PTK 195 Convergence Power Supply Question


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PTK 195 Convergence Power Supply Question

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kjones9999
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Jan 21, 2011, 5:09 PM

Post #1 of 16 (5352 views)
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PTK 195 Convergence Power Supply Question	Can't Post

Have an RCA 52929 ptk195 chassis. Convergence is off around the center perfect in the middle. Like a "fish eye"
effect. I have the convergence menu (not advanced convergence, just the first level). When green centering I have wavy lines on the outside, blue and red convergence work beautifully.

I have tested the power board for convergence voltage output with the following --- ground to the outside of the rf input, positive to the pins on the output side. I get no voltage whatsoever-- I have confirmed 120 on the input side at the connector.

I bought a used power supply from a reputable dealer who had tested the part before sending it and switched them out. Same thing with NO power on the outputs, but convergence menu is gone and there appears to be no convergence at all. How could this be? If they are outputting no voltage how could there be a difference? Perhaps a faulty ground?

Is there a way to check the power board disconnected from the chassis?

dont want to troubleshoot further until I can rule out the power supply, since all roads seem to lead in that direction.

Here's what I would really like to know. Is my test of the output voltages flawed? If I have confirmed 120 on the hot side can I get a voltage reading by disconnecting the convergence voltage out connector, taking the ground to the rf connector and testing each pin on the power board (with the output connector removed) is this correct? Or do I need to take the readings at the convergence board itself? (where if so?) I need to discover where the board picks up the chassis ground--- and the schematics aren't helping. Until I am sure that I have power off of this board I am at a standstill.

If I had the board completely removed from the tv, applied 120 to the and referenced the voltage back to the transformer ground, would this be a correct method also to check voltages?

Thank for your time.

Ron.M
Veteran

Jan 21, 2011, 8:42 PM

Post #2 of 16 (5347 views)
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Re: [kjones9999] PTK 195 Convergence Power Supply Question [In reply to]	Can't Post

kjones9999;....

My schematic (Albeit a different model , but the SAME chassis) shows 2 connectors...
One is J/P19700...
This one is the AC power in...
You need to read across the 2 pins for 110/120 volts AC...
The other connector is J/P19701....(6 pins)
This is the output connector that supplies the convergence output ,etc , voltages...
These voltages are read from one of the pins to chassis ground...
Chassis ground is the tuner coax fitting , the tuner case cover or other locations common to those locations....
Use your ohm meter to verify...
On that connector (P/J19701);...

Pin #1= ~ -46 vdc
Pin #2= ~ -15 vdc
Pin #3= CHASSIS ground !!!
Pin #5= ~ +15 vdc
Pin #6= ~ +46 vdc

Now those volts ARE read from the pins to CHASSIS ground....
I'm not sure what other grounds you are using , but , these are the correct ones.....
IF your power supply(ies) is(are) working , those volts WILL be there when you turn the TV on....
IF they are not there OR are off value , the power supply IS bad.....
What schematic do you have & where did you get it ????

GOOD LUCK.... Wink

....

Later...Ron.M.... Cool

....
Veteran & Retired TV technician

kjones9999
New User

Jan 21, 2011, 9:16 PM

Post #3 of 16 (5344 views)
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Re: [Ron.M] PTK 195 Convergence Power Supply Question [In reply to]	Can't Post

Thanks for your reply!

I have the sams photofact.

Am I suppose to have 120 at the power input even when the tv is off but plugged in? I do.... and that confused me. Shouldnt this mean that this board is always outputting? Or does it need a load to output? And if that is the case when I disconnect the load to get to the pins I take the load off.

How is that board grounded to the chassis -- through the power input? Or does the board even need to be grounded to the chassis to make these readings?

Wondering here-- if I use pin 3 as a ground I should be able to get readings at the other pins?

Boy am I lost--- help!

kjones9999
New User

Jan 21, 2011, 11:58 PM

Post #4 of 16 (5337 views)
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Re: [kjones9999] PTK 195 Convergence Power Supply Question [In reply to]	Can't Post

realized i couldnt test without the connection to the convergence board----my values all look good except for pin 4 reads 20.4 -- is that in range?

