Receiver Cap Replacement

[Mike/W8BAC]

I have an old Westinghouse AM receiver that I want to bring back to new spec. It's a fairly high quality circuit and the blond wood case is in great shape.

It has two electrolytic caps and 16 or so waxed paper foil caps. I'm going to order a set of caps from Mouser but I have a question or two for the receiver gurus here.

All of the non electrolytic caps have a band or marking on one end that says "Foil Side" just curious what that means.

My other question is what is the best manufacturer for replacements? I hear "orange drop" caps here often, Is that short for Sprague since I see Sprague caps are sometimes orange?

The cap value range is between .005-.1 and 400-600 volts.

Thanks for the help.

Mike

[w8khk]

Hello Mike,

The "foil side" indicates this is the lead to the outermost layer of foil in the capacitor.  Although not extremely critical, the outer foil can afford a bit more shielding on bypass caps, and allow you to experience less hum on coupling caps, as follows:  Connect the foild side to chassis ground on the bypass caps, and to the lowest impedance side of coupling caps, normally the plate of the driving stage, or the cathode in the case of a cathode follower.  The inner foil would then be connected to the grid, or higher impedance side of the capacitor.

I really don't have a preference for brand or style of capacitor, since my ears cannot detect the tessitura of the sound stage.  My ears can separate signal from QRM and QRN in most cases.   I will allow someone else to make recommendation on the brand or color that is best.

73, Rick

[W1GFH]

Ease of fitting the caps into tight spaces is more important to me than the tessitura of the sound stage....I like the axial 630V polys.

[N2DTS]

I don't know about all the different cap types that you can get today, but I am sure a google search could clue you in.
I would tend to use the smallest ones with extra voltage ratings, go well over the normal operating voltage and things will likely be fine.

I have a lot of orange drops, the original ones, they dont seem to go bad, but are likely big for the ratings these days....
I know mylar caps would likely be less then 1/2 the size of orange drops...

There ARE differences between caps types, maybe big differences in inductance, leakage, shielding, etc.
In most audio applications, they might not matter much, except to the crazy audio guys in search of well defined highs, and transparent midrange, or precise low end with unsurpassed clarity, or whatever gibberish they spout...


Brett

[WB6NVH]

Orange Drop was a trademark of Sprague, although the line has since been sold.

I have to agree with the above, I like the yellow axial jobs which you can get from many sources.  They are cheaper than Orange Drops and I think Orange Drops look ugly and out of place in vintage equipment.  It's unlikely any difference in quality between them would be detected in this lifetime.

A 1930's-40's electrolytic is going to be dried up by now.  Usual procedure is to saw open the aluminum can styles and put new radial lead electrolytics inside, to keep the appearance original.  Or, sometimes there's room under the chassis to just tack them there and leave the disconnected original in place.

I wouldn't get preoccupied with the "outside foil" issue.  It's a rare occasion where that would matter.  There was an article in Electric Radio a few years ago about how to make a little fixture which would tell you which end was going to the outside foil.  Presuming the manufacturing process is uniform, I would think you could probably sacrifice one with an X-Acto knife to see, based on the label orientation, and follow that, or just reverse a suspect cap where it mattered and see if that improved anything.

Nine times out of ten you can just use ceramic discs as well, but they don't look original in an old set either.

[Jim, W5JO]

The orange drop thing has made those things expensive for what your get, I wouldn't bother.  The yellow ones the guys have mentioned are a good replacement.  If you want to maintain the appearance, then remove the guts of the old ones and put the little yellow ones in their place and seal.

[N4LTA]

Mouser has the Mallory 150 series of axial caps - they are small size and excellent as mentioned above. They are not as "pretty" as they used to be as recent ones are white rather than yellow.

That's what I would use .

Pat
N4LTA

[Mike/W8BAC]

OK done deal, I ordered a full set from Mouser. All Mallory 150 series. I couldn't get exact replacements for some so I went just a bit above on some values. For the six .01 @ 400 volts I went to 600 volts. For a .05 @ 600 volts I had to settle for .047. For a .2 @ 400 volts I had to settle for a .22. They should do fine and NO I could care less about Pure sound. This is a 1940's tabletop radio.

