I have an Emerson 543 AA5 radio. I have totally recapped this radio and repaced almost all the resistors in this set since they tested more than 20% off spec. The audio section is working since I get a
loud hum when I touch the grid lead on the 12SQ7. However, it will not pick up any stations. Nothing when the tuning dial is turned, not a blip, nothing, nada!!

I checked the tube voltages (using an isolation transformer) from B- as shown on the chart with the schematic. There were two things I could not explain, the chart indicates there should be 116 volts on
pin 5 of the 35Z5, but this can't be right, there is no pin 5 on a 35Z5. In fact, the lug for pin 5 is used as a tie point for C16 and R11 on my set. This must be a misprint on the voltage chart as I
measure -1.3V at this junction. Additionally, I get 90V where I should have 116V on pins 4 and 8 on the 35Z5. However, all the other tube voltages look good except for the fact they are a little low (76V
where I should have 89V) even with the suggested input of 117V from my Variac. This is probably due to my Fluke 112 as opposed to a VTVM.

The other problem, and probably the one stopping my oscillation is I measure 73V at pin 5 of the 12SA7 where the chart calls for -10V. This is definately a problem. Does anyone have a suggestion? I worked on this radio all weekend and I'm ready for some suggestions from the guys and gals out there. Anyone have any ideas?

David

:I have an Emerson 543 AA5 radio. I have totally recapped this radio and repaced almost all the resistors in this set since they tested more than 20% off spec. The audio section is working since I get a
:loud hum when I touch the grid lead on the 12SQ7. However, it will not pick up any stations. Nothing when the tuning dial is turned, not a blip, nothing, nada!!
:
:I checked the tube voltages (using an isolation transformer) from B- as shown on the chart with the schematic. There were two things I could not explain, the chart indicates there should be 116 volts on
:pin 5 of the 35Z5, but this can't be right, there is no pin 5 on a 35Z5. In fact, the lug for pin 5 is used as a tie point for C16 and R11 on my set. This must be a misprint on the voltage chart as I
:measure -1.3V at this junction. Additionally, I get 90V where I should have 116V on pins 4 and 8 on the 35Z5. However, all the other tube voltages look good except for the fact they are a little low (76V
:where I should have 89V) even with the suggested input of 117V from my Variac. This is probably due to my Fluke 112 as opposed to a VTVM.
:
:The other problem, and probably the one stopping my oscillation is I measure 73V at pin 5 of the 12SA7 where the chart calls for -10V. This is definately a problem. Does anyone have a suggestion? I worked on this radio all weekend and I'm ready for some suggestions from the guys and gals out there. Anyone have any ideas?
:
:David
:
:

::I have an Emerson 543 AA5 radio. I have totally recapped this radio and repaced almost all the resistors in this set since they tested more than 20% off spec. The audio section is working since I get a
::loud hum when I touch the grid lead on the 12SQ7. However, it will not pick up any stations. Nothing when the tuning dial is turned, not a blip, nothing, nada!!
::
::I checked the tube voltages (using an isolation transformer) from B- as shown on the chart with the schematic. There were two things I could not explain, the chart indicates there should be 116 volts on
::pin 5 of the 35Z5, but this can't be right, there is no pin 5 on a 35Z5. In fact, the lug for pin 5 is used as a tie point for C16 and R11 on my set. This must be a misprint on the voltage chart as I
::measure -1.3V at this junction. Additionally, I get 90V where I should have 116V on pins 4 and 8 on the 35Z5. However, all the other tube voltages look good except for the fact they are a little low (76V
::where I should have 89V) even with the suggested input of 117V from my Variac. This is probably due to my Fluke 112 as opposed to a VTVM.
::
::The other problem, and probably the one stopping my oscillation is I measure 73V at pin 5 of the 12SA7 where the chart calls for -10V. This is definately a problem. Does anyone have a suggestion? I worked on this radio all weekend and I'm ready for some suggestions from the guys and gals out there. Anyone have any ideas?
::
::David
::
::
Hi David,
Grid to screen short on the 12SA7? Not too likely. Just for grins you can check the tube for shorts with an ohm meter. A short like that would not likely be dependant on the heater being on.
I only mention it because the test is easy. It is unlikely to be the problem, but if it is, replacing a tube is always easy. The more likely problem will likely involve dismantling circuitry under the chassis.
More likely you have B+ getting into the oscillator tank circuit from a wire rubbing, a miswiring, or a defective silver Mica capacitor. I recommend tracing back through the coil with a volt meter, looking for where the voltage is getting in. If that failes, disconnect wires from the node until that high + voltage goes away. This will be a clue as to where it is coming from.
These radios are not very complicated. You will get it working.

Best Regards,

Bill Grimm

Hi, David. Have you checked the oscillator coil, T4, to make sure that none of the windings is shot?

