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 Post subject: Changing caps on an Atwater Kent 46
PostPosted: Apr Fri 12, 2019 4:15 am 
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Location: Lake City, SC
So I am enjoying my first "good" radio, a 1929 Atwater Kent, which still plays fine at 90. Super excited about that.

However, I don't want to run it on 90-year-old filter caps. There are 2 cans inside full of tar, I think they are transformers. Then inside a large tin box, there is a cluster of old cloth wires and enough asphalt to look like a mini parking lot.

I think the filters are inside that thing. How do I fix it while keeping it all original-looking and not busting up the old iron-wire transformers?

Atwater Kent spared no cares in awesome design but they really didn't count on us using their ancient receivers almost a century later. I hope mine can make it that far without melting down or catching on fire, so...any way to do an at-home repair job on those pesky caps?


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 Post subject: Re: Changing caps on an Atwater Kent 46
PostPosted: Apr Fri 12, 2019 5:43 am 
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http://www.atwaterkent.info/TechData/Dr ... 100sch.pdf

Some heat the tar and pour it out. makes stinky mess. Others freeze the tar and chip it out.


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 Post subject: Re: Changing caps on an Atwater Kent 46
PostPosted: Apr Fri 12, 2019 12:34 pm 
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Unless I am mistaken, your model has the capacitors in a separate metal can and they may not be potted in tar. You will need to inspect your power supply to confirm this. The can in the power supply contains capacitors 10a, 10b, 10c, 10d, 10e

Here is a link to the chassis layout and power unit. The capacitor box in the power unit is on the right side. http://www.atwaterkent.info/TechData/Im ... 06_070.gif

You will also want to identify and label the wiring going to the capacitor pack so you can disconnect the old pack and correctly connect the new capacitors. The new capacitors you put in will be physically smaller than the old ones. This means you can mount them on a piece of insulated perf. board and install this in the space where the old capacitor box was.

There is also a second capacitor can mounted on the chassis. It contains capacitors 2a, 2b, 2c, 2d,.

Attachment:
ak46.jpg
ak46.jpg [ 54.46 KiB | Viewed 1107 times ]

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 Post subject: Re: Changing caps on an Atwater Kent 46
PostPosted: May Fri 10, 2019 1:26 am 
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Location: Lake City, SC
Update:

I am going to be investigating some more about the workings of this radio soon, but what I am reading on the forum here suggests that the radio is unsafe to use unless every cap and resistor in the whole chassis have been replaced.

The resistors? Really? Well, now I know...

So while it's still working it's not at all usable. That's fine. It worked for 90 years, I can retire it a few months. But now I have to familiarize myself with the mysterious Grid-Leak...any basic tips
here with how to get all the stuff out?


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 Post subject: Re: Changing caps on an Atwater Kent 46
PostPosted: May Fri 10, 2019 2:48 am 
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VanEpsFan1914 wrote:
Update:

So while it's still working it's not at all usable. That's fine. It worked for 90 years, I can retire it a few months. But now I have to familiarize myself with the mysterious Grid-Leak...any basic tips
here with how to get all the stuff out?


The grid leak is part of the radios detector circuit. It is one resistor that is usually easily accessed. The fact that your radio is working suggests that the grid leak is probably ok. Like most old resistors, they often increase in value. The grid leak in your radio is supposed to be 2 Meg-ohms, but will probably still work if it increases somewhat.

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 Post subject: Re: Changing caps on an Atwater Kent 46
PostPosted: May Fri 10, 2019 7:41 am 
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VanEpsFan1914 wrote:
Update:

I am going to be investigating some more about the workings of this radio soon, but what I am reading on the forum here suggests that the radio is unsafe to use unless every cap and resistor in the whole chassis have been replaced.

The resistors? Really? Well, now I know...
The resistors are generally not a safety issues like the capacitors are.

They're a performance issue due to having drifted significantly in value, as Paul mentioned.

My suggestion is to replace the capacitors, then check the radio for proper operation and correct voltages on the tube elements. Those voltages in a good radio can vary + or - 20% from the values shown on the schematic due to resistor tolerances and tube performance.

