View Full Version : width problem


radio nut
07-11-2009, 04:24 PM
I had another thread about my Motorola 21t16. I got some advice, fixed the problem of the picture drifting to the left and wouldn't you guess 10 minutes later my flyback burns up. Ok, It happens. I got a new one from Moyer's, reinforced the coating and waited about 2 weeks. I tried the set and now the pic is not wide enough. The width control is on the fly and is active.I checked what the sams diagram said, I also have a book by Sams and did what it said. I have subbed in tubes and it is still not wide enough, Now what do I do? By the way the fly was a direct replacement thordarson.

7"estatdef
07-11-2009, 05:50 PM
May want to double check screen and cathode resistors on the HO tube. If the screen voltage is too low or cathode is too high it could narrow the picture.
Terry

radio nut
07-11-2009, 07:24 PM
The screen resistor is 12 ohms high-should be 680 reads 692 and the other should be 330k and is 343k. Is this far off enough to cause problems?. Both per diagram are well with-in tolerance.That's what is throwing me off. I put new caps in the spots where the Sam's book and diagram said " check these".This does not seem heat related either. The set comes up locked in both vert. and horiz. and stays there, just not wide enough. Could the fly be "off" but not bad?

old_tv_nut
07-11-2009, 08:39 PM
Is the flyback a replacement for more than one model? (Wondering if there might be different yoke taps). Is the width control an inductor in series with the yoke, or??

radio nut
07-11-2009, 09:53 PM
First question, I do not know. The paper that came with it said exact replacement. This fly is two seperate coils with a metal U that goes inside of each coil. As you adjust the width it will move out or in one coil while pivoting inside the other. Yes it moves smoothly and as much as the original. Using a variac to make the line voltage 117 like the diagram inorder to check voltages, its 235 volt line is 236. this goes to the damper and then to the fly but the 435 boost line is only 410.that goes to the horiz. output tube grid and it is giving the tube only 127, not 135. If I boost my B+ the width stays the same even if boost voltage goes up.

radio nut
07-11-2009, 10:31 PM
Maybe I did not read far enough. Got to looking at the Sam's for the tv again.I had to get a fly 64 for my set, There is a note with connection data. Ok, Now, Looking closer it says that there is an alternate vert. osc and vert. output transformer. I thought that this meant I would have to use them only if I had to replace them. Now I am beginning to wonder if they mean that I NEED the alternates if I use their Horiz. fly to begin with. So, If I need A thordarson fly 64 I also need the others. The vert output does connect with the horiz. in the yoke.Someone please tell me if I am now just getting it!