[TheUniversalDave1]

    I got this gem today for $45. It still works, sort of. With a really good antenna, you can pick up a few stations, but you can't hear it unless the volume is all the way up. All the tubes check out good, and it has had its electrolytics heen replaced. I just don't know if it was done correctly. I was told that it has no B+. I think someone mucked up the capactors. What do you all think?

[sam]

hey dave
need to resize pic  number and schematic is nice
looks like 38-62 ?
same

[TheUniversalDave1]

Here is the scematic.

[TheUniversalDave1]

I just made a very interesting discovery. I opened it up, and I found that one of the .05 MFD capacitors is disconnected. I got a gator wire and clipped to where I think it went, and I got a whole bunch of loud obnoxious humming and feedback at higher volumes, but no stations.

[Raleigh]

It's hard to resist playing a new acquisition before doing a recap, but one again you are playing with fire if you do. Replace all electroytics, paper caps, out of spec resistors and flaking rubber wire, do an alignment, and most of your problems with a radio will disappear, most of the time. And you'll know it's safe.

With resistors, you ought to test them with one end disconnected. There is a shortcut that some people use. Since most resistors fail high, if your resistor tests low because of effects of other components in the circuit, the resistor is probably good. If it reads high in the circuit, it's probably bad, so it should be replaced.

I give a resistor 10% before replacing. A lot of guys say replace if more than 20% out of spec. These radios are pretty tolerant of out of spec parts, but definitely replace if over 20%. And replace electrolytic and paper caps no matter what.

[TheUniversalDave1]

Well, things are starting to get very interesting. I managed to get 850 AM very loud and crystal clear, but none of the other stations. I put the chassis back in and started messing with my antenna, and it starts playing! This radio is being very phinicky!

[Eliot Ness]

You're never going to get satisfactory results leaving in those 70+ year old capacitors.  Even that somewhat "newer" yellow electrolytic is probably leaky.  I bought a whole bag of new yellow Atom 'Lytic capacitors at the Dayton hamfest over 10 years ago and even back then they all tested leaky on both of my capacitor testers.  The only way I'd use one in a radio is by restuffing it with a new electrolytic.


John's (Raleigh) advice is sound, replace all of the capacitors and out-of-spec resistors and you'll save yourself a lot of headaches troubleshooting now and with future problems down the road.  Those black Bakelite blocks all contain capacitors that need to be replaced.  Mike (morzh) wrote a step-by-step procedure for easily replacing them:

http://philcoradio.com/phorum/showthread.php?tid=9107

[TheUniversalDave1]

    This Saturday, I will be restuphing the philter can and replacing all the wax paper caps NOT in the bakelite blocks. Those will come at a later date, as I only have 2-3 hours to work on Saturday morning. If somebody could post a picture of their 38-62 chassis underside, I would greatly appreciate it.

Is this drawing I made of the philter can correct? 

[Nick3092]

That drawing is correct. All 3 negative leads connect together and go to the center tap of the transformer. The red and blue 8uF leads will go each go to one side of the field coil. The 10uF green one goes to chassis ground.

[TheUniversalDave1]

Well shucks. This is going to be interesting. I opened this thing up again, and I phound that both the blue and the red on the philter can have been disconnected. The blue was cut close to the can, and the red was capped off with old wax tape. If my brain is perceiving this correctly, I should be able to disconnect the Sprauge Atom, and the blue and the red each go to one side of where the Sprague is currently soldered on. If not, I'll have to hunt for the 1100 ohm phield coil.

[TheUniversalDave1]

I also just discovered that the black of the philter can is connected to the negative of the Sprauge Atom, which goes to the transphormer. The green is also connected to the transphormer. Can someone tell me what's going on?

[klondike98]

When the original electrolytic capacitors in these sets failed, the repair guys would often just clip the connections to the original cap and then solder a new one into the circuit under the chassis. That Sprague is one of these repair additions. You will want to take the Sprague out, stuff new electrolytics into the original can and wire it into the circuit. As Nick said, the black (negative) leads on the electrolytics connect to the center tap of the transformer.

[TheUniversalDave1]

Which tap is that? Where is the 1100 ohm phield coil? That's all I need to know to get started on this set.

[Nick3092]

The center "tap" is the yellow with green tracer wire coming from the PT. Given that the wire colors will be faded and dirty, you'll have to trace it out. It will be connected to the negative of the lytics, to one side of R25 (200 ohm) and to one side of R21 (1 meg).

The field coil will be two of the 4 wires coming from the speaker. One side of the coil connects directly to the filament on the rectifier - either pin 7 or 8. The other side is going to connect to R31, R7, R11 and the red lead from the 1st and 2nd IF cans.

[TheUniversalDave1]

One more thing I thought of. Since I only get one or two stations on a good day, could a resistor have failed high? Perhaps the signal is being resisted too much resulting in not enough getting to the amplifier circuit. Or maybe it is after the audio output causing the signal to be weak at the speaker. Just a thought.