[VintageVolts]

First, let me introduce myself...

My name is Jeff. I run a website called Vintage Volts (http://www.vintagevolts.com) where I report on, reminisce, and generally discuss vintage electronic devices of all types.

While I usually focus on electronic devices which existed during my lifespan, I have found myself intrigued by a much older radio model, a Philco 19.

It was mainly my wife's desire to have an old "cathedral style" radio in the house because our house was built in the early 1930's. She is adding period items to our current decor.

We picked up this Model 19 at a flea market for $45. It looked nearly complete and the body was in very good shape. A small section of laminate is lifted, but can easily be glued back down and looking good as new. We were even able to scrape off some (duct tape?) residue along the back edge of the radio. It looked like someone had taped a cover on the back at one time and used strong tape to do so. The tape residue was very dry and could easily be scraped away using the edge of a credit card.

After a bit of cleaning and wood treatment, the finish is astounding for it's age. A previous owner must have intended to replace the speaker cloth eventually, but opted to cut out a section of cardboard from a restaurant picture menu and fill the cloth space with that instead. We had just replaced that cardboard with replica cloth.

What this leaves us with is getting the radio chassis running. Throwing caution to the wind, I checked to see if everything was where it needed to be (tubes, etc.) and I fired it up. I got lights, I got static from a dirty volume knob, but I got no signal, just a minor hum. Oh... and I saw a 44 tube that wasn't quite glowing as much as the other 44 tube. So, I decided to check the tubes.

The 44 that was glowing good had a broken top connector. It pulled right off, leaving a thin wire coming from the glass tube. Nothing appeared wrong with the other 44 tube. As I pulled each tube out of their sockets to clean/inspect them, I noticed the 75 tube glass was "twisting" slightly in its base. I've worked with tube TVs a LONG time ago and realized that a tube is NOT supposed to do that. The rest of the tubes appeared to be in good condition.

After ordering a used 75 and two NOS 44 tubes. I replaced the bad ones and fired it up again. The "activity" of the radio seemed different. I heard more of a hiss and hum, instead of just a hum as before, but could not receive any stations. Now it was time to break out the multimeter.

Let me point out that I have a trade school degree in electronics, but I don't practice in the field. However, I am more than comfortable, if not experienced, with repairing electronic devices such as these radios.

I first checked the filament voltages. On all tubes but the 80, I got 6.6v. The 80 only had 5.5v. That made no sense until I looked at the schematic and seeing that the 80 gets a different filament feed from the transformer. That makes sense to me as to why the filament voltages are different, but it doesn't make sense to me as to why they designed it that way. Why not feed all filaments from the same source?

Then, using a repair reference I found online, I checked the P-K voltages on the tubes. Most of them should be in the 230-260VDC range, but mine were all over the place, ranging from 160-270VDC. At this moment, I'm typing these results from memory as I'm not at my workbench to double-check the values and to which tubes those values belong. All I know at the moment is that there is something wrong with the radio.

My first assumption is that the transformer is bad. Which will be an issue for me because I'm not finding any good (affordable) resources for authentic replacements. The transformer is not leaking any material, but I believe it's not running to specifications because of what I noticed on the filament voltage for the 80.

BTW, the two electrolytics that would have been mounted between the transformer and tuning dial have been replaced with more modern versions, which are mounted in the rats nest with all of the other under chassis components. When I say "more modern", I mean in the 1970's or something. Those electrolytics just have that kind of appearance and manufacturing finish to them.

Assuming (and hoping) that this radio still has a chance to live again, I'm stuck on what I should do next. Should I trace the problems, fixing them as I go, or should I just consider completely dismantling the chassis and rebuilding it stage by stage, replacing defective parts as needed?

I'm thinking it'll be best (albeit more arduous) to dismantle the chassis. The hardest part will be keeping track of where everything goes, even if I take plenty of pictures beforehand. However, the chassis looks "unclean." Stripping it down would give me the opportunity to clean and polish it to look brand new again. I'll just need to commit to the time that level of restoration will take.

