Width & Focus in DuMont RA-103

[Phil Nelson]

The width coil was not taken out of circuit. I temporarily unsoldered one of its leads at the flyback and tested it, as well as the 5-6 connections on the flyback. Neither is open.

I will look at the WW resistors next.

Look at how far off-kilter the focus coil has been cranked. Kosher? (If not, why would they give you adjusters with that much leeway?) It looks like none of this stuff, including the CRT, has been touched in ages.

Phil

[jeyurkon]

Originally Posted by Phil Nelson

The width coil was not taken out of circuit. I temporarily unsoldered one of its leads at the flyback and tested it, as well as the 5-6 connections on the flyback. Neither is open.

I will look at the WW resistors next.

Look at how far off-kilter the focus coil has been cranked. Kosher? (If not, why would they give you adjusters with that much leeway?) It looks like none of this stuff, including the CRT, has been touched in ages.

Phil

That's odd. Unless I'm brain dead, which is a distinct possibility, adjusting the core of the coil out should reduce the width in spite of anything else going on. Although come to think of it, adjusting it out should cause the flux in the core of the flyback to be reduced as the current in 5-6 bucks it. This would reduce the horizontal sweep but also the HV and the effects could cancel each other.

I must be brain dead. They wouldn't design something that can't work would they?

If you get bored you might measure the HV at two setting of the width coil.

John