Anyhow, my first mistake was buying an “as is” radio on ebay – the Airline 04WG-803B. (the schematic is here: http://www.nostalgiaair.org/Resources/032/M0011032.htm). It was caked with dirt and looked like it had sat around a barn for the last 50 years or so. After a couple of days of cleaning the thing up I was able to take a look at the guts. The power transformer was melted, the insulation had decayed on many of the wires, and the magic eye tube was missing.
I had a half mind to throw the thing out, but instead I threw good money after bad and bought new caps, a transformer and an eye tube. Well miracle of all miracles after I replaced those things and did some rewiring the thing worked. And it didn’t just work – it worked really well. I put it back in the cabinet and hooked up my ipod to the phono jack and that thing could crank some serious music.
Now all I needed was a new grill cloth and I was done. I ordered the new grill cloth which took a couple of weeks to arrive, but in the meantime I listened to stations all across the BC and SW bands just about every day – everything was working fine.
Finally the grill cloth showed up so I pulled the chassis out to make the switch, but now the radio doesn’t work right. The BC band seems misaligned – I get the same stations in multiple places on the dial and the signal isn’t as strong as before. I don’t get anything but noise on the SW bands. The magic eye stays fully lit no matter where I tune it. Input from the phono jack is still good so I guess the problem is somewhere to the “left” of the volume control on the schematic. I’m thinking I’ve got a loose wire someplace, but I can’t find anything. Does anyone have an idea where I should focus my attention?
Any help would be appreciated because I’m in a little bit over my head.
Did a wire break around the antenna coil? Without this coil connected you could receive stations weak and at two places on the dial.
Norm
:Let me start out by saying that I’m a newbie, and my knowledge of electronics is limited to what I learned in 8th grade shop class about 40 years ago. I can sort of read a schematic, but I don’t understand the details like many of you do.
:
:Anyhow, my first mistake was buying an “as is” radio on ebay – the Airline 04WG-803B. (the schematic is here: http://www.nostalgiaair.org/Resources/032/M0011032.htm). It was caked with dirt and looked like it had sat around a barn for the last 50 years or so. After a couple of days of cleaning the thing up I was able to take a look at the guts. The power transformer was melted, the insulation had decayed on many of the wires, and the magic eye tube was missing.
:
:I had a half mind to throw the thing out, but instead I threw good money after bad and bought new caps, a transformer and an eye tube. Well miracle of all miracles after I replaced those things and did some rewiring the thing worked. And it didn’t just work – it worked really well. I put it back in the cabinet and hooked up my ipod to the phono jack and that thing could crank some serious music.
:
:Now all I needed was a new grill cloth and I was done. I ordered the new grill cloth which took a couple of weeks to arrive, but in the meantime I listened to stations all across the BC and SW bands just about every day – everything was working fine.
:
:Finally the grill cloth showed up so I pulled the chassis out to make the switch, but now the radio doesn’t work right. The BC band seems misaligned – I get the same stations in multiple places on the dial and the signal isn’t as strong as before. I don’t get anything but noise on the SW bands. The magic eye stays fully lit no matter where I tune it. Input from the phono jack is still good so I guess the problem is somewhere to the “left” of the volume control on the schematic. I’m thinking I’ve got a loose wire someplace, but I can’t find anything. Does anyone have an idea where I should focus my attention?
:
:Any help would be appreciated because I’m in a little bit over my head.
:
:Bill
:
: Did a wire break around the antenna coil? Without this coil connected you could receive stations weak and at two places on the dial.
:
:Norm
:
::Let me start out by saying that I’m a newbie, and my knowledge of electronics is limited to what I learned in 8th grade shop class about 40 years ago. I can sort of read a schematic, but I don’t understand the details like many of you do.
::
::Anyhow, my first mistake was buying an “as is” radio on ebay – the Airline 04WG-803B. (the schematic is here: http://www.nostalgiaair.org/Resources/032/M0011032.htm). It was caked with dirt and looked like it had sat around a barn for the last 50 years or so. After a couple of days of cleaning the thing up I was able to take a look at the guts. The power transformer was melted, the insulation had decayed on many of the wires, and the magic eye tube was missing.
