[Kico]

Where/what does the loose end of this wire attach too? Small circle is the attached end.

Thanks.

[Radioroslyn]

Can't see the other end to see where it comes from. That big 26K resistor is in the way.
Terry

[Kico]

Morning Terry,

Without taking a new pic, the attached end goes to the post where one end of the mica cap and solid blue resistor are attached (small red circle at the bottom of image). BTW, this is a model 84B...I'm betting you knew that though.

[Radioroslyn]

Morning !
Looks like it should go over the to pin 4 or 5 ( should be hooked together ) of the 77 mixer tube.
It's part of the oscillator feedback circuit. It's common on these set of the feedback winding to
rot and on open. Your wire may have been disconnected to troubleshoot the coil.
Terry
ps Replace your filter condenser both sections lest you want to replace both section of the filter the 80 tube and the power transformer later!

[Kico]

Thanks Terry...yes, I'm replacing both sections of the PS cap and was wondering if it's ok to increase the capacitance here and by how much...it's not much now now, I think 4uf and 8uf. Being a reasonable purist, I'll probably put the new caps in the orig can.

[Radioroslyn]

Value isn't critical you could go as high as 47mfd or so. Back in the 1920's and 30's electrolytics where expensive to make so most of the filtering is done with inductance. If you look at diagrams say of a Philco model 87 the filters are like 1 or 2mfd and two or three chokes. Very important to observe polarity and voltage rating. 450v for this one. Philco in the '30s some times would use a small paper cap across the filter choke a help resonate L/C to 60cy.
Have Fun & happy new year!
Terry

[Kico]

Value isn't critical you could go as high as 47mfd or so. Back in the 1920's and 30's electrolytics where expensive to make so most of the filtering is done with inductance. If you look at diagrams say of a Philco model 87 the filters are like 1 or 2mfd and two or three chokes. Very important to observe polarity and voltage rating. 450v for this one. Philco in the '30s some times would use a small paper cap across the filter choke a help resonate L/C to 60cy.
Have Fun & happy new year!
Terry

Terry,

I'm getting ready to replace PS cap on my Model 84B and I see a red, green, and black dot on the bottom of the cap. Do I assume correctly the red and green are the 4uf and 8uf (+) and the black is the common ground--the can itself appears to be isolated from the chassis clamp with a band of insulation material. I'm looking to install 47uf @ 450V on both sides.

Thanks.

[Radioroslyn]

That's what it looks like on the diagram.
Terry

[gary rabbitt]

HI,
I am working on the same set. That loose wire goes to nothing. It wraps around another wire, as a 'gimmick' capacitor. I will check, and get a photo where it wraps wround.

[gary rabbitt]

I have to disagree with Terry about that high of capacitance, I would not use 2x 47uf caps as a replacement. The first cap may be way too much for the 80 rectifier tube, or so I have heard on the other forum.The first cap is usually the one you need to get close to spec. The second cap is less critical. Personally, I would try to get caps closer to spec. Right now, I have temporarily installed 2 10uf/450 caps.

The can is isolated from the chassis, you are right. A floating ground or B-
The cap lead going to the 80 rectifier will be the 8uf cap, the remaining terminal is the 4uf. Make sure that your can remaons isolated after you restuff the can.
=================================================================================

From what I see, that loose wire' is your coupling to the center terminal on the volume control. Part #3 on your list.
Loosen and turn your volume control 180 deg. so the terminals are on the other side. Then wrap that loose wire 2 times around the wire going to the center terminal.
BUT, please verify that your "loose' wire is going to the coil terminal shown in the second photo. It sure looks like that's where you point it out to be.

[Image: http://antiqueradios.com/gallery/d/131995-2/gimmick.JPG]

[Image: http://antiqueradios.com/gallery/d/13199...mmick2.JPG]


I see some added caps to the blocks. I assume that you will rebuild your blocks for a neater appearance. They are not hard to do and there is documentation on what is inside them on your diagram. It took me about half an hour to do all four.
Done right, you don't need to contend with messy tar. Cut the fine wire leads on the lugs, the wires that come from within the block. Warming the block just enough to release the tar, then you push it out in one piece.
Chuck's site has a good tutorial on how to do them.
You don't need to unsolder the block. Remove the hold down bolt, then you can flip the block on it's side for warming. I use s small embossing heat gun, it has a 3/8" nozzle. You could use a blow dryer with a concentrator tip. Do not melt the tar, just get the block hot enough so it releases when you push it out.

