Zenith 25" color TV SM2568S CRT board color adjustments

[Jacques Carrier]

Gretings from Montreal to all fellow techs,

I fixed the vertical problem on this nice 25" 1994 color TV (bad solders).
I would like to know how to properly adjust the 3 potentiometers
located on the CRT board.I did not find any grey scale pots ??
Maybe the CRT is getting old ......The colors are not crisp enough
and there is a light green hue.
If you have a service manual please get in touch with me.

Many thanks for your help,


Jacques [email protected]

 

[Andy Cuffe]

Gretings from Montreal to all fellow techs,

I fixed the vertical problem on this nice 25" 1994 color TV (bad solders).
I would like to know how to properly adjust the 3 potentiometers
located on the CRT board.I did not find any grey scale pots ??
Maybe the CRT is getting old ......The colors are not crisp enough
and there is a light green hue.
If you have a service manual please get in touch with me.

Many thanks for your help,


Jacques [email protected]

Those 3 pots on the CRT board are for grey scale. They adjust the red
green and blue bias. There are no drive controls on that set. Being
a 1994 Zenith you probably won't be able to get a good picture. Those
sets have CRT which go weak within a couple of years.
Andy Cuffe
[email protected]

 

[Asimov]

"Jacques Carrier" bravely wrote to "All" (27 Sep 04 05:44:16)
--- on the heady topic of "Zenith 25" color TV SM2568S CRT board
color adjustments"

JC> From: [email protected] (Jacques Carrier)

JC> Gretings from Montreal to all fellow techs,

JC> I fixed the vertical problem on this nice 25" 1994 color TV (bad
JC> solders). I would like to know how to properly adjust the 3
JC> potentiometers located on the CRT board.I did not find any grey scale
JC> pots ?? Maybe the CRT is getting old ......The colors are not crisp
JC> enough and there is a light green hue.
JC> If you have a service manual please get in touch with me.

Emission might be low on the red and blue. Maybe a crt restoration would
help. Adjusting the bias in a weak gun only leads to overload and
flaring. Turning down the strong gun isn't much better either. If it is
for yourself you might jump the heater series resistor. This will raise
the cathodes' temperature and perhaps it might get enough emission back
to clear up the green cast. Apparently the crt's in that year range were
not very durable and went weak prematurely.

A*s*i*m*o*v

.... New computer? But I like my vacuum tubes... They keep me warm.