::
::I had a half mind to throw the thing out, but instead I threw good money after bad and bought new caps, a transformer and an eye tube. Well miracle of all miracles after I replaced those things and did some rewiring the thing worked. And it didn’t just work – it worked really well. I put it back in the cabinet and hooked up my ipod to the phono jack and that thing could crank some serious music.
::
::Now all I needed was a new grill cloth and I was done. I ordered the new grill cloth which took a couple of weeks to arrive, but in the meantime I listened to stations all across the BC and SW bands just about every day – everything was working fine.
::
::Finally the grill cloth showed up so I pulled the chassis out to make the switch, but now the radio doesn’t work right. The BC band seems misaligned – I get the same stations in multiple places on the dial and the signal isn’t as strong as before. I don’t get anything but noise on the SW bands. The magic eye stays fully lit no matter where I tune it. Input from the phono jack is still good so I guess the problem is somewhere to the “left” of the volume control on the schematic. I’m thinking I’ve got a loose wire someplace, but I can’t find anything. Does anyone have an idea where I should focus my attention?
::
::Any help would be appreciated because I’m in a little bit over my head.
::
This may not help with the problem but I can explain eye tube operation. The eye tubes light with B+ voltage on the target pin. The radio doesn't have to receive a signal.
AVC voltage causes the eye to open and close. Stronger stations generate more negative AVC voltage which closes the eye.
The eye being open is normal when not receiving stations. If the eye is fully closed the radio may be having unwanted oscillation. This can be caused by bad caps or missing tube shields.
In some radios using metal tubes in place of glass can cause oscillation. Pin #1 on a metal tube needs to be grounded. If not the stage can go into oscillation.
Norm
:Thanks for your help Norm, but that doesn't seem to be the problem. I checked everything out very carefully related to the antenna coil but couldn't find a problem. The thing that puzzles me is why does the magic eye stay fully lit no matter where I tune the radio?
:
::Bill
::
:: Did a wire break around the antenna coil? Without this coil connected you could receive stations weak and at two places on the dial.
::
::Norm
::
:::Let me start out by saying that I’m a newbie, and my knowledge of electronics is limited to what I learned in 8th grade shop class about 40 years ago. I can sort of read a schematic, but I don’t understand the details like many of you do.
:::
:::Anyhow, my first mistake was buying an “as is” radio on ebay – the Airline 04WG-803B. (the schematic is here: http://www.nostalgiaair.org/Resources/032/M0011032.htm). It was caked with dirt and looked like it had sat around a barn for the last 50 years or so. After a couple of days of cleaning the thing up I was able to take a look at the guts. The power transformer was melted, the insulation had decayed on many of the wires, and the magic eye tube was missing.
:::
:::I had a half mind to throw the thing out, but instead I threw good money after bad and bought new caps, a transformer and an eye tube. Well miracle of all miracles after I replaced those things and did some rewiring the thing worked. And it didn’t just work – it worked really well. I put it back in the cabinet and hooked up my ipod to the phono jack and that thing could crank some serious music.
:::
:::Now all I needed was a new grill cloth and I was done. I ordered the new grill cloth which took a couple of weeks to arrive, but in the meantime I listened to stations all across the BC and SW bands just about every day – everything was working fine.
:::
:::Finally the grill cloth showed up so I pulled the chassis out to make the switch, but now the radio doesn’t work right. The BC band seems misaligned – I get the same stations in multiple places on the dial and the signal isn’t as strong as before. I don’t get anything but noise on the SW bands. The magic eye stays fully lit no matter where I tune it. Input from the phono jack is still good so I guess the problem is somewhere to the “left” of the volume control on the schematic. I’m thinking I’ve got a loose wire someplace, but I can’t find anything. Does anyone have an idea where I should focus my attention?
:::
:::Any help would be appreciated because I’m in a little bit over my head.
