[jerryhawthorne]

Andrew, I might also suggest when measuring resistors, I measure them in circuit. If they are high, replace them. If they are low (seldom) then lift one end and measure, they may be in parallel with something like a coil. I never just lift an end to measure unless it is low. If high they need replacing.

[Andrew Fleck]

Thanks Jerry. I will keep that in mind when I check them out today. I only see the value of the resistors listed in ohms in my schematics. Isn't wattage important too? From what I have been reading you don't want to go low on your wattage or you risk overheating. Is there a way to see what the original wattage of these are providing I have to replace any of them?

Andrew

[Radioroslyn]

My little red meter was 4.95 at HF
Measures up to two Megs Won't
measure anything over 500vdc
as one of them lit up inside and
never worked again.
Terry

[Mondial]

Andrew, have you tried cleaning the bandswitch with contact cleaner? If the radio has not been used for years, chances are the contacts have a layer of corrosion which can cause a no reception condition. This radio has a very complicated band switching arrangement and a single contact can cause a problem.

Do all of the tubes light? The loctal tubes used in this set have a tendency to develop bad contacts from the pins to the sockets.

Try to localize the problem before randomly replacing parts. Chances are a resistor which has changed in value will not cause the radio to fail to receive at all. Start by taking voltage readings at the tube sockets and compare them to what is shown on the schematic.

[Andrew Fleck]

Mondial, I have not cleaned the bandswitch, but I will shortly.

The tubes do all appear to light up. I was looking at them yesterday.

Andrew

[Andrew Fleck]

I just got done cleaning the bandswitch, but it is hard to get in there let alone see what I am doing. I used an aerosol cleaner with a straw tube to try and get to the contacts the best I could. The radio still will not play anything. Does anyone know of a better way to clean these?

[morzh]

Andrew

I can see this is turning into some "I am gonna try bunch of unsystemathized moves, so keep telling me in what direction to run".

Again: get methodical about it. Can you get lucky? - yes you can, but you won't learn anything and you might not get lucky.

Get a meter.
Measure voltages.
Clean the switch a proper way (try that Fader Lube thing, Deoxit).

Check continuity of various coils.

But get methodical.


PS. In tube schematics resistors most of the time are loaded with what becomes open circuits when powered down. Those biases to the grids, loads and such - they often meet a tube electrode (grid, anode) on one end and when powered down this end is disconnected.
So, tube-based circuits lend themselves that much better to in-circuit resistor measurements than say transistor or any semiconductor curcuits do.
So when checking resistors, it is often enough to just place the meter leads across the resistor and see if it is higher value by more than 20%.
There are some exceptions, but they are few.

[Andrew Fleck]

morzh,
I have a meter coming in the mail. I couldn't justify paying almost double in the store as opposed to online. When it comes on Tuesday I plan on testing everything I can to include the new capacitors I put in. I plan on starting with all of the resistors, then moving on to the capacitors, and finally finish with the coils as you mentioned. Once those are tested I will clean the bandswitch again. Thanks for the tips on the resistors. It would be nice to not have to disconnect an end if it can be helped.

Andrew

[morzh]

Yes, that is good not to disconnect.
However do not expect this to work with caps - it won't. Unlike with the resistors, to measure a cap most of the times you do have to disconnect.

But you did say you replaced the caps, so you do not have to measure them. You only have to recheck that you soldered them in correctly. It is not likely, or rather is downright unlikely that
you got bad caps.So you could forgo testing the caps. Just check the connections.
PS. FOr your sake I hope you simply were pulling out the old caps and soldering in the new ones. It is a bad idea to take out all the old ones and then put the new ones using the schematic: Philco schematics are know to have errors in them, and then you might read the sch wrong too.

[Andrew Fleck]

Oh no. I replaced the capacitors one at a time with a matching capacitor. I checked all of the connections for continuity between the appropriate post and wire lead and they all checked out fine.

The only part that has me a little worried is the electrolytic capacitor. The old ones I removed were replacements to the originals at some point in time and they were the wrong values according to the schematic. On my schematic it calls for one 18 mfd cap and one that says 8-8. The ones I pulled out were a 40 mfd in place of the 18 mfd and a 20+20 which had replaced the 8-8. The 20+20 was tube with the positive side having 2 wires come out and the negative side having 1. I'm assuming that there were actually two 20 mfd capacitors inside that tube based on that configuration. My replacement caps are one 20 mfd and two 10 mfd. This in my eyes is much closer to the schematics. With the two 10 mfd I wired their negative wires together to achieve the same type of configuration. This is the only part I really had to guess on. It makes sense to me, but it still has me a bit worried.

Andrew

[Warren]

Sounds like you shouldnt have a problem with the way you setup your caps. As far as the resistors, thats true, check them and if they seem good dont worry about unhooking one side but if it is off then unhook one side just to make sure. Good Luck checking everything.

[morzh]

...that is if it is off on the LOW side, then unhook and measure. If it is off on the high side and way above target - then it is 100% candidate for replacement..

[Andrew Fleck]

I have began to check the resistors in this radio and I may need some help with this. Is it normal for a resistor that is supposed to be 56 ohms to read at 961,000 ohms? I'm pretty sure that I am doing this correctly, but that seems awfully high to me. Most of the resistors that I have checked so far don't seem to be corresponding with what they are supposed to be at. All I am doing is using a multimeter on the resistance setting and putting a probe on each side of the resistor to get my reading. I have a resistor that is supposed to be at 10 ohms and the multimeter will not detect it.

Andrew

[jerryhawthorne]

Andrew, first step, if you have any new resistors, measure them on your meter to confirm that the meter is reading right. Yes possible that something like a 56 ohm is reading close to a meg if it an open wirewound or a really burned out carbon. Should you have some new resistors measure them to make certain you meter is working.
Regards, Jerry

[morzh]

Andy

Multiple times I came across this: an old resistor will not measure correctly on the multimeter.
The reason happened to be oxidation on the resistors' leads and solder: there were no connection. It took some pressing and rubbing the leads with the meter's probes' pointed ends to be able to see the resistance.

In your case, as Jerry has suggested, first use a known good resistor to make sure your meter is working although to me you only have to put the leads together and see 0.2 - 0.3 (or close ) Ohm resistance measured, that to me would validate the meter. In case you have no resistors available.

Now, I hope the question does not offend you, but: you do understand that you always measure resistance with the power OFF and NEVER EVER do it with the power ON. Right?