Also, be aware that the schematic voltages were taken with a 1000-ohms-per-volt meter. If you use a modern high-impedance voltmeter, some of your readings will be higher.

Individual resistors can be replaced as required.

= Leigh

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 Post subject: Re: Changing caps on an Atwater Kent 46
PostPosted: May Tue 14, 2019 7:03 pm 
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I believe by the time that AK started making the type 46/53 they started to make those power packs more modular. I know on my model 53 the condenser pack is separate.

This fella here, put together a very nice general guideline document:
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=2ahUKEwjgwaqtxJviAhXxRt8KHZc-A20QFjAAegQIABAC&url=http%3A%2F%2Fwww.atwaterkent.info%2FArticles%2FAKPower.pdf&usg=AOvVaw3-y1D486_jIcoZawiQCt-R

But, keep in mind it's not necessarily particular to one model type. For example resistor R1a for the 46/53 models is 1k.

Be careful of those wire wound resistors as they can be fragile and can unwind...but even if they do they can be readily replaced with modern day power resistors.


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 Post subject: Re: Changing caps on an Atwater Kent 46
PostPosted: May Tue 14, 2019 7:39 pm 
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Kent started putting the filter caps in a can quite soon after introduction of the AC power supplies because of the high failure rate of the caps. It was easier (and cheaper) to replace the entire can under warranty than the individual parts.

And the complete cans were sold as service parts.

- Leigh

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 Post subject: Re: Changing caps on an Atwater Kent 46
PostPosted: May Wed 15, 2019 3:20 am 
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Location: Lake City, SC
All this is very interesting. Thanks very much to those who responded.

I am putting off the Atwater Kent project as I am trying to hone skills on regular radios. The resistors--well, the old thing does pick up 2 daytime stations with half an antenna & no ground wire so we'll have to catch the skip some fine night and see what kind of performance it is really getting in its current state.

The bit about storing capacitors in different canisters than the power-supply is indeed intriguing. Re-stuffing the canisters would be much simpler than the whole power supply. Modern caps could even be hidden under the cans, I suppose--or would this be heresy, collectors instead preferring to hide them inside the canisters?


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 Post subject: Re: Changing caps on an Atwater Kent 46
PostPosted: May Wed 15, 2019 2:52 pm 
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VanEpsFan1914 wrote:

The bit about storing capacitors in different canisters than the power-supply is indeed intriguing. Re-stuffing the canisters would be much simpler than the whole power supply. Modern caps could even be hidden under the cans, I suppose--or would this be heresy, collectors instead preferring to hide them inside the canisters?


There is often more than one way to replace capacitors. For the capacitors in the can located in the power unit, I don't think there is enough room to cram new filter capacitors in the power pack without removing the old capacitor can first, but someone may have done it before. IMO, it just makes a neater job to remove the old capacitors first.

As far as the second capacitor can that is located outside of the power unit, it is possible to mount new capacitors separately and disconnect the old can. Again though, restuffing the can is so much neater and retains the original appearance of the radio. Either method works, but I like to keep these A-K radios looking original on the inside since it is easy to remove the lid to inspect them and the original component layout inside is cool in its own special way.

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Last edited by processhead on Mar Sat 21, 2020 8:39 pm, edited 1 time in total.

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 Post subject: Re: Changing caps on an Atwater Kent 46
PostPosted: May Wed 15, 2019 3:19 pm 
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I agree with Paul ^ ^ ^

- Leigh

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http://www.AtwaterKent.info
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 Post subject: Re: Changing caps on an Atwater Kent 46
PostPosted: May Thu 16, 2019 3:31 am 
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Posts: 246
Location: Lake City, SC
I think I also agree with Paul. Hate to ruin something as unintentionally steampunk as a pristine vintage radio.

