1970s J. C. Penney 19" Color TV issues

[vortalexfan]

Hello everyone, earlier today I had picked up from a local electronics recycling facility/computer store a 1970s vintage solid state J. C. Penney 19" Portable Color TV that when I got it home to try it out everything on it except the picture worked on it, it has audio and the channel selector lights work and everything.

When I turn on or off the TV I see the colors wash across the screen like it was showing some sort of picture but when the set is actually one or powered on the screen is completely blank, no snow or anything.

Any ideas as to what could be wrong with this TV?

Also who made this TV for J. C. Penney? It says Made in Japan on the back of the set.

Pictures of the set in question posted below.

[Electronic M]

Odds are it is missing G2 voltage or one of the other elements common to all 3 guns is not getting power.

Time to check voltages against CRT datasheet or schematic.

[vortalexfan]

Originally Posted by Electronic M

Odds are it is missing G2 voltage or one of the other elements common to all 3 guns is not getting power.

Time to check voltages against CRT datasheet or schematic.

It does have a service switch on the back which I can't tell if its in the normal position or if its in the service position.

Also I don't know who made this set for J. C. Penney or what the model number is so I'm not sure if I'll be able to find any service data on this set.

[zeno]

The set is a Panasonic.
If you have audio ( hiss) but a total black pix you have a video
problem. Try cleaning the service switch, I thing it has one.
Also try turning up the G-2 a little. After that it gets "interesting".
Post a few chassis pixs also.

73 Zeno
LFOD !

[vortalexfan]

Originally Posted by zeno

The set is a Panasonic.
If you have audio ( hiss) but a total black pix you have a video
problem. Try cleaning the service switch, I thing it has one.
Also try turning up the G-2 a little. After that it gets "interesting".
Post a few chassis pixs also.

73 Zeno

LFOD !

Yes it does have a service switch, but it's only accessible with the back cover off oddly enough (it only has a small slit in the cover for it).

Is this a fairly early solid state set like my Sylvania is?

And what do you mean by it gets "interesting"?

[zeno]

The set has no crazy circuit designs so easy to deal with. You may need
a manual, what is the model number ?
Most likely set has low G-1. Normally it adjusts from abt 200-800 VDC
with abt 400 V for a normal picture.

73 Zeno
LFOD !

[MadMan]

Perhaps the vacation switch would turn off the remote receiver?

[zeno]

One of these ! Very nice set. Its a delta tube so has 3) G-2
controls one for each color. Not sure but it may have separate
outputs for hoz sweep & HV. Do you have HV ?? Also find
that model number & it may have a chassis number on a white tag.

73 Zeno
LFOD !

[vortalexfan]

Originally Posted by zeno

One of these ! Very nice set. Its a delta tube so has 3) G-2
controls one for each color. Not sure but it may have separate
outputs for hoz sweep & HV. Do you have HV ?? Also find
that model number & it may have a chassis number on a white tag.

73 Zeno
LFOD !

Ok, will take a look.

[old_tv_nut]

Originally Posted by zeno

... Not sure but it may have separate
outputs for hoz sweep & HV. ...
73 Zeno
LFOD !

Interesting - first I've heard of a consumer set with separate H sweep and high voltage. Only ones I ever saw were broadcast monitors, with both sweep and HV regulated individually so no size modulation with brightness.

[zeno]

Originally Posted by old_tv_nut

Interesting - first I've heard of a consumer set with separate H sweep and high voltage. Only ones I ever saw were broadcast monitors, with both sweep and HV regulated individually so no size modulation with brightness.

Sony did it before the SG613 sets. Panasonic & I think a few more
also did. Very short lived design from the early 70's but it did work good.

73 Zeno
LFOD !

[old_tv_nut]

Originally Posted by zeno

Sony did it before the SG613 sets. Panasonic & I think a few more
also did. Very short lived design from the early 70's but it did work good.

73 Zeno
LFOD !

thanks for the info!

[vortalexfan]

Originally Posted by zeno

One of these ! Very nice set. Its a delta tube so has 3) G-2
controls one for each color. Not sure but it may have separate
outputs for hoz sweep & HV. Do you have HV ?? Also find
that model number & it may have a chassis number on a white tag.

73 Zeno
LFOD !

OK I think I found the chassis number tag and also the model number as well, both on a small white tag affixed to the chassis frame.
See picture below for the tag in question.

[old_tv_nut]

G2 = "screen grid." Although it's in the same order of electrodes as a screen grid (second grid) in a small signal tube, it doesn't perform the same function (screening the control grid [grid 1] from capacitive coupling to the plate) in a CRT. Instead, it is used for setting the cutoff point of voltage between the cathode and G1.