .3 V. When the AVC is turned on the G signal starts dropping to .1 V and then the relay kicks the power off and the voltage returns to .3V. I'm thinking the G pin is sending a signal back to another IC chips that senses failures, but I'm not sure. It looks to me like the G pin should send a signal to another IC chip that also as a "gate" pin -- the low level drifting signal looks like were he problem is . Guru, please comment, I think I'm close, but I need help.

Hi,
Thats good that you are so close to sort out problem on component level repair.
Please check R1729 and D1717 marked with red circle in below image.
PLG CK is on/off command to control Q1709 through IC1705, please check PLG CK command that may appear to turn Off Q1709 chip.


Hi,
Thats good that you are so close to sort out problem on component level repair.
Please check R1729 and D1717 marked with red circle in below image.
PLG CK is on/off command to control Q1709 through IC1705, please check PLG CK command that may appear to turn Off Q1709 chip.

Good to hear from you and glad to see you have the schematic. The 9V supply goes to an output plug on the back of the AVC unit. Since it is not being used, the plug check wire is at 0v and the IC is turned off -- just as it is designed. Additional checks show the following --on P1752 pin 7, P1781 pin1 Good to hear from you and glad to see you have the schematic. The 9V supply goes to an output plug on the back of the AVC unit. Since it is not being used, the plug check wire is at 0v and the IC is turned off -- just as it is designed. Additional checks show the following --on P1752 pin 7, P1781 pin1

All of last message did not get sent. It continues as -- no 6V or 35V signal on plugs P1702, P1752 and P1781. IC592 has 15V inputs on pins 18-21 but no output on pins 11-14. Pin5 is 0V so IC is turned on and pin 28 has 4.9V reference. Pin 8 has Vboot of 8V and spec is 6.5V with max of 7.6V. How do you suggest I proceed with this circuit? Data on IC952 is available at "www.datasheetarchive.com" and search for "MD1222N". There is a 2 pg. PDF file with chip data. All of last message did not get sent. It continues as -- no 6V or 35V signal on plugs P1702, P1752 and P1781. IC592 has 15V inputs on pins 18-21 but no output on pins 11-14. Pin5 is 0V so IC is turned on and pin 28 has 4.9V reference. Pin 8 has Vboot of 8V and spec is 6.5V with max of 7.6V. How do you suggest I proceed with this circuit? Data on IC952 is available at "www.datasheetarchive.com" and search for "MD1222N". There is a 2 pg. PDF file with chip data.

Good news, I think. I was checking the IC592 and noted that when I turned the AVC on, I did not have the white screen, the AVC seems to be working. I will check it out. Any ideas on what I should do while the DC/DC inverter card is exposed and available for testing? I am concerned that the recovery may be temporary. On the internet, I saw someone else had the white screen problem, had recovery, but it died again several months later. Good news, I think. I was checking the IC592 and noted that when I turned the AVC on, I did not have the white screen, the AVC seems to be working. I will check it out. Any ideas on what I should do while the DC/DC inverter card is exposed and available for testing? I am concerned that the recovery may be temporary. On the internet, I saw someone else had the white screen problem, had recovery, but it died again several months later.

Check out my last reply that I incorrectly posted to your 5 day old response. Here it is repeated. "Good news, I think. I was checking the IC592 and noted that when I turned the AVC on, I did not have the white screen, the AVC seems to be working. I will check it out. Any ideas on what I should do while the DC/DC inverter card is exposed and available for testing? I am concerned that the recovery may be temporary. On the internet, I saw someone else had the white screen problem, had recovery, but it died again several months later. " Check out my last reply that I incorrectly posted to your 5 day old response. Here it is repeated. "Good news, I think. I was checking the IC592 and noted that when I turned the AVC on, I did not have the white screen, the AVC seems to be working. I will check it out. Any ideas on what I should do while the DC/DC inverter card is exposed and available for testing? I am concerned that the recovery may be temporary. On the internet, I saw someone else had the white screen problem, had recovery, but it died again several months later. "

More information -- I accidently shorted pins 25 and 26 and got the white screen again. It stayed white through a couple of power on/off cycles but came back OK when I powered up while trying to measure one of the pins in the 23 to 27 range. The first OK power up an hour ago happened while I tryed to measure pin 1. There is some problem in the start up of the IC952 chip. I have the steady state voltages for all the IC952 pins. I wonder if the hi Vboot value (8V with white screen) could be the problem. The steady state value for Vboot now is 6.57V. Your ideas? More information -- I accidently shorted pins 25 and 26 and got the white screen again. It stayed white through a couple of power on/off cycles but came back OK when I powered up while trying to measure one of the pins in the 23 to 27 range. The first OK power up an hour ago happened while I tryed to measure pin 1. There is some problem in the start up of the IC952 chip. I have the steady state voltages for all the IC952 pins. I wonder if the hi Vboot value (8V with white screen) could be the problem. The steady state value for Vboot now is 6.57V. Your ideas?

