Lowew CRT TV

[shorteddiode]

Lowew CRT TV model # PLA350PL, has anyone had any experience with this make? I was told it is German made but googeling doesn't turn up that model. I tried Elektro
Tanya but no luck.
It turns on with a blue screen and some whit horizontal lines. After about 5 seconds the picture starts to turn white and it shuts down. It stays in standby, and there are no obvious defects on the boards
could the Video output amplifier TDA6111Q be causing this? There are 3 of them on the neck board

[tom66]

Re: Lowew CRT TV

Doubt German made. Probably Vestel. Need the chassis code which will be written on largest board in set.

[shorteddiode]

Re: Lowew CRT TV

It has a Phillips CRT. The numbers on the board are

87 185 001576
062

[tom66]

Re: Lowew CRT TV

Thinking about that I don't think Vestel has every sold out of Europe. So it might not be made by them. Any part #'s on the boards aside from those?

[shorteddiode]

Re: Lowew CRT TV

No none that I found, I'll get some pics posted. I checked the HOT and the caps on the main board and all are good

[tom66]

Re: Lowew CRT TV

I'm not really into CRT TVs but I know the basic operation of them.

If you've got horizontal scanning the HOT's probably OK. Same if you've got a lit screen. Bad caps can cause vertical deflection issues.

[shorteddiode]

Re: Lowew CRT TV

It uses 3 Phillips video amps on the neck board and since it fades to white before it shut downs I am suspecting one of them

[tom66]

Re: Lowew CRT TV

Perhaps, check B+.

[RJARRRPCGP]

Re: Lowew CRT TV

It turns on with a blue screen and some whit horizontal lines. After about 5 seconds the picture starts to turn white and it shuts down. It stays in standby

Sounds like that POS 2005 RCA CRT TV (except for the lines) that's now in the back yard, about to be covered with snow!

[shorteddiode]

Re: Lowew CRT TV

I figured B+ was good since it turns on and I do get a picture for a short time. I am thinking like shut down circuit, but can't find a schematic for it. Would the video amps cause a shut down if one was bad?

[tom66]

Re: Lowew CRT TV

Perhaps if they are providing excessive load. I'm thinking one of the supply voltages is collapsing. Best way to be sure is to measure them.

[shorteddiode]

Re: Lowew CRT TV

OK< I'll get some voltage measurements and photos and post the tomorrow.
Thanks everyone

[randtek]

Re: Lowew CRT TV

I haven't done much CRT work in the last 3 years, so this is reaching back into the cobwebs a bit. The problem you are describing sounds like a grid short in the CRT to me. Try adjusting the Focus pot on the flyback. If it affects the screen brightness, or if the screen control affects the focus of the lines, it would tend to confirm this. Measure the G2 voltage (the small wire coming from the flyback to the CRT board, the one that DOES NOT go into the CRT socket, it will be soldered straight into the board. The voltage on that wire will probably be in the 200-300 volt range, so be careful. Turn the focus pot on the flyback up and down while monitoring this voltage. The focus control should not affect it. The screen control WILL adjust it, probably a range of about 70-400 volts. If the focus pot causes the G2 to change, you have a grid short. Even if these tests don't show anything conclusive, it could still be a shorted CRT.

If it was just a blue screen with white lines, I would say it could be a video drive. The fading to white and shutting down scream shorted CRT to me.

[shorteddiode]

Re: Lowew CRT TV

I have a CRT tester/rejuvenator I have never used. Guess it's time to break out the black box and see what it can do. I'll run the voltage tests you suggested first randtek. I'll post the results

[shorteddiode]

Re: Lowew CRT TV

I payed a little more attention when I turned on the TV and heard an arching noise coming from the picture tube. So sent the TV to to that big repair shop in the sky.