Whining 100 Hz PHILIPS TV w vertical bars

Jan 21, 2006 3 Replies
M

Hello from Finland.



I have Philips TV 29PT8702 chassis: MD2.12E which whines a lot. It has also odd phenomenon which looks like ringing or ghost. Few vertical bars on the left and the right part of picture.



I have varnished the L.O.T. and linearity coiletc. but no help at all. The whining comes (I'm quite sure) from L.O.T. I took few pictures if you like to take a look of the phenomenon.



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I remember that I have seen this phenomenon in Barco monitor and it was caused by bad voltage. I checked the voltages from PWR but they were quite OK (if I haven't missed one or two).



Thanks a L.O.T!


Matti Kaki at iki dot fi http://www.sci.fi/~oh2bio =========== Location: 60.414 N 25.097 E =========== Navigare Necesse Est - Vivere Non Est Necesse
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S

Did you also measure the ripple on these voltages? I had a similiar error with an older ITT tv set caused by a bad cap in the 12V-branch.

Whining on another set was caused by bad B+-cap.

I?d simply test the caps for high ESR.

HTH, Sebastian

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M

Yes I tested the ripples but it is possible I have missed one or two voltages because Philips TP-markings are terrible.

Allright. I'll measure again or just replace the capasitors anyway.

Matti Kaki at iki dot fi http://www.sci.fi/~oh2bio =========== Location: 60.414 N 25.097 E =========== Navigare Necesse Est - Vivere Non Est Necesse
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M

I now took a stethoscope and removed the chest piece and listeded with the tube and the whining is NOT comiming from the L.O.T but from the power transformer. The sound circulates so nasty that it is impossible to locate the whining using only my ears.

So there must be sometkihg. I measured the ripples once but must do it once again. Any ideas (modifications)?

Matti Kaki at iki dot fi http://www.sci.fi/~oh2bio =========== Location: 60.414 N 25.097 E =========== Navigare Necesse Est - Vivere Non Est Necesse
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