Majestic 130A

[mkoser]

Hello,

Just today I picked up at Majestic 130A cabinet radio for $30. $30 is my absolute MAX for any old junk, so as you can tell, I was pretty happy to get it.

The cabinet is in really good shape. Someone has done some backyard refinishing on it, but it looks ok for now. No missing pieces and the only damage is to one leg (that I bumped the corner of the living room door with....)

The seller, who obviously doesn't know anything about old electronics, bought a schematic with the intention of getting it going. He told me that he got it for free and plugged it in and it didn't work. He did the same for me. All the tubes glow, and there is a very faint AC hum at the speaker, but that's it.

I took that 70 pound chassis out of it and was going to jump into replacing caps, but then quickly learned that all the caps are in cans, buried in tar. Nice.

Anyone ever recap one of these sets and have some advice for me? My 1928 RCA was a million times easier to figure out...

I have the copy of the schematic he gave me, and a bare bones schematic in my 1936 original radio service book. It's too late and I'm too tired to attempt to figure out what wires go to which caps tonight...

Thanks,

MK

[mkoser]

Well, I couldn't sleep so I got up and fiddled with this set some more. I quickly realized that my tube tester won't test 4 pin tubes...

All the tubes have been replaced with Zenith replacements, except one 45 tube that has a label on it that says "warranty replacement, warranty valid until 7-1-39."

I did notice that one of the 45 tubes does get hot while the other gets just barely warm.
Both schematics I have don't list voltages on anything, so other than proper filament voltage, I don't know where else to start.

I thought I'd see if any of my other 30's or 40's sets had 45 tubes, but none do.

[Reece]

Not too good an idea to plug in the radio for very long without checking everything out first. Do all the tubes light? If any doesn't, pull the tube and check for continuity with your ohmmeter between the two large pins (filament pins.) Should have continuity if the filament is good. Most of the time if the filament is good the tube probably is.

Pull the rectifier tube. Turn the chassis over and set your voltmeter for high AC voltage. Be sure the line cord is OK and not frayed. Clip the leads to the two small pins of the rectifier socket and turn the set on. Should read several hundred volts. Now check between each pin and chassis ground: each should read about half of the original high voltage reading, OK if there's a little difference between them. This would prove that the high voltage winding of the transformer is good. If so, leave the set on for about 20 minutes and watch carefully, sniff, feel the power transformer. If it just gets a little warm, good sign! Turn the set off and unplug.

If you have good tubes and a good power transformer, with the set off now check continuity on the speaker field coil, output transformer, RF coils, and so on. With your ohmmeter check resistance of each of the wire wound resistors and chokes shown in a long string across the bottom of the wiring diagram coming off the rectifier. Anything open or way off there could be a problem. You don't have to dig out the caps from the tar but can leave them disconnected and put the new caps under the chassis as they will be much smaller than the originals. Notice that caps A, B, and C are all 2 mfd. You can use 2 mfd poly film caps @ 630V or 4 or 5 mfd. electrolytics at 450V for all three of these caps.

Once you check out ALL parts to see that they are within spec, not shorted, not open, get the power supply working and go from there. No tube should have glowing red plates! Shut off immediately if seen and check for a short.

It's a process of elimination, part by part, checking it off the schematic as you go.

[mkoser]

Thank you for the tips.

Yes, I've already done the brief "safety checks" you described. I've brought the set up on a variac, and then with a dim bulb. I've metered the rectifier tube pins, and do have high voltage present. My filiment voltage is a bit high. All coils have continuity, as do the output and field coil transformers.

I'm leaning towards bad tubes, especially with the high filament voltage (about 10 volts), and the fact that ALL of the tubes are replacements in a set that looks as clean as this one is. There isn't a chip, fray, or rust spot on the cabinet or chassis.

This is about the 50th radio and television I have gone through. I've just never run into an animal such as this one before. My oldest set is a 1928 RCA, and the rest are late 30's to early 60's.

Thanks,
MK