Sanyo 25" Standard Tube Vertical Deflection Problem
I have an older 25" Sanyo Standard Tube TV with a Vertical problem, all I have is a Horizontal line across the screen, have sound and there is a picture there, just can not view it because of the no vertical deflection issue.
I have gone through the vertical circuit, replaced the output checked and replaced capacitors in the circuit, also checked voltages, however I'm not sure what the Pump Up Voltage should be, still no vertical deflection, I'm thinking its a vertical drive signal issue, but do not have a working scope to determine this, any ideas on this, has anyone run into this before?
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Absence of horizontal scan signal to the deflection yoke. Check all the connection to the deflection yoke. If found OK, the deflection yoke winding [horizontal] is open. If you wish to get some details; check the site linked here. Pull up older posts. Surf the site with patience. http://electronicshelponline.blogspot.com/
NO VERTICAL DEFLECTION MEANS YOU HAVE A HORISONTAL BAR IN THE SCREEN?, Check the power supply for the correct voltage to the vertical circuit, check the vertical DRIVER circuit, check the conductivity of the YOKE (vertical winding) on the neck of the tube
if you have a VERTICAL bar in the screen (common mistake) check all of the above relating the HORISONTAL circuit
You will need to resolder the vertical IC and replace three capacitors that are near or next to the vertical IC. This will restore you television. If you must do the repair I suggest having someone replace the starting capacitor or capacitors in the the horizontal deflection section of the TV as well. The values in the deflection may be 160 or 200 volts at 1Mf and 160 volts at 4.7 Mf. You will correct two problems in one repair. Your TV will last a few more years. Thanks for asking!
If the vertical is not defective or shorted there is a possiblity of bad solder connections on the vertical ic. If connections are good and has b+ voltage to the chip replace chip which is IC 501 LA7841 or LA7845 and change c511 (decimal point 1 film capacitor)