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 Post subject: Help with a Freed Eisemann NR-5
PostPosted: Sep Tue 14, 2021 5:49 am 
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Joined: Jun Tue 23, 2015 4:37 am
Posts: 997
Location: SE Iowa 52626
Someday I am going to answer some questions rather than ask them but unfortunately I am still in the "asking stage". I have this Freed Eisemann NR-5 radio that is in such great shape that it actually looks new, not even a scratch on the face. Everything appears to original and it all checks to specifications or within 10%. As far as picking up stations it is one of the best, if not the best, battery radios that I have. The detector jack and the 1st audio jack work just great but the 2nd audio jack is the problem. It just squeals no matter where the tuning is at unless I turn the amplifier and detector controls down to around 20 and then there is silence.

It is the version that does not use the "C" voltage but I do have a schematic for what appears my radio except for one thing. I have attached a schematic image with C9 circled in red. Although I don't think that is my problem my radio does not have the C9 and related wire. Again, everything works great and appears to be in spec except for my 2nd audio jack.

Any suggestions would be appreciated.

Don


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nr5.jpg
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 Post subject: Re: Help with a Freed Eisemann NR-5
PostPosted: Sep Tue 14, 2021 1:22 pm 
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Joined: Nov Tue 14, 2017 5:09 am
Posts: 4298
Location: Austin, Texas
C9 would be important in preventing the problem you describe. After the detector, there should be only audio signals going to the amplifier stages. Some RF will get through the detector stage and C9 is there to stop that RF from going to the next stage. Without C9, the RF gets amplified and gets on the headphone or speaker wire. From there it can couple back to the antenna and make the radio into an oscillator.

Edit: C10 would also help in bypassing RF. Check that C10 is OK.

Jay


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 Post subject: Re: Help with a Freed Eisemann NR-5
PostPosted: Sep Tue 14, 2021 3:13 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 1293
Location: Bristol TN 37620
Don,

Assuming your 2nd audio is ok, I'd concentrate in the
2nd audio stage. C10 should be a small mica cap. These
rarely go bad, but its possible. I'd look for a broken or
loose connection from the grid to A-.

From the condition you describe, it would seem (to me)
that the grid of the 2nd audio is not connecting to the A-

The schematic was published way after the first sets were
produced. The first sets weren't set up for C volts. I'd
go with what is in your set, and ignore the schematic, as to
parts or features your set doesn't have. Also check the
wiring to the jack for loose, broken or bad connections.


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 Post subject: Re: Help with a Freed Eisemann NR-5
PostPosted: Sep Wed 15, 2021 1:56 am 
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Joined: Jun Tue 23, 2015 4:37 am
Posts: 997
Location: SE Iowa 52626
brnhornet52 wrote:
Don,

Assuming your 2nd audio is ok, I'd concentrate in the 2nd audio stage. C10 should be a small mica cap. These rarely go bad, but its possible. I'd look for a broken or loose connection from the grid to A-.

From the condition you describe, it would seem (to me) that the grid of the 2nd audio is not connecting to the A-


Okay, following is probably more than you wanted or needed to know:

As far as the 2nd audio transformer goes the secondary shows 4.98k resistance all the time. The primary shows resistance as follows:
- 173 ohms with jack in 1st audio and radio turned on.
- 5.3 ohms with jack in 1st audio and radio turned off.
- 1.3k ohms with no jack in 1st audio and radio turned off which is the same as the 1st audio transformer.
- 0.0 ohms with no jack in 1st audio and radio turned on.

Between the grid of the 2nd AF tube and A- is 5.0k ohms which would be the secondary of the 2nd transformer.
C10 shows 1,850 pF when out of circuit so it appears okay.
For the heck of it I did try jumping in a capacitor at C9 but no joy.
It seems like the radio takes a long time to come on...around three minutes.
All the tubes test good but I should try switching them around.

If you want to hear the noise that the radio is making I make a youtube which you can find at https://www.youtube.com/watch?v=33_nyaSj6Fo for your listening pleasure. :D

What's next?