:::
You could have trouble in this circuit (a bad wire, even, say on the eye tube, or perhaps a short inside of the IF transformer, either across the resistor or from the eye tube winding to the plate winding). You could also have unwanted oscillation, like Norm said. See if metal tubes help, if you are using glass ones in the RF circuits (glass in the audio is acceptable). You could also have trouble in the AVC circuit. An open circuit would cause a dead or quiet radio, and would allow the eye tube circuit to go completely positive, which would close the eye tube (if the AVC circuit is open, it will likely saturate to its most negative potential, though not necessarily).
Also check every component in the radio. Check coils for continuity. Check resistors for drifting. Check capacitors for shorting and leaks (you really should replace all capacitors for reliability...if you want originality, purchase metalized film units, which fit nicely inside of the old units). Check tubes for shorts and poor performance. If you washed the tubes, be sure that water did not get into their bases. If it did, let them dry. You can speed the process with a hair dryer. Don't put them in the oven, though.
Make sure that none of the IF transformers have been disrupted, that would allow a wire or some other object to short to the can inside. Check the wiring well. It is rubber. Rubber wiring fails a lot. Also, one of the first things you should do is wiggle the tubes to see if there is a bad connection in one of the sockets. Your problem happened when you moved the chassis, so something moving is probably your problem.
This radio use a 6AD6G. Like Thomas said it operates differently. AVC controls the 6SK7, IF tube, which causes less screen current to be drawn. Lest screen curent causes higher voltage which controls the eye.
Norm
:Interesting radio. It is interesting to note, too, that the eye tube is not connected to the AVC circuit. It does not have a control triode, but is simply a target with two deflectors. The deflectors are connected to B+ through a resistor, and also to the screen grid of the IF tube, through a coil in the IF transformer. I have a feeling that B+ normally closes the pattern on the tube when AVC cuts down on the IF tube's conductivity. I am not sure what the extra winding in the IF transformer is for. I would think that it would induce extra voltage for closing the eye even more, because that would be its only logical purpose. Normally the eye closes when a station is strong, and the only time you're going to get voltages induced in that winding is when there's a signal.
:
:You could have trouble in this circuit (a bad wire, even, say on the eye tube, or perhaps a short inside of the IF transformer, either across the resistor or from the eye tube winding to the plate winding). You could also have unwanted oscillation, like Norm said. See if metal tubes help, if you are using glass ones in the RF circuits (glass in the audio is acceptable). You could also have trouble in the AVC circuit. An open circuit would cause a dead or quiet radio, and would allow the eye tube circuit to go completely positive, which would close the eye tube (if the AVC circuit is open, it will likely saturate to its most negative potential, though not necessarily).
:
:Also check every component in the radio. Check coils for continuity. Check resistors for drifting. Check capacitors for shorting and leaks (you really should replace all capacitors for reliability...if you want originality, purchase metalized film units, which fit nicely inside of the old units). Check tubes for shorts and poor performance. If you washed the tubes, be sure that water did not get into their bases. If it did, let them dry. You can speed the process with a hair dryer. Don't put them in the oven, though.
:
:Make sure that none of the IF transformers have been disrupted, that would allow a wire or some other object to short to the can inside. Check the wiring well. It is rubber. Rubber wiring fails a lot. Also, one of the first things you should do is wiggle the tubes to see if there is a bad connection in one of the sockets. Your problem happened when you moved the chassis, so something moving is probably your problem.
:Hi
:
: This radio use a 6AD6G. Like Thomas said it operates differently. AVC controls the 6SK7, IF tube, which causes less screen current to be drawn. Lest screen curent causes higher voltage which controls the eye.
:
:Norm
:
:
:
::Interesting radio. It is interesting to note, too, that the eye tube is not connected to the AVC circuit. It does not have a control triode, but is simply a target with two deflectors. The deflectors are connected to B+ through a resistor, and also to the screen grid of the IF tube, through a coil in the IF transformer. I have a feeling that B+ normally closes the pattern on the tube when AVC cuts down on the IF tube's conductivity. I am not sure what the extra winding in the IF transformer is for. I would think that it would induce extra voltage for closing the eye even more, because that would be its only logical purpose. Normally the eye closes when a station is strong, and the only time you're going to get voltages induced in that winding is when there's a signal.
