21EAP4 mod

[rickfray]

I have a Predicta Holiday with a 21EAP4 tube and when removing the main circuit board, noticed there is a component not on the schematic that is connected to the binding post (don't have the number handy at the moment) which is normally where the CRT cathode connects to. A picture is below. It looks like an RF choke maybe? Any idea what this would be for? Should I remove it since it isn't on the schematic?
http://videokarma.org/picture.php?pi...016515&thumb=1

Thanks

Rick

[old_coot88]

The pic is too blurry to make out, but I'll take SWAG that it's a spark gap.

[Eric H]

I can't see any picture at all.

[rickfray]

wow that would electrifying. Assume you were kidding. Here's a hopefully better picture. I'm pretty sure it's an RF choke - question is what would it be used for since it's not on the schematic and do I need it?

http://www.videokarma.org/picture.ph...pictureid=3366

[Eric H]

I'm still not getting a picture, just a single pixel GIF

[bandersen]

You can see all his Predictas photos in this album: http://www.videokarma.org/album.php?albumid=616

They are on the small side though.

[StellarTV]

It's a peaking coil... no idea why that's there; I've never seen that installed on a stock Holiday.

After you get it going, see what the difference is with/without that peaking coil.

[ChrisW6ATV]

The first link gives me a one-pixel picture, too, and the second one shows several components including a couple of "bumblebee" capacitors. Those need to be replaced, of course.

[Tim]

I believe that the coil pictured is shown on the Sams schematic as L14. Used in some runs and not others. The sets I have restored have had it.

[rickfray]

Originally Posted by Tim

I believe that the coil pictured is shown on the Sams schematic as L14. Used in some runs and not others. The sets I have restored have had it.

OK. I just got the Sams schematics and will lokk at that. I was going thru the Philco docs against the main board last night and noticed some drastic differences in the values of some of the bumblebees vs the parts list values. Does someone have a source on how to read the BB values? I'm not sure whcih end to start at and am not sure what all the bands are for. I'm guessing some for tolerance.

Sorry about the small photos-still trying to figure that part out. The originals are large high res ipad fotos, but not sure how to disply them properly in a forum post yet.

[rickfray]

Originally Posted by ChrisW6ATV

The first link gives me a one-pixel picture, too, and the second one shows several components including a couple of "bumblebee" capacitors. Those need to be replaced, of course.

Roger on the bumblebees - that was my plan. My post was just focusing on the coil attached to one of the wirewrap posts that goes to the CRT cathode.

[rickfray]

Originally Posted by rickfray

OK. I just got the Sams schematics and will lokk at that. I was going thru the Philco docs against the main board last night and noticed some drastic differences in the values of some of the bumblebees vs the parts list values. Does someone have a source on how to read the BB values? I'm not sure whcih end to start at and am not sure what all the bands are for. I'm guessing some for tolerance.

Sorry about the small photos-still trying to figure that part out. The originals are large high res ipad fotos, but not sure how to disply them properly in a forum post yet.

Nevermind - just googled and got the following links to Bumblebee info

http://classicamplification.net/Guit...Bumblebees.htm

http://www.pickguardian.com/pickguar...ee%20Chart.pdf