Wonky Picture on 1977 Panasonic 12" Set

[YamahaFreak]

I have a 1977 Panasonic Quintrix II set my grandmother gave to me, and I adore it because when it's working right, the picture is gorgeous. Almost like Technicolor color. It has a problem with the picture. After it runs for a time, the picture will, at random intervals, quickly become very dark. Usually changing channels fixes it, but it is stubborn and I occasionally have to just wait for it to "fix" itself. Anyone know what this could be? Not sure, but I think the problem could be triggered by onscreen brightness levels.

[jpdylon]

try jiggling the channel selector and see if that solves it.

If this uses a varactor (pushbutton tuning with presets) then the varactor presets may need a deoxit bath.


sounds as though its just falling out of tune, but.....

You should also check the brightness, picture/contrast, and panabrite/panacolor switches. If they are dirty the symptom can occur as well.

[radiotvnut]

All the customer controls should be cleaned. There could also be a bad solder connection on the chassis.

[zenith2134]

Reminds me of a 1980 or so Quasar I had which would go blank randomly. Turned out to be a combination of weak soldering around the flyback and also very dirty controls. Set worked for about 10 more years then I tossed it when the CRT began bleeding the highlights. Might not have even been bad, but I remember I used to run that set with the color and brightness very high. Probably also had around 1Billion hours on it too.

Your set sounds very cool. Maybe you can post a pic?

[YamahaFreak]

Originally Posted by jpdylon

try jiggling the channel selector and see if that solves it.

If this uses a varactor (pushbutton tuning with presets) then the varactor presets may need a deoxit bath.


sounds as though its just falling out of tune, but.....

You should also check the brightness, picture/contrast, and panabrite/panacolor switches. If they are dirty the symptom can occur as well.

No varactor tuner. Flipping channels on the VHF knob seems to make it go away about 50% of the time. No bad reactions from the Quintrix or AFT switches, but the Contrast and Brightness knobs seem to sometimes mess with the picture. I realize the symptom is hard to explain--the picture will very suddenly (instantaneously) go dark. Colors are still visible, but very dark. It's almost like somebody stuck a really dark filter over the screen. Everything except the brightest parts of the picture are hard to see.

[jpdylon]

This set may be too new, but check and see if it has a service switch on the back. It should have two positions: normal / service.

without switching it into service mode, tap or giggle the switch to see if the picture flickers. If it does, clean that switch.

[YamahaFreak]

Originally Posted by jpdylon

This set may be too new, but check and see if it has a service switch on the back. It should have two positions: normal / service.

without switching it into service mode, tap or giggle the switch to see if the picture flickers. If it does, clean that switch.

Yes, there is a service switch. Should I do this with the set on or off?

[jpdylon]

check it with the set on, clean it with the set off.