::
::You could have trouble in this circuit (a bad wire, even, say on the eye tube, or perhaps a short inside of the IF transformer, either across the resistor or from the eye tube winding to the plate winding). You could also have unwanted oscillation, like Norm said. See if metal tubes help, if you are using glass ones in the RF circuits (glass in the audio is acceptable). You could also have trouble in the AVC circuit. An open circuit would cause a dead or quiet radio, and would allow the eye tube circuit to go completely positive, which would close the eye tube (if the AVC circuit is open, it will likely saturate to its most negative potential, though not necessarily).
::
::Also check every component in the radio. Check coils for continuity. Check resistors for drifting. Check capacitors for shorting and leaks (you really should replace all capacitors for reliability...if you want originality, purchase metalized film units, which fit nicely inside of the old units). Check tubes for shorts and poor performance. If you washed the tubes, be sure that water did not get into their bases. If it did, let them dry. You can speed the process with a hair dryer. Don't put them in the oven, though.
::
::Make sure that none of the IF transformers have been disrupted, that would allow a wire or some other object to short to the can inside. Check the wiring well. It is rubber. Rubber wiring fails a lot. Also, one of the first things you should do is wiggle the tubes to see if there is a bad connection in one of the sockets. Your problem happened when you moved the chassis, so something moving is probably your problem.
Everything you are suggesting are absolutely all correct good ideas .. but aren't we getting a little far afield too soon?
... because, if you remember ...he said it was working ''gang-busters'' before he removed the chassis just to replace the grill cloth.
It's always been my experience in many years of trouble shooting any sudden weird failures ....that it is usually and PROBABLY related to the last thing you just did.
So I would very very carefully look for broken wires and especially near the antenna coil. The wires in the windings are very thin and can be hard to see if they broke. Even a chassis to cabinet screw can sometimes be too long and then possibly be shorting some thing. So look for any areas that were disturbed during cabinet removal.
I would not start pulling tubes and caps or whatever just yet.
T.
:Yeah. I was thinking along the lines of possibly a faulty wire in the eye tube circuit. A faulty deflector wire would short out the screen grid voltage, and would make the IF circuit perform poorly. ...Also, a faulty antenna wire, like Norm suggested, would cause weak reception. Also check tubes for bad socket connections (rock tubes).
:
:T.
I got tired of working on the 04WG-803B and put it aside for a while to move on to my next project. The next project was an Airline 04BR-730A. This radio was my grandmother’s and I loved it so much as a kid that she left it to me in her will when she died back in the 1960s. As a matter of fact the 803B was just a “practice” radio to get my feet wet for this ultimate project.
Well it turns out that the 730A was in pretty good shape because it had sat safely in my parent’s attic for the past 35 years or so. All I did was put in a new set of caps, swapped in another 6SK7 that had tested bad, and replaced the frayed power cord. I cleaned up the cabinet, replaced the grill cloth, and voila! – It looks and plays as well as it did the day my grandmother paid $39.95 for it at the local Montgomery Ward.
Sheesh, the whole job probably took < 8 hours. Now it’s back to the 803B – my practice radio that I started working on in mid-August.
Bad antenna coils usually just affect signal strength (except with high frequency short wave, where stations can also shift from a misadjusted antenna coil (your's is tapped, so there are multiple windings)). Troubles in the oscillator circuit are more likely to shift stations. Also, troubles with the IF transformers can shift stations and can reduce reception. If one of the trimmers is acting up, and it somehow got bumped out of position, the stations can be shifted, and reception can suffer. I am somewhat suspicious of the 2nd IF transformer and its associated circuitry, because that would most likely keep the eye tube closed. Weak reception should keep it open.
T.
You should check voltages throughout the set. Be sure that there are no shorting wires. Places that should have full B+ should have full B+, and those that are connected via a resistor should have less.
