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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: Jul Wed 03, 2019 8:58 pm 
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Joined: Feb Tue 27, 2018 11:46 pm
Posts: 41
Jeff,

424 ohms

Jim


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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: Jul Thu 04, 2019 4:26 pm 
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Joined: May Sat 30, 2015 11:49 pm
Posts: 1315
Location: Keystone Heights, FL, USA 32656
Darn,
424 ohms, good reading primary of 2nd audio transformer OK.
90v at P5, OK.
Can you CAREFULLY, with the tube not all the way in, reach under and measure the pin voltages with the set ON, black meter lead at terminal 1, red lead on each of the #5 tube pins? Maybe with a thin piece of wire.

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


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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: Jul Thu 04, 2019 8:30 pm 
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Joined: Feb Tue 27, 2018 11:46 pm
Posts: 41
The filament is 3.3V.
The plate is 90V.
The grid is -4.6V.

Jim


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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: Jul Fri 05, 2019 12:07 am 
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Joined: May Sat 30, 2015 11:49 pm
Posts: 1315
Location: Keystone Heights, FL, USA 32656
Sorry to be a pain but I asked for specific measurements. Black lead on terminal 1 and red lead to each of the tube pins, 4 measurements.

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


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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: Jul Fri 05, 2019 12:58 am 
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Joined: Feb Tue 27, 2018 11:46 pm
Posts: 41
The other side of the filament is ground - it actually measures 15 mV.

Jim


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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: Jul Fri 05, 2019 4:35 pm 
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Joined: May Sat 30, 2015 11:49 pm
Posts: 1315
Location: Keystone Heights, FL, USA 32656
Yes, the other side of the filament is connected to ground, but it also is A- and the return path for B-. A bad wire would keep the tube from conducting B voltage. Your reading of 15 mV tells us that the wire is conducting A voltage, current is flowing, and that the wire has no excessive resistance; in simple terms, the measurement proves that the circuit is OK.
I see nothing wrong with any of those readings. You should have heard clicking or scratching when you measured the grid voltage.
I am at a loss as to why the 2nd audio does not work, all the recent measurements tell me it should work.

I would leave the 2nd audio for now and see if the radio will pick up and play stations through the headphone jack. Strong stations should drive the speaker at a low level; this is one way they controlled volume on these old radios. On my 20s I hear nothing until the battery volts is above 3.1 and the right-most rheostat almost all the way up. Amplification set at about 7, tune the station selector very slowly.

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


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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: Jul Sat 06, 2019 5:43 pm 
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Joined: May Sat 30, 2015 11:49 pm
Posts: 1315
Location: Keystone Heights, FL, USA 32656
Just for reference, here is my model 20, all 199 tubes, running on batteries, showing the cable connections.
Attachment:
Radiola20BatteryHookup.jpg
Radiola20BatteryHookup.jpg [ 318.72 KiB | Viewed 1038 times ]

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


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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: Jul Sun 07, 2019 8:55 pm 
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Joined: Feb Tue 27, 2018 11:46 pm
Posts: 41
SUCCESS!!!

As I suspected, the solution is somewhat obscure and simple (easy to say after all the searching).

First, am I to assume that the plugs for the speaker and headphone are different lengths?

I just tried using a modern plug since that is the only thing I haven't replaced. I noticed immediately that the modern plug is shorter than the original plug that I have been using. Upon examining the modern plug in the speaker jack and comparing it with the original plug I saw that the original plug tip is contacting nothing - it protrudes too far in. The modern plug tip, however, contacts the spring clip which connects directly to the plate of tube #5.

I now have sound. I tested it using the generator. Then I tuned in a local station.

We were fooled during the testing by the fact that the spring clip contacting the sleeve of the original plug provided 90V to the plate and provided a path through the speaker that indicated continuity. What I never checked for was a direct connection from the plate to the actual tip of the plug - which was open.

What an exercise this has been! The plus side of all this is how much I have learned about TRF receivers, regeneration and grid leak detection not to mention the old tube knowledge including regeneration of tubes.

