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 Post subject: ERLA Radio Repair/Replacement of Audio Transformer?
PostPosted: Jan Sun 07, 2018 3:47 pm 
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I have an audio transformer with an open primary. Is there a replacement that will fit under into the housing or is their someplace to send it to be rewound? Housing reads 6 to 1. Please see photos, all help appreciated.


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 Post subject: Re: ERLA Radio Repair/Replacement of Audio Transformer?
PostPosted: Jan Sun 07, 2018 5:31 pm 
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Play Things of Past

Gary Schneider

http://www.oldradioparts.com/2a23cfl.txt

1019-025 INTRSTGE ERLA 6:1 SP-SG, 1.2K/6K, BLK, 4 TOP POST, RED TAG, 4 HOLE MTG, USED 1 2 3/4 2 3/8 1 3/4 $13.50

A rewind will be about 5x as much...

Act quickly, fill out your order with other goodies you have been looking for.

Gary may have an ERLA detector, if it can be opened, ask, a modern diode buried inside permanent fix if there are detector woes...

Gary works alone in a huge store/warehouse, it does take time, be patient.

GL

Chas

With the transformer open, take note of the start and finish of each winding and what terminals are related. If a mod or repairs are made, kind of important as I said in another post.

I never had an ERLA apart, didn't know it had sheet iron wrapped core...

Wait until you see the transformer in an A-K island. Looks like a homemade Hegehog without a frame.


Last edited by Chas on Jan Sun 07, 2018 9:51 pm, edited 1 time in total.

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 Post subject: Re: ERLA Radio Repair/Replacement of Audio Transformer?
PostPosted: Jan Sun 07, 2018 8:32 pm 
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Thanks again Chas, your help is much appreciated.

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 Post subject: Re: ERLA Radio Repair/Replacement of Audio Transformer?
PostPosted: Jan Sun 07, 2018 8:52 pm 
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Detector checks 150K ohms one way and 16K ohms reversed on Simpson 260.

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 Post subject: Re: ERLA Radio Repair/Replacement of Audio Transformer?
PostPosted: Jan Sun 07, 2018 9:54 pm 
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atwaterkent1 wrote:
Detector checks 150K ohms one way and 16K ohms reversed on Simpson 260.

Not really ideal...

IMHO sub a 1n34 during the testing phase, save the aggravation until the set is running.

You NEED 6:1 the voltage gain is very important.

Chas


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 Post subject: Re: ERLA Radio Repair/Replacement of Audio Transformer?
PostPosted: Jan Sun 07, 2018 10:01 pm 
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I'll email Gary when he re-opens on January 14th.

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 Post subject: Re: ERLA Radio Repair/Replacement of Audio Transformer?
PostPosted: Jan Sun 07, 2018 10:17 pm 
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Diode ordered from Antique Electronics.

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 Post subject: Re: ERLA Radio Repair/Replacement of Audio Transformer?
PostPosted: Jan Mon 08, 2018 1:27 am 
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Close but no cigar on the transformer for fit into housing. Original is 2.5 W X 2.0 H X 1.5 D.

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 Post subject: Re: ERLA Radio Repair/Replacement of Audio Transformer?
PostPosted: Jan Mon 08, 2018 4:17 am 
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Just got a tip from Mark Oppat about a company here in Michigan called Heyboer that can rewind the transformer. Will make it my back-up plan. You are right Chas, more expensive but it would be worth it to me to have the radio working.

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 Post subject: Re: ERLA Radio Repair/Replacement of Audio Transformer?
PostPosted: Jan Mon 08, 2018 5:55 am 
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I understand Heyboar is 1st. class, no matter who does the job remind the rewinder about the start/finish and to which terminals.

For the A-K transformer there are 3:1 windings from the ARBE III web site.

http://www.arbeiii.com/Transformers/

Pick a core winding of the correct size and jam soft iron wire through, fold over to complete magnetic path, drop into tar after heating. While open restore the grid leak it's under the cover too...

GL

Chas


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 Post subject: Re: ERLA Radio Repair/Replacement of Audio Transformer?
PostPosted: Jan Mon 08, 2018 6:45 am 
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Thanks Chas, I'll let you know how it's going.

