Philips RPTV CRT White screen!!


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Philips RPTV CRT White screen!!

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CJWalker
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Oct 25, 2009, 12:20 AM

Post #1 of 19 (8147 views)
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Philips RPTV CRT White screen!!	Can't Post

Screen went completely white today and all three CRT's were brighter than heck so I shut it down. Problem seemed to start when vid out to CRT boards became disconnected during a convergence adjustment. Obviously I reconnected the cable, but the unit would not work right since. I am thinking either the video amps on teh CRT boards are blown or the HOP board has gone out.

It really seems as if the CRT's are getting waaaaay too much voltage. I haven't found any bad resistors and even have replaced the TDA vid amp IC's with no luck.

This TV has not had any problems except for convergence IC's and coolant which were both replaced this week.

ANy help would be greatly appreciated.

Ron.M
Veteran

Oct 25, 2009, 1:55 AM

Post #2 of 19 (8142 views)
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Re: [CJWalker] Philips RPTV CRT White screen!! [In reply to]	Can't Post

CJWalker;...

Quote

haven't found any bad resistors

They're there...Trust me...

Quote

ANy help would be greatly appreciated.

How about we start with a MODEL# & maybe even a chassis # ???..... Unsure

...

None of us here are psycics !!!.... Mad

....

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

....
Veteran & Retired TV technician

CJWalker
New User

Oct 25, 2009, 1:59 AM

Post #3 of 19 (8140 views)
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Re: [Ron.M] Philips RPTV CRT White screen!! [In reply to]	Can't Post

Oh crap completely forgot the model lol.

55PW9363/17F
Chasis DPTV 335

Thanks.

Ron.M
Veteran

Oct 25, 2009, 2:49 AM

Post #4 of 19 (8135 views)
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Re: [CJWalker] Philips RPTV CRT White screen!! [In reply to]	Can't Post

CJWalker;....

Lets start with CRT voltages....
Here's what I suggest:
Take ALL 3 CRT modules off (Use care, as they can be fragile)...
Hang them in space AWAY from anything else & each other ...
You will need a good DVM or equivalent...
Turn on the TV...
If anything snaps , crackles OR pops , turn the TV OFF IMMEDIATELY !!!
It's not likely , just a safety precaution...
Handle the module with care as there are some high voltages on the board...
Take voltage readings from the CRT socket on any one you can do SAFELY....
Pins 4 , 5 , & 11 should read about -18 volts DC....
Pins 6 & 7 are filament , skip these....
Pin 8 should have about +125 volts DC...

This part you need to use EXTREME CARE...
Read & write down the voltages on ALL pins on the IC that's on the CRT board...
We are only doing one board as they are basically the same...

Post the pin #'s & voltages you get from the CRT & IC here...
IF you feel uncomfortable doing ANY of the above, do NOT do it...
If you are inexperienced ,let we/us know & we'll figure another way to tackle this...(remember this:I do NOT do hospitals OR funerals... Sly

....)
A little background info about your electronic experience or lack of it , would be helpful...

Later...Ron.M... Cool

......
Veteran & Retired TV technician

CJWalker
New User

Oct 25, 2009, 3:35 AM

Post #5 of 19 (8131 views)
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Re: [Ron.M] Philips RPTV CRT White screen!! [In reply to]	Can't Post

Great! Will do, thanks.

I have been working with electronics for a good while, on and off. Usually it's analog audio stuff (pre/power amps, guitar effects, etc.), power supplies and digital/analog automotive. I have good basic knowledge and have also designed a few very simple digital circuits (just to get a feel for things), though I have just recently gotten into TV's and video. There is so much that is new to me since for the most part this is just a spare time hobby. I have a nice meter but no scope yet :(

Thanks again for the help!

-Chris

CJWalker
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Oct 25, 2009, 8:15 AM

Post #6 of 19 (8125 views)
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Re: [CJWalker] Philips RPTV CRT White screen!! [In reply to]	Can't Post

Here are my measurements.

Blue CRT
Pin 4: Not used
Pin 5: -17.9v
Pin 8: 100v
Pin 11: -18v

Red CRT and green CRT came back about the same.

Ic's were different however.