Ron.M
Veteran

Jan 22, 2011, 3:03 AM

Post #5 of 16 (5332 views)
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Re: [kjones9999] PTK 195 Convergence Power Supply Question [In reply to]	Can't Post

kjones9999;....

I also have a Sams Photofact , which these manuals are pretty much a piece of s#!t for the last 20 or so years....

The 120 volts AC is there ALL the time.....
Follow the wires on P/J1700 & you'll see they should go to the AC on the main board....
My guess is that that power supply is functioning ALL the time whether the TV is on OR off...
I can NOT find a power on/off control on the power supply schematic in my manual....
The board seems to be always outputing...

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Or does it need a load to output?

Possible , but , not that I can see.....

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And if that is the case when I disconnect the load to get to the pins I take the load off.

Re-read that & you'll see that answers itself....OR re-phrase it...

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How is that board grounded to the chassis

Thru P/J19701 pin #3....

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Or does the board even need to be grounded to the chassis to make these readings?

This one confuses me....
IF you are talking about just taking voltage readings for test reasons , NO...
IF you mean for operational reasons , YES....
You need the ground connection to return the voltage (Actually , the mini amps) from the convergence output transistors on the convergence board ...

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Wondering here-- if I use pin 3 as a ground I should be able to get readings at the other pins?

Yes.....On that connector & others that use the same ground....

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Boy am I lost--- help!

That makes 2 of us...
Been awhile since I worked on one of these....

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my values all look good except for pin 4 reads 20.4 -- is that in range?

According to my schematic , 22.5 vdc....
So I would say it's OK...

Have fun..... Wink

...

Later...Ron.M.... Cool

.....
Veteran & Retired TV technician

kjones9999
New User

Jan 22, 2011, 4:41 AM

Post #6 of 16 (5328 views)
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Re: [Ron.M] PTK 195 Convergence Power Supply Question [In reply to]	Can't Post

Thanks! Learning here.... Got the power board tested and I think we are good on the output voltages. Boy I felt stupid trying to test that power supply with the output disconnected.

Can you give me a best guess on my next "learning project" (youll be happy to know i have stayed out of the service menu Smile

) i have bowed top and bottom, bowed left and right, great center focus and convergence, not great focus and convergence as you travel outward. Colors are separated at the edge by about half an inch. The screen looks like about 10% is off the screen.
I have a convergence menu -- green centering shows a wavy line at the top and a wavy line at the bottom-- it moves, but i am thinking there should be a green cross. Blue and red convergence appears to be working as designed with crosses. The user manual says i should have an advanced convergence menu, but i dont.
Best guess?

Ron.M
Veteran

Jan 22, 2011, 6:47 PM

Post #7 of 16 (5317 views)
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Re: [kjones9999] PTK 195 Convergence Power Supply Question [In reply to]	Can't Post

kjones9999;....

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Can you give me a best guess on my next "learning project"

SORRY , No I can't....
The only thing I can suggest at ths time would be to resolder all the pins on the flyback transformer....

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youll be happy to know i have stayed out of the service menu

Me & about everyone else here...Service Menus are for TRAINED Techs ONLY...
UNLESS someone EXPERIENCED here gives you SPECIFIC info , STAY OUT...

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The user manual says i should have an advanced convergence menu, but i dont. Best guess?

May be a reference to the ones in the Factory/Service Menu...

One thing that concerns me is this;=>.....

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but i am thinking there should be a green cross.

You are correct...
The fact you don't have one indicates a more serious problem....
One that may be over your head to fix...

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green centering shows a wavy line at the top and a wavy line at the bottom-- it moves,

This sends up another red flag....
No way , no how does the green move in a normally functioning set such as yours....
The green is factory set & consumers are NOT given access to ANY green convergence adjustments in the consumer menu....
IF it is moving by itself , then you DO have a more involved problem & will require a TV tech to come over to your home & diagnose the problem....

GOOD LUCK.... Sly

....

Later...Ron.M.... Cool

....
Veteran & Retired TV technician

kjones9999
New User

Jan 22, 2011, 6:57 PM

Post #8 of 16 (5314 views)
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Re: [Ron.M] PTK 195 Convergence Power Supply Question [In reply to]	Can't Post

Thanks!

