Hi folks;

This is the second RCA HDTV RPTV to have a broken blue CRT. I remember
a job about two years ago where the estimating tech ordered a CRT for a
Mits. I found a power supply fault that caused the tube to crack. This
time it's a bit different.

You may ask why I didn't disconnect the CRTs one by one, and I say
thiis, maybe there was a bit of wishful thinking, and their HVB could
get damaged due to it's cheapness. The next tech put the fly in and it
still shuts down immediately. He was going for the HVB but then saw
fluid in the neck of the blue CRT. Just so you all know, this is one of
two RCA HDTVs in which we had to replace the blue CRT for breakage ( I
thought Ii disconnected the whole thing from he fly )

The other was an ITC series RPTV but the tube looked about the
same.That one was cracked at the neck, but we found out later that the
screen was broken as well.

So consider that a heads up on the blue CRT in RCAs. My problem now is
that I have an HV short induced problem.

Now the boss is not a tech anymore, but he says something like "Alot of
coolant leaked out of that thing". Hmmm. There were issues about the
socket board, it was drenched with coolant but you coudn't see it. Even
better it's a two sided board.

That has been taken care of, now I got a problem that may be obvious.

The ABL circuit is damaged, no doubt by the HV short. Obvously some
kind of current limiting is working, just not ABL to the video.

I put the CRT in and l let it align itsellf, then it did some wierd
thing and shutdown. Great huh ? OK it was coolant, but now, like I
said, watching it, it is fantastic. I tuned into a terrestrial HDTV
broadcast and yes, you can tell the difference. Thing that got me was
how bright it is ! Damn !

You could just about watch this thing in the front lawn at noon. Then I
saw WHEN it shutdown. I reduced the picture control and instead of
runninng for five minutes, it runs for hours.

You know what I am looking for, some stupid buffer transistor feeding
the video with ABL Possibly a shorted Zener or cap.

Did they put these components near the fly or are they on the other
side of the PCB ?

Thank you, and thank you in advance. This NG has helped me quite a few
times.

One more time ? (well not really only one)

JURB

On 15 Dec 2005 21:48:24 -0800, wrote:

Hi folks;

This is the second RCA HDTV RPTV to have a broken blue CRT. I remember
a job about two years ago where the estimating tech ordered a CRT for a
Mits. I found a power supply fault that caused the tube to crack. This
time it's a bit different.

You may ask why I didn't disconnect the CRTs one by one, and I say
thiis, maybe there was a bit of wishful thinking, and their HVB could
get damaged due to it's cheapness. The next tech put the fly in and it
still shuts down immediately. He was going for the HVB but then saw
fluid in the neck of the blue CRT. Just so you all know, this is one of
two RCA HDTVs in which we had to replace the blue CRT for breakage ( I
thought Ii disconnected the whole thing from he fly )

The other was an ITC series RPTV but the tube looked about the
same.That one was cracked at the neck, but we found out later that the
screen was broken as well.

So consider that a heads up on the blue CRT in RCAs. My problem now is
that I have an HV short induced problem.

Now the boss is not a tech anymore, but he says something like "Alot of
coolant leaked out of that thing". Hmmm. There were issues about the
socket board, it was drenched with coolant but you coudn't see it. Even
better it's a two sided board.

That has been taken care of, now I got a problem that may be obvious.

The ABL circuit is damaged, no doubt by the HV short. Obvously some
kind of current limiting is working, just not ABL to the video.

I put the CRT in and l let it align itsellf, then it did some wierd
thing and shutdown. Great huh ? OK it was coolant, but now, like I
said, watching it, it is fantastic. I tuned into a terrestrial HDTV
broadcast and yes, you can tell the difference. Thing that got me was
how bright it is ! Damn !

You could just about watch this thing in the front lawn at noon. Then I
saw WHEN it shutdown. I reduced the picture control and instead of
runninng for five minutes, it runs for hours.

You know what I am looking for, some stupid buffer transistor feeding
the video with ABL Possibly a shorted Zener or cap.

Did they put these components near the fly or are they on the other
side of the PCB ?

Thank you, and thank you in advance. This NG has helped me quite a few
times.

One more time ? (well not really only one)

JURB


While on topic of RCA

Always the blue CRT broken? I have one too, neck dropped off. Prior
to this, history: replace blue CRT for bad spot, then had to replace
all other 2 CRTs to get it balanced and adjusted properly without
shutting down too much. Still have intermittent shutdown, one moment
running, pic vanished. Had to drag TV back to shop and get down with
it with heavy guns and attached PC with test pictures to it, need to
take a leak then back to find tv shut down and find that CRT broken.

I"ll pull up the model # and chassis for 61" and HEAVY. This is D
shaped wooden chassis on casters.

Cheers, Wizard

Ok, it is DTV307 chassis and 60" size. Another edsel!

Originally had to change blue CRT for a bad spot which means unit was
functioning prior to this. After the CRT change, the unit kept
shutting down and had diffcult time getting them adjusted to get all
CRT playing together or else it shuts down or awful pic, have to
adjust per service manual to balance CRTs and do grey scale set up.
For this, had to replace other 2 CRT to get all this working. Except
this doesn't stop the shut downs.

So set is now at our shop with test image of windows via DVI cable
getting around to checking with scope probe and check voltages. Come
back to find unit dead, CRT neck broken in two where CRT flares out
from neck. Sigh.

Contacted RCA local service area and suggested vertical problems but
I'm not sure of that.

So what can do this one this time?

Cheers, Wizard