Philips BA51RJF01021 Power Supply- How do I test it?

[circuitmonkey]

I am fairly new to actually trying to repair SMPS that don't have an obvious fault, like a bad cap or burnt whatever. I am about 4 for 5 and I would really like to get this one done. It is one of the more complicated I have worked on at this point. Schematic is attached to this thread. On initial diagnostic, Q601 was blown, capacitor C615 was low capacitance high ESR. After replacing both items, powered up slow with no excessive current draw. No output voltages on the cold side. IC601 had about 130V on VH(pin 8) and nothing else. After learning a little about the PWM, I decided the lack of Vcc seemed to indicate the Start circuit was not working. I replaced it and that brings us to where I am now. I now have voltage on the secondary side of the board. I just have no idea how to "trick" this board into thinking it's on. There is no 5V standby. I should have 3.3V, 21V and 13V on the main connector and 12V for the LCD. Instead, I have about 12.8V where I should have 21 and 8.9V where I should have 13. So before I do something I may regret, I thought I would ask the community and also have an excuse to upload the schematics. I have a sneaky suspicion that if I put this board in the set and gave it a go, it might work. I also remember that set from 2 years ago that I fixed 3 times because it "looked good", blowing the same FET and diode every time I turned it on. Because I am slow, okay.

The set is across town and I will try putting it in this weekend if I haven't figured it out by then. Do we think it just needs a load? Should I give it a dummy? What are the normal procedures for tricking SMPS into thinking they have a job to do and do those procedures change with the different topology? This is what I would be asking my professor if I could afford one. Feel free to leave comments and regardless, I will finish out the post when this thing is either repaired or hits the inside of the dumpster. Thanks.

[R_J]

Re: Philips BA51RJF01021 Power Supply- How do I test it?

The power supply needs around +5 volts on P-ON-H2 to turn on, try a 1K from the P-ON+21V to P-ON-H2 (there already are 10k's to the transistor bases but this is just as a precaution)
The voltages are low because the power supply is in standby (it does'nt use a seperate standby circuit like other power supplies)

[circuitmonkey]

Re: Philips BA51RJF01021 Power Supply- How do I test it?

Thank you for the quick reply. I connected pin 7 (P-ON-H2) to pin 15 (P-ON+21V) through a 1.5K resistor (it was the closest I could find at 5:30 in the morning) and it worked! All rails are present and correct. I will post again after I actually get a chance to put it in the unit and test it out. Learning the different methods of operation is tricky, but it is progressing. I could see from the schematic and my voltage measurements that it was in some sort of standby mode, but I honestly had no idea how to wake it up. Now it makes perfect sense. Thank you.

[budm]

Re: Philips BA51RJF01021 Power Supply- How do I test it?

What is the model number of this TV?

[circuitmonkey]

Re: Philips BA51RJF01021 Power Supply- How do I test it?

The model is Philips 55PFL5402/F7 A. After installing the PS board, there was no response from the set. Standby mode voltages are present and I was able to follow the voltages from the power supply all the way to the power switch. The switch gets power from the LED/remote sensor board which gets power from the control board. I unplugged all the peripherals and still no difference. There was roughly 1.8V on the power switch when open and 2.3V when the switch was pressed. Further testing will have to wait until I talk to the owner and see what she wants to do with it. To be clear. 3.3V, 13V and 8.9V are present on the PS outputs and main board, 3.3V on the sensor board, and 2.3V on the power switch/menu board. Ideas are welcome and I will post again when we determine what we are doing. For the record, I am thinking the control board may have taken some damage to an IC or processor.

[circuitmonkey]

Re: Philips BA51RJF01021 Power Supply- How do I test it?

Also, while I neglected to get any pics of the open set, I did manage to get a pic of the model info. In my defense, the was much coffee consumed this morning. Apologies.

[circuitmonkey]

Re: Philips BA51RJF01021 Power Supply- How do I test it?

Furthermore, I did take the time to search the forum for other entries and all I came up with was this:
https://www.badcaps.net/forum/showth...ight=55PFL5402

I was hoping to find some schematics for the main board. No joy, but it does contain a firmware upgrade that one may find useful.

