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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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11ak30 chassis
Hi there,
vestel 11ak30 tv. here's the story so far...set had a shorted HOT (would not come out of standby, if keys pressed set just chirped and red led stayed on). Set powered up fine without HOT in place. Connecting bulb across c-e showed b+ OK. No obvious solder problems, just resoldered one or two slightly suspect joints. Now for the annoying bit: Replaced BU808DFI HOT and c618 (according to schematic,7n2). New transistor blows out immediately. Now suspecting LOPTX shorted internally, before I replace it though, has anyone seen this problem before on this chassis? best regards, Ben |
#2
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11ak30 chassis
b ha escrito: Hi there, vestel 11ak30 tv. here's the story so far...set had a shorted HOT (would not come out of standby, if keys pressed set just chirped and red led stayed on). Set powered up fine without HOT in place. Connecting bulb across c-e showed b+ OK. No obvious solder problems, just resoldered one or two slightly suspect joints. Now for the annoying bit: Replaced BU808DFI HOT and c618 (according to schematic,7n2). New transistor blows out immediately. Now suspecting LOPTX shorted internally, before I replace it though, has anyone seen this problem before on this chassis? best regards, Ben For the record: replaced HOT BU808DFI, and LOPTX (HR 7950), also 10uF 63v horiz drive cap and 8n2 cap across HOT. Set now works. -B. |
#3
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11ak30 chassis
b wrote: b ha escrito: Hi there, vestel 11ak30 tv. here's the story so far...set had a shorted HOT (would not come out of standby, if keys pressed set just chirped and red led stayed on). Set powered up fine without HOT in place. Connecting bulb across c-e showed b+ OK. No obvious solder problems, just resoldered one or two slightly suspect joints. Now for the annoying bit: Replaced BU808DFI HOT and c618 (according to schematic,7n2). New transistor blows out immediately. Now suspecting LOPTX shorted internally, before I replace it though, has anyone seen this problem before on this chassis? best regards, Ben For the record: replaced HOT BU808DFI, and LOPTX (HR 7950), also 10uF 63v horiz drive cap and 8n2 cap across HOT. Set now works. -B. |
#4
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11ak30 chassis
b wrote:
b ha escrito: Hi there, vestel 11ak30 tv. here's the story so far...set had a shorted HOT (would not come out of standby, if keys pressed set just chirped and red led stayed on). Set powered up fine without HOT in place. Connecting bulb across c-e showed b+ OK. No obvious solder problems, just resoldered one or two slightly suspect joints. Now for the annoying bit: Replaced BU808DFI HOT and c618 (according to schematic,7n2). New transistor blows out immediately. Now suspecting LOPTX shorted internally, before I replace it though, has anyone seen this problem before on this chassis? best regards, Ben For the record: replaced HOT BU808DFI, and LOPTX (HR 7950), also 10uF 63v horiz drive cap and 8n2 cap across HOT. Set now works. -B. hi I am newby in tv repair, sory for stupid questions, what did you meen when you say HOT? and when you say : cap and 8n2 cap across HOT. Thanks.... jonhyr19 |
#5
Posted to sci.electronics.repair
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11ak30 chassis
b wrote:
b ha escrito: Hi there, vestel 11ak30 tv. here's the story so far...set had a shorted HOT (would not come out of standby, if keys pressed set just chirped and red led stayed on). Set powered up fine without HOT in place. Connecting bulb across c-e showed b+ OK. No obvious solder problems, just resoldered one or two slightly suspect joints. Now for the annoying bit: Replaced BU808DFI HOT and c618 (according to schematic,7n2). New transistor blows out immediately. Now suspecting LOPTX shorted internally, before I replace it though, has anyone seen this problem before on this chassis? best regards, Ben For the record: replaced HOT BU808DFI, and LOPTX (HR 7950), also 10uF 63v horiz drive cap and 8n2 cap across HOT. Set now works. -B. hi I am newby in tv repair, sory for stupid questions, what did you meen when you say HOT? and when you say : cap and 8n2 cap across HOT. Thanks.... jonhyr19 |
#6
Posted to sci.electronics.repair
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11ak30 chassis