Don


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 Post subject: Re: Help with a Freed Eisemann NR-5
PostPosted: Sep Wed 15, 2021 2:15 am 
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User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 17242
Location: S. Dartmouth MA 02748-1225 USA
The second audio jack is the maximum amplification from the last audio tube. The chirping sound can be caused by many things.

The easy:

Swap the last audio tube with another tube...

Clean the contacts of last audio tube socket.

Solder or loosen re-tighten the connections to:

The last audio tube socket, check the resistance of the 2nd audio transformer. You are looking for an open primary or secondary. Be sure all the jacks are unplugged at the time of checking and that the power is off.

Be sure if the radio provides for "C" voltage, that "C" is connected, if not join, the C- and C+ connections at the radio and do not connect any "C" from the power supply...

It is possible the 1st audio jack is mal-functioning and not connecting the plate circuit of the 1st audio tube when the plug is removed from the first audio jack, check solder joints or bad jack contacts.

Worst case the 2nd audio transformer has an open winding.

Do use your analog meter to measure the resistance of the audio transformers.

Freed used (re-labeled) AmerTran transformers, the same brand also re-labeled DeForest.

These transformers do not stand up well and often go open but originals can be found, in any of the other brands. If you would like to keep the transformer authentic looking change the strap around the laminations to the "Freed" strap...

GL

Chas

_________________
List' & I will Enchant Thine Ear


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 Post subject: Re: Help with a Freed Eisemann NR-5
PostPosted: Sep Wed 15, 2021 2:49 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 1293
Location: Bristol TN 37620
I'd follow Chas's recommendations first, so as not to
cause confusion. When you do resistance checks, the
set must be off. Having the power on will distort your
readings.

Did this set just start doing this, or are you repairing it now?
(first time)

Another observation - A 3 minute warm-up? Battery sets
usually play when turned on. You just might have a bad
Intermittent or shorted tube. (the easiest fix)

See what you come back with and we'll go from there.


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 Post subject: Re: Help with a Freed Eisemann NR-5
PostPosted: Sep Wed 15, 2021 4:52 am 
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Joined: Jun Tue 23, 2015 4:37 am
Posts: 997
Location: SE Iowa 52626
Chas wrote:
The second audio jack is the maximum amplification from the last audio tube. The chirping sound can be caused by many things.

The easy:

Swap the last audio tube with another tube...
Done, no change

Clean the contacts of last audio tube socket.
Done, no change

Solder or loosen re-tighten the connections to:
All done, no change. Transformer is good.

The last audio tube socket, check the resistance of the 2nd audio transformer. You are looking for an open primary or secondary. Be sure all the jacks are unplugged at the time of checking and that the power is off.
4.98k and 1.13k

Be sure if the radio provides for "C" voltage, that "C" is connected, if not join, the C- and C+ connections at the radio and do not connect any "C" from the power supply...
No "C" connections

It is possible the 1st audio jack is mal-functioning and not connecting the plate circuit of the 1st audio tube when the plug is removed from the first audio jack, check solder joints or bad jack contacts.
The second audio tube has filament and plate voltages ONLY when a jack is plugged into the second audio jack.

Worst case the 2nd audio transformer has an open winding.
That transformer is fine.

Do use your analog meter to measure the resistance of the audio transformers.
I did.

Freed used (re-labeled) AmerTran transformers, the same brand also re-labeled DeForest.
The transformers are "Thordarson Amplifying Transform" 3.5 to 1 and both are the same.

These transformers do not stand up well and often go open but originals can be found, in any of the other brands. If you would like to keep the transformer authentic looking change the strap around the laminations to the "Freed" strap...

GL

Chas


Thanks for all the suggestions.

Don


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 Post subject: Re: Help with a Freed Eisemann NR-5
PostPosted: Sep Wed 15, 2021 5:00 am 
Member

Joined: Jun Tue 23, 2015 4:37 am
Posts: 997
Location: SE Iowa 52626
brnhornet52 wrote:
I'd follow Chas's recommendations first, so as not to
cause confusion. When you do resistance checks, the
set must be off. Having the power on will distort your
readings.

