TV Troubles... any ideas?

[ojTHEd]

Okay, while watching TV tonight, the TV decided to fart around. It's a 36" RCA Twin Tuner PIP made in '96 or so. I recently took it in and had the flyback replaced and it has worked perfectly since.

Here's what happened... It greyed out the screen and said something about a channel block. I turned it off, then back on and I get black. The audio is there, the menu and channel overlays work. Tuning works, PIP appears to work, but no display. Only the menu and channel overlays appear on screen. Even the Closed Captioning appears onscreen when I mute the sound. Same thing on both of the video inputs.

Yes, I've checked the Parental Controls "Channel Blocking" and it is off.

What else could be going on?

[rca2000]

It's BROKE!!!!!!!!!!!!!!!!!!!

[ojTHEd]

:thmbsp: Thanks! :thmbsp:

[rca2000]

Your welcome!!!!!!!!

Ok-- SERIOUSLY(I am trying a little to shed my perpetual "nice guy" image, just a little:;

DO THIS::

Go to the menu, and bring up "picture controls' Then-- check to see, if someone has not turned down the contrast, or brightness, all of the way. If so-- the menus will STILL show somewhat, but you will have NO video throughput.

[ojTHEd]

Okay, because I'm also a nice guy...

I was watching it when it happened. Picture controls are fine. In fact, I have already checked them just in case - all centered except sharpness. I goosed them all around just in case.

Currently, I'm following the "unplug it for a while" rule.

[rca2000]

Almost sounds like a corrupt EEPROM to me. If the old fly arced any, that COULD have happened.

[ojTHEd]

hrmm... that sounds bad. Should I take the back off and look around? I read on another site that it could possible be the Gemstar Guide thing interfering and that you should pull it off and turn the TV back on to see.

[ojTHEd]

hrrm... I unplugged it for about 1~2 hours and fired it back up and the picture's back. Does this add more info to the problem?

[rca2000]

Your eeprom probably DID get scrambled, and then, it was reset, at power-on(as is the normal case). you were lucky.. This time. Happens a lot, on modern, digitally-controlled tv sets.

[ojTHEd]

Well, hope I stay lucky. Thanks!

[hamop]

what is the chassis # ? that info would be helpful in determining the culprit.
cold solder joints is an ongoing problem w/many mfgrs( including rca). thus a miriad of symptoms may exist.


73 de hamop

[Doug]

didnt one of those chassis have problem with static discharge to the speakers from the crt causing eprom to get shocked. Something about a modification by adding a resistor to the speaker frame to chassis or one lead of the speakers???.

[ojTHEd]

Hrmm... I just had the damn thing apart before I read this. Where would I find the chassis number? On the label on the back of the tv?

The problem seems to fix itself if I unplug the TV and wait a short while.

[hamop]

chassis # will be on the rear tag of set . model/serial/chassis in that order left to right.

same info will be inside on a small tag on tuner shield or large heat sink on chassis.

# will be a ctc number ...... example ctc203ac9 , ctc177a etc........



73 de hamop

[ojTHEd]

CTC197CD2

Anyhow, I took it apart, removed and reseated an audio board. Thought it might be the Gemstar Guide module that I've read has some problems. It wasn't. And, it doesn't appear that there is a gemstar module on this TV.
Well, the TV has been fine through a few warm starts. I'm going to hope that my TV was just playing an early April Fool's gag on me.

Of course, if you've got any suggestions, I'd still like to hear them. I'm sure it'll act up again sometime.

[hamop]

the ctc197 series does have a history of ihvt failures.

the oem replacement includes a new 82k ohm .5w res and a .001uf@2kv (i think) cap . it is highly recommended to replace res/cap or premature ihvt failure may occur. rca prt # 237506

ur ihvt may (?) be on the verge of failure- producing an intermit arc ( loud snap) that is causing a syscon glitch . resettable by dis/reconnecting ac source.


got serv call sat 4/2/05 on a 197 thats doa. bettin' shorted h.o.t. and ihvt....

73 de hamop

[ojTHEd]

I'm sorry, I'm new to TV repair!

Can you explain a little more what I need to buy/replace? What's an "IHVT", etc.? Also, where can I get that part? I can replace resistors and capacitors, if I know which one I'm replacing. I could take a picture, post it and you could highlight the parts or tell me where to take a better picture so you can point out the pieces.
FWIW, I'm not hearing any noise (snaps, pops, or crackles) when I lose video. That doesn't mean your suggestion won't fix it. I'm sure it will.

Thanks, in advance.

[hamop]

not having ur set on the bench, i can't be 100% sure the "integrated high voltage transformer" (ihvt) or flyback for us old timers ,is indeed the culprit.
it has been known to, at times, cause the symptom described.as can a brief arc inside the crt , or even poor grounding of tube. etc...
changing the part is not difficult. however, pending ur de/soldering skills (?)might be safer 2 call a pro. also, the anode voltage on the set is around
30kv. the crt may retain a protion or close to full change for many years...! ALWAYS UNPLUG TV FROM AC , AND DISCHARGE ANODE B4 REMOVING LEAD FROM TUBE. :yes: (anode lead is the heavy red wire from ihvt to crt)
failure to comply may result in a rather unpleasant shock. :thumbsdn:
also note: focus voltage 8kv-12kv, screen 150-500v, cathodes around 110-200v.
excersize caution and common sense when dealing with high voltages.
(best to keep one hand in pocket) "there are old technicians and there are bold technicians. but there are few old bold technicians" :thmbsp:
73 de hamop

[ojTHEd]

Well, the flyback was very recently replaced. Before that was replaced, the set wouldn't even power on. No menu, no anything. So, that shouldn't be it.

Oh, and I've done work on computer monitors and I am sufficiently afraid of that big red wire. I usually touch it to a safe ground to discharge it.

[hamop]

good to know ur not a "newbie" at this.. don't be afraid of hv but, RESPECT
it at all times.. if the fly replacement was oem, next step would be to inspect the board for any questionable solder connections and resolder as needed.
ground paths have been an ongoing issue w/thomson products.also, inspect the electrolytic capacitors for evidence of electrolyte leakage. replace if find any.
intermittents can be the most difficult problem to correct. paitience and luck
are needed in some cases..
if this model has guide plus, would also be suspect of gemstar module.
(located above tuner in 197 chassis if have feature)

73 de hamop

[ojTHEd]

Next time it buggers out, I'll crack it open again and take pictures. I thought it had the "Guide Plus", but I didn't see a module where you indicate. I also didn't see any components that looked iffy. When/if it goes "silly" again, I'll just pull the whole board and check it very carefully. Thanks for all your pointers!