:I have an Emerson 543 AA5 radio. I have totally recapped this radio and repaced almost all the resistors in this set since they tested more than 20% off spec. The audio section is working since I get a
:loud hum when I touch the grid lead on the 12SQ7. However, it will not pick up any stations. Nothing when the tuning dial is turned, not a blip, nothing, nada!!
:
:I checked the tube voltages (using an isolation transformer) from B- as shown on the chart with the schematic. There were two things I could not explain, the chart indicates there should be 116 volts on
:pin 5 of the 35Z5, but this can't be right, there is no pin 5 on a 35Z5. In fact, the lug for pin 5 is used as a tie point for C16 and R11 on my set. This must be a misprint on the voltage chart as I
:measure -1.3V at this junction. Additionally, I get 90V where I should have 116V on pins 4 and 8 on the 35Z5. However, all the other tube voltages look good except for the fact they are a little low (76V
:where I should have 89V) even with the suggested input of 117V from my Variac. This is probably due to my Fluke 112 as opposed to a VTVM.
:
:The other problem, and probably the one stopping my oscillation is I measure 73V at pin 5 of the 12SA7 where the chart calls for -10V. This is definately a problem. Does anyone have a suggestion? I worked on this radio all weekend and I'm ready for some suggestions from the guys and gals out there. Anyone have any ideas?
:
:David
:
:

David, Wondering if you might be counting the tube pins in a CCW direction instead of clockwise from pin 1.

Richard

:David, Wondering if you might be counting the tube pins in a CCW direction instead of clockwise from pin 1.
:
:Richard

Richard,

I'm counting the tube pins clockwise starting at the first pin right of the alignment notch being pin 1. Looking at the tubes upside down as they are installed in the radio.

David

When you say you start with Pin 1 to the "right" of the alignment notch, that could be ambiguous depending on how you're looking at it. Pin 1 is the first pin CW of the alignment notch, looking from the bottom of the chassis.
Doug
:
:I'm counting the tube pins clockwise starting at the first pin right of the alignment notch being pin 1. Looking at the tubes upside down as they are installed in the radio.
:
:David

David R,

You probably will find that the 35Z5 does have a pin 5 (plate) if you start with the first pin to the left of the index key as pin 1 and count clockwise.

Radiodoc

::David, Wondering if you might be counting the tube pins in a CCW direction instead of clockwise from pin 1.
::
::Richard
:
:Richard,
:
:I'm counting the tube pins clockwise starting at the first pin right of the alignment notch being pin 1. Looking at the tubes upside down as they are installed in the radio.
:
:David

Looking at the bottom of the tube socket pin #1 is to the RIGHT clockwise if the alignment notch is at the 12 o'clock position.

Pin #1 is the first to the left counting clockwise only if the alignment notch is at the 6 o'clock position.

Did I say that right??? lol

Peter,

I dun it again...assuming one would be looking at the socket with the index at 6 o'clock position. However, let us not forget that some mfgrs left pin 1 out of the socket. I have made the mistake a few times thinking I was looking at pin 1 when it was really pin 2 I was looking at.

Radiodoc

:Looking at the bottom of the tube socket pin #1 is to the RIGHT clockwise if the alignment notch is at the 12 o'clock position.
:
:Pin #1 is the first to the left counting clockwise only if the alignment notch is at the 6 o'clock position.
:
:Did I say that right??? lol

Pin 1 is first pin going clockwise from keyway, no matter where keyway may be (12,3,6 or 9 o'clock).PL

:Looking at the bottom of the tube socket pin #1 is to the RIGHT clockwise if the alignment notch is at the 12 o'clock position.
:
:Pin #1 is the first to the left counting clockwise only if the alignment notch is at the 6 o'clock position.
:
:Did I say that right??? lol

: Pin 1 is first pin going clockwise from keyway, no matter where keyway may be (12,3,6 or 9 o'clock).PL
:
PS from under chassis. PL

::Looking at the bottom of the tube socket pin #1 is to the RIGHT clockwise if the alignment notch is at the 12 o'clock position.
::
::Pin #1 is the first to the left counting clockwise only if the alignment notch is at the 6 o'clock position.
::
::Did I say that right??? lol

Yes, certainly that's of course the simplest clearest way to say it... sure.

Regardless of the position of the tube, I always start at the keyway and go clockwise for pin #1, looking at the bottom of the tube installed in the radio.

At any rate, I wrote back to thank everyone for their suggestions, I now have the radio fixed.

It turned out to be a broken teeny tiny wire where the oscillator coil connects to the solder lug. I had to use a magnifying glass to repair it, but it is working well. A quick touch up of the alignment, and it's ready for the cabinet.

Thanks again to all that helped!!

David R