I love the controls on the Atwater Kents, specifically the tactile side to it. The power switch isn't a flimsy pushbutton, it's a heavy brass lever that snaps when you switch on the power. The speaker hums like a marine engine while the tubes heat up, then the sound wakes up and the radio comes to life. Tuning? Oh, I love it. Turning the big old vernier dial is a hoot--then the fine-tuning wheel underneath, which may or may not work, but gets you close. To get any decent sound out of it, you work the volume knob as well, jockeying through a crowd of dirty spots on the rheostat for the quiet spot that will let a loud station play without roaring or turning up the power to pull in a distant station. Faraway station? Crank it up to eleven and let that coffee-can of a speaker do its stuff.

No AVC, a very limited tuning range, TRF and not the best receiver in the world, the "stylish" designs of a kerosene stove and the weight of a power lawnmower--yes, these radios are terrible. But they have a certain late-twenties dignity to them. Long live Atwater-Kents.


One--WHYM Lake City, at 1260
Two--WJAY, Mullins, SC, 1280 (didn't hear call sign but it was right next to WHYM.)
Three-WWRK, Florence, SC, broadcasting on low power 27 miles away. 970 AM.

Logging 3 stations, including the rather faint WWRK, on a early unrestored radio using scrap for an antenna, is pretty fun. There were other stations on the lower bands that tried to pick up, but were so faint I could make out nothing. Maybe I need a better antenna, or to have my tubes tested--though I don't know what could be wrong with them, the radio store labeled them saying that they tested just fine in 1933 and 1934! :) And this was in the daytime. With new caps I hope I can do some real work some night catching the skip.

My antenna is a piece of insulated copper wire looped around the curtain rod brackets of my room and draped over to the Atwater Kent, and the new groundwire is a piece of aluminum from an old electric fence run through the window down to the outdoor faucet & wrapped around that a coupla times, then hooked up to the ground post inside the radio. Speaker is, of course, the old F-2 model that I have no idea what it looks like inside.


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 Post subject: Re: Changing caps on an Atwater Kent 46
PostPosted: May Thu 16, 2019 12:32 pm 
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When these radios are working correctly, you should expect daytime reception on par with many newer AM radios.
How to get there? You have heard us harping on replacing capacitors which can have multiple positive effects on performance. Improved set reliability, better reception, better audio fidelity.

Some of the other common problems that can degrade radio performance include: tube socket dirt/corrosion that impacts tube performance. Usually tube sockets can be cleaned with contact cleaner and minor adjustment will deal with this. Same applies to tube pins. Tube pins can sometimes suffer from dirt/corrosion and less often from a bad solder connection to the inside of the tube pin. Wiggling tubes while the radio is playing and noting any change in volume or distortion is one way to identify suspect tube/socket combinations. Having a couple of known good tubes to substitute in the radio is one way to evaluate tube condition if you don't have a tester. Also, 80 year old tube test decals don't really mean much.

Cleaning the volume control, and other controls with contact cleaner can also sometimes improve performance like your scratchy volume control pot.

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 Post subject: Re: Changing caps on an Atwater Kent 46
PostPosted: Mar Sat 21, 2020 8:33 pm 
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OK. Finally I get ready to open it up and figure out how to try making it work again. I've read some articles about Atwater Kents and think that when I am done with the capacitors in the power supply, I'm also going to replace all resistors and whatever else is in this radio, just to make it work a little better. Apparently glass cartridge resistors are noisy...it still has original ones.

Anyway, I got the top terminal board off (from inside the power unit,) pulled the chassis out of the radio (disconnecting power cord and switch just to remove the thing) and now I have the power unit out on its own.

The top is off and so is the top terminal board with its big cable that runs to the chassis. There is now only the second board to remove. On top of that second circuit board, I'm running into some problems:

1) there is a big resistor thing on top; it was broken in half. It appears to have four contacts on it; I think it was working before because the filament or wire winding was still intact, but this can't be put back in. What replaces this?

2) How on earth do I remove the lower terminal board? The nuts are in some sort of locking nut jail thing that keeps them from turning. I don't know the name for this part. If I can get that out, then I can get to the two cans underneath including the one with the capacitors.

