Hi All !!

Newbie poster here...
not new to electronics though...
but TV's give me a headache http://www.venicetalk.com/forum/images/smilies/1087.gif

My Y2K (remember that?) Phillips that cost me
10 grand back in 2000 had decided to go
on summer hiatus.

While watching the TV I noticed a flash of sorts
with a ringing pattern on the screen... a quick
channel change showed the same ring and
I then said UH-OH !!

I powered it off... said a "HAIL MARY"...
but alas when I powered it back on there was

- NO VIDEO (neither tuner nor inputs)
- AUDIO is GOOD
- TUNER does change channels (audible)
- Remote works

There were NO burnt electronic smells.
NO visble scars on the internal PC Boards
NO fried components.
NO apparent wiring anomalies.

and YES I did unplug the unit to do a master reset.

Well I'm ready to get into this deeper.
Any suggestions would be appreciated.

I figure it's somewhere in the High Voltage...
I've located the board.
Scares me to yank it out and start buzzing it
but I am prepared to take a deep breath and dive in.

But first I figured I'd consult all you experts.
I've read such sage posting from so many on here.

I'm hoping JOHN MASON will chime in.
I noticed he has a 64...
but I am unable to make contact with him...
ARE YOU OUT THERE JOHN !!! :D

sorry.
i used to be a philips service engineer, but after many months of very poor ASC support and neglect to acknowledge my warranty claim submissions and core parts return reimbursement from the company, i dropped them for good.
good luck finding a reputable service center that knows what theyre doing.
there isnt many out there to begin with.

..While watching the TV I noticed a flash of sorts with a ringing pattern on the screen... a quick channel change showed the same ring
What does a ringing pattern look like?

In general, most common problem on these is convergence IC failure. It can result in your situation.

What does a ringing pattern look like?

Hammerdwn: Thanks for the link to hometheatershack and tip re: conv.

By ringing I meant a sort of damped sinusoidal
waveform of the picture... there was a quick flash
where the picture began to shrink and ring and
then POOF in 3 seconds it was gone !!

...I meant a sort of damped sinusoidal waveform of the picture... there was a quick flash where the picture began to shrink and ring and
then POOF in 3 seconds it was gone !! Oh that sounds more like power / deflection failure. You should get a tech out to diagnose.

yeah... that was my original thought...
convergence seems unlikely because as the
picture shrank it did so with all colors intact.

And as far as "a tech" goes... that's probably me !!
Just gotta get my hands on the schematics...

UPDATE:

I've been slowly chipping away at my Phil now that
I have that Service Manual !!

All voltages on the POWER SUPPLY BOARD are good.

The CRT PROTECTION circuitry is indicating Sweep Failure.
CRT Protect line is High, thereby causing the High Voltage
to go into shutdown mode. (see attached)

The scan circuitry and HV power are all on the SCAN/HV BOARD (duh!)
I plan to back track this further and still expect to find
the problem on the SCAN/HV BOARD but I wonder if it is
possible that the problem could be on another board?
SYNC CONDITIONER? CONVERGENCE? MICROPROCESSOR?

Care to venture a guess as to what component(s) are the culprit?
(most likely NOT in the below schematic)

I have attached a ZIP file containing 2 JPEGS

- The Overall Block Diagram
- The High Voltage Output Circuit w/description.

Any and all thoughts are GREATLY appreciated.

Shorted crt? One at a time disconnect the HV anode lead from the flyback/tripler to each crt. Apply power and see if HV comes up on one crt at a time. Flyback/tripler can be taken out by a bad crt too.

Post some pics of your chasis. I'm curious what these sets look like on the inside as I've never seen one in person.

Pics were previously posted... look back a few !! :D

>>>> Phillips Scan Board.jpg

Ok, I forgot. Disconnect the big red wire that runs from the Flyback to the Tripler at the tripler end so the wire hangs out of the Flyback. MAKE SURE THE END OF THAT WIRE IS NOT GROUNDED OR CLOSE TO METAL and apply power. Does the HV start up? If not, replace Flyback.

It's actually a doubler !! ( pickey pickey pickey :) )

I'll give that a try later... THANKS!

Let's also keep in mind the CRT PROTECTION is shutting
down the HV due to a SWEEP problem NOT a HV problem...
it's conceivable (at least in my mind) that disconnecting
"BIG RED" will still leave the HV muted if the sweep is
not functioning correctly. That's my interpretation
from the below blurb... but as I confessed before,
TV's are not really my thing . . .

