My Stromberg Carlson model 1110 gets loud static that comes and goes on both the radio and phono. Sounds just like your car radio when you are close to high voltage lines. I have recapped the unit. What can be wrong?

Since you have the problem with the phone, too, the problem must be in the audio section.

Pull the 6SQ7 tube out. If the problem is still there, it's in the audio output section or power supply. Check all of the ground points at the 6SO7 and 6K6. If this set uses the tube socket ring as a ground point. It is possible the rivets are not making good contact with the chassis.

Hi John

Remove cap C26, 100pf, from plate of the 6SQ7 to ground. This cap can cause a similar noise to silver mica disease in IF Transformers.

http://www.nostalgiaair.org/PagesByModel/280/M0021280.pdf

Norm

:My Stromberg Carlson model 1110 gets loud static that comes and goes on both the radio and phono. Sounds just like your car radio when you are close to high voltage lines. I have recapped the unit. What can be wrong?
:

Hi everybody,
Thanks for your ideas. I'm still in a quandry. Clipped that 100pf cap. Norm suggested and no luck. This set takes a tab from a tube socket pin and solders it to the chassis for grounds...resoldered them...no luck. When I get the static storm sound I pulled the 6SQ7 and it quits right away. Sometimes when the radio is playing good and I switch to phono I get that loud static sound and sometimes it occurs on the radio band at random. When there is static if I turn the tone control fully cw it is reduced almost completely.

:Hi John
:
: Remove cap C26, 100pf, from plate of the 6SQ7 to ground. This cap can cause a similar noise to silver mica disease in IF Transformers.
:
:http://www.nostalgiaair.org/PagesByModel/280/M0021280.pdf
:
:Norm
:
:
::My Stromberg Carlson model 1110 gets loud static that comes and goes on both the radio and phono. Sounds just like your car radio when you are close to high voltage lines. I have recapped the unit. What can be wrong?
::
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:

The problem would seems to be with in the AF amp. Try another 6SQ7. The volume control could also be suspect. A crack in the carbon disk, or bad contact from lug to disk. Wiper arm could also have poor contacts. May try subbing in another 1 meg pot.

Thanks Warren,
I have tried another 6SQ7 and no luck. Will try to sub a volume control tonight.

:The problem would seems to be with in the AF amp. Try another 6SQ7. The volume control could also be suspect. A crack in the carbon disk, or bad contact from lug to disk. Wiper arm could also have poor contacts. May try subbing in another 1 meg pot.
:

60 cycle buzz. Like you hear when driving under power lines. This would not indicate that it's something to do with the volume control, since the volume control handles DC, and any scratchiness it would have would not 'buzz' at 60 cycles, but rather at random frequencies, and would be heard as scratch and crackle, with no definite frequency. Could possibly be the 100pF tone cap, though this would more likely crackle at a random frequency than at 60 cycles, and we have ascertained that this is not the source of trouble.

I would look at the power switch and the power transformer, and possibly any other wiring having to do with 60 cycles (possibly the filament wiring, though not definitely). I'd check any RF filtering capacitors across the AC cord for arcing. I'd check the power switch for dirty contacts. I'd check the power transformer for arcing, and possibly the rectifier and/or socket. This set uses a 6X5 rectifier, whose filament is connected to B-, and whose cathode is at 120 cycle pulsating DC potential (the filter capacitors should normally smooth voltage here to almost pure DC, but if a strong enough arc occurred between the cathode and the filament, this might overcome filtering, and a 60 or 120 cycle buzz would be heard).

Then, if no trouble was found here, I might assume that the 6SQ7 is merely picking up this static from something nearby (a cell phone charger, fluorescent, or other source of 60 cycle buzz). The 6SQ7 has a 10Meg grid leak resistor and a 1Meg volume control, so this thing is going to have TONS of gain and sensitivity. I'd listen to this radio and another radio and see if the static could be heard on both. If so, then I'd unplug this radio and see if the static went away. If so, then the static is being created within this radio. If not, however, I'd assume that the 6SQ7 has some incredible gain, and that the grid wiring isn't amply shielded. I'd either shield the grid wiring (and capacitor) or try to find the source of static within my home (or both). Shielding of the grid wiring may be obtained by slipping a spring over the wiring and grounding this spring to the chassis. 5 to 10 turns of wire can be wound around the grid capacitor and also connected to the chassis.

T.