[TheTesterMan]

Re: Philips BA51RJF01021 Power Supply- How do I test it?

Monkey, did you ever fix this TV ? If so, could you post solution ? I have the same exact issue and starting to troubleshoot now

[TheTesterMan]

Re: Philips BA51RJF01021 Power Supply- How do I test it?

The power supply needs around +5 volts on P-ON-H2 to turn on, try a 1K from the P-ON+21V to P-ON-H2 (there already are 10k's to the transistor bases but this is just as a precaution)
The voltages are low because the power supply is in standby (it does'nt use a seperate standby circuit like other power supplies)

I disconnected cable from PSU to Main and connected the 1k jumper. I hear a slight buzz but I do not see the LED strips light, should that happen with the 1k cheater jumper ?

I powered all the LED strips with external PSU and they are all good, no bad LEDS.

[R_J]

Re: Philips BA51RJF01021 Power Supply- How do I test it?

I disconnected cable from PSU to Main and connected the 1k jumper. I hear a slight buzz but I do not see the LED strips light, should that happen with the 1k cheater jumper ?

I powered all the LED strips with external PSU and they are all good, no bad LEDS.

The jumper resistor, turns on the power supply only. The backlight-sw and the backlight-adj lines control the backlights, these lines come from the main and go to the led driver board

The only way to check each led string is to check the current, If one led is shorted, the current will change and this can shut down the led driver. The only other way would be to have the panel open and look at each led as the string is powered on.

[TheTesterMan]

Re: Philips BA51RJF01021 Power Supply- How do I test it?

The jumper resistor, turns on the power supply only. The backlight-sw and the backlight-adj lines control the backlights, these lines come from the main and go to the led driver board

The only way to check each led string is to check the current, If one led is shorted, the current will change and this can shut down the led driver. The only other way would be to have the panel open and look at each led as the string is powered on.

Good to know, thx.. Each LED Ring measures the same current so I will assume they are all good.

[TheTesterMan]

Re: Philips BA51RJF01021 Power Supply- How do I test it?

At this point I have concluded with high confidence that the Power Supply Board is not at fault. I then concentrated my efforts on the Main Board measuring voltages and visually inspecting components.
All the voltages check out except for the SOC_CPU_1.1v rail which looks to be dead. Further visual inspection revealed a small blown cap ( I think ) on the PCB backside near the CPU_1.1v rail
I am not sure what is regulating the 1.1V but instead of continuing to troubleshoot/replacing components, I simply purchased a replacement board for $12 on ebay. I'll report back as soon as I swap boards.

[R_J]

Re: Philips BA51RJF01021 Power Supply- How do I test it?

Is the cap shorted? if it is just remove it and see if the cpu_1.1v returns IC3606 will be the ldo for that voltage

[TheTesterMan]

Re: Philips BA51RJF01021 Power Supply- How do I test it?

Is the cap shorted? if it is just remove it and see if the cpu_1.1v returns IC3606 will be the ldo for that voltage

I removed the component, cleaned the PCB and verified that there is no short. Still no CPU 1.1v.
I checked IC3606 and it looks like Pin1 is getting a 13V input voltage, I am not sure about the rest of the pinout but there are no shorts to ground that I can find. I cannot read the legend on the IC so I have no clue what the pinout is supposed to be.

I should be getting replacement board soon but would still like to troubleshoot this board for future reference.

[R_J]

Re: Philips BA51RJF01021 Power Supply- How do I test it?

What are the numbers/letters on IC3606, or a closeup picture to be able to see the markings, you may need to use alcohol to clean the top of the ic to read it.

[TheTesterMan]

Re: Philips BA51RJF01021 Power Supply- How do I test it?

What are the numbers/letters on IC3606, or a closeup picture to be able to see the markings, you may need to use alcohol to clean the top of the ic to read it.

Pain in the butt, had to use a magnifying station at work to read the legend.
UTH 233, confirmed by colleague just to make sure. Searched and found nothing.

Replacement MAIN due in today, I will report back this weekend with findings/results.

[TheTesterMan]

Re: Philips BA51RJF01021 Power Supply- How do I test it?

Replacement MAIN due in today, I will report back this weekend with findings/results.

Main Board replacement resolved the issue, TV back up and running.