You are definitely the most helpful person I have ran into on the net.

The user manual does say that the green moves-- it is suppose to be "centering" the picture. But I thought maybe there would be lines AND a cross that would move. I do havea a green cross when doing Blue and red convergence.

I have found a convergence board for cheap, ill give that a go. If that is not it ill wrestle with the flyback.

Found this (literally) on the side of the road and it actually has a pretty good picture, just not perfect. I may just live with it before I break it!

It has been a tremendous learning experience. Quite a contrast to my 1942 Zenith radio that took 15 minutes and two caps to fix.

Anyway, thanks for your help -- folks in other groups call you the guru-- and they are right!

ill probably be back with more stupid questions.

Ron.M
Veteran

Jan 22, 2011, 7:33 PM

Post #9 of 16 (5312 views)
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Re: [kjones9999] PTK 195 Convergence Power Supply Question [In reply to]	Can't Post

kjones9999;.....

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The user manual does say that the green moves-- it is suppose to be "centering" the picture.

What page is this on ????
PLEASE answer.... Smile

....

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Anyway, thanks for your help -- folks in other groups call you the guru-- and they are right!

You are MOST Welcome..... Smile

....
Whoa !!!!....I'm used to being called other names.... Wink

....
Quite a compliment....
THANKS & for telling me about that....

Later...Ron.M.... Cool

....
Veteran & Retired TV technician

Ron.M
Veteran

Jan 22, 2011, 7:55 PM

Post #10 of 16 (5308 views)
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Re: [kjones9999] PTK 195 Convergence Power Supply Question [In reply to]	Can't Post

kjones9999;.....

OK , I think I found what you are talking about in reference to the green convergence....

1st off;....I was expecting a green "cross"....
This set apparently has a green "square" in step #5....
So I was wrong about the cross....SORRY.... Unsure

...
99.99999% of projection TVs of this type have a green cross that does NOT move....
IF you didn't get the square , a new convergence board may/may not work.....
IF you don't get the "Advanced Convergence" when you press 4 , then you may be on the right track....
Keep us posted & GOOD LUCK..... Sly

....

Later....Ron.M.... Cool

....
Veteran & Retired TV technician

(This post was edited by Ron.M on Jan 22, 2011, 8:01 PM)

kjones9999
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Jan 23, 2011, 1:48 AM

Post #11 of 16 (5302 views)
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Re: [Ron.M] PTK 195 Convergence Power Supply Question [In reply to]	Can't Post

Thanks for the clarification!

I have the first three but no advanced.

I was going over the schematic and had an idea, but wanted to make sure I wasnt going to goon anything up.

There are three connectors on the convergence board labeled red green and blue yoke. If I reversed green with red, and tested the results in the convergence menu could this hurt anything? Looking at the schematic this seems like it could help determine whether this is a problem on just the green circuit or a broader issue.

sound crazy?

Ron.M
Veteran

Jan 23, 2011, 7:01 PM

Post #12 of 16 (5293 views)
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Re: [kjones9999] PTK 195 Convergence Power Supply Question [In reply to]	Can't Post

kjones9999;.....

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I have the first three but no advanced.

Houston , you have a problem.....
BTW , are you using the original remote ????

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If I reversed green with red, and tested the results in the convergence menu could this hurt anything?

The connectors should be the same...Short answer , no....
Your pix WILL change because the red , green & blue convergence pulses ARE different...
So be suprised at what you see , but not shocked....

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Looking at the schematic this seems like it could help determine whether this is a problem on just the green circuit or a broader issue.

I don't know what you mean by "broader issue"...
What you are doing is switching the intentional distortion that the convergence circuits develop for each color (from red to green)....
You may not see any results due to the fact that the green is in the center of the rack & the red is on the outside of the rack....
This means that since the green is in the center , little modification of the pix is needed to get a square undistorted pix on screen (Optics)...
Since the red (& blue) is off to one side , the angle of the pix getting to the screen is different than the green , hence more intentional distortion....
IF you were to remove the screen & take a look DIRECTLY at the pix on the CRT face thru the lenses , you can actually see the distortion...
I'm not sure the results will prove anything....
Do NOT try to adjust the red/green convergence after you switch the connectors...
Reason is that when you switch back , you will have an even bigger mess than when you started...