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 Post subject: Re: ERLA Radio Repair/Replacement of Audio Transformer?
PostPosted: Jan Mon 08, 2018 10:00 pm 
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I'm having a hard time locating a replacement transformer without a schematic. I just got off the phone with Steve Johnson and he couldn't find a three tube schematic under ERLA or as it was later known as Sentinel. The one I posted previously in this thread is close, but my radio's voltages are different (45v for B) and the A- & B- power lines connect to the same post (actually different posts but they are bridged underneath the chassis, also a couple more components in the posted drawing that mine does not have. Also checked out about 40 schematics at Antique Electronics Supply and no dice there either. With three 01A tubes (at least that's what it came with) it must be an early model.

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 Post subject: Re: ERLA Radio Repair/Replacement of Audio Transformer?
PostPosted: Jan Tue 09, 2018 12:51 am 
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atwaterkent1 wrote:
I'm having a hard time locating a replacement transformer without a schematic. I just got off the phone with Steve Johnson and he couldn't find a three tube schematic under ERLA or as it was later known as Sentinel. The one I posted previously in this thread is close, but my radio's voltages are different (45v for B) and the A- & B- power lines connect to the same post (actually different posts but they are bridged underneath the chassis, also a couple more components in the posted drawing that mine does not have. Also checked out about 40 schematics at Antique Electronics Supply and no dice there either. With three 01A tubes (at least that's what it came with) it must be an early model.
Dan,

From your other posting on the ERLA, I can only assume that this is the same radio...

http://antiqueradios.com/forums/viewtopic.php?f=1&t=331115&p=2795485#p2795485

I cannot see all of the "floor plan" from the images you posted but there is enough to lead me to believe that it is the same radio as shown on page 13 of this document:

http://www.americanradiohistory.com/Archive-Radio-in-the-Home/20s/RitH-1923-Nov.pdf

There is also an image of the interior of the three tube radio in the same page.

I took a screen shot of page 12 and processed the image of the three tube ERLA schematic so I could post it here:

Image

And:

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What is substantially different about the set that you have and the set the schematic represents (page 13)?

There may have been undocumented changes between the two, that said there are three tubes, two radio transformers and two AF transformers, one being the 6:1.

Minor variations in layout, more or less jacks, filament control jacks, use of more or less rheostats, different tuning inductor, different tuning capacitors, even a different crystal detector diode, use of bypass capacitors to stabilize the circuit or even the inclusion of a "stabilizer" control. Those changes do not constitute a schematic that is substantially different from the radio from one example to another. Voltage requirement can be different depending if there was a re-routing of bias to prevent oscillation. IMHO use any "B" voltage that works and does not stress the tubes.

Only the routing of the RF/AF path, meaning which tube(s) are dual purpose or using one of the three tubes as a detector would constitute a different radio. Yes, there are many variations of reflex receivers when considering the signal path.

That said why would an "exact" schematic be required for a third party to obtain an audio transformer that IS DESIRED to "bolt-in" so there is no rerouting of the bus wires?

There is much to be gained by drawing the schematic from what exists, using the page 13 drawing as a layout guide, placing major symbols in the same locations and connecting as the example.

Look at the date of the magazine November 1923. Generally, it would take some three months to publish so the radio shown would be around July of 1923. Yep, I would call that early ERLA. Just about as early as it can get with the introduction of 1/4 amp tubes.

PTOP (Gary) appears to have the 6:1 ERLA transformer, a communication will confirm if the PTOP list is not up to date...

YMMV

Chas


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 Post subject: Re: ERLA Radio Repair/Replacement of Audio Transformer?
PostPosted: Jan Tue 09, 2018 1:44 am 
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Looks like Gary's gone until the 14th of this month. I will contact him as soon as he gets back. The photo is very close, aside from an extra capacitor that attached to the G&A posts of the transformer I removed, the different location of the other capacitor and the battery voltage and hook-up. Here's some more photos.
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Matt from TubesandMore informed me that he needed a schematic.