Readout from Blue vid amp:
Pin 1: .4v
Pin 2: .3v
Pin 3: .41v
Pin 4: .3v
Pin 5: 1v
Pin 6: 11v
Pin 7: 0v
Pin 8: 0v
Pin 9: 0v
Pin 10: .29v
Pin 11: 0
Pin 12: 3v
Pin 13: 1v

And Green CRT:
Pin 1: 0v
Pin 2: 0v
Pin 3: 0v
Pin 4: 0v
Pin 5: 2v
Pin 6: 11v
Pin 7: 3.7v
Pin 8: 0v
Pin 9: 0v
Pin 10: 200v
Pin 11: 0
Pin 12: 4v
Pin 13: 93.6v

Looks like the live test worked much better.

Pin 10 on the BLUE CRT video amp isn't receiving 200v from the HV module. 1ohm resistor that feeds the TDA chip on the CRT board got toasted causing an open short. I am getting 200v on the board from the PSU, so...

I am assuming that the connection came loose and reconnected itself from the HOP board cable and sent a huge signal to the video amps on the CRT board, which in turn killed the amps and pulled too much of power through that little 1/3w 1ohm resistor. Feasible?

Ron.M
Veteran

Oct 25, 2009, 7:14 PM

Post #7 of 19 (8112 views)
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Re: [CJWalker] Philips RPTV CRT White screen!! [In reply to]	Can't Post

CJWalker;....

First off;...>>""CRT board got toasted causing an open short.""...
Ain't no such thing in electronics....
You can have a "Open" OR a "Short" circuit , NOT an "open short"...
Kinda like "dry water"...

I have to guess you did not change the 1/3w 1 ohm resistor...Correct ???
If not check to see if you have the 200v on one side of the resistor....<< On the blue board only...
With the set OFF check on the other side of the same resistor to ground for ohms....
Give the TV some time to discharge any stray volts...
Your meter reading may need a bit of time to settle down...Please post....
Go to connector 1217 on any CRT board & read the volts (all pins) & post here...
Do you recall which connector got disconnected during the convergence ???...
Let's go ahead & check the IC on the Red CRT board just for comparison...Please post...

Quote

I am assuming that the connection came loose and reconnected itself from the HOP board cable and sent a huge signal to the video amps on the CRT board, which in turn killed the amps and pulled too much of power through that little 1/3w 1ohm resistor. Feasible?

In a word; NO...Cables don't reconnect themselves unless moved by humans & the likelyhood that the signal got huge is nil.........
At the moment , your green CRT amp IC seems OK....
You may have blown the blue...
Try this ONLY IF the red CRT IC volts are close to the green voltages:==>...Hook up the green & red CRT boards to the CRTs...
Leave the blue OFF...Turn the TV on...Post result here...

Quote

Looks like the live test worked much better.

Huh....splain please...

PLEASE do everything above & post ALL info I asked for...THANK you....

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

.....
Veteran & Retired TV technician

CJWalker
New User

Oct 26, 2009, 1:00 AM

Post #8 of 19 (8103 views)
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Re: [Ron.M] Philips RPTV CRT White screen!! [In reply to]	Can't Post

Connector #1721 on the HOP board to the blue CRT was disconnected. This is the cable that passes through the Blue CRT board at #1207 and onto the other boards.

Readings at HOP board #1721

Pin 1 +b: -.5v
Pin 2 Bias: .3v
Pin 3 12v: 12v
Pin 4 Gnd: 0v
Pin 5 AKB: 0v

Readings after 1ohm resistors on CRT boards

Blue : 50
Green : 50
Red : 10M

Other side of the 1ohm resistor on blue CRT board was seeing less than 1v.

Red CRT video amp
1: .05v
2: -.1v
3: .05v
4: -.3v
5: 2v
6: 11v
7: 22v
8: 0v
9: 0v
10: 210v
11: 0v
12: 93v
13: 92.5v

Live test made it much easier to find blown resistors since I could trace voltages.

I haven't fired it back up with the CRT's connected.

Ron.M
Veteran

Oct 26, 2009, 8:00 PM

Post #9 of 19 (8096 views)
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Re: [CJWalker] Philips RPTV CRT White screen!! [In reply to]	Can't Post

CJWalker;....

