Trying to repair CRT TV Philips 14GR1220

[crt_cowboy]

Hello,
I have a Philips 14GR1220 (also known as Discoverer) a TV that shows a dark bar in the center of the screen.
See attached picture. I never seen similar issue.

Any advice on where to start for troubleshooting ?

Service manual can be found https://elektrotanya.com/philips_14gr1221.zip/download.html

Many thanks in advance !!

[inse]

Is a signal source connected?
Try to make a photo showing a picture where one can imagine what it should look like.
A test pattern in best case.

[Uunoctium]

An slow moving vertical bar (asynchoneous) is mostly associated with huge hum from PSU. Check ripple on voltages, check also electrolytic capacitors in PSU, bridge rectifier...

[AndyBeez]

Is that a static of crawling bar? Are you driving the screen with a clean signal source or is it just floating static? For clarity, PAL, NTSC or SECAM?

One visual observation, the width of the dark bar is about the same width as the sync pulse or back porch. Has the horizontal deflection drifted?

I would certainly check all capacitors for ageing and the pcb for dry joints > when unplugged and grounded.

[PKTKS]

Hello,
I have a Philips 14GR1220 (also known as Discoverer) a TV that shows a dark bar in the center of the screen.
See attached picture. I never seen similar issue.

Any advice on where to start for troubleshooting ?

Service manual can be found https://elektrotanya.com/philips_14gr1221.zip/download.html

Many thanks in advance !!

1) Service Manual   - ok
2) a clean  CRT signal generator.
3)  possible source of signal.... with a decent scope probe 2 channel

You need a reasonable clean source signal with options to switch each gun and also RGB at all to have a simple BW and synch signals..

Injecting this signal in TDA3xxx family will show you a reasonable guess from where the spurious signal came in..

Got mine on the very early 80s.. used way so much paid for itself in the first year....
Paul

[crt_cowboy]

Thanks for all the replies. I found a damaged trace near the FBT, fixing it removed the bar that was visible on the picture. I take note for next time to display a test signal on the screen.

You need a reasonable clean source signal with options to switch each gun and also RGB at all to have a simple BW and synch signals..
Injecting this signal in TDA3xxx family will show you a reasonable guess from where the spurious signal came in..

Just for my education, you would directly inject the signal in the TDA IC ? I guess on the signal input pin ?
Is the idea to rule out the tuner part of the TV ?

[PKTKS]

Thanks for all the replies. I found a damaged trace near the FBT, fixing it removed the bar that was visible on the picture. I take note for next time to display a test signal on the screen.

You need a reasonable clean source signal with options to switch each gun and also RGB at all to have a simple BW and synch signals..
Injecting this signal in TDA3xxx family will show you a reasonable guess from where the spurious signal came in..

Just for my education, you would directly inject the signal in the TDA IC ? I guess on the signal input pin ?
Is the idea to rule out the tuner part of the TV ?

Yes.  The proper CRT signal generator is designed for that.

All TDA3xxx  accepts  plain  luminance CHROMA or just composite on the proper pins.

Provided that you also put the synch (sand castle) it will function - maximum Vpp is on datasheet.
Usually you put the composite on the direct RCA jack at first and in turns switch the generator to see the outputs.

Provided the proper setup you also use this to trim the DELAY LINE ( 1L or 2L cf the chip)

Still have some... very hard to find these days

Paul

[shakalnokturn]

You haven't answered some of the questions asked that would be useful to better understanding the problem.
One thing that strikes me on the photo is the blue / red skirting. Is convergence that bad? Any chance TV has been dropped?