Pin Cusion Distortion on old RCA TV

Mar 30, 2008 1 Replies

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Bob Donahue 18 years ago

I have a 15 year old RCA F27120WN that has just developed what I think is called "pincushion" distortion. The entire picture is filled in, but vertical lines near the sides are bowed inward. (Horizontal lines are fine.) Any particular circuit or component I can check? Other than the pincushion distortion, the set still has an excellent picture.

I'm experienced in electronics and radio design, but not so much with TVs.

Bob D.

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whit3rd 18 years ago

Usually the horizontal sweep circuit has a 'pin amp' transistor ((basically, the Hsweep drive is a high voltage, but instead of returning to GND, current returns to a low voltage pincushion amplifier). The pincushion symptom often means the transistor has shorted (or otherwise lost gain).

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