And more detail -- I turned off/on power and got white screen again. After several trys I was able to get the unit to power up OK when I measured the voltage on pin 2 during power up. Measuring pin 8 and pin1 during start up did not fix the white screen. And more detail -- I turned off/on power and got white screen again. After several trys I was able to get the unit to power up OK when I measured the voltage on pin 2 during power up. Measuring pin 8 and pin1 during start up did not fix the white screen.

Here are steady state on pin voltages on IC952 1 - 4.9 2- 4.6 3- 4.7 4- 0 5- 0 6- 15 7- NC 8- 6.57 9- 2.44 10- NC 11-6.35 12- 6.35 13- 6.35 14- 6.35 15- NC 16- 0 17- NC 18- 15 19- 15 20- 15 21- 15 22- NC 23- 8 24- NC 25- 12 26- 0 27- .7 28- 4.8 29- NC 30- 1.8 31- NC 32- 2.4 Here are steady state on pin voltages on IC952 1 - 4.9 2- 4.6 3- 4.7 4- 0 5- 0 6- 15 7- NC 8- 6.57 9- 2.44 10- NC 11-6.35 12- 6.35 13- 6.35 14- 6.35 15- NC 16- 0 17- NC 18- 15 19- 15 20- 15 21- 15 22- NC 23- 8 24- NC 25- 12 26- 0 27- .7 28- 4.8 29- NC 30- 1.8 31- NC 32- 2.4

Hi,
Due to intermittent problem in DC-DC board, I would suggest to resolder all surface mount chips (ICs) / resistors on DC-DC converter board as it seems dry solder joints some where and requires touch up/ resoldering to refresh solder contact.
Thanks.
Hi,
Due to intermittent problem in DC-DC board, I would suggest to resolder all surface mount chips (ICs) / resistors on DC-DC converter board as it seems dry solder joints some where and requires touch up/ resoldering to refresh solder contact.
Thanks.

I don't know that my problem is intermittent, so I am reluctant to try resoldering. I also hesitate to resolder because I'm concerned I will do more harm than good. The AVC unit has only restarted successfully when I have been measuring voltages on the IC952 chip during power up. If the IC952 circuit does not start when power is applied, it never starts. By power up, I mean plugging the unit in, not turning it on and off. The DC inverter board is always active if power is applied, even if the unit is turned off. So far, the unit has been consistent, not intermittent -- more history may change that. I would still like to see your thoughts on the high Vboot voltage. The problem is definately in the start up circuit. I don't know that my problem is intermittent, so I am reluctant to try resoldering. I also hesitate to resolder because I'm concerned I will do more harm than good. The AVC unit has only restarted successfully when I have been measuring voltages on the IC952 chip during power up. If the IC952 circuit does not start when power is applied, it never starts. By power up, I mean plugging the unit in, not turning it on and off. The DC inverter board is always active if power is applied, even if the unit is turned off. So far, the unit has been consistent, not intermittent -- more history may change that. I would still like to see your thoughts on the high Vboot voltage. The problem is definately in the start up circuit.

I have had the exact same experiences. I have been able to get IC952 to start by heating it. I touched up the solder, but no help. I've checked all the parts around it and they are all OK (I'm an EE - hardware design engineer). I'm going to try to get the replacement part, but looks like it has to be bought through international parts brokers. That may create a problem... I have had the exact same experiences. I have been able to get IC952 to start by heating it. I touched up the solder, but no help. I've checked all the parts around it and they are all OK (I'm an EE - hardware design engineer). I'm going to try to get the replacement part, but looks like it has to be bought through international parts brokers. That may create a problem...

BTW - [email protected] BTW - [email protected]

Hi,
I thought you got AVC of HC-37HV6U for this monitor and would be enjoying tv shows. Hi, I thought you got AVC of HC-37HV6U for this monitor and would be enjoying tv shows.

welcomegee, thanks for letting me know John27670 has the same problem I do. I can help John get his unit started. My fix is still temporary. If I lose power to the unit, I will need to open the box up to make it restart. Once it powers up OK, it continues to operate OK (now about 23 days) until it loses power. John27670, can you hear me? What is the best form to communicate with you? Here or by E-mail? Let me know. WE can fix this, I think it is a problem with the circuit design. I suspect all the components function OK but because the design is weak, noise or some other random factor causes the malfunction. welcomegee, thanks for letting me know John27670 has the same problem I do. I can help John get his unit started. My fix is still temporary. If I lose power to the unit, I will need to open the box up to make it restart. Once it powers up OK, it continues to operate OK (now about 23 days) until it loses power. John27670, can you hear me? What is the best form to communicate with you? Here or by E-mail? Let me know. WE can fix this, I think it is a problem with the circuit design. I suspect all the components function OK but because the design is weak, noise or some other random factor causes the malfunction.