Phillips 37PF5521D dead after power cut

[selldoor]

Re: Phillips 37PF5521D dead after power cut

no the relay is not clicking, there is no component at 9320 it a wire link, yes i think the component on the heatsink is a bridge rectifier,r3318 100ohm 1/2 watt was ok but i have changed it for 470ohm 1/2 watt . do you think it could be the rectifier would i need to take it off the boar to test it ?

I am just trying to establish how far the voltage is getting.

Obviously you should have 230 v ac at the black and white mains socket?
You should have 230vac at the ceramic fuse.
Next usual thing to check is the Bridge - should be 230vac on the centre pins (should be marked ~~ and 320VDC on the outer pins which should be marked + and -.
If you dont get those then you test what is in between - Budm's resistor?

[flocko]

Re: Phillips 37PF5521D dead after power cut

OK, just checked the voltages on the bridge AC, something odd is going on. The two centre terminals AC when I checked with the meter are reading 0 volts. If I check AC again with one lead to the negative cap, other lead to bridge, again 0 volts.
Only when I connect my meter to one side of the incoming supply and either one of the centre pins(AC) do I get 240 volts to each pin. I cannot work this out.
Would appreciate any help pointing me in the right direction.

[tom66]

Re: Phillips 37PF5521D dead after power cut

That relay is not clicking on, so you will not see main power (bridge will appear dead.)

[selldoor]

Re: Phillips 37PF5521D dead after power cut

It would help if you answered the questions as asked without getting sidetracked and asking another question.
Do you get 230vac at the fuse?
Do you get 230vac at the two~ contacts on the bridge.

There are a couple of test for a bridge - this is one

Get a felt tip pin and follow the pins through the board and mark the board
...... + ~ ~ -
Pins 0 0 0 0
...... 1 2 3 4
Mains power OFF
Set your meter to measure 2000 ohms.

Place positive (red) probe on the + pin. 1 above
Place negative (black) probe on the ac pin 2 above.
Write down the result. ohms

Place positive (red) probe on the ac pin. 2 above
Place negative (black) probe on the + pin 1 above.
Write down the result ohms

Place positive (red) probe on the ac pin. 2 above
Place negative (black) probe on the ac pin 3 above.
Write down the result ohms

Place positive (red) probe on the ac pin. 3 above
Place negative (black) probe on the ac pin 2 above.
Write down the result ohms

Place positive (red) probe on the ac pin. 3 above
Place negative (black) probe on the - pin 4 above.
Write down the result ohms

Place positive (red) probe on the - pin. 4 above
Place negative (black) probe on the ac pin 3 above.
Write down the result. ohms

You can cut and paste the above and write in your results

[flocko]

Re: Phillips 37PF5521D dead after power cut

yesi have 240v mains in and though fuse, on the bridge i am only getting a reading of 240v if i put one probe in the mains in and the other to the 2 or 3 pin. if i go on pins 2 and 3 i get o volts the above test all show OL on the meter

[selldoor]

Re: Phillips 37PF5521D dead after power cut

Bridge is probably shot - remove and test again off board.
Try the test on the bridge you already removed?

[tom66]

Re: Phillips 37PF5521D dead after power cut

Bridge rectifiers very rarely fail open, the fuse would blow if the bridge was bad. I suspect because the relay isn't clicking over you're not seeing the right voltages. Does the TV click when plugged in? Since it is dead, it will probably not. There is a second small bridge for standby and audio.

[flocko]

Re: Phillips 37PF5521D dead after power cut

no clicking on the relay, no standby light,i will look at the standby board bridge , i still cannot get my head around the voltages on the power board why do i not read a voltage across the feed to the standby board without an incoming voltage there will be no output to feed the relay or am i just not getting this

[tom66]

Re: Phillips 37PF5521D dead after power cut

The rectified, unswitched AC comes onto the "AUDIO STANDBY" board to provide audio power and standby power. It also looks like that board has the audio amplifier on it. I would suspect this board or the AC being supplied to it if you've got no power at all.

[selldoor]

Re: Phillips 37PF5521D dead after power cut

If you disconnect the cables from the PS to the standby are there any voltages on the PS. Care - high voltage.

[flocko]

Re: Phillips 37PF5521D dead after power cut

voltage at link plug with plug pulled 9.5v ac across the two pins, i read on a post with these two boards that the output should be up around 70v ac

[tom66]

Re: Phillips 37PF5521D dead after power cut

It should be DC volts around 325V, measured across the pins, not relative to chassis. I assume the fuse next to it is OK.

[flocko]

Re: Phillips 37PF5521D dead after power cut

yes fuse is good ,i have change the 10uf 450v cap by the fuse and the two 10uf 450v caps on the input to the standby board

[selldoor]

Re: Phillips 37PF5521D dead after power cut

Did you check the resistor Budm referred to

[flocko]

Re: Phillips 37PF5521D dead after power cut

yes i have already replaced it with a 470 ohm

[tom66]

Re: Phillips 37PF5521D dead after power cut

What is the chassis code for this TV e.g. LC4.1ED. It will be written on rear of unit. Usually on main sticker. I have got 32" version service manual.

[tom66]

Re: Phillips 37PF5521D dead after power cut

Just checked and the SM I have is good for 37" too.
http://www.tgohome.com/ServiceManual...&Search=Submit

Page 12 has a useful block diagram, you should have 325V across that small bridge rectfier and going into STBY board. STBY board then provides relay signal to turn on rest of PSU.

[selldoor]

Re: Phillips 37PF5521D dead after power cut

Can you post a picture of the back of the power board - we seem to be going around in circles - Id have thought the mains voltage should appear at the bridge even if the
relay was not working - perhaps Tom can confirm?.
My understanding is the resistance test on the bridge should give readings one way and off scale the other. perhaps do the test again but use the diode setting.

[tom66]

Re: Phillips 37PF5521D dead after power cut

Relay switches in power to the big bridge on the heatsink. Rest of PSU is dead until that clicks over. And that will only click over on signal from main board, which uses standby power. I'll bet somehow the standby PSU isn't working. The block diagram simplifies it all.

[flocko]

Re: Phillips 37PF5521D dead after power cut

thanks again for your help with this, if you wish i will post photo off the under side of power board