Philips 32PFL3606/58

[nbdy]

It says 49uF

[dick_barton]

The TNY277PN must be working since it generates the 5V output. In your case a little low at 4.74V.
However it also generates the voltage to run IC808 and IC902 via another winding from the same transformer (T902) which is then rectified and smoothed by D904 and C912 but only measures 10.8V.
IC808 requires a minimum of 11.5V and typical 12.5V to turn on which it's not getting. The voltage at D904 is too low which I think may be the reason that it is not running IC808 to boost the voltage to 380V

[dick_barton]

Originally Posted by nbdy

It says 49uF

Can you check it's ESR?

[nbdy]

Nope,can only change the whole capacitor

[dick_barton]

It would be worth trying that.

[nbdy]

Still the same 10.80V

Faund the ESR meter,it says 0,75 ohm,0.7% loss

[dick_barton]

Sorry but I'm now out of ideas at the moment. Perhaps others can offer further advice.

[nbdy]

thx for now ..

If you got new ideas let me try :-)

Any other advice is welcome 2

[nbdy]

Any one with some idea ???

Does any one know where to buy another PSU ... Looked on ebay there is none ...

thx

[R_J]

When checking voltages in the primary side, use the large (100µf/450v) capacitors negative lead for ground.
Check the voltage across the large capacitor, in standby the voltage should be around 325vdc. When you connect S/B to +5v that voltage should go to around 380vdc. check it. and if it does not change, check pfc ic, using hot ground check the vcc voltage on pin8 of ic909, it should be around +20vdc

[nbdy]

@R_J : Got 325V on the capacitor in both states with the S/B on 5V or not ...

The IC909 has 10V on pin 8 ..

[R_J]

The PFC circuit is not being turned on. If it was, the voltage on the main cap would icrease. I suspect you are not getting 20v VCC, this VCC voltage also supplies ic902 pin6.
The 10 volts on IC909 pin 8 is supplied by it's internal startup cell. Check the voltage on Q903, The emitter should have ~25vdc, the base is controlled by optocoupler IC905. When IC905 is ON, pin4 will be low turning on Q903 which supplies the +20dc for IC909 and IC902 VCC

[nbdy]

I have 13.3V on Q903 ...

[R_J]

Originally Posted by nbdy

I have 13.3V on Q903 ...

Is this the voltage on the emitter? This voltage needs to be higher, check that C912 is not bad, also ZD910 and ZD903 could be bad and zenering at too low a voltage

[nbdy]

The C912 Shows 49uF ESR 0.54 Loss 0.8%

The ZD910 shows 720 in one direction, 6V reading on board or -6V turning the probes

The ZD903 shows 717 in one direction, 4.3V reading on board or -4.3V turning probes

Diodes desoldered from board for testing ...

Could it be that the IC901 is not OK

[R_J]

If ic901 was bad you would not have any +5v standby voltage. You can't check the zener point of zener diodes with a meter. Have you tried replacing C912? Have you checked if R918 is ok?

[nbdy]

The R918 showing 4R7 ...

The C912 replaced,all the same ...

[R_J]

If your +5v standby is ok. disconnect thge s/b line from 5vstb, now check the voltage across IC906 pins 3&4. There should be some voltage there. Now connect the S/B line to +5v and see if that voltage goes to 0 volts. It should if the optocoupler is working.

[nbdy]

I have 970mV on both states with S/B on 5V,and without the S/B on 5V ...

and without the ENA to 5V connected ...

With ENA to 5V all the same - 970mV

So i think changing the optocupler maybe be the solve ... will try tomorrow ...

[R_J]

Check the voltage across IC906 pins 1&2, that will tell you if the internal led is being turned on or not. Use the same method for testing by disconnecting and reconnecting S/B to +5v
You can also monitor the voltage across C912 and try shorting IC906, pins 3&4 to see if the voltage changes and goes up to around +20v
There could be a fault wiith Q908 not turning on the optocoupler, when S/B is connected to +5v, Q908 drain should go to 0 volts, the same with Q907