Color Classic Problem :(

[macEfan]

i aquired a color classic not too long ago(with a LC 575 logic board upgrade),but it has a bad problem...

the screen is VERY dark.. The macine boots up fine and all, but the display is Hardly Readable! The brightness controls do nothing... please help... i dont want to have a dead CC for the rest of my life

 

[Spock]

Have You opened the case and checked the Yoke cable? Also on the back above the door for the logic board are the main CRT adjustments I cant remember but I think the brightness setting is on the side, I cannot stress enough the importance of being carefull as the CRT can kill You.

 

[macEfan]

thanks for the reply.... Sorry for my lack of skills, but what is the yoke cable? And how can i be carful around the CRT? thanks!

 

[CanadaRAM]

thanks for the reply.... Sorry for my lack of skills, but what is the yoke cable? And how can i be carful around the CRT? thanks!

Oooo Kay. Your response indicates that you should not attempt to work on the CRT, but you should take it to a television repair shop where they know their way around a CRT and how not to get electrocuted. This is the last thing you should be attempting if you are not skilled with electronic repair.

Basically, there are components in any 'tube' style display that hold 10's of thousands of Volts **even when the machine is off and unplugged **

A TV shop has a special tool to safely drain that voltage away before working on it.

 

[macEfan]

i know how to discharge a CRT:
i would need

-Insulated Screwdrive
-Grounded outlet
-thick insulated wire
-electrical tape or wire clamp

all i need to do is connect the wire from the screwdriver to the grounded outlet. Then, touch the screwdriver's tip to the underside of the suction cup on the CRT..
i am not worred about discharging the CRT, i just have no clue what is wrong with my Color Classic.

 

[Spock]

thanks for the reply.... Sorry for my lack of skills, but what is the yoke cable? And how can i be carful around the CRT? thanks!

If You take apart the Classic to the point You can see the CRT the controls Im speaking of are on the back away from the 3 parts of the CRT that hold the charge, just use common sense and dont touch anything close to the CRT.And nevermind the Yoke cable.

 

[Laser47]

The high voltage to the CRT, while 200 times greater than the line input, is not nearly as dangerous for several reasons. First, it is present in a very limited area of the TV or monitor - from the output of the flyback to the CRT anode via the fat red wire and suction cup connector. If you don't need to remove the mainboard or replace the flyback or CRT, then leave it alone and it should not bite. Furthermore, while the shock from the HV can be quite painful due to the capacitance of the CRT envelope, it is not nearly as likely to be lethal since the current available from the line connected power supply is much greater.

If you are not going to be removing the CRT anode connection, replacing the flyback, or going near the components on the little board on the neck of the CRT, I would just stay away from the fat red wire and what it is connected to including the focus and screen wires. Repeatedly shoving a screwdriver under the anode cap risks scratching the CRT envelope which is something you really do not want to do.

From http://www.repairfaq.org/sam/crtfaq.htm#crtcsa

I dont think you need discharge the tube, just be really careful around it.

 

[Spock]

Here, this isnt that complex.

 

[macEfan]

Here, this isnt that complex.

thanks, that will help!