Did this set just start doing this, or are you repairing it now?
(first time)

Another observation - A 3 minute warm-up? Battery sets
usually play when turned on. You just might have a bad
Intermittent or shorted tube. (the easiest fix)

See what you come back with and we'll go from there.


I tried all of Chas suggestions but unfortunately none of them helped.

I just go into it for the first time and it was doing it.

I think that I found the warm up time problem. My clip to the antenna was not making contact. Once I touched the clip it started immediately...I should have noticed this before.

Could this problem have something to do with that neutralizing business that I have read about?

Don


Don


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 Post subject: Re: Help with a Freed Eisemann NR-5
PostPosted: Sep Wed 15, 2021 3:04 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 1293
Location: Bristol TN 37620
Don't think so - think its in the audio section. You're saying
the audios are good, right? Continuity on both sides of the audio
(Primary - B+ to P) (Secondary - G to F-) right?

Now check out the circuitry. No tubes in, no jacks used,
no power. Plug a jack into 1st audio, and see if you have
continuity from B+45 to the plate on the detector tube.
(You have the tube layout - right?). Then check Grid of
1st audio to A- terminal. If you're Ok, so far, we'll move on.

Move the plug to 2nd audio. Now check continuity from
B+90 to plate of 1st audio, and Grid of 2nd audio tube to
A-. If this is OK, check plate of 2nd audio to B+90 when the
jack is in 2nd audio.

Freed Eisemann used a complicated jack switching arrangement to prevent battery drain by switching the
Filaments on and off depending on which jack was
selected. Example - If you plug into Detector, only 3 tubes
light up - the 2 RF tubes and the detector. If you use 1st
Audio, 4 tubes light up. The jacks also tend to control
the volume on strong stations. In most cases the 2nd
Audio isn't used on powerful stations. If you use headphones, you usually just use Detector stage.

Let's see what you find.


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 Post subject: Re: Help with a Freed Eisemann NR-5
PostPosted: Sep Wed 15, 2021 4:41 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 1293
Location: Bristol TN 37620
In looking at your video, there is almost no amplification
In the 2nd audio stage but the whistle. I strongly suggest
either your 2nd audio is open or you have bad connections
to it.


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 Post subject: Re: Help with a Freed Eisemann NR-5
PostPosted: Sep Wed 15, 2021 5:29 pm 
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User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 17242
Location: S. Dartmouth MA 02748-1225 USA
I'll say now, NOT neutralizing, that is unless the neutralizers have been recently moved...

Reason is they are in the RF section, the reception is good with just the detector or 1st AF.

So the AF tubes have been eliminated as a cause

I'll ask?

What is the resistance of the primary and the secondary of the 2nd AF transformer?

I would have to look at my NR-5 to tell if that is the left one or right, as the transformers are at each end of the chassis. The first AF should be the one close to the detector and the detector jack, so the other must be the 2nd AF transformer...

There HAS to be either a bad transformer, bad jack or bad connections in that area... Oh if the radio calls for "C" battery, use it or short it...

Chas

_________________
List' & I will Enchant Thine Ear


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 Post subject: Re: Help with a Freed Eisemann NR-5
PostPosted: Sep Wed 15, 2021 6:28 pm 
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Joined: May Sat 30, 2015 11:49 pm
Posts: 2135
Location: Keystone Heights, FL, USA 32656
Don, if the radio is out of the cabinet, can you tell me how may wires are connected to each jack?

I think the 2nd audio transformer is on the left.

_________________
Jeff
“Nothin’s worth nothin ‘till somebody wants it.”—Irv Metter


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 Post subject: Re: Help with a Freed Eisemann NR-5
PostPosted: Sep Wed 15, 2021 11:41 pm 
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Joined: Jun Tue 23, 2015 4:37 am
Posts: 997
Location: SE Iowa 52626
brnhornet52 wrote:
Don't think so - think its in the audio section. You're saying
the audios are good, right? Continuity on both sides of the audio
(Primary - B+ to P) (Secondary - G to F-) right?