[Image: http://antiqueradios.com/gallery/d/13200...+plugs.JPG]

Hope all this helps you or anyone else who stops by
Good luck.

[Kico]

I have to disagree with Terry about that high of capacitance, I would not use 2x 47uf caps as a replacement. The first cap may be way too much for the 80 rectifier tube, or so I have heard on the other forum.The first cap is usually the one you need to get close to spec. The second cap is less critical. Personally, I would try to get caps closer to spec. Right now, I have temporarily installed 2 10uf/450 caps.

The can is isolated from the chassis, you are right. A floating ground or B-
The cap lead going to the 80 rectifier will be the 8uf cap, the remaining terminal is the 4uf. Make sure that your can remaons isolated after you restuff the can.
=================================================================================

From what I see, that loose wire' is your coupling to the center terminal on the volume control. Part #3 on your list.
Loosen and turn your volume control 180 deg. so the terminals are on the other side. Then wrap that loose wire 2 times around the wire going to the center terminal.
BUT, please verify that your "loose' wire is going to the coil terminal shown in the second photo. It sure looks like that's where you point it out to be.

[Image: http://antiqueradios.com/gallery/d/131995-2/gimmick.JPG]

[Image: http://antiqueradios.com/gallery/d/13199...mmick2.JPG]


I see some added caps to the blocks. I assume that you will rebuild your blocks for a neater appearance. They are not hard to do and there is documentation on what is inside them on your diagram. It took me about half an hour to do all four.
Done right, you don't need to contend with messy tar. Cut the fine wire leads on the lugs, the wires that come from within the block. Warming the block just enough to release the tar, then you push it out in one piece.
Chuck's site has a good tutorial on how to do them.
You don't need to unsolder the block. Remove the hold down bolt, then you can flip the block on it's side for warming. I use s small embossing heat gun, it has a 3/8" nozzle. You could use a blow dryer with a concentrator tip. Do not melt the tar, just get the block hot enough so it releases when you push it out.

[Image: http://antiqueradios.com/gallery/d/13200...+plugs.JPG]

Hope all this helps you or anyone else who stops by
Good luck.

Hi Gary,

Seems we're working on the same beast!

Thanks for the information and the photos. I wrapped the "loose wire" around the middle tap wire to the vol pot as you suggested, and "yes", other end does connect to the correct post on the coil. BTW, I remember when rebuilding a 1959 Dynaco FM3 a few years back, it also had a short wire used as a "dummy capacitor"--guess certain things don't change.

I've installed new 40uf (smallest I had on hand) caps to replace the old can cap for a temporary test/fix. I'll order some smaller values for the permanent repair.

My latest puzzler...I can receive no stations with an antenna connected to the antenna terminal...however, if I connect the antenna wire to the front most protruding eyelet of the tuning capacitor (on the right side viewed from front), I get lots of stations and good volume--nothing on the other eyelet. In this arrangement however the volume pot is rendered inoperative...it has no effect on volume whatsoever. Pot tests good on my VOM reading 0-20,000 ohms and the on/off part of switch works fine also.

Any ideas??

Thanks.



I'm not the best diagnostic technician, but trying to learn...any ideas here?

[Radioroslyn]

Open winding on the antenna coil.
Measure the resistance from ground the the antenna post with the set unplugged and volume all the way up. Should show a low resistance like a few ohms. If it higher than that the small winding on the ant coil is open. Remove coil and rewind(easy). About 25t of 36G will work fine
Good luck
Terry

[Kico]

Open winding on the antenna coil.
Measure the resistance from ground the the antenna post with the set unplugged and volume all the way up. Should show a low resistance like a few ohms. If it higher than that the small winding on the ant coil is open. Remove coil and rewind(easy). About 25t of 36G will work fine
Good luck
Terry

Terry,

Do you mean from the actual antenna connection point to chassis ground? Did that and got a reading (about 20,000 ohms) i.e.---the volume pot.

[Radioroslyn]

Yup Coil is open.
Terry

[Kico]

Yup Coil is open.
Terry

Gee---I was hoping you wouldn't say that! The antenna coil is the middle one correct?