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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: Apr Mon 22, 2019 7:24 pm 
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Joined: Feb Tue 27, 2018 11:46 pm
Posts: 39
I'm back.

I tried an additional test of the output by using an 8 ohm to 500 ohm xformer to connect the output to an 8 ohm speaker. I'm assuming I would hear something if the radio is working - quiet as a mouse.

Next I have tried to find settings on the Simpson 555 tube tester in order to conduct some type of a test. There are no settings specified for 199s or 30s. So I decided to try twiddling knobs after reading the manual and looking at the schematic for the tester. I got it to put approximately 3.5VAC on the filament pins open circuit. However, when I plug the tube in, the voltage drops to a few mv. I find it hard to believe that there is something in the tube tester that causes that kind of a drop once current is flowing (of course, anything is possible). Maybe I have some switch in the wrong position (switching in a resistance) but I haven't discovered anything yet.

I have 7 199s and tried every one of them.

I have done numerous searches looking for 199 settings for the Simpson but haven't found anything.

Any ideas or comments?

Jim


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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: Apr Mon 22, 2019 11:10 pm 
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Location: Keystone Heights, FL, USA 32656
You said that you did all the continuity tests, good. I asked, did it pass all 26 tests? Testing at the terminal strip? If so, repeat the test at the battery cables instead of the terminal strip. If it passes all the tests it has to at least make noise when plugging in the speaker, a click or something.

Batteries hooked up according the the card inside the lid? A-, B- C+ batteries connected to terminal 1?
Jeff

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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: Apr Mon 22, 2019 11:28 pm 
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Tube test info:
http://radiorestorer.com/simpson555tubesup.pdf

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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: Apr Tue 23, 2019 12:47 am 
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Joined: Feb Tue 27, 2018 11:46 pm
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Jeff,

At first it failed 3 tests. This led me to the bad ground connection of terminal 1 to the frame and the open audio transformer winding.

It now passes all 26 tests.

I have since checked the voltages to be sure they are correct at the correct connections. At your request here I re-checked the A-, B-, C+ connection to ground at the frame.

Thanks for the tube info. I see that 99 is on that list.

Jim


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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: Apr Wed 24, 2019 8:34 pm 
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Joined: Feb Tue 27, 2018 11:46 pm
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OK, here is the latest.

Thanks to Jeff I got the correct settings for the tubes for the Simpson tester.

I tested my 7 199s and 2 120s. Here are the results (same for all tubes).

1. Filament continuity - Good

2. Inter element leakage - Good

3. Quality - Bad.

Does this indicate I should flash?

Jim


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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: Apr Wed 24, 2019 10:28 pm 
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Location: S. Dartmouth MA 02748-1225 USA
Flashing is a final step. there is a first step with less risk see: Nostalgia Air tube Rejuvenation. For data.

Do re-solder all the pins of the tube. Poor connections to the filament can cause reduced voltage. Heat sink the pins as heat will blister and loosen the pin in the Bakelite base.

First step:
Using an interposer, a tube base with a socket mounted so only the filament is connected, plate and grid are NOT connected, insert into test socket and set filament voltage for 4 to 4-1/2 volts and burn the tube for an hour. Then remove interposer and test. If the tube is acceptable then fine, if not return the interposer to the tube tester and follow the directions from Nostalgia Air. Under no conditions should the tube have the plate or filament connected during the rejuvenation process and do not attempt to test at an elevated filament voltage.

Why? because the temperature of the filament is so hot the thorium is boiling on the surface, testing or applying any voltage to the grid or plate will strip off the thorium. There may not be any thorium left in the filament to recover, the tube will be ruined...

A tube that has given long service will have filament etching, raising the voltage to boil more thorium to the surface may cause the filament to part. So, that is it for that tube... It was no good to begin with.

Note, excess plate current or operating the radio above 4 volts will slowly strip the thorium, that is why the bias and the filament voltage has to be correct.