Now check out the circuitry. No tubes in, no jacks used,
no power. Plug a jack into 1st audio, and see if you have
continuity from B+45 to the plate on the detector tube.
(You have the tube layout - right?). Then check Grid of
1st audio to A- terminal. If you're Ok, so far, we'll move on.

Move the plug to 2nd audio. Now check continuity from
B+90 to plate of 1st audio, and Grid of 2nd audio tube to
A-. If this is OK, check plate of 2nd audio to B+90 when the
jack is in 2nd audio.

Freed Eisemann used a complicated jack switching arrangement to prevent battery drain by switching the
Filaments on and off depending on which jack was
selected. Example - If you plug into Detector, only 3 tubes
light up - the 2 RF tubes and the detector. If you use 1st
Audio, 4 tubes light up. The jacks also tend to control
the volume on strong stations. In most cases the 2nd
Audio isn't used on powerful stations. If you use headphones, you usually just use Detector stage.

Let's see what you find.


I had an eye appointment this morning but with dilated eyes this is what I found.

You are correct, I do have continuity on both sides of the audio transformer.
B to P = 1.12 k ohms
G to F = 4.92k ohms

The following is with no tubes or power:
B+45 to detector tube plate with jack in 1st audio = 1.15k ohms.
A- to grid on 1st audio tube with jack in 1st audio = 5.03k ohms.

B+90 to plate on 1st audio tube = 1.12k ohms
A- to grid of 2nd audio tube = 4.93k ohms
B+90 to plate of 2nd audio tube with jack in 2nd audio = open

I have a feeling the problem is in one of the jack receptors, probably the 2nd audio.

Don


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 Post subject: Re: Help with a Freed Eisemann NR-5
PostPosted: Sep Wed 15, 2021 11:44 pm 
Member

Joined: Jun Tue 23, 2015 4:37 am
Posts: 997
Location: SE Iowa 52626
Chas wrote:
I'll say now, NOT neutralizing, that is unless the neutralizers have been recently moved...
Reason is they are in the RF section, the reception is good with just the detector or 1st AF.
So the AF tubes have been eliminated as a cause
I'll ask?

What is the resistance of the primary and the secondary of the 2nd AF transformer?

I would have to look at my NR-5 to tell if that is the left one or right, as the transformers are at each end of the chassis. The first AF should be the one close to the detector and the detector jack, so the other must be the 2nd AF transformer...

There HAS to be either a bad transformer, bad jack or bad connections in that area... Oh if the radio calls for "C" battery, use it or short it...

Chas


The primary of the 2nd audio transformer is 1.12K and the secondary is 4.92k.
BTW, the 2nd audio transformer is on the left side looking from the front.

Don


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 Post subject: Re: Help with a Freed Eisemann NR-5
PostPosted: Sep Wed 15, 2021 11:47 pm 
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Joined: Jun Tue 23, 2015 4:37 am
Posts: 997
Location: SE Iowa 52626
jrehkopf wrote:
Don, if the radio is out of the cabinet, can you tell me how may wires are connected to each jack?

I think the 2nd audio transformer is on the left.


Detector jack has 6 wires.
1st Audio has 4 but 2 are common on the jack.
2nd Audio has 4 wires. I THINK this might be where the problem is.

Don


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 Post subject: Re: Help with a Freed Eisemann NR-5
PostPosted: Sep Thu 16, 2021 12:13 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 1293
Location: Bristol TN 37620
Don,

Think you found the problem. 2nd audio is not getting
Plate voltage. With the plug in 2nd audio, you should
have 90 volts.

Clip your test leads to the B+90 terminal and plate on the
2nd audio tube. Set to ohms. Wiggle the wires from the
2nd audio jack, and see if any are loose or broken.
Resolder the wires to the jack if nothing is loose.
Might just be a bad connection.

