Contrast uncontrollable GE 10T1 - Videokarma.org TV - Video

mattdavala · #1 10-08-2007, 12:40 PM

Hi Everyone,

My 10T1 seems to have the contrast running at 100%. Its very annoying because it overloads the IF sections.

The contrast control works, well at least it varies resistance. It is supposed to be a 2 meg control, yet when I checked it with my ohmmeter it was reading around 150, possibly a meg and a half. Thats if I read it right. Would that cause my contrast be be full blast and unnafected when I turn the control?

I am unable to upload the contrast control part of the schematic due to it being 290KB. I can always email it to you.

Thank you,
Matthew D

Tube TV · #2 10-09-2007, 11:30 PM

Have you done a recap on this TV ? I would check the cap #C 32 0.5 and the 470 1.5meg and 2 meg resistors and see if they are within limits I would also check for wires touching in this area . I cut this part of the schematic then we know what were dealing with .

anyone have suggestions ?

best of luck with it .

mattdavala · #3 10-10-2007, 12:09 AM

Hi,

Thanks for replying. Yes I have done a full recap on this TV. I will have to check that 1.5 meg resistor tommorow. Do I have to clip one of the leads to check the resistor, or can I just put the ohmeter on either side?

Thank you for your help,
Matt D

Tube TV · #4 10-10-2007, 01:28 AM

One on either side should do in , but you might want to disconnect one side , somtimes when mesuring high impedance resistors there will be another part in the circuit that will change the values and give a incorrect reading also dont touch both metal leads on the resistor that can also set things out . Especially above 1 meg . I have noticed this more so in digital multimeters . The other thing you might check is the video detector diode .
It might be easier to replace it , it would probably test good but could be weak enough to cause the problem . I would not bother with it until I had checked closer to the contrast control . I would emagine that your tubes are good but I would check the RF Amp ,Mixer oscillator , video amp ,video output tubes .

Murray.

mattdavala · #5 10-10-2007, 02:11 AM

Hi Murray,

After my initial recap the TV had no pic and no sound so I did replace the video detector with a switching diode. Replacing the diode restored picture and sound.

I will measure that resistor tommorow.

Thanks again
MD

Tube TV · #6 10-10-2007, 02:57 AM

I wonder if the replacement might not be as compatable with the set as the original ? what is the # on it I have the ECG cross reference I could comare it with the original , I would say it is good though.