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 Post subject: Re: Radiola Grande Restoration
PostPosted: Mar Sun 22, 2020 4:49 pm 
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Looking at a radiolaguy photo, the rubbed off label says "+A1 and Ground".

Going by the schematic, B- would somehow connect to the other terminal of that big capacitor.

B45, for sure should not go to +A3. Maybe someone put the terminal on there? How many wires are connected to the +A3 post?

I noticed that the photos on RM show 2 wires connected to the post by the big condenser. Yours looks like 3 wires connected there. I bet one of those wires is B- (black one with funky-looking terminal?). Again, the schematic shows B- connected to one side of the rheostat, so it returns to A- through the rheostat.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Mar Sun 22, 2020 8:13 pm 
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Three wires going to funky terminal ( looks to be original since its color matches exactly the interior of the radio) are 90v, +A2 (wire coming from that terminal and third wire runs to large condenser.
Original B- wiring tag is attached to wire from Ground/A1+ terminal.
20 volt tag attached to wire coming from +A3 terminal.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Mar Sun 22, 2020 8:25 pm 
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Interesting does it all for 4 separate A batteries?


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 Post subject: Re: Radiola Grande Restoration
PostPosted: Mar Sun 22, 2020 8:40 pm 
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Not sure what's going on yet mrx, still trying to figure it out. Twenty volt tag on wire from +A3 terminal has to be wrong since that's a filament voltage terminal. I'm wondering if these tags are even on the right wires. Schematic doesn't even show a 20v power supply.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Mar Sun 22, 2020 8:57 pm 
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Sounds to me like it has been re-wired to change the meaning of the posts on the back, 4 connections. (1)Ground/+A1 and B-; (2)+A2 is now B+90;( 3)+A3 is now B+Detector; (4)-A. Don't know what +A4 is connected to.

I sure would verify voltages with a meter before putting any tubes in.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Mar Sun 22, 2020 9:23 pm 
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Probably is, I'll have to go through it all now. Original sketch does not even show 20volts but 20v wiring tag is original. ?

Here's a sketch of what I'm looking at underneath....


Attachment:
Radiola Wiring Terminal Sketch.jpg
Radiola Wiring Terminal Sketch.jpg [ 361.24 KiB | Viewed 502 times ]



And a photo of inside, rear terminals....

Attachment:
SAM_2206.JPG
SAM_2206.JPG [ 704.51 KiB | Viewed 502 times ]



And tags.....

Attachment:
SAM_2201.JPG
SAM_2201.JPG [ 800.8 KiB | Viewed 502 times ]

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Mar Sun 22, 2020 10:53 pm 
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Let’s say the radio worked wired up the way it is right now. Then -A is -A; +A4 is +A/ground; +A3 is +B det; +A2 is +B 90; +A1 is -B; jumper wire at the batteries from -A to -B. C battery -C to right terminal, +C to left terminal of C battery clip.

I would connect it that way and then verify voltages at the tube sockets. Easy for me to say...

Very cool wire tags.

Answer to mrx, yes, it shows 4 1.5 volt batteries in the RCA red book.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Mar Sun 22, 2020 11:14 pm 
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IMHO the harness is botched...

The schematic appears clear to me. Each tube has a separate "A" source. I suppose it is a possible coupling problem via the batteries if all the tube + filaments are in parallel connected to the same battery bank.

I don't know, but that kind of a hookup for the "A" batteries would not work well with a power supply, it would require 4 sources... Impractical, so at the back of the radio jump all the A+ together or at the power supply. The "B" seems straight forward, B- on A-, +45 for detector, seems high, maybe 22-1/2, and +90 on the amp. Looks like there is an internal "C", that 3-cell flashlight battery...

It has occurred to me, that, the "B" battery of a smaller pattern was stored inside the cabinet. There does not appear to be any external connections or harness for it...

The circuit in very much like a Radiola IIIA, regenerative detector 1st audio is a driver for a push-pull output...

IMHO what seems to be foreign is the very early parts all are made for purpose.

Dan did you check out the driver for operation and mechanical sensitivity adjustment?