Anybody have a 25L6 tube? One is a bit flaky. Thanks

[Jim, W5JO]

Higher voltage is fine in any application, it is the capacitance value that you should be careful about.  A bit above is ok on the capacitance, but not a lot.  For example, yesterday's .05 is .047 today.  If you want 20 uf, then today you get 22 uf., etc.

[N3DRB The Derb]

yellow jobs are what was used at Golden Age Radio. A typical cap order from that shop would run 500 pc's a month. At that time there was much debate on orange drops vs the yellow jobs. Sam elected to go with yellow mylar 630's and we never had a single cap failure the 2 years I worked there.

We saw many cases of recapping using orange drops where the installer cut a lead a bit too short n thought nothing of stretching the lead over a bit. 9 times out 10 this resulted in the lead pulling out the bottom of the cap. It was because orange drops are radial leaded, and putting radial lead caps in where axials go result in that kind of thing.

If it had a axial, use a axial. if the cap was a radial, use a radial.

[KM1H]

I prefer disc ceramic up to .02 or .05 for RF bypassing as they do a better job than the alternatives plus give a highly uncluttered appearance. For higher values and especially in audio circuits with high peak voltages I use the axial film type and use mostly green and brown that I buy in quantity from Ebay surplus sellers. The yellow ones available from many sources are back up when Im out of stock.

I refuse to use ugly radial Orange Drops unless a customer demands it.

Carl
KM1H

[Mike/W8BAC]

Good points Carl. I have some disc ceramics that will cover the voltage requirements for the .01 and .05 range. If it's not to far to stretch the leads I'll try them.

This receiver uses a pair of 25L6GT tubes in push pull for the audio. It only has an 8 inch speaker with a wimpy magnet. Seems unusual to me. I picked up 6 GE NOS 25L6GT's from an eBay store yesterday. One of mine has an intermittent short. Could be the reason the receiver was retired. Anyway, that seems to be an odd choice for tubes since everything else has 6 volt filaments.

It's fun to work on something different. I have a really nice looking console receiver that needs work up next for repair. This one is practice. The console is much more complicated.

[KM1H]

I have a National NC-46 with matching speaker as a BC and 160-40M AM listener in the kitchen eating area. It has PP 25L6's, 25Z5, and seven 6V tubes. All that and not even a RF stage but is OK for what I use it for and nice audio.

Carl
KM1H

[W9GT]

The orange drop thing has made those things expensive for what your get, I wouldn't bother.  The yellow ones the guys have mentioned are a good replacement.  If you want to maintain the appearance, then remove the guts of the old ones and put the little yellow ones in their place and seal.

Yes, that practice is called "stuffing".  Such a thing might be desireable to purist collectors or for really high end radios, such as a Zenith Stratosphere.  If you just want the radio to work properly, replace the caps with high quality yellow axial types that are commonly available from a number of on-line sites as well as on eBay.  I have fixed hundreds of radios with that type of capacitors with no problems.  'Lytics are sometimes a little more work to find direct replacements and the practice of leaving the old can-type cap in place and putting tubular types under the chassis is perfectly acceptable, and works fine.  Very few people are going to be looking or digging under the chassis to see if the caps are the original types.  Of course, it is definitely wise and just good workmanship to do a neat job of mounting and soldering the leads of the new caps in place.  Try to make sure you have a decent strong mechanical connection, as well as a good solder job.
Helps prevent future troubles.

73,  Jack, W9GT

[Todd, KA1KAQ]

Mike, I didn't see it in any of the posts so I wanted to add that the rule of thumb for caps if not marked was always that the foil side was the lead to the right side of the lettering. Not a big deal as others pointed out, but handy to know anyhow.

The OD issue was more to do with quality and buying USA made goods to help keep a supplier in business. Sprague sold out the line many years ago now to SB Electronics in Barre VT, which was the site of one of their early capacitor plants. All the equipment used then was still in use until recently. The company sold a few years back to a fellow named Ed Sawyer who happens to be a ham.

ODs are/were very high quality, so if you could put up with the radial leads and wouldn't lay awake night worrying about all that orange hiding under the chassis, they were a good option. Sadly, when I was up there last year I found out from one of my contacts there that Ed has finally moved all of the production to China, though they do still have the equipment in Barre and use it for custom runs. IIRC, they'll make them in different colors, too. I suspect the ridiculous VT taxes along with labor costs had a lot to do with it, as they weren't a terribly big company.