_________________ http://www.venicetalk.com/forum/images/smilies/pcangry.gif _________________

(Figs 23, 24 are in the previously attached ZIP)


HIGH VOLTAGE OUTPUT CIRCUIT
After the Scan circuits are working, Horizontal drive is fed to 7700, to the Driver circuit, and to the Horizontal output transistor 7714 to drive the High voltage transformer. (Figure 23 ) Regulation feedback for the High voltage regulation is fed to 7710 and 7700 from the High voltage divider block. There are three shutdown circuits for the High voltage section. They are Sweep failure detection, Overvoltage or Overcurrent, and Reset.

Horizontal drive is fed to Pin 3 of 7700 to the Horizontal Sync detector, Voltage controlled oscillator, and then to the Pulse width modulator. (Figure 24 ) The duty cycle of the output on Pin 7 is controlled by the feedback voltage on Pin 4 of the IC. This signal drives 7703, 7717, 7716, 7708, and the Horizontal output transistor 7714. Transistor 7714 drives the High Voltage output transformer 5701. The Transformer produces 30 KV of high voltage and the focus voltage for the focus divider block. The High voltage is sampled on Pin 2 of the High voltage splitter and is fed back to a comparator 7702. 7702 drives 7710 which provides the feedback voltage on Pin 4 of 7700. Changes in voltage on Pin 4 will cause the pulse width of the drive signal on Pin 7 to change. This keeps the output of transformer 5701 at a constant 30 KV. Beam current is monitored at the bottom of the stack on Pin 10 of 5701 and is fed to the Beam Current shutdown circuit 7705 and 7709. This also provides feedback to the automatic brightness limiter circuit, ABL. Minor changes in beam current are fed back to Pin 4 of 7700 to make minor corrections in the High voltage. This ensures that the High voltage stays constant as the contrast levels of the picture change. If the change is beam current is excessive, Pin 1 of 7701 will go High, causing the latch in the IC to activate. This will cause Pin 6 to go Low, which will mute the Horizontal drive to 7716 and 7708, shutting the High voltage Off. Pin 6 of the High voltage transformer is rectified by 6705 and is fed to Pin 3 of 7701. This circuit monitors for excessive High voltage. If the High voltage goes above 30 KV, Pin 3 of 7701 will go High, latching 7701, shutting off horizontal drive. It will be necessary to turn the set Off to reset the latch in 7701.

To protect the CRTs it is necessary to monitor for a failure of the Horizontal and Vertical sweep circuits. Horizontal and Vertical drive is fed to the base of transistor 7713 keeping the transistor turned Off. This keeps ransistor 7712 turned On, turning transistor 7706 On, which keeps transistor 7707 turned Off. If Horizontal or Vertical sweep should fail, transistor 7713 will turn On, turning 7712 Off, turning 7706 Off. The 15 volt standby supply will then be applied to the base of 7707 through resistors 3737 and 3739 turning transistor 7707 On. This will shut the Horizontal drive Off to the Horizontal output transistor. This will shut the High voltage Off. This also turns transistor 7704 Off (My 7704 is OFF - pin 2 of 1119) which will cause the CRT protect line to go High, muting drive to the CRT's.

If the power should be disconnected to the set, the Power Fail Reset line will go Low. This turns transistor 7718 Off which turns 7719 On. This will shut the High voltage Off. This will ensure that the High voltage is shut Off before operating voltage to the sweep circuits is shut Off. This is to protect the CRTs from possible damage.

As mentioned in our PMs, my 64PH9905 went early this year. Video went to a black screen instantly. I suspected a zapped horiz. output transistor, which proved correct. But had to remove the hv/scan board to confirm with a meter. But suspect I misplaced one of the many board wires after installing a new transistor. Still didn't work and I was then getting an overheated component smell. Paid a Philips servicer for a check and he concluded the pwr supply and hv/scan boards were bad. With ~10 years use, decided the cost/time wasn't worth it, so junked the RPTV and acquired a nice 65" 1080p plasma (http://www.avsforum.com/avs-vb/showthread.php?p=16424503&highlight=th+65vx100#post16424503). (Missed your note earlier above since I'd switched to tracking the plasma forum.)

For troubleshooting, I'd planned to input a DVRed color bar pattern, then chase the signal with a scope, but all those hissing HV leads in the way changed my mind. With that service CDROM I sent, it might be possible to follow signals with a scope to isolated test points on the schematics--maybe attaching the probe first to avoid getting zapped. -- John

EDIT: Recalled seeing a small warning tag inside the set cautioning about unplugging CRTs one by one.