Pilot 37" LCD : PIL37AV Stuck on standby

[s_henya]

Hey all,

I found this TV on it's way to the trash..

It had been opened and the speakers were missing.

It got no power at all, so i found and replaced 4 bad caps:
1X220u 25v-> totally open
3X22u 50v-> high ESR

I got standby voltage!
But didn't manage to turn it on

I don't have the remote but there is 3.8v on the power button.

Got 315vdc on main filter cap.

Power supply board:KAS300-5S241812HL

All of the other caps looks pretty much fine
3x1000u 35v were missing some of their capacitance
almost 900 instead of 1000.
i am going to replace those as well.

Any other tips would help me out.

im not sure if its the PS fault or the Logic board....

[Andrew F. Ali]

Re: Pilot 37" LCD : PIL37AV Stuck on standby

Once you replace all parts that you think are faulty and you are getting 5Vdc Standby Voltage. If you can determine the appropriate pins, probably you could try to force the Pwr Sup On by using a 1k-10k resistor from Std-By to Pwr-On and another 1k-10k resistor from Std-By to BL-ON. The connector from the Pwr Bd to the Main Bd must be disconnected from the Main Bd before attemting this operation.

[s_henya]

Re: Pilot 37" LCD : PIL37AV Stuck on standby

I tried force power it by jumpering
pin 1 ON CNR4 connector its ON/OFF with GND with mainboard and inverter disconnected.

i can hear it's trying to start but i can hear some clicks as i have a short on something...

i checked all of the small diodes, all seemed ok.

the next thing is to check the transistors which is a pian,

i hate to wick them out....

any more ideas?

[multimeter]

Re: Pilot 37" LCD : PIL37AV Stuck on standby

what voltage are you getting on the 2 middle pins of the bridge rectifier?,the voltage on the main filter cap seems to low

[s_henya]

Re: Pilot 37" LCD : PIL37AV Stuck on standby

testing this board with ac on, is a pain... there is some residue on the back side,

and in order to test anything, i need to press real hard with the probs,

haha im afraid to slip....

just to clarify one pin on the middle pin of the bridge and the other on hot side gnd?

[multimeter]

Re: Pilot 37" LCD : PIL37AV Stuck on standby

testing this board with ac on, is a pain... the is some residue on the back side,

and in order to test anything i need to press real hard with the probs,

haha im afraid to slip....

just to clarify one pin on the middle pin of the bridge and the other on hot side gnd?

no just the 2 middle pins AC volts marked ~~

[s_henya]

Re: Pilot 37" LCD : PIL37AV Stuck on standby

i added some fresh solder, now the contact is better,

i get 222vac between the middle brigde legs.

never had the chance to thank you multimeter :-)

what next?

[selldoor]

Re: Pilot 37" LCD : PIL37AV Stuck on standby

Surely if he has 315vdc on the big cap the bridge must be ok?

[multimeter]

Re: Pilot 37" LCD : PIL37AV Stuck on standby

Surely if he has 315vdc on the big cap the bridge must be ok?

to confirm line voltage,it still seems low to me.....

[s_henya]

Re: Pilot 37" LCD : PIL37AV Stuck on standby

Could it be that the jumper i connected wasn't right, that caused the clicks?

Because without it (mainboard and inverter connected) there isn't any sound...

CN4, CN6 goes to the mainboard,
CN2,CN3 goes to the inverter.

[CapLeaker]

Re: Pilot 37" LCD : PIL37AV Stuck on standby

maybe the main board isn't returning the on signal for the power supply.

[selldoor]

Re: Pilot 37" LCD : PIL37AV Stuck on standby

What is the part number of that 8 legged IC in the middle of the board just above the BIG cap in your picture

[multimeter]

Re: Pilot 37" LCD : PIL37AV Stuck on standby

could possibly be main board,but that filter cap voltage is bugging me ...,test all output voltage on pins to GND on the PSU connectors,a shorted rail could also cause the problem,you want to see very high KOHM to infinate

[selldoor]

Re: Pilot 37" LCD : PIL37AV Stuck on standby

to confirm line voltage,it still seems low to me.....

Sorry I missed the bit where you said it seemed low - but in Israel they only work on 220vac not 230 -240 so 315vdc is ok. But only as the board is not fully functioning - I suspect it has pfc so if it was all working it would be nearer 380vdc

[multimeter]

Re: Pilot 37" LCD : PIL37AV Stuck on standby

Sorry I missed the bit where you said it seemed low - but in Israel they only work on 220vac not 230 -240 so 315vdc is ok. But only as the board is not fully functioning - I suspect it has pfc so if it was all working it would be nearer 380vdc

absolutly PFC is there,what i expected was around 380VDC ?! a short could load down primary side,do any of the output voltages pulse?could indicate a faulty start up cap ,or shorted secondary diode,have you tested to ground the 5v,12v,24v etc?

[s_henya]

Re: Pilot 37" LCD : PIL37AV Stuck on standby

IC is: 2A180Z

[s_henya]

Re: Pilot 37" LCD : PIL37AV Stuck on standby

multimeter, for you question about testing resistance between outputs to gnd, no i didn't.

give me a quick brief, and i will do it right now.

:-)

[multimeter]

Re: Pilot 37" LCD : PIL37AV Stuck on standby

on the connectors that go from the psu to mainboard,measure the +rails with respect to cold ground chassis,and measure the resistance readings,with psu disconnected and post them up here

[s_henya]

Re: Pilot 37" LCD : PIL37AV Stuck on standby

could i use the GND in the connector itself as cold ground?

i have just thought of something,

this pcb uses multilayer, is it possible that the upper side didn't get contact with the part it was soldered to. i am saying that because i just noticed a cold jont on the upper side of a resistor i took out in order to test out of circuit.

[multimeter]

Re: Pilot 37" LCD : PIL37AV Stuck on standby

could i use the GND in the connector itself as cold ground?

i have just thought of something,

this pcb uses multilayer, is it possible that the upper side didn't get contact with the part it was soldered to. i am saying that because i just noticed a cold jont on the upper side of a resistor i took out in order to test out of circuit.

yes