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Phillips Convergence or HV Block/Splitter   Goto page 1, 2  Next  
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TVRE



Joined: 03 Jun 2008
Posts: 6

PostPosted: Tue Jun 03, 2008 3:07 pm    Post subject: Phillips Convergence or HV Block/Splitter Reply with quote

Hello

I have a Phillips 50in Projection TV:

model: 50P8341
chassis: PTV-915

The picture is very blurry and you can't make anything out.

If I adjust the color for the green and red tubes the image clears up ,but the blue tube stays blurry.

The coolant has been recently changed.

My questions is:

Is this problem with the HV splitter or STKs?

What are symptoms of a bad HV block?

What is the part number for this block?

Also sometimes the HV block behaviors erratically. (The green adjustments affect the red tube)

Thanks





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Jesse Mack



Joined: 22 May 2008
Posts: 600
Location: The Last Frontier

PostPosted: Tue Jun 03, 2008 3:56 pm    Post subject: Reply with quote

I have not seen a HV block cause what I see in your pictures. However, pictures are difficult at best to acquire looking directly into the lense.
The picture I see of the overall picture seems to look like you have a great deal of snow in the picture. You need to do your testing using a VCR or DVD as the picture source.
That being said, Philips/Magnavox is famous for contaminated coolant and if it is not changed by someone knowledgeable the problem will return within 6 months. (you cannot just change the coolant, you have to remove and disassemble the CRT and its lensing, remove the scum (which is an alge that grows in the fluid) decontaminate using DENATURED alcohol, and reassembled using new seals and coolant.)
This process will also require a fairly major convergence and I can show you a shortcut if it turns out that you have to reprocess the CRT's
To check, turn the color completely off/down as the color information will just confuse you. Use a KNOWN GOOD signal source that is not snowy.
Look directly into the lense of each CRT (picture tube).
Adjust the focus control for each color, adjust for the least amount of fuzz for each color. (this is the 3" square black box that has six controls on it that consists of a red/green/blue G2(screen) control and a red/green/blue focus control) take a paint brush and clean the dirt off of the box and use a flashlight to tell which is which.
You will be able to see the scum that collects in the crt in two ways if it is contaminated coolant. With the set "ON" looking directly into the CRT and with the set "OFF" using a flashlight.
If there is scum or when using a flashlight there is a kind of yellowish look you have contaminated fluid.
If the picture is clear on all three CRT's when observed directly you have miss-adjusted lenses.

I hope this helps

Jesse
TVRE



Joined: 03 Jun 2008
Posts: 6

PostPosted: Tue Jun 03, 2008 5:25 pm    Post subject: Reply with quote

Hi

Thanks for your reply.

I have checked the coolant and it is mostly clear with a very very small tint of yellow.

There is actually no good way to disassemble the tube.

Each tube has only a drain/fill plug.

Here is a picture of the CRTs.

Also there seems to be small droplets of liquid on the lenses, but on the inside.

Can you help figure out how to disassemble them?


Jesse Mack



Joined: 22 May 2008
Posts: 600
Location: The Last Frontier

PostPosted: Tue Jun 03, 2008 6:59 pm    Post subject: Reply with quote

I can do that, however, first it is important that you do not do this unnecessarily. It is a long process that takes me about 1~1.5 hours to do two CRT's. Please note that the problem will exist in only the green or the blue CRT's. The red CRT will never have the problem. (Due the the wavelength of the Red Light) So read the previous reply and make sure of your problem. From the last set of pictures, my first reaction is that there is NO coolant in that CRT. There will never be any droplets of that size. It looks like (because of the angle of the picture) that the CRT may only be partially full. This would cause a definate focus departure line that goes from left to right with either the upper or lower half of the picture to be far out of focus as projected on the screen. When you are looking straight into the green lense with the set on you should be able to see scan lines. Scan lines are what makes up the picture and it is these lines that will go in and out of focus when adjusting the focus block.
Who changed the coolant?. Was you there and was the CRT disassembled?

Jesse
TVRE



Joined: 03 Jun 2008
Posts: 6

PostPosted: Tue Jun 03, 2008 8:33 pm    Post subject: Reply with quote

Hi

I bought the TV from someone that told me that the tv had been serviced.

I understand what you mean when you focus the the CRT block.

When focusing the tubes all go into a very clear focus except the blue.

I am able to see clearly the scan lines on both the red and green tubes, but the blue does not focus properly.

There is coolant in all 3 tubes, but the amount is unknown.

I bought a 16oz tube coolant bottle.

I would like to know if the CRT has been destroyed.

Is it repairable?

I don't think the CRTs have been disassembled.

