obe1
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***WARNING*** This next step is dangerous and should be carried out very carefully.
The HT lead needs to be discharged of any remaining current by earthing it. There is equipment to do this but as I cannot afford one and do not have access to one I use this method. Make sure the monitor is UNPLUGGED, you will need two long reach screwdrivers (one must be a flat headed driver). One screwdriver tip should be placed against either the top left screw head or top right screw head that holds in the tube whilst holding the shaft around six inches from the tube, the FLAT HEADED screwdriver is then placed perpendicular on top of the first screwdriver and the flat tip is then gently slipped under the seal until you can feel it hit the metal clip in the middle (see photo 9).
If there is any current left in the lead, this will discharge it through the earthing strip that surrounds the tube.
Once it has been discharged the lead needs to be unclipped from the CRT, this is done with a pair of long nosed pliers and a small flat head screwdriver. Slip the small screwdriver under the bottom half of the seal and lift gently to reveal the clip, when you see the clip use the long nosed pliers to squeeze the two legs together and gently lift out.
Now the lead is unplugged, check the rubber seal to see if it has become hard. If it is hard you will need to reseal it with dielectric silicone rubber sealant (Dow Corning is a good make). Clean the underside of the seal and the CRT where the seal fits with Isopropanol fluid and a cloth. Run a small amount of silicone around the edge of the underside of the seal and using the long nosed pliers to squeeze together the legs of the clip, push the seal back in place whilst holding the seal away from the pliers so as not to remove the silicone (this does get easier with practise).
If the seal is still flexible and looks in good condition (see photo 10)
Once it has been discharged the lead needs to be unclipped from the CRT, this is done with a pair of long nosed pliers and a small flat head screwdriver. Slip the small screwdriver under the bottom half of the seal and lift gently to reveal the clip, when you see the clip use the long nosed pliers to squeeze the two legs together and gently lift out.
Now the lead is unplugged, check the rubber seal to see if it has become hard. If it is hard you will need to reseal it with dielectric silicone rubber sealant (Dow Corning is a good make). Clean the underside of the seal and the CRT where the seal fits with Isopropanol fluid and a cloth. Run a small amount of silicone around the edge of the underside of the seal and using the long nosed pliers to squeeze together the legs of the clip, push the seal back in place whilst holding the seal away from the pliers so as not to remove the silicone (this does get easier with practise).
If the seal is still flexible and looks in good condition (see photo 10)
then damp is probably the cause of the arcing. If this is the case then clean the seal and CRT as described above and leave to dry for about 1 hour. DO NOT use a hair dryer or any other type of heater to try to dry it out quicker as this will only create condensation. Once it has dried replace the seal as described above but without using the silicone sealant.
In both cases once the seal has been replaced leave to stand for about 1 hour. When 1 hour has passed plug the monitor into a PC and into a wall socket as described in the section 'Locating and testing the LOPTX' and then turn on the PC then turn on the monitor at the wall socket to test, there should now be no more arcing.
Checking the main chassis board
Making sure the monitor is unplugged and gently holding the front casing turn the monitor upside down and sit it on a flat surface gently placing the top of the front casing and the top of the tube base (the board attached the end of the CRT) onto the flat surface so as not to break the neck of the CRT (see photo 11).
In both cases once the seal has been replaced leave to stand for about 1 hour. When 1 hour has passed plug the monitor into a PC and into a wall socket as described in the section 'Locating and testing the LOPTX' and then turn on the PC then turn on the monitor at the wall socket to test, there should now be no more arcing.
Checking the main chassis board
Making sure the monitor is unplugged and gently holding the front casing turn the monitor upside down and sit it on a flat surface gently placing the top of the front casing and the top of the tube base (the board attached the end of the CRT) onto the flat surface so as not to break the neck of the CRT (see photo 11).
Now you can see the underside of the Chassis (see photo 12)
you may see signs of arcing by way of burn marks, if not plug the monitor into a PC and into a wall socket as described in the section 'Locating and testing the LOPTX' and then turn on the PC and then turn on the monitor at the wall socket to check if any arcing occurs, if there is no arcing straight away leave the monitor tuned on to warm up the components, this should only take 5 to 10 minutes but could take up to about 30 minutes. Once you have located the source of the arcing unplug the monitor from the PC and unplug the mains lead if connected. The area now needs to be cleaned using Isopropanol fluid and a small stiff brush such as a tooth brush. Now carefully check the area using a magnifying glass if needed to find the faulty solder joint or the crack making sure not to touch any of the components.
Once you have located the specific problem this needs to be fixed by soldering. A faulty solder joint is easily fixed by adding a little solder to the joint whilst heating the existing solder with a soldering iron. A crack however is slightly more difficult cure. If the crack is across 1 run of circuit track then the track needs to be linked with a piece of insulated wire soldered to the first available soldered joint on either side of the crack. If the crack spans several tracks then this needs to be repeated for each track. In each case gently rub off the coating to reveal the copper of the track either side of the crack and use a multimeter with a continuity test function to trace the first available joint on that track to solder the link to. You can of course check your work with a magnifying glass to check your solder joints, once you are happy with your work reconnect the monitor as described above to check that all the soldering has worked.
Replacing the monitor back
Replacing the shielding and the monitor back is basically a reverse of the removal process with the exception that some aligning needs to be done. Gently place the monitor upright as described in 'Locating and testing the LOPTX' and replace the shielding.
Now gently place the monitor face down on the towel as described in the section Removing the monitor back. There should be a slot on either side of the inside of the back casing that the main chassis board should slide into when the back is replaced. Make sure the chassis is aligned with these slots as you slide the back casing back onto the monitor. When the back casing meets the front casing make sure that all the edges are aligned so that they fit together properly and replace the casing screws.
Now turn the monitor upside down as described in 'Removing the monitor stand' and replace the stand by sliding it into the slots the opposite way in which it was removed.
Now turn the monitor the right way up and you are finished.
Once you have located the specific problem this needs to be fixed by soldering. A faulty solder joint is easily fixed by adding a little solder to the joint whilst heating the existing solder with a soldering iron. A crack however is slightly more difficult cure. If the crack is across 1 run of circuit track then the track needs to be linked with a piece of insulated wire soldered to the first available soldered joint on either side of the crack. If the crack spans several tracks then this needs to be repeated for each track. In each case gently rub off the coating to reveal the copper of the track either side of the crack and use a multimeter with a continuity test function to trace the first available joint on that track to solder the link to. You can of course check your work with a magnifying glass to check your solder joints, once you are happy with your work reconnect the monitor as described above to check that all the soldering has worked.
Replacing the monitor back
Replacing the shielding and the monitor back is basically a reverse of the removal process with the exception that some aligning needs to be done. Gently place the monitor upright as described in 'Locating and testing the LOPTX' and replace the shielding.
Now gently place the monitor face down on the towel as described in the section Removing the monitor back. There should be a slot on either side of the inside of the back casing that the main chassis board should slide into when the back is replaced. Make sure the chassis is aligned with these slots as you slide the back casing back onto the monitor. When the back casing meets the front casing make sure that all the edges are aligned so that they fit together properly and replace the casing screws.
Now turn the monitor upside down as described in 'Removing the monitor stand' and replace the stand by sliding it into the slots the opposite way in which it was removed.
Now turn the monitor the right way up and you are finished.