There is a filament voltmeter accessory that plugs into the two pin jacks on the front panel it has a red line at FWIR 3 volts. The battery setting rheostat is used for that setting, the supply voltage is 4-1/2 volts, battery setting is used to follow the batteries down until the batteries are flat. The resistance of the battery rheostat and the volume rheostat also set up some of the bias. So setting the power supply to 3 volts is not a good idea. Excess plate current can flow :(

Also, there were tube rejeuvenators made, one of which is a Jefferson, flashes, ages and tests the tube all in one device. These do show up on eBay from time to time...

GL

Chas

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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: Apr Thu 25, 2019 8:20 pm 
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Random thoughts...

I would think that if it passes all of the RCA tests, it should play.
Power supply (batteries) hooked up according to the hook-up card?
Hard to believe that all 9 tubes, with good filaments, are all bad.
For testing, try 01A tubes in detector and both amp sockets, C- set to 4.5v. Touch detector grid with probe.

Jeff

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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: Apr Thu 25, 2019 9:34 pm 
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I could see where 99's may have very low emission. Filaments are small and Thorium may be depleted. Tube rejuvenation works but only until Thorium is no longer available.

How does your 120 tube test? A 120 usually holds up better than a 99.

Don't think 01A's will fit in a Radiola 20. Number 30 in place of 99 and 31 in place of 120 will work. These two types require 2 volts for filament.

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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: Apr Fri 26, 2019 4:18 pm 
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Here is what I was talking about. 0As, using 4.2v, 22v, and 45v; A-, B-, both C- tied together. Touch grid pin of detector, makes a nice noise, proving operation of this section of the radio.
Jeff
Attachment:
DSC03544.JPG
DSC03544.JPG [ 207.81 KiB | Viewed 343 times ]

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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: May Sun 12, 2019 12:26 am 
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I'm back! I have been ill for the past 3 weeks and didn't feel like doing much of anything; let alone troubleshooting a Radiola.

I have resorted to flashing all the tubes and re-testing them on the tube tester. None of them show up as good quality. I am doubting the tester is reliable for quality testing of these tube types.

I have a total of 8 199s and 2 120s.

I decided to put the tubes back in the radio anyway. Still no joy.

I have checked my power connections several times during this process.

I do not have access to 01A or 0A tubes.

I think I am going to basically start over to be sure I am not doing something stupid. I am going to put the audio transformers back the way they should be (the one that was replaced has only been wired in with clip leads during the testing). I am going to re-check all connections being careful that the power connections are correct.

I don't know what else to do other than performing some signal injection which wasn't successful before.

Thanks again for sticking with me.

Jim


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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: May Wed 15, 2019 8:30 pm 
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Location: Keystone Heights, FL, USA 32656
Had some spare time today.
Signal injection, using a signal generator, AF out, 400Hz.

1. Test 2nd AF tube plate to speaker jack.
-No power applied; remove 120 tube. Red probe in 2nd AF plate, black lead at either of speaker plug leads (try both). Should get a tone.
Attachment:
DSC03594.JPG
DSC03594.JPG [ 176.41 KiB | Viewed 268 times ]


2. Test 2nd AF tube operation.
-Hook up all power cables and turn on the radio.
-Slightly lift 120 tube and carefully apply audio (red lead) to the tube grid pin. Should get louder tone in speaker.
Attachment:
DSC03592.JPG
DSC03592.JPG [ 149.24 KiB | Viewed 268 times ]


3. Test 1st AF tube operation.
-Same as step 2 but place probe on grid pin of the 1st audio tube. Should get really loud tone in speaker.
Attachment:
DSC03593.JPG
DSC03593.JPG [ 141.13 KiB | Viewed 268 times ]

Attachment:
Radiola20_SG.jpg
Radiola20_SG.jpg [ 73 KiB | Viewed 268 times ]

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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: May Tue 28, 2019 3:38 pm 
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Joined: Feb Tue 27, 2018 11:46 pm
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Jeff,

I have been away from this for a few days and just caught your post. Thanks for the info but I think I may be confused about some things.