Chas

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Mar Mon 23, 2020 1:58 am 
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Chas- B battery is supposed to be internal, there's a hold down bar for it. Also a holder for a C battery inside, I have not done anything yet but put in the rewound transformer, check most of the connections and try to figure out how to hook up the batteries. Schematic says 45v which would be the dectector voltage, funny that original tag says 20v.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Mar Mon 23, 2020 3:38 am 
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Dan,

Well, it is still a triode gridleak regenerative detector using a low mu tube. So the 20 volts on the cable is more likely correct. It does not have to be 20 volts, it is like a sort of speed limit sign on a deserted back road...

Chas

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Mar Mon 23, 2020 4:16 am 
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I'll try the 20v first and if it works fine there's no reason to change it. Thanks Chas.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Mar Tue 24, 2020 12:12 am 
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jrehkopf wrote:
Sounds to me like it has been re-wired to change the meaning of the posts on the back, 4 connections. (1)Ground/+A1 and B-; (2)+A2 is now B+90;( 3)+A3 is now B+Detector; (4)-A. Don't know what +A4 is connected to.

I sure would verify voltages with a meter before putting any tubes in.



+A4 are the filament connections.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Mar Tue 24, 2020 12:24 am 
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Seems like what was done to move the B battery out of the cabinet,by combining all the A+ to one lead... Frees up A1, 2 & 3 for the B and C circuits... Just have to totally ignore the existing labels as well as the shock hazard...

Chas

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Mar Tue 24, 2020 1:26 am 
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I hooked up the 1.2v,20v and 90v and 4.5v. I have the antenna wired up. I'm not sure about the ground. With the power on I'm just getting a buzzing sound. When I connect the ground wire it cuts out.
Filament power checks good at all the sockets. Buzzing was barely audible through the speaker. Bypassed the headset jack and no change in volume coming out of speaker. Speaker passed the 9v battery check loud and clear.
Buzz was heard through the headset before the 90v was hooked up, buzzing was noticeably louder after 90v was connected. That's where I'm at now.

Using 864 tubes, it hurts less if you fry them then WD-11's do. :wink:
Does the tube switch make a difference? Isn't the 864 a superior tube to the WD-11?

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Last edited by atwaterkent1 on Mar Tue 24, 2020 5:33 pm, edited 1 time in total.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Mar Tue 24, 2020 2:24 pm 
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Dan, those are 1 volt tubes. I hope it was mistake when you said 6 volts.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Mar Tue 24, 2020 4:05 pm 
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jrehkopf wrote:
Dan, those are 1 volt tubes. I hope it was mistake when you said 6 volts.


Yeow!!

All the + filaments are or were supposed to be connected together PARALLEL for 1-1/2 volts.

FWIU (understand) +A4 was to be the A+ 1-1/2 volts, the other A's were to be assigned B voltages.

Overall circuit design does NOT permit wiring the filaments in series, the bias will be all messed up...

? ? ? ?

Chas

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Mar Tue 24, 2020 4:18 pm 
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Battery hook-up, as I understand it:
Attachment:
Untitled.jpeg
Untitled.jpeg [ 134.74 KiB | Viewed 448 times ]

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Mar Tue 24, 2020 5:33 pm 
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jrehkopf wrote:
Dan, those are 1 volt tubes. I hope it was mistake when you said 6 volts.


Typo Jeff, thank for catching that.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Mar Tue 24, 2020 5:35 pm 
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Chas wrote:
jrehkopf wrote:
Dan, those are 1 volt tubes. I hope it was mistake when you said 6 volts.


Yeow!!

All the + filaments are or were supposed to be connected together PARALLEL for 1-1/2 volts.

FWIU (understand) +A4 was to be the A+ 1-1/2 volts, the other A's were to be assigned B voltages.

Overall circuit design does NOT permit wiring the filaments in series, the bias will be all messed up...

? ? ? ?

Chas


Filaments are in parallel coming from the +A4 terminal. A- is parallel wired also per original schematic. Typo on the 6v, it is 1.2v. Right now the power is wired up as, apparently, the last owner had it wired per the drawing.

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 Post subject: Re: Radiola Grande Restoration
PostPosted: Mar Thu 26, 2020 2:03 am 
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Wiring is correct for ground. Large black can condenser checks 1.68uf on my LCR. Since I have no specs on the print, I have no idea if that's right or not.
Also checks 170K ohms, should check open. Leakage?

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