[TheGorper]

First let me say thanks to everyone that has assisted me so far.

The radio will pick up a few strong local stations now faintly and they come through the speaker with a significant amount of buzz / static.

I am using a 20 foot long wire antennae.

My question now is: How can I proceed to clear up the buzz / static and get the sound to come through clearer now that I have made it this far? I also get an intermittent beep through the speakers that is not part of the over the air broadcast.

Any ideas are greatly appreciated. You all have been very kind and patient with my silly questions thus far and I appreciate it.

Repairs thus far include:

1) Replaced all capacitors including the electrolytics, all bakelite blocks, all filter bank capacitors in metal boxes, the caps in the tone control. Used correct safety capacitors for the line to ground caps. The only capacitors I did not replace were the various compensating capacitors around the radio.

2) Replaced all resistors in the radio. So were still right on some were off and had drifted in value, but all were replaced.

3) Replaced any and all wires I could see that had bad insulation or in some cases were nibbled by mice and had no insulation.

4) Speaker was completely rebuilt by the "Speaker Shop" in Lima Ohio. I thank them for the excellent job they did reconning and refurbishing.

Notes:

A) Tube fillaments all glow and the 80 tube and two 42 tube get fairly hot (like a light blub) but don't seem to be getting excessively hot.

B) I have made an attempt to provide air space between wires under the chassis (were it looked logical) but see no arcing sparking or other problems indicating any insulation issues.

[TheGorper]

Update: Saw the other thread out here about the Oscillator Coil part #19 part # 05985, so I checked it as described in that thread.

Measure the resistance between the cathode pin of tube 36 to the Oscillator coil lug with the mica cap and resistor on it. It measured 5.6 ohms.

Base on what I saw in the other thread this sounds within the normal range. Still looking and researching....any assistance is still appreciated.

Going to continue to read the other thread for anything else I might find.

[Ron Ramirez]

The "beeping" is probably local interference, and the buzzing/static might be as well. Wall warts, light dimmers, some newer ceiling fans...in other words, most modern household items generate a lot of RF that can wreak havoc with AM reception.

[TheGorper]

Ron - That was a really good call on the interference!!!!!! Thanks for your posting that response.

Of course, I feel really foolish that I didn't guess that myself, but really glad to know what the problem was.

The room I was working in had a wall dimmer switch nearby and two ceiling fans overhead with dimmers and electronic controls built into them.

I got a small portable battery powered AM radio and walked around the house. First, I started in that room and I had exactly the same horrible buzzing, etc. as on the Model 91. So I walked around the house and found a spot with minimal interference and then moved the model 91 radio there.

I re-strung my antennae and grounded the set as before an man did it play great! I was picking up stations (here in suburban Charlotte, NC) from all over the country.

Bottom line: It plays and works great!!!!!

New list of problems include:

1) The shadow meter doesn't appear to be working.

2) The set appears to be about 30 KHz off. Example: Dial says 1080 when I pick up 1110 WBT, or 1030 when I get WKYW at 1060. Alignment problem?

3) I noticed my ground wire sparking when it touched the chassis or ground lug. I measured 60 volts AC by putting my meter in AC mode and measuring by touching one probe to the chassis and the other to the well grounded ground wire. Obviously, somewhere I have a hot wire leaking to ground. Note: Used safety capacitors for the line to ground capacitors in part 53 (part number 3793-E).

4) At the top end of the dial (above 1430) the set goes quite sometimes and I have to tune way down to around 900 and then run the dial back up and re-tune the station (above 1430 or so) to get it to play again.

I am sure these issues can be cured with time and patience and a little work. But wanted to thank you for the help.

[Ron Ramirez]

I forgot to mention CFL bulbs. The ceiling fan in our living room has four CFL bulbs in it. My 41-616 was making a low grinding noise when on, that it did not make on the bench. Turned off the lights in the ceiling fan...the noise stopped.

Anyway, to answer your issues:

1) If the shadow is not changing at all, you have either a mechanical problem (vane doesn't want to move) or a weak/dead magnet inside. Yes, there is a tiny magnet inside the shadowmeter, and these can go bad. Chuck's site has helpful info on shadowmeters:

http://www.philcorepairbench.com/tips/svctip01.htm
http://www.philcorepairbench.com/tips/svctip01a.htm

2) Yes, alignment problem.

3) The safety caps from each side of the line to ground are causing the sparking. The only way to eliminate the sparking is to eliminate the line bypass caps, which I do not recommend.

4) Oscillator issue. First, try changing resistor (21) from 10K to 7.5K. Schematic here:
http://www.philcoradio.com/tech/images/1491.jpg

If that doesn't help, you may have to pull the oscillator coil and either bake it in your oven for 30 minutes at 200 degrees F (do not exceed 200 degrees), or carefully go over it with a heat gun on low setting for several minutes. I recommend the oven method. Set the coil, lugs down, on an old baking pan lined with aluminum foil. The wax will collect on the foil. When done, let cool then throw the foil with the old wax away. By baking the coil, you are removing moisture that has built up over the decades and which impedes normal oscillator operation.

Read about a similar experience I had with a Philco 89 on Chuck's site:
http://www.philcorepairbench.com/tips/svctip42.htm

[TheGorper]

Thanks Ron - Will try the above advice and let you know how it goes.

[TheGorper]

One other question....

I noticed that having the antennae wire attached or detached makes no noticable difference in receiption.

But I also noticed that if I put my hand over the three coils around tube 36 that the receiption gets noticable and substantially better.

I still haven't changed the resistor to 7.5 K Ohm yet but was surprised that the antennae makes no difference at all.

I checked to make sure the antennae clip was isolated correctly from ground and it is.

[TheGorper]

As far as #4 the Oscillator issue goes.....

I replaced the resistor with the 7500 Ohm resistor and it didn't make a big difference.

So next I pulled and baked the coil as directed, which helped the radio to pick up stations across the dial correctly without cutting out as it was before.

The antennae being connected or not connected doesn't seem to make a huge difference in receiption, but placing my hand over the coils does.

Does anyone have a recommendation for finding or obtaining a signal generator to try and conduct an alignment?