MONITOR REPAIR HELP
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, voltage on pin 7 of ic601 is 12-15 volt(flactuating in between ) it should be 16 volt to generate Vref (5volt)on pin 8 of ic601 to start?!capacitor c626 have been replaced , but still does not start!& the fault is still unknowen !
Your help will be usefull.
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Re: Help on monitor repair
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
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Hi. Almost all the crt type monitors should work, it's flat screen monitors that seem to give computers problems with aspect ratios, and resolution settings.
I personally use an NEC AccuSync 70. It might not be the newest monitor in the world, but the colors are crisp, clear, and bright. And It allows a setting of 1024x768@85 hz refresh rate, which works great for my games.
As far as flat screens, I would probably go with an Acer, or a Dell monitor, as these two companies seem to have better quality from their monitors than most other manufacturers.
mountainmom, Always state make, model number, and TYPE of unit. Is it a big old CRT type or is it a LCD monitor? Need more information. What is the "date of manufacture" from rear label on monitor. 12fixlouie
According to the model type, it has likely reached the end of its service life. It would cost a great deal more to have it repaired than to replace it. Here is an example of an inexpensive alternative in the new market ( http://www.walmart.com/ip/Acer-ET.LBF09.030/5013901 )and there are thousands of used lcd monitors available from places like Ebay.
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.
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.