New Issue: Philips 52UP56 Pin Cushion Problem all three tubes


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New Issue: Philips 52UP56 Pin Cushion Problem all three tubes

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streetchariot
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Jun 5, 2007, 6:54 PM

Post #1 of 22 (815 views)
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New Issue: Philips 52UP56 Pin Cushion Problem all three tubes	Can't Post

I know you may say, "Why are you even bothering with this 11 year old TV?" The reason is, that I like repairing things, it's a hobby of mine.

Now for the issue at hand.

52UP56 Philips-Magnavox Rear Projection TV powers up, has no picture, but rear filaments do glow on all three CRTs. (RGB)

Upon turning the unit on, I can hear a low hissing sound at / around the FB-XFMR, and there is zero to little voltage measured from the Flyback to the Focus/Adjustment plate mounted in the back of the cabinet.

I cannot check for sound, as this chassis has no speakers or outputs. When I hooked up RG6 cable, the hiss was variable, as if it was adjusting for changing picture.

If the Flyback has 0.00 to 0.05 volts during operation, should the Flyback be suspected first, or a cap, or a resistor? All of the boards look to be in good shape for their age.

All three of the CRTs are is good overall shape, and do not appear to be cracked or damaged.

Please correct me if I am wrong in my assumption, but it seems that the issue with this unit is the Flyback Transformer. All of the other TVs I have worked on have had the focus adjustment built into the Flyback, but this unit has a seperate unit for adjusting focus.

Thanks,
Andrew

(This post was edited by streetchariot on Jun 20, 2007, 7:20 PM)

streetchariot
Novice

Jun 5, 2007, 9:40 PM

Post #2 of 22 (804 views)
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Re: [streetchariot] Philips 52UP56 No Picture/Does power up [In reply to]	Can't Post

A little more information:

The TV appears to respond to RF comands from my Logitech Harmony Remote.
If I press the power button, the bottom of the CRTs glow amber.
If I press the power button again, they go off.

Though the CRTs glow at the bottom, there is no light emitted from the actual color tubes.
The glow is very faint if you look at the base of the CRT where the driver board is connected.

The unit is built by GVC, which I cannot find any information about.
GVC seems to be an OED, which uses Philips parts to make their own units.
Philips 52UP56 is stamped on the back.

I am getting nil voltage from the flyback, and have not seen any voltage from the flyback yet. The three tubes glow amber with the flyback red cable disconnected or connected. It does not seem to matter.

There is a slight (faint) humming sound from the same area on the board (as the Flyback), if I tap the chassis, the humming sound subsides.

I'm almost certain it is the Flyback now that I have read that voltage should be 30,000 times what I have seen from the unit.

Let me know what you think.

TV guy 1966
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Jun 5, 2007, 11:50 PM

Post #3 of 22 (801 views)
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Re: [streetchariot] Philips 52UP56 No Picture/Does power up [In reply to]	Can't Post

If this unit is 11 yrs old or so this must be the chassis that is split into to modules, signal or the left and power supply deflection on the right. If you have filiments on your tubes that that meens that your sweep is worrking (that hum you hear) and the switch mode power supply is working. Good chance the flyback is defective and ALSO the Horz.output transistor mounted on the heat sink just left of the transformer is shorted and a open resistor off the emitter of that transistor. The resistor value is around .22ohm 1/2watt. Also If you do get this beast fired up and working you might find a poor color,blurry,color green or blue halo around images and the osd display. If so you have another problem to conquor. Check out your set and get back with me. Good luck.

streetchariot
Novice

Jun 6, 2007, 12:05 AM

Post #4 of 22 (800 views)
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Re: [TV guy 1966] Philips 52UP56 No Picture/Does power up [In reply to]	Can't Post

I knew this TV would be work, but it seemed to not be that hard of an issue to correct.
In past repairs, I have learned if the TV powers up, that is half the battle. :)
Your description of the internals is correct.

IC Convergance mounted inside left wall (from the rear). green ribbon / red ribbon from IC to right driver board (bottom left from rear). several (yellow/blue/green/red) ribbon cables from left to right board.
The Flyback is on the right hand board (right bottom viewed from back), and it looks like it has a vertical crack on the side of it from top to bottom on the tower. I know it has to be part of the problem, since I am able to write this post (since I wasn't shocked to death when pulling out the red conductor cable).