Good luck with the project, Mike.

[KM1H]

As a few on here know I have a few collector radios with historical significance that werent obtained to be shelf queens. These have had paper caps and electrolytics restuffed and new resistors made in a few cases. Its time consuming but it keeps me from walking by the high school in my raincoat

A Zenith Stratosphere should be following me home in March. Ive restored a few for customers but the performance isnt as good as its looks IMO which may explain the poor sales, the depression notwithstanding.

Carl
KM1H

[Mike/W8BAC]

Jack/W9GT said

Of course, it is definitely wise and just good workmanship to do a neat job of mounting and soldering the leads of the new caps in place.  Try to make sure you have a decent strong mechanical connection, as well as a good solder job.
Helps prevent future troubles.

Hi Jack, I built my first Benton Harbor kit in 1975 and I can still remember the advice in the manuals about making a good mechanical connection before soldering. I learned it early and still practice it today. It's funny you mention it regarding this rebuild. You should see this OEM build. The point to point component work is not very good. Hardly any mechanical connections. Just the wire poked through and slurped with solder. On the other hand I have been faced with undoing my own work after an over enthusiastic mechanical/solder job and cussed. To much of a good thing.......

Todd/KA1KAQ said

Mike, I didn't see it in any of the posts so I wanted to add that the rule of thumb for caps if not marked was always that the foil side was the lead to the right side of the lettering. Not a big deal as others pointed out, but handy to know anyhow.

Todd, That is exactly the kind of knowledge that makes a difference here and something I can use. Thanks for posting that. I might be prejudice but I think a thread like this should be preserved. 

Carl/KM1H said

A Zenith Stratosphere should be following me home in March. Ive restored a few for customers but the performance isnt as good as its looks IMO which may explain the poor sales, the depression notwithstanding.

Are you talking about a model 1000Z Carl? I'm speechless.... That's awesome. I want to know all about it please. I have to say however I am more a fan of the Crosley Super Power Receiver. Can you find me one?   

[KM1H]

A Zenith Stratosphere should be following me home in March. Ive restored a few for customers but the performance isnt as good as its looks IMO which may explain the poor sales, the depression notwithstanding.

Are you talking about a model 1000Z Carl? I'm speechless.... That's awesome. I want to know all about it please. I have to say however I am more a fan of the Crosley Super Power Receiver. Can you find me one? 

[/i]

Yep a 1000Z one family owned since new in above average condition but far from perfect.  I'll farm out the cabinet work.  It was promised to me a few years ago and they are selling their place in Maine and moving to NC in March. I regularly visit it when Im up visiting my wifes family which is how I found it.

Good luck on the WLW, there are only 2 known. If another surfaces be prepared to pay Duesenberg prices if its in top shape!

Carl
KM1H

[Mike/W8BAC]

Good luck on the WLW, there are only 2 known. If another surfaces be prepared to pay Duesenberg prices if its in top shape!

Oh....... I know, but every time i drive past a garage sale I look. Kind of like buying a lottery ticket. The Super Power, 1000Z and Hallicrafters DD1 receivers are the things dreams are made of. Like I said please keep all of us up to date on the 1000Z. Have fun!

Mike

[N3DRB The Derb]

yep, radios like those are candidates for cap restuffing and  all other such measures to keep it as original looking as possible.

I got rid of my big Philco because I realized I simply was not going to be able to handle the job and needed to get it to someone that could. I saved it from the dump, but it wasn't meant for me.

[Mike/W8BAC]

I just finished the Westinghouse H-130 recap project and the receiver actually works!     I did run into a problem. I had four wax covered caps stacked in a small space and had a devil of a time. I had to snip and lay back parts to get at the connections. Well, I lost track of one of the caps and couldn't figure out where it went. 20 years ago this might have meant weeks of wait. NO Problem, I Googled it and actually found a download of the Photofact. Back in business in no time.

I'm sitting here enjoying my local AM news radio station and thinking about picking up some Shellac and thinner to make it look a bit fresher. That is if I can make it to the hardware store. I'm going to have to string myself up and pour hot led on me because I made very nice mechanical connections before I soldered.

Thanks for the help guys, on to the next one.

Mike