Dumont RA113 "Burlingame" restoration

[bandersen]

Thanks. The ceramic caps and a few others parts I needed arrive tomorrow. With a bit of luck I'll try firing it up later that night or on Saturday.

[bandersen]

Crap! I just missed the Fedex guy and he left a tag saying another attempt would be made on Monday I've been using Fedex for years they've always left the package somewhere on the property if no one answered the door.

[IsthmusTV]

Bummer. Maybe it's a new driver. Here in Madison, they give you the option of picking up the package after 5:00 PM on the day of the attempted delivery. I live only 4 miles from their depot, so I have done that on occasion. But in Chicago, it's probably way out in the burbs somewhere.

[bandersen]

I finally took a closer look at the tag and realized the depot was only a couple miles away and open to 9:30pm on a Friday night so I got my parts after all

Here are the 500pF, 15kV ceramic caps I'm going to try.

[IsthmusTV]

Cool. I have a feeling they'll work just fine in this application.

[Kevin Kuehn]

Are those the Vishay Cera-Mite 615R Series? If so their data sheet lists them for TV and Monitor applications. Nice to know someone is still looking out for us.

[wa2ise]

East Paterson changed their name to Elmwood Park a few years ago. That town is about 10 miles from my mom's.

Paterson NJ is a real dive, so this town didn't want that association anymore...

[bandersen]

Originally Posted by Kevin Kuehn

Are those the Vishay Cera-Mite 615R Series? If so their data sheet lists them for TV and Monitor applications. Nice to know someone is still looking out for us.

They sure are

[bandersen]

I'm not sure what to do about this resistor. It's R268 and is in series with the 6BG6 HOT grid. The schematic and parts list show 100 ohms but this is a 47 and appears to be original. When I measure it, I get 98 ohms.

It seems to me that if it really is twice what it should be, it could reduce the 6BG6 drive and flyback output. Should I leave it alone since it's close to the 100 specified in the service info, or replace it with a new 47 ?

[Kevin Kuehn]

My chassis has a 100 ohm in there(looks original), so apparently yours should be fine. Sams schematic shows a 47 ohm(with see note). Note 6 on parts list says some models use 100 ohm. I think it's purpose is to damp out parasitic oscillations, so it's probably not super critical on value. You see those used on audio outputs too.

[Zenith6S321]

During my 21CT55 restoration I found that SAMs showed the production changes of later sets than the RCA schematic showed, so the 100 ohm may have been a production change in later sets. I guess you need to decide if you want to restore it to original condition or incorporate the production changes. Is that 47 ohm resistor discolored, like it has been getting way too hot? That would explain why it measures high. If so, I would replace it with another 47 ohm resistor of higher wattage.

Dave

[bandersen]

No, it's not discolored - just dirty. I guess I'll leave it alone and see how it plays.

Here's another head scratcher. This section of the candohm resistor R282 B measures about 5300 but the schematic shows 2140. I've seen plenty of candohms go open but not drift in value that much.

Perhaps it's another production change ? What does the Sams show ?

[Kevin Kuehn]

Sams says 2140. You're measuring out of circuit?

[bandersen]

Nuts, I guess I'll have to bypass it. Yes, I measured it out of circuit.

Scratch that - I didn't fully take it out of the circuit after all. Now I get 322K so it's probably corroded or partially burned out inside. There's no wattage specified in Riders but I suppose 25W should be good enough.

[Kevin Kuehn]

Sams lists each section at 10 watts.