Question about NEC AccuSync 90 19 in.CRT Conventional Monitor

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Accusync90 continues to burn out q505 (SCR), and Q504 (Horiz output). All this happened after the curcuit was shorted to ground by the support bracket that is under the center of the chassie. The short also burned that a hole through the board, I replaced six other componets by copying from another accusync 90 and had to straight wire the burned traces. This seems to be a design problem as the other was had shorted in the same place. I was able to repair that one. NO schematic available.

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1 Answer

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if the transistor gets very hot in under 30 seconds the problem is in the driver circuit in front of it--open or off value cap is most common. 5 minutes is waiting too long---touch the face of transistor--can be mildly warm but not HOT.

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1 Answer

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From Wendell

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1 Answer

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The set tries 3 times to come on (3 blinks) if there a problem such as a short, it will cycle without turning on. Unfortunately your set is notorious for having bad flyback transformers. Most likely the horizontal output transistor is shorted as well. Common causes for your symptom are: LL05 (horiz out transformer) RCA part# 257805; TL 02 ( horiz output transistor) 2SC5148; and open connections on the printed circuit board at LL 04 and L14401 (coils) all of which can cause the horizontal output transistor to be shorted.













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1 Answer

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   test.......T.

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1 Answer

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2 Answers

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1 Answer

Part number


oh an easy one LOL That part # is 1-453-268-21 and available at http://www.partstore.com at a price of $82.12. One thing though Make sure you check the horizontal output transistor with all the leads disconnected from the curcuit as this part sometimes goes bad when the fly does. My regular practice with any flyback replacement is to automaticly replace the HOT(horiz. output transistor) as well as resoldering the hhorizontal driver transformer and the horiz. driver transistor. Hope this assist yout repair and makes a happy one. Thats what were here for! Good Luck.

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