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Old 17th Dec 2018, 11:07 am   #101
1100 man
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Join Date: Apr 2016
Location: Ventnor, Isle of Wight, & Great Dunmow, Essex, UK.
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Default Re: CRT is brighter to one side [Hitachi CTP213]

The RGB output transistors, TR851, 852 & 853 are mounted on the board plugged into the back of the tube. They amplify the 3 primary colour signals (red, green & blue) to drive the tube.

The 200V supply for them is derived from the line o/p transformer (FBT on the diagram), via CR707 & R734. The supply is smoothed by two capacitors, C737 & C754. These are shown as 3.3 mfd at 315V. They will be found somewhere near the LOPT.

These will be a good first step to change as they will address the original shading fault as well. These capacitors are polarised, ie it matters which way round they go!

Looking at the circuit, the chassis metalwork is 'at half mains potential' which was quite normal for colour sets of this period. Consider this to be LIVE when the set is powered so don't touch it or connect it to anything else!

Cheers
Nick
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