The original statement was letting the hv arc to a screwdriver to ground....
No direct contact made.... Just a quick arc, no 1/2 hour welding job, popping
pop corn, roasting a turkey stuff like that..... One quick Zap! Yup there is HV, move on....

.

Understood.

But why take the risk, even briefly, when there is no need for the screwdriver to be grounded to make that test?

High voltage RF will arc to an ungrounded metal object just fine, without the danger of the DC following the arc path to ground and overloading the transformer winding.

I've never had the guts to play the arc-cap-to-screwdriver game. Neon bulbs are cheap.

Yep, I quit playing the "arc-cap-to-screwdriver game" 35 years ago, when I got zapped good fashion, in a Customer's home, from a 23" Philco tube color set, in a metal cabinet! I'll never forget lessons learned from that one:)!

This. Thank you Sir. :rockon:

Never had a problem with RF. The anode lead, on the other hand will usually whack you pretty solid. For that, I use a high voltage probe.

Tim
not sure where to get a doorknob , i did buy some 15kv 470pf caps from mouser that will sub , you could always pull one from another set that you know is good just to test , or if you disconnect the one in the dumont and bring the set up on the variac and try to feed the set with 100 to 105 volts ac from the variacit should be safe and you may get an answer if the doorknob is at fault , had one take out hv in a rca , a dumont that uses three doorknobs had one that was bad and it caused all kinds of issues with not enough hv and a dim image............ i just noticed you still have the horz output tube in the socket when testing the fly , your supposed to remove it and the hv retifier and the damper , but the damper probably isn't in that hv box , i have the same set and have yet to restore it
mike

I can only recall replacing one doorknob. Anyhow, Surplus Sales of Nebraska has some. You might need to adapt the mounting a little -- it has been a while.

http://www.surplussales.com/Capacito...cap_trans.html

(Hey, I didn't say they were cheap :) )

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

There's always a bunch on ebay.

http://www.ebay.com/sch/i.html?_from...citor&_sacat=0

Replaced the doorknob, same result. Since my flyback tester told me that the flyback was shorted, and since everything else has been replaced, I'm going to stick with that diagnosis.

And now, the search begins.....

Was your flyback tester a ringer that can detect shorted windings more accurately than a DC resistance reading on an ohmmeter would?

Yup, it's an Eico 944 flyback/yoke tester.....

Just for a bit of easy help, Ill take a resistance reading on the DuMont Savoy chassis I have. And post it here as an edit.
I have a Heathkit Flyback-yoke-HV probe meter that is similar in that it has 6 selectable ringwaves to test with.

Tim:

I have an RA-110 that is not yet restored and I pulled the HV cage and measured the fly. Mine looks toasty like yours and measures nearly the same as yours on the EICO 944 shorts test. I guess either they are both bad or both good. Resistance measurements for the primary winding are: 1 <84 ohms> 2 <286 ohms> 3. Secondary is 7.3 ohms. If the schematic is correct for the 110, then the primary on mine definitely has shorted turns from 1 to 2. It could also be that the resistance measurements are only for the 103 fly. When Dave posts his readings we will have more data.

I also pulled Rider 3 which has one page on the 110 and have attached a photo, including the note regarding the RA-110 flyback difference from the RA-103. The 103 uses the same fly as used in the early 630 type sets and clones. Thordarson FLY-1, Merit HVO-3, Stancor 8127, Triad D-11, etc. As a test you could probably sub one of those in and see what it does.