Tip & How-To about Televison & Video
You have no vertical drive, only a small horizontal line across the screen. In older projection TVs this can be caused by broken solder joints in the area of the vertical IC and over the entire board.
Disconnect the power. Remove the back cover. This requires removing all the screws around the perimeter of the lower cover. Remove any screws holding the boards in the set. The boards will be mounted in a plastic frame. For the time being only remove the screws holding the frame in.
Slide out the frame and boards being careful not to break anything. Some wires may need to be taken out of holders or disconnected. Before disconnecting any wires use a sharpie to mark each connector, on each end, for easy reassembly.
Most sets you can get the board out far enough to turn it over and resolder the connections. If you cannot do this easily, remove all wires, after marking, and remove the screws holding in the board, then remove the board. Now you can turn it over and work on it.
Usually the board in question is on the right. It will be the one with the flyback on it. The flyback looks like a small cylinder with about 4 large wires coming off of it. They will be rubber and flexible. One each goes to each CRT.
You will need to remove the entire assembly to get to the underside of the boards to solder the unit. Sometimes removing the restraints will allow enough room to flip the board over and do the work.
Once the underside of the boards are exposed, solder all connections on the boards. Be careful not to bridge any connections.
The vertical IC is mounted on a heat sink and has 12 or more connections. The number on it almost always begins with "LA" followed by 4 digits. It should also be near where the wire from the yoke (on the CRT) attaches to the circuit board. The wires from the yoke will be Yellow, Green, Brown and Red. Yellow and Green are the vertical wires.
Once you have resoldered all the connections on the vertical IC, and any others which look bad, reassemble the unit and try it. If it still does not work you will have to replace the IC. It is available at http://www.mcmelectronicsinc.com .
After replacing the IC reassemble the unit and give it a test. If things went well the unit should work ok. If it still does not work check all the resistors, diodes and look for any fusible links in the vicinity of the vertical IC and replace any which check bad or open.
This should repair the set.
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Posted by Kim... on
Oct 06, 2014 | Televison & Video
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