T.
Bill
:If the eye tube wiring, which is rubber, was to short between the target and the B+ wires, the eye tube would stay fully lit all the time. The short would short out the small extra winding in the IF transformer. That would alter the tuning of the main windings (probably would increase their frequency). That would also decrease sensitivity. With the extra voltage on the screen, the circuit might behave strangely. Not all circuits like full voltage on the screen. Sometimes it helps, and sometimes it doesn't.
:
:You should check voltages throughout the set. Be sure that there are no shorting wires. Places that should have full B+ should have full B+, and those that are connected via a resistor should have less.
:
:T.
Thanks in advance for your help.
Bill C.,
It would seem that with the high plate voltage on the 6SQ7 that it is not drawing much current if any. May try another 6SQ7, check the cathode resistor, check for filament voltage to the tube. If it were drawing proper current, most of the B+ voltage would be dropped across its plate load resistor. When checking the filament AC voltage, measure from the tube pins and not the socket solder contacts.
Radiodoc
***********
plate of 6SQ7 (the so called balancing exciter) was at 298 v versus an expected 80v. Now if I remember correctly I didn’t replace the original paper caps for C27 and C28 because I didn’t have anything in my stock in the neighborhood of 0.02 uF. If one of those caps is leaky or shorted would it cause the problem I am seeing?
:
:Thanks in advance for your help.
:
You have two 6SQ7's. Are both reading high? Both tubes shouldn't be bad?
http://www.nostalgiaair.org/PagesByModel/032/M0011032.pdf
Capacitors mentioned would not cause this high voltage.
Here is a question. How can you read 298 volts when others are ok? The line which supplies your 6SQ7 also goes to 6K6 screen. The 6K6 should have 180 volts. This voltage would also be wrong...
If R15 & R16 were open plate voltage would read strange on a digital meter? Won't expect high.
Norm
::So I tested the B+ voltages versus the schematic and everything was in about the right ballpark EXCEPT the
:
:
:Bill C.,
:
:It would seem that with the high plate voltage on the 6SQ7 that it is not drawing much current if any. May try another 6SQ7, check the cathode resistor, check for filament voltage to the tube. If it were drawing proper current, most of the B+ voltage would be dropped across its plate load resistor. When checking the filament AC voltage, measure from the tube pins and not the socket solder contacts.
:
:Radiodoc
:***********
:
:plate of 6SQ7 (the so called balancing exciter) was at 298 v versus an expected 80v. Now if I remember correctly I didn’t replace the original paper caps for C27 and C28 because I didn’t have anything in my stock in the neighborhood of 0.02 uF. If one of those caps is leaky or shorted would it cause the problem I am seeing?
::
::Thanks in advance for your help.
::
When making B voltage checks, in AC radios you usually use the chassis as B-, and reference everything from there. ...So in the case of your radio, connect your negative meter lead to the chassis, and use the positive lead to check everything else. If you come across a negative voltage, and it is supposed to be negative, reverse your meter leads so that you can observe it properly.
Regarding your B voltages, they definitely are high. As Norm said, the screens of your output tubes (pin 4 of the 6K6 tubes) should be 180 volts, so it is strange that you see 298 volts. Check the output tube screens again. If they are at 180, and the 12SQ7 plates are at 298, then you have a bit of trouble on your hands. If, on the other hand, you find that the output screens are high, too, you may either have a short across the 1500 ohm power resistor, or something else in the RF section of the radio isn't drawing enough current, which would explain your poor reception.
On a side note, it is interesting that this set does not use an electrodynamic speaker, even though it is almost identical to some earlier sets that do use such a speaker. AC/DC receivers were more likely to have electrodynamic speakers dropped than AC sets.
Thomas
It turns out that I had soldered C24 to pin 5 of 6SA7 rather than pin4 where it should be. That cap had come loose when I pulled the chassis from the cabinet so I decided to resolder it ... to the wrong pin! Rookie mistake. At least I learned a good leason. It works great now.
Thanks everyone for all your help.