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 Post subject: Re: Radiola Grande Restoration
PostPosted: Mar Thu 26, 2020 4:48 pm 
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The schematic says 1 mf. Yes, it should read OL on ohms, leaking for sure.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Mar Thu 26, 2020 4:57 pm 
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Thanks Jeff, I wasn't sure what that meant in regards to the condenser, now that you pointed it out it seems obvious. I'll sit in the corner for awhile with the dunce cap on. :lol: I'll put in a new cap for now and after I get it working I'll open up the black box and put the cap in there.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Mar Thu 26, 2020 5:11 pm 
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I missed it, too to begin with.

Make sure you get the polarity of the dunce cap correct.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Mar Thu 26, 2020 10:35 pm 
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LOL!

There are two caps connected to the output transformer. One checks .02uf and the other .05uf. The resistance starts at around 10m ohms and slowly climbs. After several minutes it climbed to 26m ohms and continued to climb. Seems like they should go open much faster than that. Time to sub in a couple of new caps?

By the way, I subbed two .47uf caps wired in parallel for the 1uf black box cap with the positive ends wired to the post where the +90v comes in.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Mar Thu 26, 2020 11:03 pm 
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I think in that location 10M ohm is virtually OL. I think those are OK. Check with your analog meter, if you have one. I never did that, so don’t know what to expect.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Mar Fri 27, 2020 6:13 pm 
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My Simpson doesn't go near that high in checking ohms.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Mar Fri 27, 2020 10:56 pm 
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I am guessing that you are using adapters with those tubes. I had some WD11 adapters that were assembled with rivets to the cross connections, completely open circuit until I reset the rivets with a punch and hammer, one on plate circuit and one on grid circuit. Tubes lit up just fine and tested fine, would not work in the radio (radiola III).

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Mar Sat 28, 2020 1:38 am 
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I'll double check them Jeff, thanks for the reminder on that.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Mar Sat 28, 2020 2:07 am 
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Best WD-11 adapter to UX are ones hand made from the large Bakelite based broken WD-11. Use a round ring mount socket and some #14 to #16 solid insulated wire. The wire has to crossover so insulation is required. After shaping the wire, strip and slide into the WD-11 tube base, pull the socket flush and solder the pins. No glue required the socket O.D should wedge tightly into the tube base...

May not work on some radios that have low clearance to the cover...

Trick is finding broken tubes, some will re-use the base inserting a WD-12 and call it an '11...

Chas

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Mar Sat 28, 2020 3:53 am 
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Thanks for the tip Chas.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Mar Sun 29, 2020 12:06 am 
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Replaced the 864 tubes and adapters with bakelite WD-11 tubes. I hear a wind like noise coming through the headphones and I think I'm hearing something underneath the sound but I can't be sure. I was also thinking about the antenna terminals, longwave and shortwave no medium wave, I'm hooked up to the shortwave.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Apr Wed 01, 2020 9:45 pm 
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Disconnected the "C" power and now I can hear one station through the headset, very weak volume, but its something. Wondering if this might be a clue to the problem.

Grid-leak resistor is much larger physically than any other 20's radio I've worked on, I wonder why? Checks 3.6M ohms.

Disconnecting the 45v B voltage while powered up made no difference in what I was hearing in the headphones. :?

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Apr Wed 01, 2020 11:02 pm 
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If disconnecting the C did you then connect the 2 C wires together? Needs that to complete the grid circuits.

Faint station with the detector plate no voltage? Don’t have a clue how that could be.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Apr Thu 02, 2020 12:29 am 
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atwaterkent1 wrote:
Disconnected the "C" power and now I can hear one station through the headset, very weak volume, but its something. Wondering if this might be a clue to the problem.

Grid-leak resistor is much larger physically than any other 20's radio I've worked on, I wonder why? Checks 3.6M ohms.

Disconnecting the 45v B voltage while powered up made no difference in what I was hearing in the headphones. :?
Detector is not working. From B- with the set powered is there plate voltage on the detector? If not then there is a poor connection.

Best to remove solder and re-solder the pins of those WD-12's. Still no B+? Bad connection, open tickler, open audio transformer, bad connection, the detector jack, bad tube socket...

Chas

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Apr Thu 02, 2020 12:39 am 
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I'll run through your checklist Chas and see what I find.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Apr Thu 02, 2020 12:47 am 
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jrehkopf wrote:
If disconnecting the C did you then connect the 2 C wires together? Needs that to complete the grid circuits.

Faint station with the detector plate no voltage? Don’t have a clue how that could be.