I would agree with Thomas, except the problem is being described as Static as from High Voltage lines. (arcing)
Not an actual 60 cycle hum. By pulling the 6SQ7 the problem is gone. Would think that would eliminate power supply, and audio amp. Problem is also said Intermittent. Since the problem is also in the phono position, that should leave the few components in the AF amp. Including the volume control. Or even the tone control.

Usually when I drive under power wires, the 'static' I hear has a 60 cycle buzz to it. ...Pretty much always. ....So if it sounds like you drove under a power wire, then it's going to be 60 cycle related.

If not, then it could be anything and everything in the radio. ...But if it is, then you need to look where there's AC.

T.

Hi Everyone,
I tried subbing a volume control and no difference. I found that the sound quits when I pull out the 6SQ7, but then I tried pulling out the other tubes one at a time and the buzz/static quits also except it does not quit when I pull out the rf amp. When I pull out the rf amp the sound gets a little less and changes in pitch but is still there. All this with the selector switch in phono position.I can rock the rf tube in its socket and sometimes make the buzz/static quit. Can't, however find anything loose and changed tubes but no help.

:Usually when I drive under power wires, the 'static' I hear has a 60 cycle buzz to it. ...Pretty much always. ....So if it sounds like you drove under a power wire, then it's going to be 60 cycle related.
:
:If not, then it could be anything and everything in the radio. ...But if it is, then you need to look where there's AC.
:
:T.
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When in the phono position the input grid of the 6SQ7 is switched out of the radio, and is just being used as an amplifier. However anything else in the radio that is causing static can be picked up internally. Since rocking the RF tube does stop the static. Would think there still is a bad connection around that area. I would re-solder ground connections in this area. The band switch is also the the phono selector. Could be a weak contact there. Probe the contacts with a non-conductive tool. Sometimes the rivet that holds the contact is place is loose. Can solder the rivet to contact point.

Something very strange happens. When in phono position and I'm hearing the buzz all I have to do is just touch the MTT style rf tube and the buzz quits.

:When in the phono position the input grid of the 6SQ7 is switched out of the radio, and is just being used as an amplifier. However anything else in the radio that is causing static can be picked up internally. Since rocking the RF tube does stop the static. Would think there still is a bad connection around that area. I would re-solder ground connections in this area. The band switch is also the the phono selector. Could be a weak contact there. Probe the contacts with a non-conductive tool. Sometimes the rivet that holds the contact is place is loose. Can solder the rivet to contact point.
:

The RF tube is a 6SK7 .. Make sure pin #1 is grounded well.

Hi Warren,
Well this morning I checked and resoldered the ground on pin 1 of the 6SK7 (rf amp) and they are are all fine. They tie three pins to pin one. I found that when I jumper pin 5 (cathode) to chassis with a 2ft long jumper cable the buzzing stops. So I took a piece of buss wire and grounded pin 5 directly to the chassis. This did not stop the buzz. Near as I can measure my 2ft long jumper measures .1 ohms and maybe is acting as some kind of "gimmick." I'm going to keep probing around for something loose but have been and nothing so far.

:The RF tube is a 6SK7 .. Make sure pin #1 is grounded well.
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:

Try swapping the two 6SK7 tubes around. These tube have interlead sheilds. Pin #1 should be connected to the metal case of the tube. It is possible that the lead is making poor contact.

http://www.nj7p.org/Tube4.php?tube=6SK7

Is there a poor heater connection at one of the tubes? Maybe the 6SK7? Is there a poor connection at the rectifier socket? I'd check voltages at each tube socket (especially heater voltages and high voltage at rectifier) while this static is occurring.

T.

I tried another 6SK7 [GT this time] and got static/buzz on AM but when switching to phono never got the buzz. The station I had tuned in is local but often has static and hard to receive. I don't know why. I tuned in a stronger station and played the radio for about an hour with no problems and the phono position remainedd quiet. I had previously tried this tube but forgot that that station often gives trouble and so I thought the problem was not cured. Thanks for your patience and all suggestions.

:Is there a poor heater connection at one of the tubes? Maybe the 6SK7? Is there a poor connection at the rectifier socket? I'd check voltages at each tube socket (especially heater voltages and high voltage at rectifier) while this static is occurring.
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:T.
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Or try cleaning the volume control if it hasn't already been done.

Clifton

:The problem would seems to be with in the AF amp. Try another 6SQ7. The volume control could also be suspect. A crack in the carbon disk, or bad contact from lug to disk. Wiper arm could also have poor contacts. May try subbing in another 1 meg pot.
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