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Sony kv-27s45 retrace lines    
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_Gorddo
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PostPosted: Sun Sep 20, 2009 6:03 am    Post subject: Sony kv-27s45 retrace lines Reply with quote

This TV comes on with retrace lines. The raster is also bright and gets brighter until the set shuts down moments later.I replaced IC1751 as the pins 8 & 9 are approx 0V. I'm trying to figure out the function of the 1k pin on this IC.The led flashes 2 times.
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_2
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PostPosted: Sun Sep 20, 2009 6:03 am    Post subject: Reply with quote

check for your 200v scan derived from the flyback. Its goes through a diode then smoothed out by a filter and thru a small resistor.
That 200v source may be missing.
_Don
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PostPosted: Sun Sep 20, 2009 6:04 am    Post subject: Reply with quote

If this is a CRT tv, try replacing the filter on the 200 volt supply going
to the CRT module. This causes the voltage to drop, thus the excessive
brightness.
_Gorddo
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PostPosted: Sun Sep 20, 2009 6:04 am    Post subject: Reply with quote

Ok
I'm getting my 200V supply rising from 195V to 215V just when the set shuts down. The 1K from pin 21 of IC301 rises up to 4V while the ABL, pin 3 is about 0.3V and goes down to about 0V. Pin 11 on the flyback goes down to about -10V. I'm wondering if I'm looking at a bad flyback.
_specialK
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PostPosted: Sun Sep 20, 2009 6:05 am    Post subject: Reply with quote

Sony's mute the picture when the ABL isn't right. Maybe someone turned the screen way up, you see retrace lines on a black picture, and the set shuts down from over current?
You need to scope the cathodes of the crt, - which these should also measure 195-215V with the picture muted. If the bias is wrong, then the cathodes would be much lower.
But with a scope, you should see the negative AKB pulse on the cathodes of the tube at a minium, and these should change with the screen brightness.

Flybacks generally don't work if they're bad
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_JamesV
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PostPosted: Sun Sep 20, 2009 6:05 am    Post subject: Reply with quote

Here is what 2 blinks means:

Two blinks - B+ over current protection (OCP), unit goes to the standby mode then displays the 2 blink fault. Could be a short in the power supply of any of the circuits.
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