Philips BP2.2u Chassis Vtun overvoltage?

[Engineersfoot]

Hello everyone,

I'm trying to diagnose this TV with a BP2.2U chassis.

Service manual is attached.

My symptoms on it are that it powers on with an almost completley dark screen and after a few seconds it starts flashing on certain areas, mostly towards the left with a very dark purple image and a few vertical lines. I see what looks like static in the brief moments where the screen flashes and the side controls seem to have no effect. There is also no sound. Disconnecting Y and Z boards did not make sound re-appear as suggested by this guide https://www.badcaps.net/forum/showpo...42&postcount=4

Fuses are not blown in either the Y or Z boards.

The alarm LED on the power supply (the one on a small vertically mounted board) stays on throughout the duration of the power being on.

There is a blinking LED on the upper right hand corner of the logic board. The one located below the small signal board.

The power supply makes a noise that sounds somewhat like a fridge running, it's not very loud or anything but it's the best way I can describe it and I also notice it goes along someone to the rythim of the blinking LED on the logic board. it's aso comparable to the sound of a CRT TVs vertical stage oscillating except like I said the sound fluctuates to the rythim of the blinking LED on the logic board.

The ambi lights arent coming on despite their being voltage at their tap on the power supply, however I'm not sure if they're activated.

I measured all the voltages coming out of the power supply and a lot of them seem to fluctuate quite a bit, in some cases up to 2 volts which I wouldnt expect from a switching power supply. The only one that i got that was really stable, only fluctuating about 0.2V was Vscan. Voltages arent quite dead on to what they're supposed to be but are tolerable. I'll post them below.

The only one that seemed way out of whack is "Vtun" at 102 volts when it's apparently supposed to be 33V.

I'm comparing voltages to the ones on page 65 of the philips training guide also attached below.

Vs 204V
Vscan -190V
Ve 82V
Vset 190V
Va 68V
Vg 14V
D5V 5.1V
D3v3 3.38
8V6 8V
+VSND 19.7
-VSND -19.8
5V_SW 5V
12V 11.9B
12VL 12V
Vtun 102V
5V2 5V


Again as I said there's fluctuation on a lot of the voltages and it seems to go along with the noise of the power supply and the blinking LED on the logic board.

Any help with this would be much appreciated.

[tom66]

Re: Philips BP2.2u Chassis Vtun overvoltage?

Vtun is for the tuner. It is bad, but that should not cause your fault. Any fluctuation in those voltages? Can you post pictures of the X-main and Y-main boards?

[Engineersfoot]

Re: Philips BP2.2u Chassis Vtun overvoltage?

Note: I just discovered that the philips training guide says that the voltage list it has is for 42SDV4 and this is apparently 42HDV4 however that doesnt seem to make this 102V reading to be plausible as a normal thing. The thing is that on the BP2.2U service manual I cant find the Vtuner voltage listed on the power supply diagram although it is mentioned else where in the manual. Not sure what's up with that. The only tuner voltage I can find is for 5v but it's not called the same.

I currently need to find my camera charger and I'll try to post pictures when I dig it up but for now if you look at the first page of that philips training guide you can see a picture of what I have of mine, not a detailed or close up pic but might give some guidance until i get my own pics.

[Engineersfoot]

Re: Philips BP2.2u Chassis Vtun overvoltage?

OKay quick update, I tried testing the power supply unloaded, completley seperate from the TV. Jumping J8004 and J8003 as well as BJ8902. All three LEDs come on LED8002 and LED8001 as well as BD8903. By the training manual standards this says the PS is not deffective but I usually wouldnt just trust that.

I found out two interesting things out of all of this.

1. Voltage fluctuations are pretty much completley gone with the exception of VSND +18V which fluctuates about 0.12V which isnt much and perhaps nothing to note.

2. The pulsating fridge/TV vertical sound isnt there, only the kind of noise which I would assume is normal from this kind of thing which is a more even type sound.

2. Vtun DOES fluctuate tom, but in an interesting manner. The inicial voltage reading was something around 86V but I noticed the longer I measured that the voltage was discharging slowly. I didnt wait all the way to see how low it would go but it kept falling. Will have to see what's up there but something is obviously not right. some kind of regulation or load problem. I thought of maybe adding a dummy load but I'm not sure about that.

Will inspect this line of the power supply to see what I can find.

This time my voltage measurements where

VS 205-206V (bit of fluctuation here but it may be do to me being in the highest range my multimeter will go up to)
Vscan -189V
Ve 83.7V
Vset 194V
Va 69.5V
Vg 15.1V
D5V 5.2V
D3v3 3.4V
8V6 8.65V
VSND +18 15.82-15.94V (this is the one I mentioned had a bit of fluctuation, not sure what a big deal this is)
VSND -18 -16.05V (note the difference between these two, they are the sound board power, dont think it's a big deal but still)
5V_5W 5.21V
12V 12.12V
12VL 12.12V
Vtun 84V and falling indefinately
5V2 5.17V

Overall not much of a difference except for the fact of the missing fluctuation.

