"M" on this schematic denotes times 1000. 200M would be 200,000. The "M" is the roman numberal for 1000. Later "K" was used to denote times 1000. You may try tracing the leads from the 6G5 socket to points in the chassis and using clip leads try a 1 meg Ohm resistor across those points and see what you get. If the 6G5 works then you will know that the resistor in the socket has opened up.
Radiodoc
**********
:: Hi guys. I am having a problem with the 6G5 tuning eye on this radio. It glows fine, but only closes the tiniest bit on a strong signal (but it does move). I swapped it out with a 6E5 to see if I could exaggerate the response, but it is the same. The schematics for this radio show very little identification for components...no pin numbers on sockets, no voltages...pretty spartan. In particular I don't see the typical 1 megohm resistor I would expect to find between pins 2 and 4. In fact, there's just a line coming off of a 200 megohm resistor that says "to 6G5 grid". I don't read anything between pins 2 and 4 on the socket, but I don't want to crack open the socket only to find that there isn't a resistor inside. Could someone help me identify the key elements to check to be certain the AVC is OK? The radio doesn't track very well either, especially on the low end of the dial. Perhaps it just needs a good alignment? The volume and reception are very good, but some stations (especially music) do sound a bit garbled. Thanks.
:: Oh geez...why the heck didn't I think of that...I was a classical archaeology major for crying out loud. So if they were using the Roman numbering standard, would I expect 1 megohm to be a 1 followed by an M with a line over it? I'll try to trace the wires down and install the resistor, but if the original resistor did open up, wouldn't the eye be completely nonresponsive?
Paul
::Paul,
::
::"M" on this schematic denotes times 1000. 200M would be 200,000. The "M" is the roman numberal for 1000. Later "K" was used to denote times 1000. You may try tracing the leads from the 6G5 socket to points in the chassis and using clip leads try a 1 meg Ohm resistor across those points and see what you get. If the 6G5 works then you will know that the resistor in the socket has opened up.
::
::Radiodoc
::**********
::
::
:::: Hi guys. I am having a problem with the 6G5 tuning eye on this radio. It glows fine, but only closes the tiniest bit on a strong signal (but it does move). I swapped it out with a 6E5 to see if I could exaggerate the response, but it is the same. The schematics for this radio show very little identification for components...no pin numbers on sockets, no voltages...pretty spartan. In particular I don't see the typical 1 megohm resistor I would expect to find between pins 2 and 4. In fact, there's just a line coming off of a 200 megohm resistor that says "to 6G5 grid". I don't read anything between pins 2 and 4 on the socket, but I don't want to crack open the socket only to find that there isn't a resistor inside. Could someone help me identify the key elements to check to be certain the AVC is OK? The radio doesn't track very well either, especially on the low end of the dial. Perhaps it just needs a good alignment? The volume and reception are very good, but some stations (especially music) do sound a bit garbled. Thanks.
:Lewis,
If I were embarrassed about everything that I don't know concerning tube radios, I wouldn't be able to find the guts to post anything here (LOL). Seriously, do all of the very early schematics look like this? I can't make heads or tails of things compared to the schematics for my Philco. Is the 1 megohm resistor always within the socket, and is it at times omitted from the drawings. I don't see it at all. Oh well, I'm going to have to be very patient on this one, as I know there is more of a problem than the eye tube alone....bad tracking, slightly garbled sound. I don't quite know where to start I guess.
Paul
As Lewis mentioned, it is very likely the 1 meg resistor has probably increased considerably in value. Many times for values of 1 meg or larger the value was followed by "meg". If the resistor in the socket has gone bad and you are afraid to open the socket up to install a new one, you could just as well install one under the chassis instead.
Radiodoc
**********
::Doc,
::
:::: Oh geez...why the heck didn't I think of that...I was a classical archaeology major for crying out loud. So if they were using the Roman numbering standard, would I expect 1 megohm to be a 1 followed by an M with a line over it? I'll try to trace the wires down and install the resistor, but if the original resistor did open up, wouldn't the eye be completely nonresponsive?
::
::Paul
::
:Paul;
:Don't feel embarrased for falling for the old "M" vs. "K" trap. Everybody I have known has had to learn the hard way. That resistor might have changed value. Some of the higher resistances tend to do that, even today.
:Lewis
It's hard to add a resistor under the chassis if your radio has a socket with resistor built in. The eye tube socket won't have an extra wire for this resistor.