Thanks for reading, and any advice will be appreciated!

Jeff

[morzh]

Jeff

We will help you with concrete questions and troubleshooting once you get to that.

But first things first, please read through the very basic things one does when starting with an old radio.

That means:

1. No powering up before checking the state of the chassis. Big NO-NO!!!
2. No powering up before changing all electrolytic caps and all the caps that are from B+ to Chassis.
3. Very desirable - changing ALL paper caps. Leave micas alone for the time being.
4. Remove the rectifier tube, measure the load resistance to see if a short is present.
5. Check ALL tubes, so they at least present no danger and could be expected to work reasonably (even if weak) - no shorts or other BAD stuff.
6. At this point if you feel an itch, bring the transformer slowly up by using variac, measure the voltages, see if the output is reasonable and no smoke escapes.
7. Check all the resistors, replace those that are way out of spec (20% and more) or open. Make sure your wire-wound ones are not open, especially the one that connects the negative of the rectifier to the chassis. Sometimes those are Candohms and those are know to open.
8. Replace the rectifier and the tubes, then you can power it now, but ONLY slow using a variac and (very desirable, but absolutely necessary with "hot chassis'") isolation transformer. While bringing the voltage up, do the reading, making sure there are no load shorts / problems.

Now if all holds, nothing smokes and all glows, you can start troubleshooting.
That is where we come in.

[FStephenMasek]

Morzh:

I'd modify your procedure by putting the checking and replacement of resistors in with the capacitor replacement work. If you desolder the sonnection, it is easy to check all of the items connected to it at that time. To help prevent mistakes when several items at conencted to one point, the loose ends of the new and old parts can be twisted/looped together. I don't even bother keeping a stock of 1/2 watt resistors, as the 1 watt units are small enough, and provide an upgrade in circuit locations where the resistors have more of a work-out.

[Steve Davis]

Jeff, welcome to the Phorum!
Your transformer is probably just fine. The rectifier filament is 5 volts and must be supplied by a seperate winding because the B+ is also on the filament.

Steve

[VintageVolts]

Thanks for the response!

I can see it will be a while before I get anywhere with this radio. Some of the steps listed, even though I fully understand the validity of them, will take time for me to resolve. But, you're right. They should get done. I'm hoping to have an understanding of what I need before the Kutztown Radio Show in May. I'd rather get any and all parts I need from one venue. And before that time, I would like to know if this "$45 radio" is going to turn out to be a "$500 restoration project." I'm not interested in the latter. As much as I'd like to restore this radio, I'm not going to let it nickel and dime me to death. I'd settle for just putting the shell of the radio on the shelf for appearance and put a transistorized AM radio inside of it for effect IF it looks like it's going to cost more than buying another working radio as a suitable fix.

For example, Steps 2 and 3 will be time consuming. I understand the nature of aged electrolytics, but I would want to keep this radio looking as original as possible. As such, I could either spend a large sum for original looking replacements, or spend a lot of time rebuilding the cans and inserting new electrolytics in the can for function (but still keeping the same look).

Variac... out of the question. They are too expensive for something I expect to only use once. All of my other repair work is solid state circuitry and a variac is of little use to me. I don't plan on making a habit of fixing tube radios. I'd rather put my money into this radio for parts and not a one-shot piece of troubleshooting equipment. Replacing the electrolytics is the best step toward stabilizing the circuitry. That should take care of a majority of potential issues. I could just series a 2:1 and/or 4:1 stepdown transformer (items I already have) in line with the mains and put an incandescent lightbulb in series, monitoring it for excessive load when powering up the radio.

I have several isolation transformers. One of which I already plugged the radio into. I use them for arcade monitor chassis repair, which requires the use of an isolation transformer for safety.

