Pincushion Problem In CRT TV Repaired
Customer sent in this Singer CRT TV with the complaint of pincushion out. This means that the display at the right and left side will curve inward as seen from the top and bottom photos.
There are usually few common causes to this problem such as:
- Low B+ voltage to the Flyback transformer
- Shorted modulation diode
- Shorted pincushion transistor
- Open resistor at surrounding area of pincushion transistor
- No control signal to the base of pincushion transistor
However, in my case is pretty straight forward because I saw a bulged e-cap (1000uf 35 volt) at the horizontal output area-see the photo below:
Upon further inspection, I found a dry joint in the diode’s leg that is located at corresponding circuit. When i checked the diode with my multimeter I found that the diode was shorted. Checking it off board also produced the same result.
I did checked on other components as well that is related to the pincushion circuit but all seems to be good. So, just by replacing only the two components brought the TV back to life again .
If you want to be good in CRT TV repair you can check out Humphrey’s ebook in CRT TV repair. See you again in the next article.
This article was prepared for you by Suranga Bandara who owns an Electronics repair shop in Anuradapura, Sri Lanka.
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