Everyone suggests replacing the H.O.T and FB-XFMR at the same time, which I will do.

Would you mind providing me with a second set of eyes if I put up some pictures of the left and right board tonight?

I can not see any other components that seem to be on the fritz.

When I pulled off the rear input panel cover on the back I noticed there were 2 RCA inputs, as well as an RCA output that were hidden by the panel. Are these active? Could I plug the RCA out into a stereo to see if I was getting sound, to further sell my case that the flyback is bad?

Also, is there any way to get the prints for this unit? I've searched high and low, and cannot find them. I'd like to make my own front panel for the unit, as it'd be nice to see a status led or have a power sw.

I service large industrial sorters, so a 52" tv isn't too big of an issue for me. I'm up for of anything this unit could throw my way.,

Thanks,
Andrew

streetchariot
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Jun 6, 2007, 9:41 AM

Post #5 of 22 (796 views)
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Re: [streetchariot] Philips 52UP56 No Picture/Does power up [In reply to]	Can't Post

After further investigation, the Flyback is not getting any power, and it is not cracked.
The part outlined in blue is making a clicking sound (like a relay).

TV guy 1966
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Jun 6, 2007, 8:45 PM

Post #6 of 22 (790 views)
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Re: [streetchariot] Philips 52UP56 No Picture/Does power up [In reply to]	Can't Post

That circuit is the sweep section of that chassis. The transistor on the heat sink there is the output that runs that transformer to the left of the pix. which produces the filiment voltage for your glow in the bottom section of your tubes. It also provides horz. sweep for the yokes on the tubes. That blue looking thing is a coil there in that circuit. It may sing a bit because of the horz. freq. that is feed with the circuit but it will not click. There is no relay on that chassis to make that noise. Just maybe the sweep or the switch mode power supply is pulsating but not likely. If you don't have your 130VDC of B+ on the collector of your output transistor that's on your heatsink(just left of that transformer in the pix)that drives your High voltage transformer that means you have a open from your switch mode power supply to that output transistor. Looking directly at that board as if it was still in the tv you will see two identical resistor looking parts at the very left of the board near the edge. They are color coded like a resistor but in fact they are coils that couples the 130VDC to your sweep and high voltage. Look and see if one is discolored. You have the 130 v because the sweep is fed with the same supply. There is no fuses to open from that 130 supply to the colector of your output transistor. look for breaks at the edge of the board near those coils. The foils paths are close to the edge so look at that. Then it going directly to your high voltage transformer and out of that and to your colector of your out put. Good luck!

streetchariot
Novice

Jun 6, 2007, 9:51 PM

Post #7 of 22 (785 views)
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Re: [TV guy 1966] Philips 52UP56 No Picture/Does power up [In reply to]	Can't Post

OK. I replaced the Coil, as it had a crack around the bottom. (Due possibly to heat?)
Here is a picture of the High Voltage Transformer. (Attached)

A little more information now...

The TV does emit a frequecncy change (in the area of the Flyback) when I hit the channel +/- buttons on the remote, just as any other TV would.

The resistor valued .31 Ohm was blown right at the HOT. (Correction : I believe the resistor is .33 Ohm)
I am most certain that the issue is the Flyback now.

I'm looking for a vendor who doesn't charge 100.00 for the part.
The local vendor, Electronix is out of stock.

As for the HOT I found the 2SD1556 available for .99$ at tritronics, and will replace it also when I replace the Flyback.

Do you have any other suggestions as to what to look for?
The TV is so close to being workable... Just need to find the parts.

Is there any way to get the tubes to come up without the Flyback working? To test the tubes that is?

It looks like the green tube has some green fungus growing in it, so that'll be another job to tackle if I get the beast going.