It looks like you blew out the blue & maybe the green CRT module amps...In my manual they are:...TDA6120Q....
The only one that seems to be working OK is the red board...
With the exception of pins 1-4 voltages on the IC....
I'm working from #7621 Philips service manual...
Do you have the service manual for your TV ???
I can NOT find connector #1721 on my schematics....
According to my schematic , we're missing about 8.1v dc on pin #1 of connector
1207/1217 that appears to be supplied from the HOP panel.....
VERY important questions here.>>>..Was connector #1721 the one that originaly caused the problem???...Was/is it hooked up for the voltage readings you posted ???..

There's an error here somewhere...

Quote

Readings after 1ohm resistors on CRT boards

Blue : 50
Green : 50<<<
Red : 10M

Quote

And Green CRT:
Pin 1: 0v
Pin 2: 0v
Pin 3: 0v
Pin 4: 0v
Pin 5: 2v
Pin 6: 11v
Pin 7: 3.7v
Pin 8: 0v
Pin 9: 0v
Pin 10: 200 v <<<
Pin 11: 0
Pin 12: 4v
Pin 13: 93.6v

One of the bold readings IS wrong...There can not be 200v at pin 10 IF you read 50 ohms to ground at the 1 ohm resistor....Re-check those....

Quote

I haven't fired it back up with the CRT's connected.

Good, lets hold off for awhile on that....

Later...Ron.M........
Veteran & Retired TV technician

CJWalker
New User

Oct 27, 2009, 7:17 AM

Post #10 of 19 (8087 views)
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Re: [Ron.M] Philips RPTV CRT White screen!! [In reply to]	Can't Post

50ohms must have been a typo. It's reading over 4M and is getting a good 200v at pin 10 of the IC.

Green CRT IC

Pin 1: .05v
Pin 2: -.1v
Pin 3: .05v
Pin 4: -.3v
Pin 5: 2v
Pin 6: 11v
Pin 7: 6.6v
Pin 8: 0v
Pin 9: 0v
Pin 10: 210 v
Pin 11: 0
Pin 12: 94.5v
Pin 13: 93v

Connector #1721 of the HOP panel connects directly to #1207 on the CRT board via ribbon cable. #1721 was the connector that caused the issue. It was connected during testing.

Ron.M
Veteran

Oct 27, 2009, 6:01 PM

Post #11 of 19 (8081 views)
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Re: [CJWalker] Philips RPTV CRT White screen!! [In reply to]	Can't Post

CJWalker;....

I STILL can NOT find where connector 1721 is at on my schematic.... Mad

...

It's critical that we get 8v dc & 11v dc to the CRT boards...
Remove the connector from 1721 from the HOP panel...
Read all pins at 1721 ON the HOP panel & post...
I suspect that the green IC amp is also bad....

Post results,please....

THANK you....

Later...Ron.M... Cool

....
Veteran & Retired TV technician

CJWalker
New User

Nov 5, 2009, 6:58 AM

Post #12 of 19 (8046 views)
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Re: [Ron.M] Philips RPTV CRT White screen!! [In reply to]	Can't Post

HOP panel had a bad 1ohm resistor and was not providing 8v to the CRT boards.

Pin 1 now shows 8v
Pin 2 less than 1v; ~.4v
Pin 3 11.8v
Pin 4 and Pin 5 0v

Connector 1721 is the connection from HOP panel to CRT board connector 1207. Pinouts are identical as they are connected via ribbon cable.

Ron.M
Veteran

Nov 6, 2009, 12:21 AM

Post #13 of 19 (8034 views)
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Re: [CJWalker] Philips RPTV CRT White screen!! [In reply to]	Can't Post

CJWalker;....

Quote

HOP panel had a bad 1ohm resistor and was not providing 8v to the CRT boards.

Good job !!!

Pin 4 is ground....So 0 volts is OK...
Pin 5 should have about 21v dc....Now whether that comes from the HOP panel OR is generated from IC , 7201 & the ones on the other CRT boards is a mystery to me at this time...Again a service manual screw-up...
May I suggest you try reading ohms to ground from Pin 5.....Try it at connector 1721 on the HOP panel with the connector to the CRT boards connected & disconnected....We're looking for VERY low ohms one way or the other....Post readings,please......
Also on any one CRT board , check the voltages on 7200 & 7202 transistors...Please post readings...

BEFORE you do any of the above , have you tried to see if that bad 1 ohm resistor ( I'm guessing you replaced it ) was the culprit ???....
Still no pix , proceed with the above....& post....Thanks...

