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RCA XL-100 Vertical Problem    
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Splitshaft



Joined: 15 May 2010
Posts: 1
Location: California

PostPosted: Sat May 15, 2010 5:22 pm    Post subject: RCA XL-100 Vertical Problem Reply with quote

I have a 19-inch RCA XL-100 Colortrack TV manufactured May 1976. The Model number is FA 482FEN, Serial 621 54 2355, Chassis Numbers CTC 74RL4, RVB2746204.

A few years after purchasing the TV it started suffering from a Vertical problem where the picture would collapse into a bright horizontal line across the screen. For a number of years, switching the "setup" switch from normal to service and back to normal restored the picture. More than 10-years ago I had the TV serviced for the vertical problem. Upon picking the TV up following repair of the vertical problem it was still present and appeared within a few minutes of operation. I immediately drove back to the TV repair shop and told them the TV had not been repaired. After picking the TV up the second time, it has worked fine for many years. The vertical problem has now returned. This is a solid state TV, but does not use the IC chips like modern sets use. I visually inspected the high voltage, horizontal and vertical boards and components on the high voltage side of the chassis. I can find no discolored, burned, bulging, or otherwise suspicious looking parts. Solder joints all look good. I was going to try using some component cooler on the parts, but my probing around the horizontal and vertical circuitry has caused the set to work normally for now. I think the vertical collapse was temperature related. When first turning on the set the picture would be normal for about a minute before collapsing into a bright horizontal line. Once the problem stopped reoccurring after my probing, I let the set run to warm up to normal operating temperature. After letting the set completely cool down, the problem has not returned, but will as it is just a matter of time before the fault acts up. When the picture was beginning to collapse, there would be a faint high pitched squealing sound and horizontal noise lines though the whole picture, before the picture collapsed. Once the picture collapsed, the faint squealing stopped. I could not identify the parts that were making the noise. There are the two large TO3 transistors on the inboard side of the chassis on a large aluminum heat sink. Despite the size of the heat sink, it gets quite warm, probably 130 degrees. I don't know if these TO3 transistors are vertical oscillators or horizonal output transistors. The operation of the TV reminds me of an inverter circuit that doesn't want to switch or oscillate. The faint high pitched squeal reminds me of an inverter having trouble switching or running under extreme load.

My question: is there anything that might be causing my problem that an experienced technician has worked on in the past and could advise me to inspect or fix? This set is an antique TV by today's standards but has always worked well and I would like to keep and use it. However at today's service costs where I live, I would be financially better buying a new set unless I can fix this one myself. Please help me save an old TV. Smile Thanks.
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