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shawncao
Joined: 20 Jun 2007 Posts: 6
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Posted: Wed Jun 20, 2007 5:36 am Post subject: old Toshiba cf3264k TV, retrace lines in picture |
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An old Toshiba cf3264k TV - The screen was too bright and had retrace lines in it. |
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minnie
Joined: 18 Aug 2005 Posts: 2881 Location: Hell
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Posted: Wed Jun 20, 2007 10:56 pm Post subject: |
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Try turning down the screen control on the flyback, if it's still there, bad CRT. |
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bbp1
Joined: 04 May 2007 Posts: 22
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Posted: Thu Jun 21, 2007 8:14 am Post subject: |
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there can be other faulty comp causing symptom- before condemning tube, I would check electros, res, djs etc. If tube is suspect, there are ways to rejuvenate/ fix problem- but must know what doing- I know from hard won experience & making equipment needed how to do- but really, do you think anyone asking such a basic thing could do it?!- I think not!!. |
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shawncao
Joined: 20 Jun 2007 Posts: 6
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Posted: Sun Jun 24, 2007 5:38 pm Post subject: re |
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Thanks, both of you. Let me describe the problem a little more in details.
The screen is bright, the picture is pale but stable, and the white retrace lines are full of the screen. I had tried to turn down the screen control voltage, the retrace lines were gone, but the screen and the picture became very dark. I have already replaced a cap on CRT control board which is attaced to the end of the CRT. |
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cory Guest
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Posted: Mon Jun 25, 2007 12:46 am Post subject: |
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check 200 volt line going to crt neck pcb. if low find capacitor, probably near flyback. |
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mazmaz
Joined: 23 Jan 2005 Posts: 50
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Posted: Mon Jun 25, 2007 5:59 am Post subject: |
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hello
low voltage in cathods driver (180~200) may cause this problume(check fbt out line to dc circuit diode cap , ....)
if problume not stay in stable mode (variable screen voltage) change fbt
bad video driver circuit too may made this problume(zener diods,driver ic ...) |
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shawncao
Joined: 20 Jun 2007 Posts: 6
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Posted: Tue Jun 26, 2007 5:50 am Post subject: |
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The voltage is around 60-70 V. Trying to figure out the defect component now... |
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cory Guest
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Posted: Tue Jun 26, 2007 12:16 pm Post subject: |
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there should be a capacitor near flyback rated at least 250 volts.follow connector back from crt onto main pcb.there will be a diode and cap right off flyback secondary.change cap. |
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shawncao
Joined: 20 Jun 2007 Posts: 6
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Posted: Wed Jun 27, 2007 6:00 am Post subject: |
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Thanks cory. I found 2 caps (33uF 200V); and 1 cap (33uf 250v) which connects with a diode. But none of them seems defect. (I used a multi-meter to check them on board). |
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shawncao
Joined: 20 Jun 2007 Posts: 6
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Posted: Wed Jun 27, 2007 6:02 am Post subject: |
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BTW the P/N of the pcb where flyback located is PW9533-1. |
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