[AJboy123]

Hello all. I have a 40-190 and having some signal problems. It was working decent when I bought it awhile back but now the signal goes in and out. I now have to switch between broadcast and shortwave to bring the signal back in. Sometimes if I take the band switch it'll come back. Also there is some static on a lot of stations. Could resistors be the problem? Any help would be appreciated.

[codefox1]

Here are links to schematic and information on your set

http://www.nostalgiaair.org/PagesByModel...013339.pdf (free)

http://www.philcorepairbench.com/schematics.htm much (better quality $7.00 and highly recommended)


Did you clean the bandwitch and tube sockets and change out all the electrolytic and paper capacitors yet? This is a must for safety and longevity. Also install a fuse on the"hot" side of the line cord before the switch. 1 1/2 or 2 amps would do.

And yes resistors are also a possibility, and many have changed value or become noisy over the decades. I like to replace all the carbon resistors at the same time as I change the capacitors because you save time.

[AJboy123]

Codefox, thanks for the help. I cleaned the tube sockets and bandwidth but have changed out any caps or electrolytics. They all looked ok with no leaking so I thought why fix something that's not broken. Now I wish I did. I'm bouncing back and forth between that and my 1916 Compton Price Stradavera phonograph

[codefox1]

We mostly only fix broken things here.

Again do not apply power until you have fixed basics, lest you have only have landfill left.

[mgutierres]

I'm assuming you meant you haven't yet changed out any caps or electrolytics. They don't "leak" physically, but they do leak electrically due to age, especially electrolytics. The dielectric (insulator) dries out over time and renders the capacitor useless. Replace them all, paper and electrolytic. Resistors may also be a problem, but start with the capacitors.

[Raleigh]

Sometimes you can test a capacitor for leakage by disconnecting one lead and putting an ohm meter across it. A badly leaking capacitor will show some resistance on your meter, making it look like a resistor. A "good" capacitor will show an open circuit on an ohm meter. A better way to test it is to use a dedicated capacitor tester that has a "leakage" function.

But, you should assume that any of the paper capacitors is leaky and liable to short at any time. So it is better just to replace them all. All old electrolytics should be changed before even turning on the radio, as they are especially prone to aging and will damage power transformers that are difficult and expensive to replace.

Philcos from the late 1930s through 1942 used wire insulated with rubber, which becomes brittle and often breaks off over the years, creating a danger of shorting. All of that wire should be replaced or sleeved. I replace it by desoldering both ends of the wire while leaving it in place. Then I tack-solder a new wire to one end of the old one and gently pull the old wire out of the radio. This pulls the new wire through the exact routing of the old one. Routing of a few of the wires is critical to avoid interference of the signal on one wire with the signal of another. Other restorers desolder one end of the old wire and then slip a piece of heat shrink tubing over the old wire. You can either crumble the brittle insulation off the old wire or not, as you choose, but if you do it makes a better appearance.

Testing resistors is easy but a little tricky, because if it is connected in the circuit it resistance can be changed (usually lowered) by other components in the circuit. When you disconnect wire or capacitor connections you often can remove one end of a resistor connection also. Put an ohm meter across the resistor and compare the reading with the specified value in the parts list, or read the stripes to see what the original resistance was. If it varies more than 10% from the original reading, I replace them. Other restorers say 20% is good enough, and they are right. I'm just a little picky. Bad resistors almost always read higher than the original value.

You can replace resistors and capacitors with minimal soldering by cutting the part out of the circuit, leaving the leads in the radio as long as possible. Bend the leads into a loop or hook, and solder the new part the the hook. I usually desolder the old part on a radio I prize, but use the easier method on those less important to me.

If you need to switch the band switch to get good signal, your switch probably has more oxide on it that needs cleaning. Often a good cleaning job will work for a while but then it needs to be done again and again. It's a little discouraging at times, but that's life with ancient electronics.

Check out the detailed restoration threads with pictures that member Bob Anderson has posted on the phorum. (Use the search function to look for threads by "Bob Anderson.") I seem to remember he did one on a 41-255, which is similar enough to your chassis to give you many valuable hints, although the arrangement of the electrolytic capacitors is significantly different.