(This post was edited by streetchariot on Jun 15, 2007, 5:50 PM)

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TV guy 1966
User

Jun 8, 2007, 9:43 PM

Post #8 of 22 (771 views)
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Re: [streetchariot] Philips 52UP56 No Picture/Does power up [In reply to]	Can't Post

Yes that is the H.output. If you meter the leads you will find it shorted,that is why that .33ohm resistor is open. The transformer is a common problem for those versions of tvs,that's why your vender is out of stock. The transformer is NLA but generic ones are available. If you replace the transformer,H.out,resistor, you should be good to go. Once you get it fired up take a look at the pix,you may need ptv fluid in the green and blue crt assy,thats the fugus you saw. You need that 30,000 volts from the transformer to ignite the tubes.Good Luck!

streetchariot
Novice

Jun 12, 2007, 8:16 PM

Post #9 of 22 (760 views)
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Re: [TV guy 1966] Philips 52UP56 No Picture/Does power up [In reply to]	Can't Post

TV Guy thanks for all of your help!

One more question. How does the flow of electricity work between the NPN/FBXFRMR/Resistor?
Does the HOT enable the flow of electrons to the Flyback? Is it possible that the HOT/Resistor are the bad components, and the Flyback is OK?

I bought (1 qty) flyback, (3 qty) 2SD1556, (20 qty) 0.33 Ohm Flame Proof Resistor.

They should all arrive by Friday hopefully, pending nothing is on back order.
I'll post the results when I tackle the project this weekend, or by Tuesday at the latest.

streetchariot
Novice

Jun 14, 2007, 7:22 PM

Post #10 of 22 (749 views)
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Re: [streetchariot] Philips 52UP56 No Picture/Does power up [In reply to]	Can't Post

OK. Better news to report.

As I mentioned above... I purchased extra transistors and resistors so I had extra if needed...

I replaced the transistor and resistor, and the TV is actually firing up now, but is not staying on due to the bad flyback. FedEx says it should be at my door tomorrow around 9-10am... So hopefully by noon I'll be watching this darn thing.

Wish me luck!

-StreetChariot

streetchariot
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Jun 14, 2007, 7:25 PM

Post #11 of 22 (748 views)
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Re: [streetchariot] Philips 52UP56 No Picture/Does power up [In reply to]	Can't Post

The frenzel (sp?) and lenticular lenses are showing heavy wear on the TV... Where can I get used replacements for under 100$? MCM sells new ones for 350$, but I would rather not spend that kind of money on the TV.

Is it possible to use an InFocus Rear Projection Screen, and make it tight on the chassis?

Thanks,
-StreetChariot

streetchariot
Novice

Jun 15, 2007, 5:41 PM

Post #12 of 22 (740 views)
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Re: [streetchariot] Philips 52UP56 No Picture/Does power up [In reply to]	Can't Post

OK. The TV is on now, but I have some pin cushion and convergence issues.
I do not have the original remote, and all of my universal remotes will not let me converge the unit.

I know how to get to the Service and Convergence Menus, 062596 MENU / 062597 MENU.
I have the lenses cleaned, focused and the G2 Block is calibrated.
What can I do to get the convergence fixed?

I belive the Cold Side pot is set wrong also... It was not set right, and I do not know what value it should be set to. After about 5 hours of use, I turned it off. I came back an hour later and turned it on, and the TV is entering safemode after 10-20 minutes. I can turn it right back on as soon as it happens.

Thanks,
-StreetChariot

(This post was edited by streetchariot on Jun 15, 2007, 5:47 PM)

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streetchariot
Novice

Jun 19, 2007, 2:37 PM

Post #13 of 22 (712 views)
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Re: [streetchariot] Philips 52UP56 No Picture/Does power up [In reply to]	Can't Post

Anyone have any insight?

Thanks,
StreetChariot

streetchariot
Novice

Jun 20, 2007, 12:47 AM

Post #14 of 22 (706 views)
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Re: [streetchariot] Philips 52UP56 No Picture/Does power up [In reply to]	Can't Post

I am going to try to isolate the problem to see if I have any bad caps. The fact that all three tubes experience the same issue leads me to believe that there is not any control coming from the DigConv circuit. I'll try that tomorrow and post my results here after I finish working on it.

In essence the issue is that all three tubes have no calibration/convergence/pin cushion control.

It cannot be the yokes, as all three yokes would have to have the exact same problem and be moved the exact same way.

I have the schematics now, and will check all solder joints and caps to see if that will rectify the problem. Other than the issue with pin cushioning, the TV picture looks great. All three tubes were replaced, as previous owner thought that was the issue.