ONE MORE EDIT:

After inspecting the V tun line I found two things.

1. Bottom of this board says Vtun is supposed to be 50V.

2. The Vtun line has no regulation and is directly coming out from pulse transformer T8003. After the output at T8003 there is only a fuse, then a rectifier, a capacitor, followed by a 1.7K resistor which then goes to the output connector.

Would it be safe to assume that the reason for this is that there's something wrong on the small signal board that is leaving this circuit unloaded thus making it's voltage spike?

Edit #2

Okay some dissapointing results after some close examination, after looking at the board and the schematic for the small signal board DC to DC hook ups it look slike pin 8, the entrance for Vtun, is not connected to anything on this board thus explaining our overvoltage at the output of Vtun. *sigh* Back to the drawing board! Tom, I know you had said this would be causing my problem but it was still too much of an anomaly to pass up.

Now I REALLY need your ideas. Kinda wish I could edit the title for a more fitting description of the problem at hand.

[tom66]

Re: Philips BP2.2u Chassis Vtun overvoltage?

I'd like to see a picture or video of the fault before I can make suggestions, but my first guess is X-main, followed by Y-main board.

Usually, on most TVs at least, Vtun is around 30 to 35V, it is regulated by a resistor-zener network from some high voltage source (on some TV's, I've seen ac addition of 12V and 24V, others just using a spare tap) and typical load current is a few hundred microamps. It's used to bias the internal varicap diode in the tuner, allowing the selection of different stations.

[Engineersfoot]

Re: Philips BP2.2u Chassis Vtun overvoltage?

OKay here are the pictures you ordered. Second set arent very clear but I hope they help anyway.

First is the screen showing the failure. What you see in the picture is what the screen shows intermitently. The pattern you see on screen comes off and on at the same time and rythim that the blinking light on the logic board blinks and at the same time and rythim of the pulsing sorta fridge type sound that the TV makes. It seems like it's displaying static and what looks like some kind of logo on one o the corners. The picture looks like it's shifted to the side.

Next two pictures are of the blinking LED. There's two and it's the one on the left that blinks. It's called LED2011.

What else could I inspect on the Y and Z boards to see if they're faulty? I see some voltage regulators that I'll be checking out.

Screen flickers on and off showing this:

[tom66]

Re: Philips BP2.2u Chassis Vtun overvoltage?

That's an odd one - it looks like it could be a bad control board or bad panel. Very hard to tell.

[Engineersfoot]

Re: Philips BP2.2u Chassis Vtun overvoltage?

Hmm can I just ask why now you think it may not be the Y or Z boards? What of this picture makes you think these arent the symptoms relating to a bad Y or Z board and what of it makes you think it's perhaps a bad panel or control board.

Seriously hope it's not the panel!

[tom66]

Re: Philips BP2.2u Chassis Vtun overvoltage?

I thought previously from your description you had an image but it was purple tinted which heavily points in the Z-sustain direction, hence the need for pictures! Neither Y-sustain nor Z-sustain are involved in the X-axis of the image so they cannot affect that. Only control board or panel can in such a way.

[Engineersfoot]

Re: Philips BP2.2u Chassis Vtun overvoltage?

After fiddling around with the buttons I found that I did get a reaction, it being that now the screen fills out. Still flickers on and off but now the whole screen is full.

Below I've attached a video it's only 3MB so it;s easy to download, it's in a zip file as the forum attachments function wont allow a direct video.


Do you think you can give me a second opinion with this please? It displays a logo on the top right and appears to be displaying a menu below it. Notice the dark blotch at the top of the screen that doesnt really go away. It had a similar one at the bottom that gradually did go away.

[tom66]

Re: Philips BP2.2u Chassis Vtun overvoltage?

Vs/Va steady with that fault? Check -Vy, Vsc and Vzbias on the sustains - if unsure post a picture of them.

[Engineersfoot]

Re: Philips BP2.2u Chassis Vtun overvoltage?

You know this time around I measured voltages both when the screen only partially lights up and also when it lights up fully like in the video and all voltages are much more steady this time around, only varying by about 0.1 volt at the most. Not sure why but voltages are generally stable now.

Like I said the screen lights up when I fiddle with the buttons a bit, takes a lot of presses but it eventually causes a change.

I'm not sure how to check -Vy, Vsc, and Vzbias, I'll post pictures of the boards once I can dissasemble the set enough for you to see them properly.

Also I'll remind you that we dont have any audio. Would a bad panel cause a no audio fault?

Please stand by for pics of the boards.