Norm
:Paul,
:
:As Lewis mentioned, it is very likely the 1 meg resistor has probably increased considerably in value. Many times for values of 1 meg or larger the value was followed by "meg". If the resistor in the socket has gone bad and you are afraid to open the socket up to install a new one, you could just as well install one under the chassis instead.
:
:Radiodoc
:**********
:
:
:::Doc,
:::
::::: Oh geez...why the heck didn't I think of that...I was a classical archaeology major for crying out loud. So if they were using the Roman numbering standard, would I expect 1 megohm to be a 1 followed by an M with a line over it? I'll try to trace the wires down and install the resistor, but if the original resistor did open up, wouldn't the eye be completely nonresponsive?
:::
:::Paul
:::
::Paul;
::Don't feel embarrased for falling for the old "M" vs. "K" trap. Everybody I have known has had to learn the hard way. That resistor might have changed value. Some of the higher resistances tend to do that, even today.
::Lewis
If the set seems to be operating normally with the exception of the tracking, would the resistor typically be the problem? If the set were in need of a proper alignment, could that cause the eye tube to malfunction as well? I ask because of the bad tracking on the low end. Thanks.
Paul
:Hi Paul
:
: The 1 meg resistor is usually in the socket between pins #2 and #4. Your socket will come apart using a pointed knife or other sharp object.
:
: It's hard to add a resistor under the chassis if your radio has a socket with resistor built in. The eye tube socket won't have an extra wire for this resistor.
:
:Norm
:
::Paul,
::
::As Lewis mentioned, it is very likely the 1 meg resistor has probably increased considerably in value. Many times for values of 1 meg or larger the value was followed by "meg". If the resistor in the socket has gone bad and you are afraid to open the socket up to install a new one, you could just as well install one under the chassis instead.
::
::Radiodoc
::**********
::
::
::::Doc,
::::
:::::: Oh geez...why the heck didn't I think of that...I was a classical archaeology major for crying out loud. So if they were using the Roman numbering standard, would I expect 1 megohm to be a 1 followed by an M with a line over it? I'll try to trace the wires down and install the resistor, but if the original resistor did open up, wouldn't the eye be completely nonresponsive?
::::
::::Paul
::::
:::Paul;
:::Don't feel embarrased for falling for the old "M" vs. "K" trap. Everybody I have known has had to learn the hard way. That resistor might have changed value. Some of the higher resistances tend to do that, even today.
:::Lewis
The Eye tube is simply a vaccum tube Voltmeter, measuring the AVC Voltage, just as a S-meter does. As the AVC goes increasingly negative, the triode section acts as an inverter, and the second section attracts electrons th close the eye. Tune in a distant station of fairly good reception, and then a strong local one. If the volume is about the same on the two, the AVC is working. A high impedence meter across the AVC will verify the operation of the AVC circuit.
Lewis
:
::Hi Paul
::
:: The 1 meg resistor is usually in the socket between pins #2 and #4. Your socket will come apart using a pointed knife or other sharp object.
::
:: It's hard to add a resistor under the chassis if your radio has a socket with resistor built in. The eye tube socket won't have an extra wire for this resistor.
::
::Norm
::
:::Paul,
:::
:::As Lewis mentioned, it is very likely the 1 meg resistor has probably increased considerably in value. Many times for values of 1 meg or larger the value was followed by "meg". If the resistor in the socket has gone bad and you are afraid to open the socket up to install a new one, you could just as well install one under the chassis instead.
:::
:::Radiodoc
:::**********
:::
:::
:::::Doc,
:::::
::::::: Oh geez...why the heck didn't I think of that...I was a classical archaeology major for crying out loud. So if they were using the Roman numbering standard, would I expect 1 megohm to be a 1 followed by an M with a line over it? I'll try to trace the wires down and install the resistor, but if the original resistor did open up, wouldn't the eye be completely nonresponsive?
:::::
:::::Paul
:::::
::::Paul;
::::Don't feel embarrased for falling for the old "M" vs. "K" trap. Everybody I have known has had to learn the hard way. That resistor might have changed value. Some of the higher resistances tend to do that, even today.
::::Lewis
The resistor being open will have no effect on tracking or other radio operation. It will only prevent the eye from closing.
Norm
:: Thanks, Norm.
