Color issues in 1999 Toshiba

[timzmud]

Hello All

My first post to the group. I feel more at home in the antique radio groups, as I have no experience working with televisions... yet.

My Toshiba cf27h40 has had some color issues for some time. It would take several minutes for the color to appear. Once there, everything was fine. Now the color will flash before it settles down. Sometimes it never settles down. Lately a couple of other things are happening. I've noticed the yellow RCA jack that gets the video signal is touchy. Tapping it causes the picture to break-up. Swapping the cable did nothing. And a thin white line hovers near the bottom few inches of the screen; but not always. And to complicate matters, last week everything worked perfectly. The video input still needs looking at, but the display worked great. Unfortunately, that didn't last.

My plan is to open this thing up, discharge the crt, (cautiously), remove the board and look for some cold solder joints. I would really like to keep this thing working; as I do with most things around my house. Thanks in advance for any suggestions.

[Dude111]

Welcome....... Its good seeing you posting....

Im curious..... How long does it take for a tube to lose all the stored energy??

I do hope you get her fixed soon

[zeno]

Since you will have the iron out look for the following PC cons.
They are common to most sets.
PC at on/off relay, vert output ic, hoz drive transformer through
flyback, power supply area. Also in & out jacks & video outputs
on the CRT skt.
The line on the bottom is probably an electrolytic in the
vert just starting to go. Dont know about the int color, that
became a very rare symptom in later sets.
good luck

73 Zeno

[zeno]

Originally Posted by Dude111

Welcome.......

Im curious..... How long does it take for a tube to lose all the stored energy??

I do hope you get her fixed soon

On almost all solid state sets it bleeds off in seconds. The only time
I discharged one is if I were going to handle the CRT or clean
around the anode.

73 Zeno

[Dude111]

Ahhh thank you my friend,I simply didnt know...

I hope he can get things fixed

[timzmud]

An update to my first post.

The set had a couple of issues. Intermittent color, a thin white horizontal line near the bottom of the screen that moved around and a touchy video input jack. I first re-soldered those jacks and took care of that problem.

As to the color issues, since I put the set on my bench and opened it up, the color has been 100%. It has not flickered or gone out yet. And I can't seem to make it fail. The picture looks great.

Now for the horizontal line. It seem to move and disappear when I press on the board; in many locations. I've been looking at questionable solder joints and re-soldering but it has not made a difference. I suspected a transistor that is mounted to a heat sink. The heat sink is not soldered properly to the board. I'm having a difficult time with it. Are these made of aluminum, and if so, can they be soldered? There is a solder pad on the board, so I'm thinking they should be. Any suggestions?

Now for the latest. Occasionally I lose vertical; thin horizontal line in the middle of the screen. Again, tapping around restores the picture. So I'm going to focus my attention on the vertical areas; re-soldering for now, replacing components if necessary. Thanks for all help offered.

[zeno]

Find the vert output IC & resolder it even if it looks OK.
You can do a search on the IC ##'s to find out which one it
is or post a clear chassis pix. It will be mounted on a small heat sink.
Only other one is prob the audio out & the SPKR wires usually go
near it. Also there is 2 of most parts if stereo.
As far as soldering the pad goes if it wasnt soldered dont bother.
If it was you need a hot iron.
Once you find the output IC you can find all the vert components.
Example: if the IC is designated say IC401 all other vert parts
will have a 400 number. Other stages will use different series.
Works on almost any modern TV.
Keep us posted......

73 Zeno

[Reece]

While you're at it look for any slight bulging of electrolytic tops and replace.

[timzmud]

Hi All
Thanks to all for the help in repairing my Toshiba. Zeno's tip for soldering the vertical IC did the trick. The intermittent color issue looks like it's coming from my DVR. I didn't notice any bulging capacitors, so I buttoned it up and lugged it back upstairs. Next I'll see if I can do something with the DVR.