jonhyr19 ha escrito: b wrote: b ha escrito: Hi there, vestel 11ak30 tv. here's the story so far...set had a shorted HOT (would not come out of standby, if keys pressed set just chirped and red led stayed on). Set powered up fine without HOT in place. Connecting bulb across c-e showed b+ OK. No obvious solder problems, just resoldered one or two slightly suspect joints. Now for the annoying bit: Replaced BU808DFI HOT and c618 (according to schematic,7n2). New transistor blows out immediately. Now suspecting LOPTX shorted internally, before I replace it though, has anyone seen this problem before on this chassis? best regards, Ben For the record: replaced HOT BU808DFI, and LOPTX (HR 7950), also 10uF 63v horiz drive cap and 8n2 cap across HOT. Set now works. -B. hi I am newby in tv repair, sory for stupid questions, what did you meen when you say HOT? and when you say : cap and 8n2 cap across HOT. Thanks.... jonhyr19 no need to apologize. if everyone simply asked for information or help whenever they didn't know or weren't sure about things, the world would be a better place! Thr HOT= HORIZONTAL OUTPUT TRANSISTOR aka LINE OUTPUT TRANSISTOR. CAP= capacitor, in this case i changed two. One electrolytic type in the horizontal drive circuit (apparently prone to failure on this chassis) and also another polyester film type, value 8n2 , connecetd c-e across the aforementioned HOT transistor. see http://www.interq.or.jp/japan/se-inoue/e_capa.htm and www.repairfaq.org tv troubleshooting section. going back to the above parts, I usually test or change these parts first of all in any set with shorts or other problems in the horizontal stage, before moving on to the more expensive transformer. They suffer a lot in use and are generally (relatively) cheap and easy to get hold of. hope this helps. -B. |
#7
Posted to sci.electronics.repair
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11ak30 chassis
b wrote: jonhyr19 ha escrito: b wrote: b ha escrito: Hi there, vestel 11ak30 tv. here's the story so far...set had a shorted HOT (would not come out of standby, if keys pressed set just chirped and red led stayed on). Set powered up fine without HOT in place. Connecting bulb across c-e showed b+ OK. No obvious solder problems, just resoldered one or two slightly suspect joints. Now for the annoying bit: Replaced BU808DFI HOT and c618 (according to schematic,7n2). New transistor blows out immediately. Now suspecting LOPTX shorted internally, before I replace it though, has anyone seen this problem before on this chassis? best regards, Ben For the record: replaced HOT BU808DFI, and LOPTX (HR 7950), also 10uF 63v horiz drive cap and 8n2 cap across HOT. Set now works. -B. hi I am newby in tv repair, sory for stupid questions, what did you meen when you say HOT? and when you say : cap and 8n2 cap across HOT. Thanks.... jonhyr19 no need to apologize. if everyone simply asked for information or help whenever they didn't know or weren't sure about things, the world would be a better place! Thr HOT= HORIZONTAL OUTPUT TRANSISTOR aka LINE OUTPUT TRANSISTOR. CAP= capacitor, in this case i changed two. One electrolytic type in the horizontal drive circuit (apparently prone to failure on this chassis) and also another polyester film type, value 8n2 , connecetd c-e across the aforementioned HOT transistor. see http://www.interq.or.jp/japan/se-inoue/e_capa.htm and www.repairfaq.org tv troubleshooting section. going back to the above parts, I usually test or change these parts first of all in any set with shorts or other problems in the horizontal stage, before moving on to the more expensive transformer. They suffer a lot in use and are generally (relatively) cheap and easy to get hold of. hope this helps. -B. Hi again I have two tvs with problems one with 11ak30 and 11ak30-1 on 11ak30-1 i replaced HOT BU808DFI, and LOPTX (HR 7950), and all ok problem resolved on 11ak30, nothing apend, the aparent problem, the tv stay on standby and the red light flash, and a sound with the flash, if you toutch in any boton the light pass to green and again in red, and noting apend. HOT BU808DFI, and LOPTX (HR 7950) are ok, what seems to be the problem? jonhyr19 |
#8
Posted to sci.electronics.repair
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11ak30 chassis
jonhyr19 ha escrito: b wrote: jonhyr19 ha escrito: b wrote: b ha escrito: Hi there, vestel 11ak30 tv. here's the story so far...set had a shorted HOT (would not come out of standby, if keys pressed set just chirped and red led stayed on). Set powered up fine without HOT in place. Connecting bulb across c-e showed b+ OK. No obvious solder problems, just resoldered one or two slightly suspect joints. Now for the annoying bit: Replaced BU808DFI HOT and c618 (according to schematic,7n2). New transistor blows out immediately. Now suspecting LOPTX shorted internally, before I replace it though, has anyone seen this problem before on this chassis? best regards, Ben For the record: replaced HOT BU808DFI, and LOPTX (HR 7950), also 10uF 63v horiz drive cap and 8n2 cap across HOT. Set now works. -B. hi I am newby in tv repair, sory for stupid questions, what did you meen when you say HOT? and when you say : cap and 8n2 cap across HOT. Thanks.... jonhyr19 no need to apologize. if everyone simply asked for information or help whenever they didn't know or weren't sure about things, the world would be a better place! Thr HOT= HORIZONTAL OUTPUT TRANSISTOR aka LINE OUTPUT TRANSISTOR. CAP= capacitor, in this case i changed two. One electrolytic type in the horizontal drive circuit (apparently prone to failure on this chassis) and also another polyester film type, value 8n2 , connecetd c-e across the aforementioned HOT transistor. see http://www.interq.or.jp/japan/se-inoue/e_capa.htm