After taking care of all the discrete components, I'll be at a point to properly tackle the tubes. Tubes are something that I'm familiar with, but not in a practical sense. I know what a Plate/Grid/Cathode is for, but I couldn't recite the operational specifications of them. I know how to test a transistor for shorts/opens, but I don't know if the relationship to tubes is a direct one. In other words, can I check for shorts between P/G, G/K, and P/K in a similar fashion?

After thinking about it, the only way I can be absolutely sure I accounted for testing/replacing all parts, is to do a complete tear down and restore. I'm not bothered by that prospect other than the amount of time it will take.

Assuming that I never powered this radio up and wanted to restore it by starting with a teardown, where should I begin? I've seen blogs showing such restoration attempts, but they seem to lack details, or assume the reader has at least some intermediate experience with tube based radios.

Repairing this radio is an opportunity for me. It gives me something to do in which I will gain knowledge and experience, then have something to show for it later. However, I can simply dismiss the opportunity if I'm knowingly stepping into a money sucking venture.

Thanks!
Jeff

[VintageVolts]

Steve,

Thanks for the clarification. That makes sense now. When I was checking the voltages against a voltage chart I found online, it listed 6.3VAC for all filaments. I was partially believing that the voltages listed are not wholly accurate and you helped to confirm that for the rectifier filament voltage.

Instead of blindly chasing down the other voltage issues, I'm planning on tearing down the entire chassis. It's the best way I know of to ensure I accounted for every part that needs replaced. Plus, I get a well cleaned up radio out of the effort.

Thanks!

[morzh]

FStephenMasek

You can do it at any point, and I also do it at the same time when changing caps, although for most resistors it does not matter because even with the tubes in they have no DC paths and are usually measured in-circuit pretty close to what they really are. From schematics one should be able to see those that he can measure in-circuit and those he cannot.

However I usually leave resistors till the end as once I can power the radio (most times resistors do not interfere with it) it'd be more interesting for me to see if it is even worth to proceed or maybe my tranny is shut, and then why am I changing resistors now when it can take me half a year to locate the tranny.

The exception to that is the wirewound resistors. Those I usually check immediately as they do affect the operation too much. The carbon resistors are not as critical. Say if the wirewound resistor that connects the rectifier to ground is open nothing will function at all as your whole circuit is not complete.

[Steve Davis]

Jeff, you are not looking at a lot of money to restore your radio. The total cost for all the capacitors and a few out of tolerance resistors will probably be less than $25.00. You can bring the radio up fairly safely with a dim bulb tester rather than a variac. You don't need an isolation transformer at all, they are only necessary for a transformerless set. The voltages you are seeing may be a little high because of the higher line voltage we have today plus the fact modern volt meters load the circuit less than the ones from the day the radio was made. Also, leaky capactors and out of tolerance resistors will cause readings to be off. I would not tear down the whole chassis instead, I would replace the filter caps and the line filter caps, then bring it up with the dim bulb tester (a 100 watt bulb in series with the line). Get the radio working, then change one or two caps at a time, checking to make sure the radio is still working. That way if you make a mistake, you will know where it is. There is plenty of help available right here on the Phorum.

Steve

[BrendaAnnD]

Someone should point him to source for info on rebuilding the bakelite caps (he may not even be aware these ARE caps).

[klondike98]

Info on bakelite block capacitors can be found here: http://www.philcoradio.com/tech/blocks.htm here: http://www.philcorepairbench.com/bblokcap.htm and here: http://www.philcorepairbench.com/capbuild.htm

[VintageVolts]

Thanks for the info everybody!

The wasn't fully aware of the nature of the block capacitors, but the info that was posted is very useful. I'll probably be checking/replacing bad parts in those, too.

All of the above advice and tips give me a good starting point to start troubleshooting this radio. For now, it's only a matter of time until I get it working again, but I'm confident that with my own determination (and your help) another Philco 19 will someday be reproducing the sound being carried over the airwaves.