I'n going to stick my neck out here & ask you to try something....
On page 5 (to the right of "C") in the manual is the "Service Menu & Digital Convergence" adjustments....
IF , and I repeat , IF you feel comfortable doing this , follow my instructions to the letter....
I'd like to see IF you get the crosshatch mentioned in the Digital Convergence proceedure....
What I'd like you to do is get into the Digital Convergence part & check for the crosshatch & LEAVE WITHOUT adjusting ANYTHING !!!!
Are you up for that ????
IF you tinker with ANY of the adjustments , you WILL Screw up things for the new board....
The adjustments are NOT stored in or on the convergence board....
They are stored in the eprom which is a different part of the set...(Micro circuitry)...

GOOD LUCK.... Sly

.....

Later....Ron.M.... Cool

....
Veteran & Retired TV technician

(This post was edited by Ron.M on Jan 23, 2011, 7:16 PM)

kjones9999
New User

Jan 23, 2011, 8:56 PM

Post #13 of 16 (5286 views)
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Re: [Ron.M] PTK 195 Convergence Power Supply Question [In reply to]	Can't Post

I do not have the original remote but it is an rca meant for this chassis.... Did the test--get a crosshatch pattern with a cross in the middle. The lines are bowed inward pretty evenly on all 4 sides, center appears perfect. Convergence starts good in the center and gradually worsens-- the tv appears to be overscanning or off the sides by about 10%. Vertical seems in correct location. By the by, i havent put the "new" digicon board in, waiting for shipment. here is a photo: http://www.jinglejones.net/rca1.jpg I noticed taking some readings that j19503 on the digicon board shows a momentary arc on the plug. Dont know if this is related-- schematic suggests it is linked to vertical sync-- since i found this on the side of the road it could be from an old repair even. Great education piece on the placement of the guns-- id didnt hit me that the order of the guns affects the convergence in that way. As always, thanks for your help!

Ron.M
Veteran

Jan 24, 2011, 9:06 PM

Post #14 of 16 (5279 views)
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Re: [kjones9999] PTK 195 Convergence Power Supply Question [In reply to]	Can't Post

kjones9999;.....

I'm assuming this is from your TV=>...

If so , then the new board "may" be the answer....

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I noticed taking some readings that j19503 on the digicon board shows a momentary arc on the plug.

I could only find 3 of the pins on that connector & it looks like a distinct possibility that that board is a problem....
Depends on how severe & what pins the arc occured at....
Since 2 of those pins go almost directly into the digicon IC , the IC can be damaged or destroyed....
Check the volts at pins 2 & 3 for +5 vdc...
Then go to U19501 (the digicon IC) pins 20 & 21 & see if you get the same readings....
Post results....THANKS.... Sly

....

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since i found this on the side of the road it could be from an old repair even.

Very possible , also could be the reason it was left on the side of the road....

Let us know how the "new" board works out....THANKS..... Sly

....

GOOD LUCK.... Sly

....

Later....Ron.M.... Cool

.....
Veteran & Retired TV technician

kjones9999
New User

Jan 26, 2011, 7:17 PM

Post #15 of 16 (5271 views)
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Re: [Ron.M] PTK 195 Convergence Power Supply Question [In reply to]	Can't Post

An Update!

I have 4.6 volts on the 3 pin j19503. The new convergence board should be here in a few days, so i am going to wait until then before diving into testing the IC.

Ill keep updating!

kjones9999
New User

Feb 5, 2011, 3:56 AM

Post #16 of 16 (5247 views)
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Re: [kjones9999] PTK 195 Convergence Power Supply Question [In reply to]	Can't Post

Put in a different convergence board with no luck. Had the convergence menu, but could not adjust red horizontally and over all bowing was much worse. Could have a bad replacement board.

Ive learned a lot, still have a decent curbside tv, and only out 30 bucks for a digicon board.

Thanks for all the helpful responses--- this one is over my head.

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