Hi I would like to appreciate for your help
I have got an Acer monitor model G781 CRT Type
its switching power supply is not starting
300 volt supply is ok , Q602 (2SK1940 )& ic 601 (UC3842)have been changed with new one, switch transformer is ok .but it does not start .
still I have no schematic diagram to trace & trouble shoot .
any kind of help will be usefull .
I have a samsung make 29" monitor and at start up its normal but after few minints the picture is starts flickering and increase gradually and after almost 15min all screen goes spraded that even cant c the pic, please help for the same
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Re: MONITOR REPAIR HELP
The mains switch is a weak link on these, check this first. Also 1 of 2 33K 2W startup resistors in PSU goes o/c, check with DVM or if you have very high volts on main primary res cap this usually indicates a 33K has gone - change both. I've also had a small TO92 transistor hanging off the UC3842 failing causing no startup. A s/c HOT normally causes a blinking LED.
note that AC cap IS charged, DISCHARGE BEFORE WORKING ON IT!
Did you check for shorts in the secondary side of the p/s, horiz output? If there are none , look for the switching regulator. Check the support components.
I've seen these with open solder connections on the coils in the PS
due to that abominable glue they use...you'll see signs of
burning/arcing on the inside of the cabinet, too.
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Dont think they are available any more. It's becoming a throw away world.
I used to fix them.... without a schematic. Your local TV technician can often assist with repairing an older style monitor. e.g. CRT tube type.
Modern monitors are LCD & digital electronics. Although they still blow fuses & have switch mode power supplies with leaky electrolytic capacitors that stop the power supply from working.
If your knowledgable in this field then I would start with a visual of the power supply. Be careful of the shock hazards.
first check with your both power supply out put is coming 19 Volts dc. if its not coming check with multi meter primary and secondary of your adopter continuity.if no continuity replace with proper working adopter.
A white screen indicates the power supply board is not putting out the correct voltages to properly power the monitor, just the back light. This type of issue is caused by a failure of the filter capacitors on the power board. You can rebuild your power supply board and bring the monitor back to life by just replacing the the bad capacitors. The problem is that model the Acer AL1711 could come with 1 of 4 different power supply boards install depending and the date manufacturer and supply on hand. If you want to repair the monitor if you could open the unit and get either the model number of the power supply board or send a picture of the board to me I will be glad to help you repair the unit and get it back up and running. You can contact me to send the information at firstname.lastname@example.org
On these older CRT monitors when you have that type of problem it indicated that the high voltage power supply is not putting out the right voltage to charge the picture tube. As the power supply gets weaker the time to show a picture will take longer and longer. It is not worth repairing the unit because parts will run much more than a replacement monitor.
This type of problem is usually caused by a failure in the power supply board. Here is a link to a repair guide that shows how to dis-assemble and repair the power supply board. If you can do a little soldering then you can repair the monitor. http://www.ccl-la.com/blog/index.php/repairing-the-acer-al2016w-monitor/ I hope this helps, if so please rate my solution.
Sorry no fuses that can be changed. Often it is just the power supply going on the fritz, take it in for repair, due to the cost of monitors repairs are usually very reasonable, as long as you find, a place that specializes in Monitor repair, it will be OK. Anyway you can always ask for a "Quote" and decide as to repair or replace,
MY SUGGESTION IS TO BUY A REPLACEMENT MONITOR AN LCD BECAUSE IT USES LESS energy about 50% less and at a low voltage.
YOU PROBABLY CAN FIND ANOTHER RELAY AND CAPACITOR ONLINE OR AT A TV REPAIR SHOP electronics supply warehouse BUT IF THESE COMPONENTS WENT BAD
OTHER COPONENTS MAY BE BAD ALSO AS A RESULT OF THESE HAVING FAILED SOMTIMES RESISTORS,DIODES AND TRASISITORS LOOK GOOD VISUALLY BUT ARE NOT.
Save your self sometime and money by getting a new lcd monitor
even if you repair your monitor its still old if you replace this mointor with a new one you elimiate all risk because a new monitor will have all new parts and a warranty and save money on your electric bill because it takes less power to operate.
Typical failure is High voltage supply. Can you hear a high pitch whine or the relay click on and off? You will need some test point reffence voltages for the board and confirm you do not have a damaged VGA cable. It is not easy to give step by step via forum. Google "monitor repair", there were a couple good general guides that are printable. If youe high voltage tranformer (flyback) is gone, do not go any further. Price of a monitor flyback is $65 to over $100 depending on model.
Have you checked the horizontal output transistor for a short or leakage?? most of these sets will not start up unless the horizontal sweep sends the pulse to the power supply and says start me up!! I would look at bthe drive as well on the horiz. curcuit. If theres a pulsating voltage that means its waiting for something to signal it to work or its missing something.. Good luck