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

.....
Veteran & Retired TV technician

CJWalker
New User

Nov 13, 2009, 8:09 AM

Post #14 of 19 (8004 views)
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Re: [Ron.M] Philips RPTV CRT White screen!! [In reply to]	Can't Post

Yep bad 1ohm resistors all over the place. HOP panel and one on each CRT board. The resistor on the red CRT board tested good until a load was put through it so that has been replaced as well. All vid amps have been replaced.

Pin 4 has very low resistance to ground but I could not get a voltage reading however with or without CRT boards plugged in. CRT's were reconnected too.

Transistor 7200
E -.6v
B .13v
C 3.6v

Transistor 7202
E 2.8v
B 3.6v
C 8v

CRTs aren't going crazy anymore though there is a slight shakiness to the text when I have any composite channel selected.

Ron.M
Veteran

Nov 13, 2009, 6:52 PM

Post #15 of 19 (7993 views)
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Re: [CJWalker] Philips RPTV CRT White screen!! [In reply to]	Can't Post

CJWalker;....

You seem like a bright fellow....This;==>

Quote

Pin 4 has very low resistance to ground but I could not get a voltage reading however with or without CRT boards plugged in. CRT's were reconnected too.

Is because;==>

Quote

Readings at HOP board #1721 OR CRT board at #1207

Pin 1 +b: -.5v
Pin 2 Bias: .3v
Pin 3 12v: 12v
Pin 4 Gnd: 0v << =GROUND !!
Pin 5 AKB: 0v

In another post & more to the point:==>

Quote

Pin 4 is ground....So 0 volts is OK...

So if you are reading from pin 4 to ground , you are reading from ground to ground....Hence NO volts & "0" ohms....

Transistor 7200 & Transistor 7202 voltages are within range & definately OK.....

Quote

CRTs aren't going crazy anymore though there is a slight shakiness to the text when I have any composite channel selected.

Without seeing this problem , I'm not going to be of much help...You may have to reset your G2 volts...Try that...If you need help with setting G2 , please post & I'll give you info....

Overall I give you

for your success....

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

.....
Veteran & Retired TV technician

CJWalker
New User

Nov 14, 2009, 11:10 AM

Post #16 of 19 (7983 views)
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Re: [Ron.M] Philips RPTV CRT White screen!! [In reply to]	Can't Post

Ahh. That must have been a typo on my part. I had been reading off of the connection diagram for the pinouts and probably posted the wrong thing. That's what I get for doing things at 3 in the morning, but I am pretty stoked about having this TV working again. Thanks for all of the help! I will probably get some pics up here this weekend if I can't get the shakiness taken care of.

CJWalker
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Dec 6, 2009, 5:59 AM

Post #17 of 19 (7923 views)
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Re: [CJWalker] Philips RPTV CRT White screen!! [In reply to]	Can't Post

Figured I would post an update. The shaking was interference caused by Blue CRT line back to the focus block which had been a wee bit too close to the signal lines. Smile

jts1957
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Dec 6, 2009, 7:42 AM

Post #18 of 19 (7919 views)
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Re: [CJWalker] Philips RPTV CRT White screen!! [In reply to]	Can't Post

You should not get wee anywhere near a television! Ask Ron. Cool

-------------------------
Location: Far, Far Away

CJWalker
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Dec 6, 2009, 9:54 AM

Post #19 of 19 (7914 views)
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Re: [jts1957] Philips RPTV CRT White screen!! [In reply to]	Can't Post

It's not like the line was exposed or arcing, nor was it touching any of the other lines. Do you have anything useful to add?

<span contenteditable="false"><table border=0 cellpadding=0 cellspacing=0 width="100%"><tr><td width="2%"><hr width="100%" noshade size="1" color="#A1A576"></td><td width="10%" align=center><font size=1 face="Verdana,Arial,Helvetica">In Reply To</font></td><td width="87%"><hr width="100%" noshade color="#A1A576" size=1></td></tr></table></span><div style="margin-left: 30px"><img src="http://smileys.on-my-web.com/repository/Disgusting/piss.gif" border="0" />You should not get wee anywhere near a television! Ask Ron.<img src="http://www.tv-forums.com/images/cool.gif" alt="Cool" border="0"></div><span contenteditable="false"><table border=0 cellpadding=0 cellspacing=0 width="100%"><tr><td><hr width="100%" noshade size=1 color="#A1A576"></td></tr></table></span>

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