Vestel 17IPS20 R6

[rigeback]

Got this 40" TV off the tip and the power board has a problem, previous attempts have been made with the replacement of the thermo resistors.

Main filter caps have 330V although It seems Q211 has a problem as the outer pins are having continuity, caps seem okay but I suspect there is a shorted resistor some where??

[dick_barton]

The best way to test Q211 is to take it out of circuit. Also check all the components around it as shown on the schematic.

[rigeback]

Yes I been trying all the small caps around most components sre good.

C214 / C225 is shorted on board, how many Uf for a 50 volt cap?

[dick_barton]

I don't know how close the schematic matches you power supply and the values given on the schematic do not always tally with what's on the board
1uF = 1000nF so 1nF = 0.001uF

Measure the resistance between pin 2 and 3 of U202, Suspect it may be short circuit.

[rigeback]

Originally Posted by rigeback

Yes I been trying all the small caps around most components sre good.

C214 / C225 is shorted on board, how many Uf for a 50 volt cap?

Off board C214 is Ok so will have to reinstall.

U202 between 2/3 pins reads 1 so no short although my M/Meter is very basic for this work.

I am going to remove Q211 is it possible to remove without the heat sink?

[dick_barton]

I doesn't look like. Use desoldering braid to remove the solder from the heatsink legs.

[rigeback]

Yep jimmied it off and I don't it is the problem after testing it with my basic M/Meter.
Some thing else on the board is causing this short???

[dick_barton]

So with it off the board where is the short to ground on the board. Is it where the Gate or Source or Drain is connected?

[rigeback]

Gate / Source shorting to ground pins 3/4 U202

[dick_barton]

Have you checked D510 & D511 for short circuit using your meter set to diode mode. TV set powered off. I would also check transistor Q215

[rigeback]

Q215 is the Fet that I removed? Q211 is printed on the topside? Confusing this board.

D510 seems ok although not sure if its marked Q510 as prints not so clear. D511 still looking, I see it on the schematic but not board, I must getting old!

[dick_barton]

Q211 would be the mosfet attached to the heatsink.
Post some photo's of the area of the board around Q211, top and bottom to see what components are fitted on the power supply and match the schematic.

[rigeback]

Not sure if these close ups of the area will help, unless the schematic is not for this board?

[dick_barton]

Check D201 as per attachmnent

[rigeback]

D201 and D214 Check OK

[rigeback]

D213 seems to be shorted but it could be the circuit

[dick_barton]

In the schematic D213 is in parallel with a 10 ohm resistor so the only way to check it is to lift it out of circuit but remember which way around it was in before removing it.

[rigeback]

Looking at the board again!
D101 has 330V on both sides, seems strange that a diode that a diode is in place?
I'll take off board although on board it checks normal

[rigeback]

Some new findings D214 and D215 have 240V and at CON4 12V,
I replaced the FET and D101 as they checked OK off board.
I am thinking is it a matter of PS_ON not being activated or is a way to have PS_ON activated always as in other TV's?

[dick_barton]

D214 will not have 240V on it. You need to use hot ground. Connect your black meter lead to the negative leg of C105 carefully and make certain it does not touch anything else. Then connect your red meter led to D214 and measure again.

You say you have the 12V on CN4. Do you also have +5V at CN4, Pin 9 and if not is Q212 transistor soldered on the power supply?

It would be interesting to know what all the pin voltages are for CN4