How To Restore A 17″ Monitor CRT Picture Tube
How To Restore A 17" Monitor CRT Picture Tube
The first part of the piece mentioned about how you can tap from the resulting diode to get the craving crop through the 7808 voltage valve. The weakness of this trip is that it can’t muscle up the 17” overseer because the muscle bring have some regulateation in delivering existing to the better CRT tube. The muscle bring will whichever rapidlyen itself off or muscle blink. In order to answer this setback, we have to tap voltage from some other chairs in the overseer. Unfortunately there were no more chairs (principle) in the overseer where you can tap the voltage to muscle up the better CRT tube. Due to we could not locate the principle then we have to coin (sketch) our own trip. The best is to use the overseer flyback transformer ferrite staple and with rope circle around the staple will make high pulse ac. This high pulse ac can’t be quantity by your customary indicator.
With few whirling at the staple (exterior circle), you can get a advanced ac crop voltage to muscle up the CRT warmer. This system only applies if you want to recover up a Television picture tube. You can’t use this way on overseer CRT because as mentioned formerly in the first part of the piece, overseer runs on different resolution. The advanced the resolution, the advanced the B+ voltage bring to the leading winding of the flyback transformer. The advanced the B+ voltage, the larger is the voltage crop at the resulting part making the crop voltage (ac) maked by the exterior circle even advanced. hence this will make a hasty foster in the fiber voltage causing an direct vivid in the overseer raster. Some monitor sketched will rapidlyendown if it notice a hasty vividness in the raster.
Even if the monitor didn’t rapidlyendown and if the client determine to inferior the overseer resolution, the raster will hastyly become too dim due to inferior B+ voltage. You may ask manually why notebook overseer has its own 6.3 vdc crop and why not like TV, the warmer voltage comes from the resulting winding of TV flyback transformer? The answer is because the overseer sketcher needs a steady 6.3 volt for fiber and don’t want the raster to be unnatural by a shifting in overseer resolution. In order to answer this setback, after making about 7 to 10 circles around the flyback transformer staple, you have to alter this high pulse ac into DC voltage. You can’t plainly use any diodes for this principle. A universal principle diode like the infamous 1N5401-1N5408 would not be able to work in this trip. The high pulse ac voltage will immediately murder the diode once the overseer is whiped “on”. You have to use an mega rapidly recovery diode to do the job.
For your information, not all mega rapidly recovery diode can efficiently run on this trip. You have to regulateed the diode manner that has a rapidlyer race time like a 50 nanosecond and below. I had tried a 75 nanosecond mega rapidly recovery diode and it blown at 800 by 600 resolutions but work well in the 640 by 480 resolution. After done some R & D, I found that the best part number to use is the UF5404. This diode has the specification of 400V, 3A and 50ns. Once you have coupled the ac voltage to the diode, you now have to use a filter capacitor to filter off the flow. You can use a quantity of 220 to 1000 microfarad 50V. quantify the crop DC voltage and make surely it must have about at slighassess 15 to 20 over volts before you connect to pin 1 of 7808 voltage valveYou can also try to use a 7809 if the show is not vivid enough. Don’t use any voltage valve that is advanced than 7809 otherwise the warmer fiber will get too hot and burn.
Pin 3 of the voltage valve is the crop and it must dual to the warmer pin at the CRT enter as exposed in the photo. sensibly place all the ropes in a strategic site and fasten the voltage valve at the round sink bepart the flyback transformer. You are now prompt to whip on the overseer and restraint if there is recoverment in the show. If it sanction then burn in assess the overseer for couples of existence to restraint if the show is still vivid and plain. If you are not delightd with the serration, you can try to foster another volt by shifting the voltage valve part number to 7809. Some technicians desire to use a flexible voltage valve such as the LM317T with a flexible resistor so that they can adjust to the craving voltage. If the picture tube is still dim and no way that you can recover the show, I deduction the time is up for the CRT tube. You whichever exchange a worn tube or earnings the overseer back to the purchaser. I chance you have recital this piece. If so, delight feel released to allocate this piece with your links or plainly ahead this piece to everyone you want!
Jestine Yong is a electronic healinger and a essayist, for more electronic and monitor healing information, delight trip his website at http://www.electronichealingguide.com/notebook-monitor.html