First - I have buttoned up the repaired windings and core into the audio transformer housing so that is all together. I performed the continuity checks to be sure I didn't break anything.

Second - I tested the Radiola 100 speaker for continuity as specified in the service manual for the speaker. Remember that I also popped the speaker with a 9V battery. So it appears to be good.

Now for the possible confusion. I tried your first test which didn't work. Doesn't the speaker need the 135 V applied in order to work? Which brings up the next question. If I connect the signal generator the way you show with power applied it will place over 100 V at the input to the generator which exceeds my generator's spec. Are the signals applied (and measured) referenced to the 135 V applied to the speaker and not to ground? I thought the speaker leads connect to the phone plug tip and sleeve which is confusing to me. I don't quite understand how the speaker completes the circuit.

I do not have high impedance headphones. I tried using an audio transformer to drop the high impedance to 8 ohms for another speaker and headphones with no success. I still wonder if I don't understand the proper connections.

Jim


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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: May Tue 28, 2019 4:40 pm 
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Location: Keystone Heights, FL, USA 32656
"Now for the possible confusion. I tried your first test which didn't work. Doesn't the speaker need the 135 V applied in order to work?" No, the generator should be able to operate the speaker all by itself. On mine I have to turn the AF gain up quite a bit to do that. Maybe you generator does not have enough output to run the speaker?
Try test 0.5.
--Generator set to AF output, red lead to tip of speaker plug, black lead to sleeve of speaker plug. Speaker should play tone.

"Which brings up the next question. If I connect the signal generator the way you show with power applied it will place over 100 V at the input to the generator which exceeds my generator's spec." You are correct. I for sure said no power applied for test 1. In my test 1 the battery cable is not connected to anything. In test 1 the red and black line shows where to attach the generator leads, speaker plugged in (have to uncover the wire connections at the plug to do this).

Maybe something easier...
What is the resistance of the speaker, measured tip to sleeve? ________
No power applied, plug in speaker to right hand socket. Measure resistance from 120 tube plate to B+ 135 wire. Should read same as above. ______

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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: May Tue 28, 2019 7:31 pm 
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OK - some improvement.

There is an intermittent in the speaker connection.

When it works, the connection directly across the speaker leads produces an output. Also, the injection of the signal at P5 also produces an output.

So, the speaker is good.

I tried your quick test suggestion of touching the grids and still get nothing.

Now, I get back to my comment regarding voltage on the generator. If power is applied, the voltage from G5 to P5 is 121 V. Therefore,that voltage is applied to the generator in your 2nd test. Am I right? How can you successfully apply that 2nd (and also 3rd) test without some form of isolation?

Jim


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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: May Tue 28, 2019 8:14 pm 
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Location: Keystone Heights, FL, USA 32656
In test 2 and 3 the black lead of the signal generator is connected to nothing. Voltage on the grid should be -22 or -4.5. not 121 (black meter lead hooked to radio A-/B-). I just put the audio right on the grid pin but I think you can use a .1 uf capacitor to isolate, if you want. There should be no high voltage on the grid.

When you say "...produces an output." do you mean a nice clear tone?
Jeff

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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: May Tue 28, 2019 8:39 pm 
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jrehkopf wrote:
In test 2 and 3 the black lead of the signal generator is connected to nothing. Voltage on the grid should be -22 or -4.5. not 121 (black meter lead hooked to radio A-/B-). I just put the audio right on the grid pin but I think you can use a .1 uf capacitor to isolate, if you want. There should be no high voltage on the grid. When you say "...produces an output." do you mean a nice clear tone? Jeff
James,
I know you in the middle of stage by stage testing...

But.

Did you notice the link to Nostalgia Air in regard to tube rejuvenation?

If your testing of the tubes shows them to be flat, then they must be rejuvenated or replaced with tubes of ample emission. It will not matter about signal injecting.