Thanks!
StreetChariot

streetchariot
Novice

Jun 27, 2007, 5:20 PM

Post #15 of 22 (668 views)
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Re: [TV guy 1966] Philips 52UP56 No Picture/Does power up [In reply to]	Can't Post

OK.. I checked the caps, and the solder joints. Nothing looked out of whack.

I'm kind of at a standstill on this TV. Anyone have any insight?

Thanks,
StreetChariot

mikemaiertv
Enthusiast

Jun 27, 2007, 6:27 PM

Post #16 of 22 (667 views)
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Re: [streetchariot] Philips 52UP56 No Picture/Does power up [In reply to]	Can't Post

Looks like a total loss of convergance voltage, on the convergance board there are two fuses, check for 32 volts and -32 volts on f1 and f2
Mike Owens Lead tech Maier TV Spokane Wa

streetchariot
Novice

Jun 27, 2007, 6:37 PM

Post #17 of 22 (665 views)
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Re: [mikemaiertv] Philips 52UP56 No Picture/Does power up [In reply to]	Can't Post

Thanks Mike. I didn't see any fuses, but I will check again.

I'll reply with my findings.

Thanks,
Andrew

streetchariot
Novice

Jun 27, 2007, 6:40 PM

Post #18 of 22 (664 views)
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Re: [streetchariot] Philips 52UP56 No Picture/Does power up [In reply to]	Can't Post

Never mind, I see them. They are in-line fuses.

I attached a copy of the schematic.

(This post was edited by streetchariot on Jun 27, 2007, 6:41 PM)

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fuses.jpg (22.0 KB)

streetchariot
Novice

Jun 27, 2007, 7:10 PM

Post #19 of 22 (660 views)
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Re: [streetchariot] Philips 52UP56 No Picture/Does power up [In reply to]	Can't Post

Are the fuses the diode style (Small)? I am not home looking at the TV, as I am at work.
I'm trying to find a vendor for the part, but I cannot figure out which kind of fuse it is.
Thanks,
Andrew.

streetchariot
Novice

Jun 28, 2007, 3:12 PM

Post #20 of 22 (657 views)
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Re: [mikemaiertv] Philips 52UP56 No Picture/Does power up [In reply to]	Can't Post

OK. I changed out the fuses, and was able to converge the unit using the Menu convergance.

I am still left with the horrible pin cushion problem.

All three yokes are calibrated, and center convergence was completed.

Here is a picture of what the screen looks like now...

The center of the screen looks great, but as you work your way out, the picture becomes pretty bad with the pin cushion issue. I sized the screen image down a bit to see if the vertical pin cushion had gone away, it is still happening on both the vertical axis and horizontal axis.

The PIP is also not working, could this be part of the issue also?

Thanks,
Andrew

(This post was edited by streetchariot on Jun 28, 2007, 3:15 PM)

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streetchariot
Novice

Jun 28, 2007, 7:07 PM

Post #21 of 22 (647 views)
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Re: [TV guy 1966] Philips 52UP56 No Picture/Does power up [In reply to]	Can't Post

Could my issue be related to the Linearity Coil?

I replaced it with a different coil, as the original was cracked at the base.

I'm not sure what the Linearity Coil does, but that is the only item I replaced on the Large SB besdies the Transistor/Resistor/Flyback.

Thanks,
Andrew

streetchariot
Novice

Jun 29, 2007, 7:41 PM

Post #22 of 22 (638 views)
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Re: [streetchariot] Philips 52UP56 No Picture/Does power up [In reply to]	Can't Post

Well I think it may be time to give up on the TV.

I pulled the large signal board this morning to check for cold solder joints. I fixed them all, and put the board back in the chassis. When I tried to bring the unit back up, i heard a loud pop, and the TV will only make a clicking sound in the main xformer when I try to turn it on. I found the problem was that the bottom vent screen had come undone, and had shorted. There is nothing mounted to the section where the bridge occured. Here is a shot of the place where the screen touched.

I'll revisit it one more time, but after that it'll probably be on the curb.

(This post was edited by streetchariot on Jun 29, 2007, 7:42 PM)

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