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Old 18th May 2016, 10:56 pm   #11
Marconi_MPT4
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Join Date: Mar 2011
Location: Dorset, UK.
Posts: 454
Default Re: Beovision 7102 CRT TV,schematic/advice please

Quote:
Originally Posted by zens.tv View Post
TYPE 7423
anyone recall what this model suffers with ?
Hi,
Many, many dry joints on the power (6), control (46) and mother (60) boards.

5D15 and 5C47 on the line and field deflection unit, supplies CRT A1 circuitry with 750V from line flyback. Occasionally 5T11 can fail, but design was improved on later production PCB. 5TR3 (BU208) metal case corrodes which then punctures insulating mica washer causing flash over. More often faults are the result of liquid contamination due to spillage from over zealous watering of a potted plant. Also occasionally from a leaky cat.

When shut down occurs, does the power control circuit try to cycle about six times before locking out? You should hear the power transformer tick on each try. There are over/under voltage and over current safety trips on this set. For instance, Pin 6 of 46IC1 deals with over current protection and has to go above 0.7V to invoke trip.

Quote:
Originally Posted by zens.tv View Post
H.T of 165 volts, measured across C7
Is that capacitor 6C7? If so should have 295V across it measured directly on both tags.

Check carefully when using an apparently similar transformer as a substitute as sometimes the B&O pin out can vary.

Cheers
Rich
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