By expanding the rejuvenation topic at nostalgia Air there is a method to check the emission of the tube(s) by lighting the filament with the correct DC voltage and using a plate MA meter while adjusting the grid. The chart gives the current flow for a viable tube...

The Simpson tube tester may be able to accomplish rejuvenation by the use of some sort of "interposer". That is a 4-pin plug in combination with a 4-pin socket of which only the filament is connected with a possible tap for voltage monitoring. With no tubes in the tester checking the filament voltage for the various voltage settings will be a guide which settings to use. The load of a '99 is so small the measured voltage without a load is accurate enough to prevent over voltage during a rejuvenation sequence.

Many battery radio failures are from poor electromechanical joints as will as decompose solder joints.

Almost all technicians use a DVM for resistance measurement problem is moist DVM's do not pass a great deal of current through a joint, be it a mechanical one or soldered. Therefore, measuring continuity of joints will, for all but a joint nearly disconnected as good. An analog VOM of "old school" that is 5k/volt, may show some of these defective joints.

All the electrical connections in the radio are suspect, but those in the RF and tuning will create the most problems and obscure ones like the tuning condensers and coil connections.

Flexible jumper leads or springs in a tuning condenser their joints can be eroded. Some early tuning condensers were subject to corrosion between the plates and the bushings of their separate parts. FWIR the 20 has a pot metal hub(s) joining the rotor and stator plates.

Teasing the tube socket pins and burnishing the sockets is also helpful. Easy way to burnish the socket: Take any 4-pin dud tube or tube base, sand with very coarse sandpaper, the four pins very thoroughly such that the pins are very rough. Inset the sanded base/tube into the socket some 25-50 times. The roughness of the pins will burnish the contacts in the socket without leaving any grit behind... Teasing the contact with pliers will be helpful too.

Many 4-pin tubes will light and test bad but not be emission but poor solder joints to the pins. Re-soldering the pins on the tubes is helpful. Be sure to heatsink the pin as the Bakelite WILL blister from the heat and the pin get loose. Do re-solder before rejuvenation.

YMMV

Chas

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Last edited by Chas on May Tue 28, 2019 9:28 pm, edited 1 time in total.

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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: May Tue 28, 2019 9:20 pm 
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Jeff,

Regarding the 121 V I was referring to the voltage from the speaker lead to the grid which would be the voltage applied to the generator if the negative lead was connected to the speaker and the positive to the grid.

Yes, I do hear a nice clear tone.


Chas,

I flashed the tubes (see my May 11 posting).


'Im wondering if the tube sockets are corroded. I noticed the filament connection of one of the tubes can be broken by moving it around.

Jim


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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: May Tue 28, 2019 9:38 pm 
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wa4ywm wrote:
...Chas,
I flashed the tubes (see my May 11 posting).
I'm wondering if the tube sockets are corroded. I noticed the filament connection of one of the tubes can be broken by moving it around.
Jim
See my post dealing with dirty socket contacts.

What was the flashing voltage or did you use the preliminary burning of the tube(S) at 4-1/2 volts?

This is important, if the flashing was done at 4-1/2 volts there is a need to go higher and up to the limit in the NA chart for the 99 and adhering to the time of the flash...

Again, be sure no connections to the grid and plate, NONE!

If you have flashed and aged up to the limit of the NA chart then that is as far as one can go without risking parting the filament.

It IS possible for the setting of the Simpson to be incorrect.

If you suspect that, refer to the NA article and make the emission test following the schematic offered by NA..

YMMV

Chas

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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: May Tue 28, 2019 11:16 pm 
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Chas,

I did perform the preliminary burning of the tubes and then flashed them according to the article.

I will try the socket procedures you mentioned.

Jim


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 Post subject: Re: Radiola 20 troubleshooting
PostPosted: May Tue 28, 2019 11:32 pm 
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Jim, are you saying that you have 121 volts on the grid with the speaker plugged in? How are you measuring that?

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