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 Post subject: Re: ERLA Radio Repair/Replacement of Audio Transformer?
PostPosted: Jan Tue 09, 2018 2:20 am 
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if 5 to 1 is close enough (and I suspect it is).

https://www.digikey.com/products/en/tra ... ageSize=25

Steve


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 Post subject: Re: ERLA Radio Repair/Replacement of Audio Transformer?
PostPosted: Jan Sat 20, 2018 12:53 am 
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Replacement AFT and Carborundum detector arrived today and I installed them. Still not picking up any stations and adjusting the tuning capacitors makes no difference in what I'm hearing through my headphones. Both RFT's seem to check good so as far as I know, which is very little since I'm new at this, so that leaves the two mica capacitors as suspects. Everything I've read says they seldom fail. Any ideas?

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 Post subject: Re: ERLA Radio Repair/Replacement of Audio Transformer?
PostPosted: Jan Sat 20, 2018 4:36 am 
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I noted your posting about a capacitor measurement, for this radio?

A 10k/volt ohmmeter, the Simpson, will give all the info needed to be sure the mica caps are good. The meter should show a minuscule kick toward zero ohms then fade to infinity on the 10k scale.

What are you using for a power source?
Is the "A" voltage at the radio terminals set for 6 to 6.6 volts?

What is the B voltage?

Can the plate voltages be read from B-?

What does the replacement Carborundum detector look like and does it have a good front/back resistances?

Finally, do you have a circuit tracer? If not a pair of high impedance headphones?

Using the headphones, a diode and a coupling capacitor it is possible to make a simple tracer that will work for RF and AF. There are a several points on the radio that can be checked with such a tracer. Where ever the signal stops is where to look for a problem.

A simple signal injector can be made from a small 5-6 volt relay, a lantern battery and a coupling capacitor, relay wired through its normally closed contacts will make a buzzer full of RF and AF noise, a cap makes the signal injection safe.

Chas


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 Post subject: Re: ERLA Radio Repair/Replacement of Audio Transformer?
PostPosted: Jan Sat 20, 2018 8:41 pm 
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Chas -There is no brief jump to zero on either capacitor. B voltage is 45V, A was 5.8v which I've adjusted to 6.1v for future tests. I'm using a K101a battery eliminator. Detector was a match- NOS from Gary in original box. It had instructions with it on testing using headphones and a 1.5v dry cell. Run detector in series with battery and headphone connections on each end, when touching headphone connections you will get the click from the battery one way but not the other when reversing the detector. According to the instructions, if it passes this test it's good, it passed.
I will see if Gary has the condensers. Since this is a glass enclosed radio, I'd like to keep it original as possible. I know I can hide modern capacitors if I have to and leave the bad ones in place for visual effect, but I'd like to see if I can find original replacements first.

Attachment:
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 Post subject: Re: ERLA Radio Repair/Replacement of Audio Transformer?
PostPosted: Jan Sat 20, 2018 11:50 pm 
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Factoids on those two caps...

If they are leaking at all the Simpson will show a resistance reading...

They cannot have less capacity in that type of clinched stacked mica.

They are both used in a bypass application, the radio will work without them but may oscillate.

You can use a 250pf silver mica for a sub on the smaller one, the larger can be subbed with a .0022 metalized. Voltage is near irrelevant 100 volts and up are O.K.

You can also sub the 1N34 diode for the carborundum detector..

As stated keep the "A" supply up and the "B" at 45.

If you would please, loosen and re-tighten every electro/electromechanical joint in the entire radio.

Joints on tube sockets, RF transformers the tuning condensers, rheostats. Re-solderer every joint. Be cautions not to solder to connections that are screw lugged to any "Mud" insulators. Mud will flow at solder temperature. Loosen the lug and then re-solder. A cold or crystallized solder joint can be visually deceiving.

Do be sure to use good tubes, Ya, I know you have been looking for some. Use tubes that work in another radio...

I would like to see the installation and the color of the lead wires in the new transformer...

Be sure the wipers or pigtail for the rotor on the tuning condensers is working.

No bother if the radio starts to work :mrgreen:

Chas


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 Post subject: Re: ERLA Radio Repair/Replacement of Audio Transformer?
PostPosted: Jan Sun 21, 2018 12:52 am 
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Tubes are good, I have plenty of good 01a's. I don't use border line tubes and I have a newly rebuilt and calibrated Hickok 600A.
I've checked all the connections, but will do so again. The transformer is exactly the same, at least on the outside, and both primary and secondary check good. What will looking at the insides tell you?

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