[NostalgiaRadioTime]

I purchased this at the radio meet two weeks ago...inheriting someone else's headache! But the Ingraham cabinet alone is worth that I paid for it, so I don't feel too bad.

   

Anyhow here's what I have. The set was recapped by the previous owner. Grid cap wires were replaced, light sockets rebuilt. In other words, he spent some time on this.

It was missing a speaker, which I had so after hooking that up and bringing the set up on the variac, I was encouraged to see no current draw and all tubes lighting. But there clearly was a problem with the volume control, it was uncontrollable. So I replaced that with a new 2 meg control and at least the volume (and audio output section) is working. But I get no reception whatsoever on any band.

Here's the Nostalgia Air schematic. Wish I could just post the actual schematic page but not sure how to post a PDF file direct.

http://www.nostalgiaair.org/pagesbymodel...017186.pdf

Going grid cap to grid cap I can inject a signal and get a loud buzz controllable by the volume control (ie, buzz gets louder as volume is increased) on the grid caps of both 6K7's, the 6L7 and the 6B6. Voltages all run 40 to 60 volts high, except for the plate of the 6J5 which is almost 3 times what it should be (it measures 288 and should be 110). Here's the breakdown:

   

The values in red ink are what I measure, to the left in black ink is what they should measure.

So I'm hoping someone with a keen eye (paging Dr. Terry) can give it a look and see what could be causing that voltage spike on the plate of the 6J5.  Ohm-ing out the coils is next on the check list but there must be something else causing the high voltage.

[Radioroslyn]

Geez! You need to find a hobby! What your tv broken?  [Image: https://philcoradio.com/phorum/images/sm...on_lol.gif]

So what did you replace the field coil with? I'm thinking that what ever it is it's too lower in resistance making your hv too high. The voltage @ pin4 of the 6V6 should be the hv @ it's highest you are almost 50v too high. Needs to be something around 1K. As for the 6J5 check the heater voltage and R-5 should read abt 30K, M on this set =K not Meg. Do check the osc coils for continuity. If that looks good replace the 6J5. Tech note grid 1 is the control grid, grid 2 is the screen grid, and grid 3 is the suppressor grid.

[NostalgiaRadioTime]

Thanks Terry. Maybe I should stick to watching TV!

At any rate I just wanted to mention that the speaker I'm using is a field coil type. Measures 1080 ohms. The audio output transformer attached to it measures around 500 ohms.

[Radioroslyn]

The plot thickens. Does the power transformer look to be the original one? Tar under the chassis where the wires exit the transformer? Extra mounting holes near by? Since your hv is pretty high I'd add a 1000 ohm 5w resistor in series w/the field coil for now. That should get you down to a more reasonable level.

[NostalgiaRadioTime]

Yes the transformer looks to be original and untouched. Well it is nice and cool to the touch when the set is powered on for any length of time.

[morzh]

What is the:

1. Voltage shown on the radio?
2. Voltage the radio is plugged into?
3. Voltmeter used to measure the voltages?

[NostalgiaRadioTime]

1. Voltage shown on the radio?

Not sure what you mean by "on the radio", Mike. Do you mean across the line cord? I checked all of the voltages listed on the schematic and documented them on the chart pictured above. Red ink is what I'm getting, the black ink is what they should be.

2. Voltage the radio is plugged into?

My variac, which is set to 120 VAC

3. Voltmeter used to measure the voltages?

Craftsman digital multi-meter. Been using it for years and it has always been accurate. https://www.amazon.com/gp/product/B000VN...UTF8&psc=1

[Radioroslyn]

I did the math on the plate voltage on the 6J5 and it would appear that it's not drawing much current at all like 5 microamps, should be abt 5ma. From the chassis the the - side of the filter caps should have abt -15vdc. If is 0 then that would add to the high volt 15v. If you remove the cap on the 6B6 and touch the grid cap does it buzz really loud??
The number next to the cathode pin that doesn't have a "v" is indicating the cathode current not the voltage as most a tied to chassis ground so there would be no voltage there.
To get a better idea what the pri of the power trans whats to see measure the heater voltage (6.3vac) and set your variac accordingly.

[morzh]

Voltage shown on the radio is the voltage printed on the label. Say, 117V.

[morzh]

It's not the question of the rated AC voltage but the AC voltage applied now vs the AC voltage at which the measurements were taken then. Then there is input impedance of the meter now vs then.
On top of what else is wrong.

[NostalgiaRadioTime]

It was a busy afternoon and early evening....

Here's what I did:

* All coils were checked and all have resistance and continuity where they should.

* Checked all resistors. None were drastically off. The R5 was 36.8K ohms (should be 30K)

* I get the 6.3 filament voltage exact when at 110 VAC on the variac.

Terry:

>> From the chassis the the - side of the filter caps should have abt -15vdc.

I get -5.3 vdc

>> If you remove the cap on the 6B6 and touch the grid cap does it buzz really loud??

With the grid cap removed, I get no buzz on the wire itself, but a loud buzz on the grid cap of the tube.

BUT....

I think I found the smoking gun (not a smoking radio...yet) just as I was going to call it a day...

The 6J5 OSC tube is NOT LIGHTING!!! Of course no stations are going to get through without that tube! I thought it was lit, but now that I turned out the lights and looked in the dark all I was seeing was the glow from the tube right next to it.

I get the 6.3 filament voltage on the socket, and now at 110 VAC on the variac I have the plate voltage down to 267 (from 288 at 120 VAC), but the tube is not lit.

I tried a 6C5, which should be a substitute (as I don't have a spare 6J5 here) and it too doesn't light. There may be a problem with the tube socket itself. Does anyone know of a good sub for a 6J5 other than the 6C5?

[NostalgiaRadioTime]

Update #2.... radio is playing just fine, and I feel really stupid right about now.

  came on in my head and I remembered I had a box of tubes I kept as a spare set for one of my consoles, and in it was a 6J5G tube. Popped it in and the radio instantly came to life. Picking up stations all along the dial. I will re-check the voltages tomorrow but I'll bet they are back where they should be. A dead tube certainly will throw the readings off.

My tube tester didn't have settings for a 6J5 so I couldn't test it. And (initially) not finding a spare 6J5 here, all I could do was try what the tube substitution book I have suggested, and that was a 6C5. I think the pinout is different between the two tubes, though.

At any rate I can sleep well tonight knowing the radio is playing once again

Thanks to everyone for their comments, ideas, and help. Much appreciated everyone

[Radioroslyn]

Actually the 6J5 and 6C5 do share the same pinout and are very close spec wise.
Glad to hear it's working!

[NostalgiaRadioTime]

I may have grabbed a dud 6C5GT then too, as it wasn't lighting either. But this 6J5G is!

When I bought this radio, the vendor at the meet handed me a box of parts....a spare bandswitch assembly with coils attached, a spare antenna coil, a spare tele-dial mechanism and a few other items. Then seeing that it was totally recapped, yet someone stole the speaker from it, I immediately assumed the worst....that this was a project someone started, found something major wrong, and gave up on it. That and the "unload my headache on to someone else" bargain price of $25, I just KNEW it couldn't be something as simple as a dead tube. Boy was I wrong! The guy even changed out the 1 meg resistor in the tuning eye tube socket so that works properly too.

Lesson learned...never assume the worst!

[morzh]

It's a bit more straightforward with ACDC as one tube with open filament makes the rest go dark.
Personally I always test tubes before I do anything else whatsoever.

Good thing it eventually worked.