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Help Needed - Thomson 27LCDB03B not working

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Acrantophis:
Let me start by saying hello :051bye:

Now on to the problem.

I've been handed a Thomson 27LCDB03B that was reported as not always wanting to turn on. Anyway upon taking a look at it I've not been able to get it to power up at all, no power led, nothing.

Hunted high and low for a schematic and finally tracked one down and now I've done a little poking around.

I can confirm that I have 230VAC at PSU EMI board and a DC voltage of aprox 321Volts across the 100uF 450V caps, from there on the voltages appear to vanish. I don't appear to have a VCC voltage at pin 7 of U6301, nor do I appear to have any voltage present on the output stage of the transformer T6301 (pins 7 & 9).

I do have an electronics background just not in TV repairs so I was wondering if there is anyone on here who could work through this problem with me?

Thanks in advance.

astracat:
photo of psu diagram required b4 can help, but prob start up resisters or cap

Acrantophis:
 PDF service manual I have is now attached below.

Board manufacturer and Part N#; DARFON 48.B0090.001

Unfortunately I don't have a camera to take a picture of the board but there is an image of one here:- http://shop.sjstv.co.uk/ekmps/shops/sjstv/images/48.b0090.001-2444-p.jpg

astracat:
hi think you should check these first
   r6303.6304,rb301,c6311,u6301,also voltage onto d6310 cathode,what volts on q6302base connection
regards
astracat

Acrantophis:
Astracat, I may have been mistaken originally. Upon checking U6301 (VCC) pin 7 I discovered that I actually have 8.42Vdc when measured back to the ground of that device.

Q6302 voltages as follows:-
Base = 9.6vdc
Collector = 185vdc
Emitter = 9.57vdc

D6310 voltage measured at the Cathode back to Gnd is 0.57vdc

Visual inspections of the components listed show no outward signs of defect/failure, these also appear to verify as OK when tested with 2 seperate multi meters.

U6301 proving a little difficult to test. When I try and see what is happening with the aid of a scope I end up tripping my bench supply. I think that this is probably due to the 0V of the board not beign a true GND, I will try again tomorrow with our portable one tomorrow which should be back from calibration.

I don't know if the above helps at all or if you have any further suggestions but thanks so far for your help.

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