Thanks!
Jeff

[Raleigh]

Lots of folks rebuild electrolytic caps, putting modern caps inside the old. We call it "restuffing." It's not very hard, and you mostly need just ordinary household tools and supplies. It's usually the first thing I do with a radio rebuild, after some cleaning. The bakelites are also pretty easy to restuff. Not everyone restuffs the paper caps, but some do. If you are really concerned with retaining an authentic look under the chassis, you might want to look into this.

I never strip a chassis completely, but always replace one connection at a time, to reduce errors and make sure that routing of wires and placement of parts is as in the original. Take digital pictures or make detailed diagrams of parts you remove to make sure you remember where all the connections go. This is helpful when several parts connect to the same point. Some people use different colored alligator clips to mark all the connections and the various parts that connect to them.

A good web site for a lot of the basics of electronic restoration of tube radios is here: http://www.antiqueradio.org/welcome.htm This site, run by Phil Larson, is the one that got me addicted to this hobby and taught me many of the basics.

Prewar capacitor values differed from modern ones. The difference isn't terribly important, mainly because the tolerance of the old caps was so high that a few % on one side or the other doesn't matter much. A .47 uF will replace a .5 uF perfectly well. However, I still buy most of my caps from the one place I know of that stocks the old values: http://www.justradios.com/ It is important to match or exceed the voltage rating of old caps, though. Tube radio caps were in the range of 200 to sometimes 700 volts or occasionally even higher. Most of us use tubular poly caps rated at 630 volts and electrolytics at 450 volts for radios with power transformers like yours. Some use "Orange Drops" at the same ratings. You can probably get those high voltage caps, in postwar values, wherever you get your supplies for solid-state electronics (except Radio Shack.)

Your modern tech supplies like hook up wire will work perfectly well unless you are particular about originality of appearance. You can get cloth covered wire from a number of sources. Try these: http://www.tubesandmore.com/ or www.radiodaze.com Some old wires used tracers in the insulation, but as far as I know, they are no longer available except in large gauges.

It is extremely helpful to have a good quality schematic and parts list. There are places where you can download free schematics, like here: http://www.nostalgiaair.org/, but these are often low resolution and incomplete. For Philcos you have the option of getting good quality copies of the original Philco documentation from Chuck Schwark. You can order inexpensively from this site: http://www.philcorepairbench.com/. The quality is outstanding, but you'll need to send a check and receive your copies by mail. It is well worth it. Considerable Philco tech information regarding unique Philco part numbers and restoration tips is also available on that site.

Great tech information, schematics, tips, and the occasional modification, especially for 30's and older Philcos, is available from Ron Ramirez's site http://www.philcoradio.com/. Ron also hosts this forum dedicated to Philcos.

[morzh]

One note:

>> It is important to match or exceed the voltage rating of old caps,

Only if you do not want to know what voltage really the caps working with.
For example, Philco, obviously for the reasons of the uniformity, stuffed most of its backelite caps with 600V types. However many work with voltages of tens of volts at most.

Of course using 600V across the board will rid you of the necessity to think of what cap needs what voltage.

[Raleigh]

If size and cost are not an issue, why NOT rid yourself of that necessity? I stock 630 volt poly caps. I don't bother stocking lower voltages, and in fact I'd have to do more shopping around than I want to, just to find them. If there's a good reason, other than size or cost, to use lower voltage caps to replace the paper caps, let's hear it.

[VintageVolts]

Electrolytics and resistors tested (wow, what a rats nest under this chassis). I'll soon be getting to all the bakelite blocks. Meanwhile, I want to prepare myself for testing and tracing the various stages.

Just curious, where are all of the good test points to check signals on each stage of the radio? Should I find some sort of a signal on the tabs at the top of the 44/36/75 tubes?

If using an oscilloscope, what signal levels should I expect to find? Primarily, I'll want to be able to check the oscillator output and work my way through all of the stages. If I wanted to inject a signal, do I simply inject an appropriate signal on the cathode of each tube and check the output on that stage?

Thanks!