and www.repairfaq.org tv troubleshooting section. going back to the above parts, I usually test or change these parts first of all in any set with shorts or other problems in the horizontal stage, before moving on to the more expensive transformer. They suffer a lot in use and are generally (relatively) cheap and easy to get hold of. hope this helps. -B. Hi again I have two tvs with problems one with 11ak30 and 11ak30-1 on 11ak30-1 i replaced HOT BU808DFI, and LOPTX (HR 7950), and all ok problem resolved on 11ak30, nothing apend, the aparent problem, the tv stay on standby and the red light flash, and a sound with the flash, if you toutch in any boton the light pass to green and again in red, and noting apend. HOT BU808DFI, and LOPTX (HR 7950) are ok, what seems to be the problem? jonhyr19 sounds like there is something shutting down the power supply. first, check the voltage on the HOT. unsolder the HOT and connect a 60-100 watt bulb across c-e terminals.switch the set out of standby to ON, see if the bulb lights and is steady. -Set your voltmeter to DC and put the red probe on the c, black to e. measure the voltage (should be between 115 and 130v depending on size of screen). try replacing the 160v capacitors in the b+ line from the power supply if it is not.These sometimes fail causing this problem. -try also unsoldering the outputs from the line transformer, and power supply transformer one by one to see if there is one shorted bringing down the power supply. (vertical, RGB, etc etc.) note that these are all very general tests, see www.repaifaq.org for more details. it's a bit hard to be more specific over the internet, without seeing the TV set! regards, B. |
#9
Posted to sci.electronics.repair
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11ak30 chassis
b wrote: jonhyr19 ha escrito: b wrote: jonhyr19 ha escrito: b wrote: b ha escrito: Hi there, vestel 11ak30 tv. here's the story so far...set had a shorted HOT (would not come out of standby, if keys pressed set just chirped and red led stayed on). Set powered up fine without HOT in place. Connecting bulb across c-e showed b+ OK. No obvious solder problems, just resoldered one or two slightly suspect joints. Now for the annoying bit: Replaced BU808DFI HOT and c618 (according to schematic,7n2). New transistor blows out immediately. Now suspecting LOPTX shorted internally, before I replace it though, has anyone seen this problem before on this chassis? best regards, Ben For the record: replaced HOT BU808DFI, and LOPTX (HR 7950), also 10uF 63v horiz drive cap and 8n2 cap across HOT. Set now works. -B. hi I am newby in tv repair, sory for stupid questions, what did you meen when you say HOT? and when you say : cap and 8n2 cap across HOT. Thanks.... jonhyr19 no need to apologize. if everyone simply asked for information or help whenever they didn't know or weren't sure about things, the world would be a better place! Thr HOT= HORIZONTAL OUTPUT TRANSISTOR aka LINE OUTPUT TRANSISTOR. CAP= capacitor, in this case i changed two. One electrolytic type in the horizontal drive circuit (apparently prone to failure on this chassis) and also another polyester film type, value 8n2 , connecetd c-e across the aforementioned HOT transistor. see http://www.interq.or.jp/japan/se-inoue/e_capa.htm and www.repairfaq.org tv troubleshooting section. going back to the above parts, I usually test or change these parts first of all in any set with shorts or other problems in the horizontal stage, before moving on to the more expensive transformer. They suffer a lot in use and are generally (relatively) cheap and easy to get hold of. hope this helps. -B. Hi again I have two tvs with problems one with 11ak30 and 11ak30-1 on 11ak30-1 i replaced HOT BU808DFI, and LOPTX (HR 7950), and all ok problem resolved on 11ak30, nothing apend, the aparent problem, the tv stay on standby and the red light flash, and a sound with the flash, if you toutch in any boton the light pass to green and again in red, and noting apend. HOT BU808DFI, and LOPTX (HR 7950) are ok, what seems to be the problem? jonhyr19 sounds like there is something shutting down the power supply. first, check the voltage on the HOT. unsolder the HOT and connect a 60-100 watt bulb across c-e terminals.switch the set out of standby to ON, see if the bulb lights and is steady. -Set your voltmeter to DC and put the red probe on the c, black to e. measure the voltage (should be between 115 and 130v depending on size of screen). try replacing the 160v capacitors in the b+ line from the power supply if it is not.These sometimes fail causing this problem. -try also unsoldering the outputs from the line transformer, and power supply transformer one by one to see if there is one shorted bringing down the power supply. (vertical, RGB, etc etc.) note that these are all very general tests, see www.repaifaq.org for more details. it's a bit hard to be more specific over the internet, without seeing the TV set! regards, B. When i put the bull in c and e something in HOT die and the light of standby desapear.. jonhyr19 |
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