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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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possible problem with Sony flat-face WEGA
I'm posting this to see if anyone /knows/ the answer, or has a reasonable
suspicion. I do not want to initiate an interminable chain of speculation. I own a 36" flat-face 400-series Sony WEGA IDTV and, yes, I have the service manual. The set has gotten heavy use over the past decade; I often leave it on when I go to bed. It wasn't cheap, and I'd like to get at least another five years out of it. For a non-HD CRT set, it has an excellent picture, especially with RGB signals from a DVD player. When the set's turned on, the HV is apparently shut off, so that the CRT heater has time to come to full temperature, to avoid stripping the cathode. (This is speculation.) Though sound comes on almost immediately, it takes about 10 seconds for the raster to appear. Recently I've noticed "something new". For about two seconds after the raster comes on, the black level is too light. You can see the image "darkening" as the black level drops to its "correct" point. This occurs only when the set is "cold"; cycling the power doesn't cause this. I'm hoping someone will say "I've seen this. It's the ___________." Troubleshooting this set won't be easy (if only because it's close to the wall on a near-immovable stand). I don't want to tear into it until I'm reasonably certain I can fix it on the first try. Thanks in advance. -- "We already know the answers -- we just haven't asked the right questions." -- Edwin Land |
#2
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possible problem with Sony flat-face WEGA
On 1/30/2011 9:21 AM, William Sommerwerck wrote:
I own a 36" flat-face 400-series Sony WEGA IDTV and, yes, I have the service manual. Is that the same set you kept trying to give away on rec.antique.radio+phono? Jeff |
#3
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possible problem with Sony flat-face WEGA
I own a 36" flat-face 400-series Sony WEGA IDTV
and, yes, I have the service manual. Is that the same set you kept trying to give away on rec.antique.radio+phono? Are you kidding? That was an NAD MR-20A with a failing focus system. It is a classic set, and worth restoring -- if you can find the parts needed (most likely a no-longer-available HOT system). If someone wants it, it's theirs for the cost of shipping. |
#4
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possible problem with Sony flat-face WEGA
On Sun, 30 Jan 2011 07:21:36 -0800, William Sommerwerck wrote:
I'm posting this to see if anyone /knows/ the answer, or has a reasonable suspicion. I do not want to initiate an interminable chain of speculation. I own a 36" flat-face 400-series Sony WEGA IDTV and, yes, I have the service manual. The set has gotten heavy use over the past decade; I often leave it on when I go to bed. It wasn't cheap, and I'd like to get at least another five years out of it. For a non-HD CRT set, it has an excellent picture, especially with RGB signals from a DVD player. When the set's turned on, the HV is apparently shut off, so that the CRT heater has time to come to full temperature, to avoid stripping the cathode. (This is speculation.) Though sound comes on almost immediately, it takes about 10 seconds for the raster to appear. Recently I've noticed "something new". For about two seconds after the raster comes on, the black level is too light. You can see the image "darkening" as the black level drops to its "correct" point. This occurs only when the set is "cold"; cycling the power doesn't cause this. I'm hoping someone will say "I've seen this. It's the ___________." Troubleshooting this set won't be easy (if only because it's close to the wall on a near-immovable stand). I don't want to tear into it until I'm reasonably certain I can fix it on the first try. Thanks in advance. Wait until it is a problem that doesn't go away after 2 seconds. -- Live Fast, Die Young and Leave a Pretty Corpse |
#5
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possible problem with Sony flat-face WEGA
Wait until it's a problem that doesn't go away after 2 seconds.
In other words, wait until an "intermittent" becomes permanent. Definitely common sense -- but I'd rather make an end run around the problem. |
#6
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possible problem with Sony flat-face WEGA
On Sun, 30 Jan 2011 12:22:35 -0800, William Sommerwerck wrote:
Wait until it's a problem that doesn't go away after 2 seconds. In other words, wait until an "intermittent" becomes permanent. Definitely common sense -- but I'd rather make an end run around the problem. Good luck. -- Live Fast, Die Young and Leave a Pretty Corpse |
#7
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possible problem with Sony flat-face WEGA
On Sun, 30 Jan 2011 07:21:36 -0800, "William Sommerwerck"
wrote: I'm posting this to see if anyone /knows/ the answer, or has a reasonable suspicion. I do not want to initiate an interminable chain of speculation. I own a 36" flat-face 400-series Sony WEGA IDTV and, yes, I have the service manual. The set has gotten heavy use over the past decade; I often leave it on when I go to bed. It wasn't cheap, and I'd like to get at least another five years out of it. For a non-HD CRT set, it has an excellent picture, especially with RGB signals from a DVD player. When the set's turned on, the HV is apparently shut off, so that the CRT heater has time to come to full temperature, to avoid stripping the cathode. (This is speculation.) Though sound comes on almost immediately, it takes about 10 seconds for the raster to appear. Recently I've noticed "something new". For about two seconds after the raster comes on, the black level is too light. You can see the image "darkening" as the black level drops to its "correct" point. This occurs only when the set is "cold"; cycling the power doesn't cause this. I'm hoping someone will say "I've seen this. It's the ___________." Troubleshooting this set won't be easy (if only because it's close to the wall on a near-immovable stand). I don't want to tear into it until I'm reasonably certain I can fix it on the first try. Thanks in advance. William, the condition is usually caused by the crt cathode emission becoming weaker. When the picture no longer comes on, adjusting the screen control higher will allow the set to work for a few months to a year more. Chuck |