Another test you could do is run a test lead from the
B+90 to the plate terminal on 2nd audio tube socket and bypass the jack for plate
voltage. The set should work now with eliminator
connected, tubes in, plug on 2nd audio and set on.
Antenna and ground connected.


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 Post subject: Re: Help with a Freed Eisemann NR-5
PostPosted: Sep Thu 16, 2021 12:54 am 
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Joined: Jun Tue 23, 2015 4:37 am
Posts: 997
Location: SE Iowa 52626
brnhornet52 wrote:
Don,

Think you found the problem. 2nd audio is not getting
Plate voltage. With the plug in 2nd audio, you should
have 90 volts.

Clip your test leads to the B+90 terminal and plate on the
2nd audio tube. Set to ohms. Wiggle the wires from the
2nd audio jack, and see if any are loose or broken.
Resolder the wires to the jack if nothing is loose.
Might just be a bad connection.

Another test you could do is run a test lead from the
B+90 to the plate terminal on 2nd audio tube socket and bypass the jack for plate
voltage. The set should work now with eliminator
connected, tubes in, plug on 2nd audio and set on.
Antenna and ground connected.


I am not out to the shop now but just may get out there later. When the plug is about 3/4 the way in I do have continuity from 90V to the plate but when it goes on in it cuts it off. If I measure the resistance with a speaker connected to the jack and the jack all the way in I get the resistance of the speaker which is approximately 750k.

I will let you know.

Don


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 Post subject: Re: Help with a Freed Eisemann NR-5
PostPosted: Sep Thu 16, 2021 12:57 am 
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Posts: 17242
Location: S. Dartmouth MA 02748-1225 USA
Quote:
speaker which is approximately 750k.
That does not sound right for the speaker.

More like 750 DC ohms

_________________
List' & I will Enchant Thine Ear


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 Post subject: Re: Help with a Freed Eisemann NR-5
PostPosted: Sep Thu 16, 2021 2:26 am 
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Joined: Jun Tue 23, 2015 4:37 am
Posts: 997
Location: SE Iowa 52626
brnhornet52 wrote:
Don,

Think you found the problem. 2nd audio is not getting
Plate voltage. With the plug in 2nd audio, you should
have 90 volts.

Clip your test leads to the B+90 terminal and plate on the
2nd audio tube. Set to ohms. Wiggle the wires from the
2nd audio jack, and see if any are loose or broken.
Resolder the wires to the jack if nothing is loose.
Might just be a bad connection.

Another test you could do is run a test lead from the
B+90 to the plate terminal on 2nd audio tube socket and bypass the jack for plate
voltage. The set should work now with eliminator
connected, tubes in, plug on 2nd audio and set on.
Antenna and ground connected.


Okay, got back out to the shop for a few minutes but no joy. I do believe that the 90 volts from the 2nd audio jack goes out to the speaker and then back to the plate. This would be why I was showing the resistance of the speaker.

If I jump 90V over to the plate when everything is up and running (jack in 2nd audio) it totally shuts off all sound. Again, it appears that the 90 volts from the jack goes to the speaker and then back to the plate. If I have a speaker connected and no tube in I do have 90 volts between the plate and B-. If I put the tube in and measure between the plate and B- I only have about 81 volts....guess the tube is eating up some voltage.

I need to look at the various schematics and see exactly how the voltage gets to the 2nd audio plate. I have a ton to do yet tonight and will be gone most of tomorrow so I am not sure when I will get time to study the schematics.

Don


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 Post subject: Re: Help with a Freed Eisemann NR-5
PostPosted: Sep Thu 16, 2021 2:27 am 
Member

Joined: Jun Tue 23, 2015 4:37 am
Posts: 997
Location: SE Iowa 52626
Chas wrote:
Quote:
speaker which is approximately 750k.
That does not sound right for the speaker.

More like 750 DC ohms


You are correct, don't know how or why I got that "k" in there.

Don


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