3) If there's any radio repairman in South Carolina who works on Atwater Kents, please get in touch; this thing is confusing me and I really don't want to tear it up.


Attachments:
File comment: Underneath top terminal board...looking at a regular puzzle box. The wirewound resistor does not look like it's going to be reusable
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 Post subject: Re: Changing caps on an Atwater Kent 46
PostPosted: Mar Sat 21, 2020 8:47 pm 
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The two nuts in the center where the broken resistor is mounted are all that secure the lower board to the power pack.

I would make one suggestion before proceeding. Label all the wires that are soldered to the terminals on either side of the board. The terminals are numbered 1-12 as shown on some of the drawings.

Once you have them numbered, unsolder or cut the wires from the terminals. Only after the wires are removed from the terminals,will you be able to lift the terminal board off and access the resistors on the underside (after removing the two aforementioned nuts.)

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 Post subject: Re: Changing caps on an Atwater Kent 46
PostPosted: Mar Sat 21, 2020 8:55 pm 
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You will find three more wirewound filament shunt resisters and two carbon composition resistors on the underside of the lower terminal board. The wire wound resistors are almost alway intermittent due to the mechanical connection between the tiny rivets use to secure the solder tab to the resistance wire. The carbon composition resistors will almost always have drifted high in value and need replacing as well.

I am working on a model 43 at the moment for a customer. It is very similar to your radio. At last count, every resistor in that radio, with the exception of 2 were a) drifted high in value, b) physically burned/broken or c) mechanically intermittent.

It takes some creative mounting to replace some of those resistors on the lower terminal board.

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Last edited by processhead on Mar Sat 21, 2020 9:09 pm, edited 1 time in total.

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 Post subject: Re: Changing caps on an Atwater Kent 46
PostPosted: Mar Sat 21, 2020 9:07 pm 
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So it looks like I will be buying a lot more resistors.

Please let me know what you use to replace your "wire wound filament shunt resistors," as I am almost sure there are no equivalents for that in the radio parts catalog!

Thanks for the idea on numbering and then desoldering all the wires; I can do that. This radio is going to take a few days (who am I kidding; a few weeks) to get running again. I have very, very poor executive skills and probably will be forgetting to send off for spare parts; actually pushing the order button is almost a sort of crisis.

But I think once the parts are here, it might not be so bad.


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 Post subject: Re: Changing caps on an Atwater Kent 46
PostPosted: Mar Sat 21, 2020 9:27 pm 
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VanEpsFan1914 wrote:
So it looks like I will be buying a lot more resistors.

Please let me know what you use to replace your "wire wound filament shunt resistors," as I am almost sure there are no equivalents for that in the radio parts catalog!

Thanks for the idea on numbering and then desoldering all the wires; I can do that. This radio is going to take a few days (who am I kidding; a few weeks) to get running again. I have very, very poor executive skills and probably will be forgetting to send off for spare parts; actually pushing the order button is almost a sort of crisis.

But I think once the parts are here, it might not be so bad.


You should be able to use one watt rated resistors everywhere. Exact replacement values will not be available for the originals, but any standard value within +/-10% of the original value will be close enough.

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 Post subject: Re: Changing caps on an Atwater Kent 46
PostPosted: Mar Sat 21, 2020 10:00 pm 
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Also, do you think you could post a photo of the power pack after you get the terminal board removed?

I would like to see the top side view of the various compartments.
Thanks.

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 Post subject: Re: Changing caps on an Atwater Kent 46
PostPosted: Mar Sun 22, 2020 8:11 pm 
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Location: Lake City, SC
Top view of power pack. Terminal board removed. There is a metal plate here onto which the terminal board is screwed; after that there are three metal boxes: one is the big one (transformer) not under the terminal board. The other two are something else. I think the one closest to the cable going in--that one has all the capacitors, I think.


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File comment: Original wirewound resistors. The metal pieces on the bench are from a Victor Talking Machine portable phonograph & have nothing to do with a radio. Anyone want motor parts for a Victrola 2-55 or 2-65?
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