Mighty Monarch of The Air

[Phil Nelson]

Originally Posted by roundscreen

Check all the tubes in the if section and clean all the pins on the tubes in the if.

I'd extend that advice to all of the tubes. The first thing I do in every project (well, first after brushing away the dust) is to clean & test all tubes, as well as all controls & switches.

I remember the CTC-11's service switch well, and that's one reason why I've become eager to clean everything early. After recapping, the set worked very well except for one weird symptom. It was magically cured when Bill asked whether I had cleaned the service switch!

Phil Nelson

[vts1134]

Originally Posted by Phil Nelson

I'd extend that advice to all of the tubes. The first thing I do in every project (well, first after brushing away the dust) is to clean & test all tubes, as well as all controls & switches.
Phil Nelson

I'll get a brush and some contact cleaner going on all the tubes next time I have TV time. My rule is also test tubes first, it's just too bad it took me until post #115 to learn that this time around.

[vts1134]

Did a good cleaning of all of the tubes today. I also did a good scrubbing of the tuner. I tried moving the horizontal hold in both directions to the maximum. I also changed the channel on the tuner. All of which provided no video. The brightness control works and if I turn it up to maximum I have enough output to see through a phone book I think, the contrast has a very very minimum effect. I was wondering and wanted to ask all of you here is there some test I can run to verify the tuner itself is working versus the if stage not working? Another step I took while working on the underside of the set was to clean up some of my previous work. I decided that I would not accept the level of work I did on this set on future sets so why not start having that work ethic now.

Before:

After:


One other note, I hooked up the speaker to the set and I am also not getting sound output. I do get a very low hum that increases with the set brightness. Can some one tell me what the term for this is called?

[old_coot88]

Well first off, does your version of the set have the 'color' switch? If so, what happens when you click the switch back and forth? And does yours have the TV-phono switch? If so, what happens with the sound if you click this switch between TV/phono?

On the hum thingy with brightness, try turning the vert. hold from stop to stop. Does the hum change frequency ('pitch') or remain constant? If it remains constant, this tells you it's not vert. sweep bleed-through. oc

[vts1134]

Originally Posted by old_coot88

Well first off, does your version of the set have the 'color' switch? If so, what happens when you click the switch back and forth? And does yours have the TV-phono switch? If so, what happens with the sound if you click this switch between TV/phono?

Sorry should have mentioned that there is no color switch. I did clean the crap out of the TV/Phono switch. The is no difference in sound when I turn the TV/Phono switch back and forth, the raster just disappears.

[old_coot88]

Hokay, how about checking the video detector diode (M4). While you got one end clipped loose, turn the set on and with a clip lead, intermittently short the grid of the 12AU7 1st video stage (V6) pin 2 to ground. Try this with the contrast control at both ends of its rotation. If the two video amp stages are working, there should be some very robust flashing of the raster.

[vts1134]

Originally Posted by old_coot88

Hokay, how about checking the video detector diode (M4). While you got one end clipped loose, turn the set on and with a clip lead, intermittently short the grid of the 12AU7 1st video stage (V6) pin 2 to ground. Try this with the contrast control at both ends of its rotation. If the two video amp stages are working, there should be some very robust flashing of the raster.

Following this test gave me no no changes in the raster at all on either end of the contrast adjustment.