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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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No red gun on monitor.
Hello, I'm afraid I'm experiencing a bit of a problem with the red gun or it's circuitry in my VGA monitor. Any solid red colour has turned to very dark red (almost black) and there is a slight cyan wash on the screen. The monitor is a Panasonic PanaSync E70i (model numb. TX-T7F22M). My local library has not purchased the SAMs schematics since they thought the monitor schematics collection was too expensive. I'm a computer technician but I've repaired lots of TV recievers and a few monitors in the past and have some repair equipment. I can't seem to find any web sites that have free downloads of schematics (only DVD collections for sale). Has anyone ever had this problem with this model monitor or equivalent and could advise me of what to do to get the red gun to show up again? Or does anyone know of any sites that have monitor schematics for free download? Well, any assistance/suggestions are appreciated. TIA, Carl |
#2
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"Carl Jenkins" wrote in message news:AAmWe.239658$HI.60054@edtnps84... Hello, I'm afraid I'm experiencing a bit of a problem with the red gun or it's circuitry in my VGA monitor. Any solid red colour has turned to very dark red (almost black) and there is a slight cyan wash on the screen. The monitor is a Panasonic PanaSync E70i (model numb. TX-T7F22M). My local library has not purchased the SAMs schematics since they thought the monitor schematics collection was too expensive. I'm a computer technician but I've repaired lots of TV recievers and a few monitors in the past and have some repair equipment. I can't seem to find any web sites that have free downloads of schematics (only DVD collections for sale). Has anyone ever had this problem with this model monitor or equivalent and could advise me of what to do to get the red gun to show up again? Or does anyone know of any sites that have monitor schematics for free download? Well, any assistance/suggestions are appreciated. TIA, Carl Best suggestion I can offer is to trace the red signal and see where it gets weak. If you put a mostly white screen up you should have more or less equal voltages all the way from the input cable to the cathode pins on the CRT, you have three identical circuits which are relatively simple, so it should be fairly straightforward to trace them as the color signals often go straight to the little neck board and don't even pass through the big main board. Of course some monitors are a real chore just to get into so YMMV. |
#3
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"Carl Jenkins" wrote in message news:AAmWe.239658$HI.60054@edtnps84... Hello, I'm afraid I'm experiencing a bit of a problem with the red gun or it's circuitry in my VGA monitor. Any solid red colour has turned to very dark red (almost black) and there is a slight cyan wash on the screen. The monitor is a Panasonic PanaSync E70i (model numb. TX-T7F22M). My local library has not purchased the SAMs schematics since they thought the monitor schematics collection was too expensive. I'm a computer technician but I've repaired lots of TV recievers and a few monitors in the past and have some repair equipment. I can't seem to find any web sites that have free downloads of schematics (only DVD collections for sale). Has anyone ever had this problem with this model monitor or equivalent and could advise me of what to do to get the red gun to show up again? Or does anyone know of any sites that have monitor schematics for free download? Well, any assistance/suggestions are appreciated. TIA, Carl Check the crt voltages, that should lead you to the problem (although it could be a tube fault). |
#4
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On Fri, 16 Sep 2005 09:00:46 +0100, "Barney"
Gave us: "Carl Jenkins" wrote in message news:AAmWe.239658$HI.60054@edtnps84... Hello, I'm afraid I'm experiencing a bit of a problem with the red gun or it's circuitry in my VGA monitor. Any solid red colour has turned to very dark red (almost black) and there is a slight cyan wash on the screen. The monitor is a Panasonic PanaSync E70i (model numb. TX-T7F22M). My local library has not purchased the SAMs schematics since they thought the monitor schematics collection was too expensive. I'm a computer technician but I've repaired lots of TV recievers and a few monitors in the past and have some repair equipment. I can't seem to find any web sites that have free downloads of schematics (only DVD collections for sale). Has anyone ever had this problem with this model monitor or equivalent and could advise me of what to do to get the red gun to show up again? Or does anyone know of any sites that have monitor schematics for free download? Well, any assistance/suggestions are appreciated. TIA, Carl Check the crt voltages, that should lead you to the problem (although it could be a tube fault). Heck dude! Get a nice, new 19" Viewsonic CRT that can be had for less than $200 these days. Then... try to fix the ol' dog. You'll thank yourself. |
#6
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Andy Cuffe wrote:
Bad soldering on the CRT board is also common with some monitors. The CRT socket is always a prime suspect, even if it looks good, reheat the joints (especially on a intermittent).... |
#7
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Barney wrote:
"Carl Jenkins" wrote in message news:AAmWe.239658$HI.60054@edtnps84... Hello, I'm afraid I'm experiencing a bit of a problem with the red gun or it's circuitry in my VGA monitor. Any solid red colour has turned to very dark red (almost black) and there is a slight cyan wash on the screen. The monitor is a Panasonic PanaSync E70i (model numb. TX-T7F22M). My local library has not purchased the SAMs schematics since they thought the monitor schematics collection was too expensive. I'm a computer technician but I've repaired lots of TV recievers and a few monitors in the past and have some repair equipment. I can't seem to find any web sites that have free downloads of schematics (only DVD collections for sale). Has anyone ever had this problem with this model monitor or equivalent and could advise me of what to do to get the red gun to show up again? Or does anyone know of any sites that have monitor schematics for free download? Well, any assistance/suggestions are appreciated. TIA, Carl Check the crt voltages, that should lead you to the problem (although it could be a tube fault). The loss (or intermittent failure before loss) of a color on a CRT monitor is a common and simple problem that can be fixed without any schematic. In fact, a schematic cannot help. Unplug monitor, remove case, and if you want extra safety, connect a wire to the chassis (ground) first, and then to the HV cap on the CRT. Unplug the circuit board from the back of the CRT and unsolder the metal shielding box around it; there are usually tabs that need to be untwisted as well, so that the box can be removed. Then use solder wick to remove old solder from the socket leada at the PCB; and then freshly re-solder them (no need to blob as much on as was done originally). Replace the shield can, but do not re-twist the tabs (no need, and they could break off) - just re-solder. If you used a safety wire, remove it from the CRT cap first, then from ground. Then put the case back on, and you will be in business from one to 4 years more. If you look carefully, you will note a sponge in the back of the case that (when on) presses against that metal case, thereby creating stress on the solder connections from the PCB to the CRT socket. It is that stress which aggravates electromigration of the solder, creating the equivalent of a cold solder joint and/or open. The reason for the sponge is to help decrease shock on the CRT during transportation. |
#8
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CRaSH wrote:
Andy Cuffe wrote: Bad soldering on the CRT board is also common with some monitors. The CRT socket is always a prime suspect, even if it looks good, reheat the joints (especially on a intermittent).... Better to remove old solder and re-do them all. See my other posting here. |
#9
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Try this site www.shareline.net
Donald "Carl Jenkins" wrote in message news:AAmWe.239658$HI.60054@edtnps84... Hello, I'm afraid I'm experiencing a bit of a problem with the red gun or it's circuitry in my VGA monitor. Any solid red colour has turned to very dark red (almost black) and there is a slight cyan wash on the screen. The monitor is a Panasonic PanaSync E70i (model numb. TX-T7F22M). My local library has not purchased the SAMs schematics since they thought the monitor schematics collection was too expensive. I'm a computer technician but I've repaired lots of TV recievers and a few monitors in the past and have some repair equipment. I can't seem to find any web sites that have free downloads of schematics (only DVD collections for sale). Has anyone ever had this problem with this model monitor or equivalent and could advise me of what to do to get the red gun to show up again? Or does anyone know of any sites that have monitor schematics for free download? Well, any assistance/suggestions are appreciated. TIA, Carl |
#10
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Donald wrote:
Try this site www.shareline.net Donald "Carl Jenkins" wrote in message news:AAmWe.239658$HI.60054@edtnps84... Hello, I'm afraid I'm experiencing a bit of a problem with the red gun or it's circuitry in my VGA monitor. Any solid red colour has turned to very dark red (almost black) and there is a slight cyan wash on the screen. The monitor is a Panasonic PanaSync E70i (model numb. TX-T7F22M). My local library has not purchased the SAMs schematics since they thought the monitor schematics collection was too expensive. I'm a computer technician but I've repaired lots of TV recievers and a few monitors in the past and have some repair equipment. I can't seem to find any web sites that have free downloads of schematics (only DVD collections for sale). Has anyone ever had this problem with this model monitor or equivalent and could advise me of what to do to get the red gun to show up again? Or does anyone know of any sites that have monitor schematics for free download? Well, any assistance/suggestions are appreciated. TIA, Carl I believe i had explained (numerous times) how problems are caused, and how to fix them. Look it up. |
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