Jeff - connecting the C leads knocked out the signal. You are correct, according to the print they do need to be connected.

(My radios are not old and boney, they're mature!) :lol:

Chas - 43v going into post 2 on the output transformer. There's .0011v at the plate pin on the detector tube. What voltage should I be getting at the plate pin? I tried all four WD-11 tubes, 2 at a time, in a Radiola III I have set up and they worked fine. Tube sockets for Radiola III and Radiola Grande contact the sides of the pins, not the ends. Do you still think it would help to resolder the ends of the pins? Be glad to do so if you still think it could be the problem.


While running through the circuits visually I noticed there doesn't seem to be a grid leak condenser! I assumed it was on the other side of the mounting board behind the grid leak resistor, but when I dropped down one end of the mounting board there was no condenser on the backside. The grid-leak resistor is wired to the detector tube grid and the condensers at the antenna connection post as shown in the drawing, but no condenser. :shock:

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Last edited by atwaterkent1 on Apr Sat 11, 2020 12:43 am, edited 1 time in total.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Apr Thu 02, 2020 2:00 am 
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Quote:
Chas - 43v going into post 2 on the output transformer. There's .0011v at the plate pin on the detector tube. What voltage should I be getting at the plate pin? I tried all four WD-11 tubes, 2 at a time, in a Radiola III I have set up and they worked fine. Tube sockets for Radiola III and Radiola Grande contact the sides of the pins, not the ends. Do you still think it would help to re-solder the ends of the pins? Be glad to do so if you still think it could be the problem.
Check the connections between the vernier, tuner and tickler, end to end checked 1.97K ohms.
If the tubes are working no need to re-solder them... Cleaning the contact areas, yes...

Getting such a low voltage on the plate of the detector tells me the tube is could be under the following conditions...

The grid would have to be positive in respect to the B- Need a very high impedance VTVM to read this. I doubt the tube is turned on that hard. The tiny filament of the '12 would give out in a short time...so, I think there is an open circuit or a ground short in the plate circuit involving the regeneration scheme, either wiring, at the socket, defect in the regeneration or a defect in the transformer...

You have done voltage tests, so now you will need to do resistance tests. I would feel more comfortable with resistance tests made with an analog VOM.

Need to measure the primary of the transformer

Lift both leads of the transformer and measure the transformer winding either lead to the metal frame of the transformer. GOOD is a infinitely high resistance

With the leads still off, go to the connection on the plate side of the transformer to the plate pin of the detector socket adapter. GOOD is a very low resistance, maybe 2-5 ohms.

Now measure from the B+ to the B+ lead that connects to the 1st. audio transformer. GOOD is low resistance 2-5 ohms...

If any reading is not what is expected that is where the trouble is.

Oh "looks" like the grid leak and the grid capacitor are in one large cartridge, like a Radiola III

Oh, oh, That .0008 bypass cap could be shorted...
----------------------------------------------------------------------------------------
If I understand what has been done to provide "A" for this radio is to keep the "A" lead that is common to all the tubes. Then take all the other "A" leads that went to separate "A" batteries and connect them all together. That includes removing any stray connections...

The remaining "A" terminals are now "B" and"C" terminals, UNLESS a made up "B" and "C" battery are used in the cabinet...

Irregardless in/out on the B/C batteries, care of the connections has been maintained. yes?

Schematic re-posted for convenience...

Image

Chas

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Apr Thu 02, 2020 2:31 am 
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The condenser in the grid-leak resistor explains the size of it. All the transformers were pulled and checked when I started working on this per your instructions earlier in the thread. The 4 post audio output was bad and rewired by Heyboer. I checked it out before reinstalling it.
The "C" connections are inside the radio, I'm using 2 AA batts for the 3v called for in the schematic. The connections on the back of the radio are wired as , common A-, common A+, 45vB, 90vB, B-/Ground. I've checked all the battery connections to make sure they're good.
I'll make the other checks you suggested using my Simpson and report back. I will also clean the tube socket contact points as you suggested.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Apr Thu 02, 2020 6:04 pm 
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Quote:
43v going into post 2 on the output transformer. There's .0011v at the plate pin on the detector tube. What voltage should I be getting at the plate pin?

Should be getting 43 volts at the detector plate. The path is from battery-->to 2 of "H" primary-->out 1 of H-->through tickler coils-->to plate of detector socket.

The RCA redbook confirms the grid leak and condenser are combined into 1 unit.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Apr Thu 02, 2020 9:37 pm 
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Thanks for the info Jeff, I will check that also. I do have 43v going into "H" primary, I had checked it last night to make sure the battery connections were good, along with other checking.

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