September 9, 2007 (9 years, 7 months ago)

Does the TOSHIBA TA8445K Vertical Deflection IC fails when the Deflection Yoke is Dirty?


Symptom:
The "widescreen" effect: picture is squeezed towards the horizontal center.

One of the most common television breakdowns is bad vertical deflection. This one is a picture squeezed into the horizontal middle of the screen, taking about a quarter of the screen. Apparently, the vertical deflection circuit is blown up, leaving little vertical amplification. A thorough check of components associated with the vertical deflection IC TOSHIBA TA944K, showed no open resistors, shorted diodes or leaking capacitors. This leaves us to point to the IC as suspect.

What is the TA8445K?

The TA8445K is a power amplifier integrated circuit component for driving the deflection circuit of Sharp television model 21V-W99. It drives the deflection yoke through its output at pin 11 (see Fig. 1).

TA8445K Vertical Deflection Circuit in SHARP TV

Fig. 1: Vertical deflection circuit in Sharp television model no. 21V-W99.

Download the PDF version for Fig. 1

The package IC is attached to an aluminum heatsink.

Clean the deflection yoke

An important part of television standard maintenance procedure is cleaning the deflection yoke. Decade old televisions can gather dust on the upper windings of the deflection yoke that is enough to cripple the vertical deflection IC. I have overlooked this step and replaced the TA9445K deflection IC which immediately went up in smoke when the TV was turned back on. Before replacing the IC again, I took the time to clean the deflection yoke windings. It was full of burned dust on the upper inner side. This time, it worked.

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