[OZ4]

It sounds like the 7x7 and the 6v6s voltages are symptoms of the same problem. The overheating of the plate of the 7x7 says there is too much current flowing there. In reference to chassis ground what are the voltages on the 7x7 again. And check the two resistors that are hanging on the grid of the 7x7 pin 3. The 10meg and 1meg make sure they are connected correctly.

[klondike98]

yes, I'd wait until you get your other problems fixed before alignment. Hopefully you and OZ4 can sort it out.

[heats00]

I checked voltages again on the 7X7 and had these results.  

1 = 3.4 AC
2 = 158
3 = -1.14
4 = 0
5 = -123mV (this is a new problem, I previously had -.5 here, will check physical connections)
6 = 0
7 = 0
8 = 3.4 AC

The 10M and 1M resistors hanging off pin 3 of the 7X7 look to be in the correct positions.  I did double check the resistance of the 135 ohm candohm and it is reading 159 ohms.  I can provide pictures if they would be of help.

I also checked the voltages on the 6V6's  and I found higher voltages on one tube over the other.

6V6 #6 in schematic

3 = 292 (245 expected)
4 = 291 (260 expected)
5 = -12.5 (-1.8 expected)
6 = 284 (245 expected)

6V6 #7 in schematic

3 = 263 (250 expected)
4 = 268 (260 expected)
5 = -14.4 (-1.7 expected)

[OZ4]

Ok something is not right on your voltages for the 6v6s pins 4 both are the same point. Why the two different readings?

On the 7x7 the 123mv should not be a problem that is the agc diode and will vary with the signal level. It controls the gain of the previous IF stages.
 Check the cap going to the volume control. And check the resistor feeding the plate voltage (the 220k). If the value is correct there should be .6 MA flowing thru the tube. This is from the 291v on one side of it and the 158v on the plate of the 7x7. It should not be red.

Look and see if you can find anything about what kind of voltmeter was used to take the readings in the chart. Ohms/volt? When measuring grid voltages it makes a difference. (their real high impedance)
What kind of voltmeter are you using?

 I found at Nostalgia Air the info for this radio and on page 15-39 there is a chart for the voltages taken with different meters. The grid readings taken with the VTVM are like what you are getting. I would use these.
 

[heats00]

Guess I should look at more than just one service guide.  I think I saw that the readings were taken with a 20,000 ohm/volt on the Sams, but I will double check tonight.  The info on the Riders version is much more in line with the results I was getting.  Thanks for pointing that out.  I am currently using an Ideal 61-766 meter that I would like to replace, as I do not need the clamp portion of it and it makes it difficult to set on the bench and remain viewable. 

I am still having problems with volume with the radio playing, the record changer sounds wonderful and can get very loud.  I have to have the volume pretty much maxed to hear radio stations.  There are still higher than normal voltages on both pin 3s of the 7H7 tubes.  There is a 33k resistor and 240 pf capacitor leading to pin 3 of the 7F8 left to replace in that circuit, but they are under the band switch assembly. 

7H7 1st IF Amp
pin 3 = 173v (105v expected)
 
7H7 2nd IF Amp
pin 3 = 148v (125v expected)

I will double check the pin 4 voltages on both 6V6's also.

[OZ4]

On those 7H7 voltages being too high first look at the 7F8 pin 3 the plate voltage.

The 7F8 should be drawing current to set the voltage drop for the 7H7s pin 3. Is it high too? If so then check the resistors feeding from the power supply.

And of course check the other voltages around the 7F8. If it's bias into cutoff then those voltages will be high.
 

If you get the voltages right I suspect that the radio volume will come up.

[heats00]

[Image: https://lh3.googleusercontent.com/j_gxub...38-h955-no]

How do I remove this band switch assembly?  The 7F8 is underneath.  I can get readings from pins 1 and 3 and they are -2.3 and 72 respectively.  They seem to be lower than expected (-4.7, and 110).  I can see the 33k resistor and 240 pf micamold cap under the assembly but can't get in to replace them.  There are several other micamolds that look very waxy and dried out-looking resistors inside the switch also.  Should I replace them while I have it out?

Also, the readings on pin 4 of both 6V6's is identical.

[OZ4]

On the bandswitch   I would take lots of pictures first then unmount it and unsolder only the wires that are needed to take it out. I don't know of any other way to deal with it.

[heats00]

That's what I thought. Sounds like this is a project for when everyone else is in bed and I have a fresh pot of coffee.

[heats00]

I was able to work on things a bit today. PHEW! Hopefully I will find a better way to do this for next time. I'm sure my blood pressure was a bit high today. I got the potting out of the bakelite block and recapped with the safety caps, and replaced the 33k resistor and 240 pf cap feeding #3 on the 7F8 tube and also replaced a few other resistors that tested out of spec. I did find one suspicious resistor, #57 mixer plate decoupling. The schematics call for a 47K ohm (or a 4.7K depending on model) and I had one that had a green paper wrapper that said 60M, but the color code lead me to believe that it was a 60K. I replaced it with the 47K. After carefully reassembling everything I powered up and everything looked okay. I seem to get more stations now than before but I still have to have the volume turned up considerably. If I hold the antenna while tuning I get A LOT more stations at what seems to be a normal volume, but still not much below 900kHz (buzz @800 kHz) Do I need to do an alignment now?

[OZ4]

Before you try and align it how are the voltages? No more glowing plates?

[heats00]

[Image: https://lh3.googleusercontent.com/pb7uiK...98-h955-no]
This is the glow I see from the 7X7 tube in the center.  It looks much worse in the camera.  Normal?

I have not checked voltages yet as I ran out of time last night.  I will report back when I can.

[OZ4]

On that 7x7  don't forget to check the voltage drop on the plate resistor and figure the current to tell if it's too much. It's the 220K.

Here it states that 7x7 as a class A amplifier it's plate current should be 1.9MA
I am sure yours should be no more than that.
http://www.nj7p.org/Tubes/SQL/Tube_query.php?Type=7X7

[heats00]

I took all voltage readings and measured voltage on both sides of the 220K plate resistor for 7X7 (245v, 145v).

I'm only listing what I think is suspect readings, but I do have them all and these were taken @ 117V AC.  I did notice that when I clipped the test lead to pin 8 of the 7F8 I had great reception and volume.  

7F8
1 = -3.1 (-4.7)
3 = 120 (110)
5 = 6.7 (8.6)
6 = 217 (245)

7H7
3 = 125 (105)

7H7
3 = 130 (125)

7X7
5 = -108mV (-.6)

7AF7
4 = 42 (48)
6 = 40 (36)

5Y3
2 = 311 (320)
8 = 310 (320)

[OZ4]

Chase
I don't see unusual about those voltages they are not likely to be right on. As for the reception is the antenna correct? Are there any local stations to hear? (Where I live there are no local stations so all the radios I work on sound weak. I have to wait for night time.) If the antenna is correct I would look into the coils L1 and L2. Check their resistances. Sometimes they can open up.
You should be able to measure L2 in circuit and L1 you can measure if you disconnect the antenna.

If the coils check good then I would try an alignment.