Thank you for your help and time.
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Jesse Mack



Joined: 22 May 2008
Posts: 600
Location: The Last Frontier

PostPosted: Wed Jun 04, 2008 10:39 am    Post subject: Reply with quote

It is important to determine exactly what is wrong without guessing so if you will bear with me we can do that.
I am assuming that the CRT that is showing the droplets is the blue CRT.
If I am wrong, let me know.
If you have the contamination problem, the problem is VERY obvious.
It looks like there is scum inside the CRT that creates an effect like a semi-transparent curtain between your eyes and the blue picture and makes the blue impossible to focus or produce a usable picture.
The droplets should not be present. Look into the CRT and see if you can see if the fluid level is low or not. It should look just like the other two CRT's. If there is low fluid there will be an obvious fluid level departure line when looking directly into the lense with the set on.
If the fluid is low, or very low this will be your focus problem.
If the fluid is not low, it is important to be able to see the faint scan lines. put the mirror cover back on and after turning the set on with a known good signal TURN THE COLOR LEVEL ALL THE WAY OFF.
This will give you the best chance to see the scan lines in the blue CRT.
After the color has been turned down remove the mirror cover again and look directly into the blue CRT and adjust the scan lines for best focus. The blue CRT is the most difficult to see the scan lines. In your case, use a KNOWN GOOD SIGNAL WITH THE COLOR TURNED ALL THE WAY OFF and adjust the blue focus and see if you can see faint scan lines. If the blue picture is OK let me know and I will go to the next step.
TVRE



Joined: 03 Jun 2008
Posts: 6

PostPosted: Wed Jun 04, 2008 11:19 am    Post subject: Reply with quote

Hello

Thank you very much for your assistance.

Actually the picture of the CRT with the droplets is the RED tube.

The blue seems to have fluid, but it is not full.

I would like to try focusing the scan lines but before I do I want to know if turning of the TV with minimal fluid, can cause damage to the tubes.


Thanks again
Jesse Mack



Joined: 22 May 2008
Posts: 600
Location: The Last Frontier

PostPosted: Wed Jun 04, 2008 3:20 pm    Post subject: Reply with quote

The fluid is actually a mixture of ethylene glycol and glycerin (basically antifreeze and glycerin). The droplets are of concern as the glycerin is in the mixture for the specific purpose of preventing this kind of thing. If water is used instead of the proper fluid it is definately a problem that needs to be corrected. If the levels get low you need to find out where the fluid went as this is a sealed environment with an expansion chamber. The evaporation rate is extremely slow. Look on the bottom of the cabinet for a wet spot. If the circuit boards are underneath the tubes this fluid can leak and be difficult to see without touching the board. (physically).

And yes, if the fluid is very low it can damage the CRT's. The damage is in the form of cracked/broken CRT's and or burned phospher. If you have burned phospher just look thru the optics with a flashlight and the phosphor will be a dark brown. There is a nominal browning of the phospher with a set of this age but it should not be highly pronounced. The green gun is usually the one that shows the greatest amount of browning.

If the CRT's are filled correctly there will not be any visable low fluid indicators and the expansion chamber receives any excess fluid during warmup.

The biggest concern if there is leakage is where the fluid went. If it ends up on the circuit boards there WILL be a board failure if it is not removed.

hope this helps.

Jesse
TVRE



Joined: 03 Jun 2008
Posts: 6

PostPosted: Wed Jun 04, 2008 6:57 pm    Post subject: Reply with quote

Hi

I've checked the board and there was a small wet spot from where I accidentally spilled some trying to see the condition of the fluid.

It was cleaned though. It wasn't spread to any ICs.

I have ordered a bottle of coolant and I will see what happens.

Thanks again, I will keep you posted
Jesse Mack



Joined: 22 May 2008
Posts: 600
Location: The Last Frontier

PostPosted: Wed Jun 04, 2008 7:39 pm    Post subject: Reply with quote

Hold, you will also need a seal for any CRT that you are going to service. You will also need denatured alcohol, a vaccum pump like the cheap ones used to bleed your brakes and the CRT has to be completely removed to perform the procedure. DO NOT do this without the procedure or you will be very, very sorry that you did. You will end up with a royal mess that is difficult to clean up, convergence that is usually over the average persons head etc etc.. I am not trying to scare you but if you need to do this let me know and I will write the procedure out with pictures. It is also necessary for you to prep the machine properly to avoid a very involved convergence procedure.
Also, can you tell me what you do for a living! I need to get a feel for your abilities so that I do not offend you, give you too much information or not enough information.
You seem to have jumped ahead, Is there a reason??

Jesse
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