Many thanks Jeff and Chas for all your help and patience as we eliminated so many areas of this radio. BTW the other problems all came down to open windings in each of the audio transformers and an open ground from terminal 1 to the frame.

I wish you guys lived close - we could go out and have a nice dinner on me.

Jim


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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: Jul Mon 08, 2019 12:02 am 
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Joined: May Sat 30, 2015 11:49 pm
Posts: 1315
Location: Keystone Heights, FL, USA 32656
Well, blow me down! Great news!!!
You owe us some pictures of the radio and the offending plug.
I’ll pass on the dinner, more fun would be a cookout while we listened to the radio.

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


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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: Jul Mon 08, 2019 5:36 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 14708
Location: S. Dartmouth MA 02748-1225 USA
Congrats!

Another ARF member had similar issues all over his Deforest MR-5, lastly, it was the plugs he was using.

Some jack frames were adjustable with sets of spacer washers for different thickness panels.

The RCA series of 20's radios used a Bakelite bushing that tightened with a hex key. If there are spacers they are on the back side of the panel.

There were a series of W-E telephone plugs that are shorter... I have a few in the 1/4 plug box...

You passed the test of fire. Graduated and can now fix any battery radio with nothing at all :lol:

Chas

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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: Jul Tue 09, 2019 9:55 pm 
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Joined: Feb Tue 27, 2018 11:46 pm
Posts: 41
Jeff,

I have attached the photos of the 2 different plugs.

1350 shows the size difference.

1351 shows the original inserted.

1352 shows the modern one inserted.

Chas,

I don't see any way to add spacers. I think perhaps you just need to insert it based on feel.

Jim


Attachments:
IMG_1350 small.jpg
IMG_1350 small.jpg [ 142.19 KiB | Viewed 990 times ]
IMG_1351 small.jpg
IMG_1351 small.jpg [ 123.88 KiB | Viewed 990 times ]
IMG_1352 small.jpg
IMG_1352 small.jpg [ 126.48 KiB | Viewed 990 times ]
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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: Jul Tue 09, 2019 11:15 pm 
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Joined: May Sat 30, 2015 11:49 pm
Posts: 1315
Location: Keystone Heights, FL, USA 32656
The one on the right is missing it’s bakelite housing that would have prevented it from going in too far.

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


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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: Jul Wed 10, 2019 3:22 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 14708
Location: S. Dartmouth MA 02748-1225 USA
Attachment:
Three_styles_phone_plugs_MVC-423F.JPG
Three_styles_phone_plugs_MVC-423F.JPG [ 168.99 KiB | Viewed 984 times ]
The plugs shown are typical 1920'ish. There are as many variations of phone plugs as there are radio manufacturers. Even RCA had one molded, but very hard to find, it is part of the Radiola II and lives with the headphone inside the cover...

Washers, would go on the jack. If the panel is to thick/thin washers are removed or added to the inside of the radio in between the panel and the jack. There is no reason to believe that there is a problem with the jack at this point, it is the off-standard plugs...

Note the plugs I have shown have channels and a large binder head screw. The headphone tips go under the screw, the long braided tail of the cord is tied to the hole so there is no strain of the delicate headphone tinsel cord...

I will have to add jacks AND plugs to the laundry list for a 20's restoration :roll:

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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: Jul Wed 10, 2019 5:26 pm 
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Joined: May Sat 30, 2015 11:49 pm
Posts: 1315
Location: Keystone Heights, FL, USA 32656
Your speaker plug is supposed to look like this.
Attachment:
DSC03742.JPG
DSC03742.JPG [ 295.17 KiB | Viewed 971 times ]

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


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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: Jul Mon 15, 2019 7:40 am 
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Joined: Jul Tue 15, 2008 6:13 pm
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Location: Gretna, Nebraska
Given all the uncertainty with 20's era jacks, cabling, connections and accessories , it just reinforces previous discussions here.
Namely, an ohmmeter/voltmeter is your best tool for troubleshooting, and you really can't assume anything without verifying electrical continuity all the way to the end device in the circuit.

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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: Jul Mon 15, 2019 3:36 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 592
Location: Bristol TN 37620
Agree with processhead.


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