#8
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possible problem with Sony flat-face WEGA
The condition is usually caused by the CRT's cathode
emission becoming weaker. When the picture no longer comes on, adjusting the screen control higher will allow the set to work for a few months to a year more. I kinda expected that. If you're correct, it looks like I won't get my money's worth out of the set. I wonder if anyone still makes CRT heater boosters. grin Remember those? |
#9
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possible problem with Sony flat-face WEGA
William Sommerwerck wrote: The condition is usually caused by the CRT's cathode emission becoming weaker. When the picture no longer comes on, adjusting the screen control higher will allow the set to work for a few months to a year more. I kinda expected that. If you're correct, it looks like I won't get my money's worth out of the set. I wonder if anyone still makes CRT heater boosters. grin Remember those? If they use DC on the fliament check for a bad electrolyytic in it's power supply. I used to add a filamnet transformer to series string TV sets with a dropping diode to power an 84 volt string of filaments. They barely lasted a year from new, without the modification. -- You can't fix stupid. You can't even put a band-aid on it, because it's Teflon coated. |
#10
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possible problem with Sony flat-face WEGA
If they use DC on the filament, check for a bad electrolyytic
in its power supply. I used to add a filament transformer to series string TV sets with a dropping diode to power an 84 volt string of filaments. They barely lasted a year from new, without the modification. Well, this set's over 10 years old. I'll pull out the service manual and give it a look. |
#11
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possible problem with Sony flat-face WEGA
On Mon, 31 Jan 2011 11:41:03 -0800, "William Sommerwerck"
wrote: The condition is usually caused by the CRT's cathode emission becoming weaker. When the picture no longer comes on, adjusting the screen control higher will allow the set to work for a few months to a year more. I kinda expected that. If you're correct, it looks like I won't get my money's worth out of the set. I wonder if anyone still makes CRT heater boosters. grin Remember those? CRT brighteners are still available but I wouldn't go that route until the screen control adjustment is no longer effective. |
#12
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possible problem with Sony flat-face WEGA
On Jan 30, 7:21*am, "William Sommerwerck"
wrote: I'm posting this to see if anyone /knows/ the answer, or has a reasonable suspicion. I do not want to initiate an interminable chain of speculation.. I own a 36" flat-face 400-series Sony WEGA IDTV and, yes, I have the service manual. The set has gotten heavy use over the past decade; I often leave it on when I go to bed. It wasn't cheap, and I'd like to get at least another five years out of it. For a non-HD CRT set, it has an excellent picture, especially with RGB signals from a DVD player. When the set's turned on, the HV is apparently shut off, so that the CRT heater has time to come to full temperature, to avoid stripping the cathode. (This is speculation.) Though sound comes on almost immediately, it takes about 10 seconds for the raster to appear. Recently I've noticed "something new". For about two seconds after the raster comes on, the black level is too light. You can see the image "darkening" as the black level drops to its "correct" point. This occurs only when the set is "cold"; cycling the power doesn't cause this. I'm hoping someone will say "I've seen this. It's the ___________." Troubleshooting this set won't be easy (if only because it's close to the wall on a near-immovable stand). I don't want to tear into it until I'm reasonably certain I can fix it on the first try. Thanks in advance. -- "We already know the answers -- we just haven't asked the right questions." -- Edwin Land The industrial Sony's do a very similar thing as the CRT warms up. In those you're waiting for the beam current feedback to get up to speed. Since you have the service manual, is there anything in there about setting G2 by monitoring a specific set of lines in the vertical interval? G² |
#13
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possible problem with Sony flat-face WEGA
The industrial Sonys do a very similar thing as the CRT
warms up. In those you're waiting for the beam current feedback to get up to speed. Since you have the service manual, is there anything in there about setting G2 by monitoring a specific set of lines in the vertical interval? I don't know; I haven't looked yet. Is there any way to do that without reducing vertical scan? |
#14
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possible problem with Sony flat-face WEGA
On Tue, 01 Feb 2011 19:34:56 -0600, Chuck wrote:
On Mon, 31 Jan 2011 11:41:03 -0800, "William Sommerwerck" wrote: The condition is usually caused by the CRT's cathode emission becoming weaker. When the picture no longer comes on, adjusting the screen control higher will allow the set to work for a few months to a year more. I kinda expected that. If you're correct, it looks like I won't get my money's worth out of the set. I wonder if anyone still makes CRT heater boosters. grin Remember those? CRT brighteners are still available but I wouldn't go that route until the screen control adjustment is no longer effective. Once you need a filament booster it's time to get the good old Sencore CR70 'Beam Builder' out of storage. Or maybe just a bottle of Jim Beam? -- Live Fast, Die Young and Leave a Pretty Corpse |
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