:
:If the set seems to be operating normally with the exception of the tracking, would the resistor typically be the problem? If the set were in need of a proper alignment, could that cause the eye tube to malfunction as well? I ask because of the bad tracking on the low end. Thanks.
:
:Paul
:
::Hi Paul
::
:: The 1 meg resistor is usually in the socket between pins #2 and #4. Your socket will come apart using a pointed knife or other sharp object.
::
:: It's hard to add a resistor under the chassis if your radio has a socket with resistor built in. The eye tube socket won't have an extra wire for this resistor.
::
::Norm
::
:::Paul,
:::
:::As Lewis mentioned, it is very likely the 1 meg resistor has probably increased considerably in value. Many times for values of 1 meg or larger the value was followed by "meg". If the resistor in the socket has gone bad and you are afraid to open the socket up to install a new one, you could just as well install one under the chassis instead.
:::
:::Radiodoc
:::**********
:::
:::
:::::Doc,
:::::
::::::: Oh geez...why the heck didn't I think of that...I was a classical archaeology major for crying out loud. So if they were using the Roman numbering standard, would I expect 1 megohm to be a 1 followed by an M with a line over it? I'll try to trace the wires down and install the resistor, but if the original resistor did open up, wouldn't the eye be completely nonresponsive?
:::::
:::::Paul
:::::
::::Paul;
::::Don't feel embarrased for falling for the old "M" vs. "K" trap. Everybody I have known has had to learn the hard way. That resistor might have changed value. Some of the higher resistances tend to do that, even today.
::::Lewis
That's right! Don't know what I was thinking. Sometimes my gray matter is mush instead.
Radiodoc
**********
:Hi Paul
:
: The 1 meg resistor is usually in the socket between pins #2 and #4. Your socket will come apart using a pointed knife or other sharp object.
:
: It's hard to add a resistor under the chassis if your radio has a socket with resistor built in. The eye tube socket won't have an extra wire for this resistor.
:
:Norm
:
::Paul,
::
::As Lewis mentioned, it is very likely the 1 meg resistor has probably increased considerably in value. Many times for values of 1 meg or larger the value was followed by "meg". If the resistor in the socket has gone bad and you are afraid to open the socket up to install a new one, you could just as well install one under the chassis instead.
::
::Radiodoc
::**********
::
::
::::Doc,
::::
:::::: Oh geez...why the heck didn't I think of that...I was a classical archaeology major for crying out loud. So if they were using the Roman numbering standard, would I expect 1 megohm to be a 1 followed by an M with a line over it? I'll try to trace the wires down and install the resistor, but if the original resistor did open up, wouldn't the eye be completely nonresponsive?
::::
::::Paul
::::
:::Paul;
:::Don't feel embarrased for falling for the old "M" vs. "K" trap. Everybody I have known has had to learn the hard way. That resistor might have changed value. Some of the higher resistances tend to do that, even today.
:::Lewis
Also, be sure that your AVC filter capacitor (usually .05 MFD) is not leaky at all. That means ABSOLUTELY NO LEAKAGE....not even in the millions of ohms. If you put your ohmmeter across the capacitor, and the needle moves up, it should fall back to EXACTLY where it started. Any less means unacceptable leakage.
If the AVC cap is leaky, not enough AVC voltage will develop. The eye tube won't respond properly. Sound may be garbled on strong local stations due to RF circuitry overloading. It is also wise to test and replace all of the other capacitors in the radio. It is especially important to have NO leakage in high impedance circuits such as from one audio stage to the next. Leakage will throw off grid biasing, and will cause the audio to be garbled.
Have fun.
T.
Paul
:You should be getting a reading of 1 megohm across pins 2 and 4 of the 6E5 socket. If not, then your socket resistor has drifted, as the others have suggested.
:
:Also, be sure that your AVC filter capacitor (usually .05 MFD) is not leaky at all. That means ABSOLUTELY NO LEAKAGE....not even in the millions of ohms. If you put your ohmmeter across the capacitor, and the needle moves up, it should fall back to EXACTLY where it started. Any less means unacceptable leakage.
:
:If the AVC cap is leaky, not enough AVC voltage will develop. The eye tube won't respond properly. Sound may be garbled on strong local stations due to RF circuitry overloading. It is also wise to test and replace all of the other capacitors in the radio. It is especially important to have NO leakage in high impedance circuits such as from one audio stage to the next. Leakage will throw off grid biasing, and will cause the audio to be garbled.
:
:Have fun.
:
:T.