50PK550 EAX61392501/10 EAY60968801 Standby voltage

[paulstef]

Printed on the board is 5V for StBy voltage.

Can anybody confirm this?

I have one PSU which has 3.4V and the customer had bought a refurbished one, supposedly working, which also has 3.4V.

Can anybody tell me what the voltages STBY, 17V, 5.1V are supposed to be when the unit is in Standby?

Unless something is drawing so much current to pull this line down.

[paulstef]

Re: 50PK550 EAX61392501/10 EAY60968801 Standby voltage

Ok, disconnected the board from everything except AC input. Relays click on then off.

STBY goes to 5V. The 5.1V are off, VS goes to 200V, VA to 60V.

M_ON and RL_ON are both open right now, don't know if they are low or high active, going to investigate.
If anybody has info of what's normal behavior of this board and what is not, please share.

With everything connected except VS VA connectors the relays don't click and STBY stays at 3.4V, so it seems it's loaded too much. It's 3.4V even before the PTC fuse in series with STBY.

[tw2005]

Re: 50PK550 EAX61392501/10 EAY60968801 Standby voltage

Don't have time now but from the guides 3.4 in stdby and 5.1 in run for the stdby. i posted up a training guide last week

[paulstef]

Re: 50PK550 EAX61392501/10 EAY60968801 Standby voltage

Don't have time now but from the guides 3.4 in stdby and 5.1 in run for the stdby. i posted up a training guide last week

Oh great, maybe when you have time could post a link to it please.

So 3.4V doesn't sound too absurd.

[munirutech]

Re: 50PK550 EAX61392501/10 EAY60968801 Standby voltage

for this psu when u disconnect it from the unit and leave only the ac in u only the stby voltage of 3.4v the other voltages will come on when there is a signal from the processor to on them.i guess this will help

[paulstef]

Re: 50PK550 EAX61392501/10 EAY60968801 Standby voltage

Everything except AC IN is removed and the two relays are energized and I have ALL voltages present, VS VA 17V 5.1V and 5VSTBY.

M_ON and RL_ON are both open, there is 0V on them. Bridging them to 5VSTBY doesn't change anything. This is weird.

Does anybody know what AUTO_GND is for and what the voltage at AC_DETECT should be when open? It's 5V right now.

When the PSU was connected to the video/mainboard I had 3.4V and everything was off. How can it wakeup from standby if applying or not voltage to RL_ON M_ON doesn't change a thing?

[Ltank]

Re: 50PK550 EAX61392501/10 EAY60968801 Standby voltage

Standby 5vdc is suppossed to be just that in standby or fully on with set working properly. Trouble shot the 5vdc circuit, once fixed then check the other voltages. Do you have a schematic? I did not find one at my usual places that I get them from. Does your meter have a diode check function?
if not use a regular DVM. Check online how to check the diodes, transformer
and transistor or FET. Closely examine the solder joints too. Keep us posted!

[paulstef]

Re: 50PK550 EAX61392501/10 EAY60968801 Standby voltage

Standby 5vdc is suppossed to be just that in standby or fully on with set working properly. Trouble shot the 5vdc circuit, once fixed then check the other voltages. Do you have a schematic? I did not find one at my usual places that I get them from. Does your meter have a diode check function?
if not use a regular DVM. Check online how to check the diodes, transformer
and transistor or FET. Closely examine the solder joints too. Keep us posted!

All voltages are present when everything except AC IN is connected. No the schematic of the PSU is not included.

[tw2005]

Re: 50PK550 EAX61392501/10 EAY60968801 Standby voltage

Standby 5vdc is suppossed to be just that in standby or fully on with set working properly. Trouble shot the 5vdc circuit, once fixed then check the other voltages. Do you have a schematic? I did not find one at my usual places that I get them from. Does your meter have a diode check function?
if not use a regular DVM. Check online how to check the diodes, transformer
and transistor or FET. Closely examine the solder joints too. Keep us posted!

Not according to the information LG provide. yes I would have thought so too until I read this.



AC Detection (AC Det) is generated on the SMPS, by rectifying a small sample of the A/C Line and routed to the Controller (IC701) where it outputs
at P813 pin 16 (4.06V) and sent to P400 to the Main Board where it is sensed and monitored by the Main Microprocessor
(IC701).
If AC Det is missing the set will not come on, the relays will click when RL_ON arrives, but then no other functions from that point.


Any time AC is applied to the SMPS, STBY 5V will be 3.49V and will be 5.13V when the set turns on.
AC DET WILL NOT be present until set comes on.If AC Det is missing, the TV will NOT come on.

RL On is also quoted ... 3.26V

[paulstef]

Re: 50PK550 EAX61392501/10 EAY60968801 Standby voltage

Not according to the information LG provide. yes I would have thought so too until I read this.



AC Detection (AC Det) is generated on the SMPS, by rectifying a small sample of the A/C Line and routed to the Controller (IC701) where it outputs
at P813 pin 16 (4.06V) and sent to P400 to the Main Board where it is sensed and monitored by the Main Microprocessor
(IC701).
If AC Det is missing the set will not come on, the relays will click when RL_ON arrives, but then no other functions from that point.


Any time AC is applied to the SMPS, STBY 5V will be 3.49V and will be 5.13V when the set turns on.
AC DET WILL NOT be present until set comes on.If AC Det is missing, the TV will NOT come on.

RL On is also quoted ... 3.26V

Thank you very much . Guess I need the whole TV then. It's still kind of weird that with everything disconnected the PSU starts up.

[paulstef]

Re: 50PK550 EAX61392501/10 EAY60968801 Standby voltage

Now, THAT was extremely helpful. Thanks a lot.

Now I also know why it starts up by itself when left floating:

"AUTO GND Pin 18 of P813: This pin is grounded on the Main board. When it is grounded, the Controller (IC701) works in
the normal mode, meaning it turns on the power supply via commands sent from the Main board. When AUTO GND is
floated (opened), it pulls up and places the Controller (IC701) into the Auto mode. In this state, the Controller turns on the power supply in stages automatically. A load is necessary to perform a good test of the SMPS if the Main board is suspect."