Hi: I am working on a Delco 1107. I've replaced the caps and several open or out of tolerance resistors. It works but the volume is very low. The voltages on all the tubes are similar to what is shown on the voltage charts except for the 6D6 AF and 42 output tubes. Grid 2 of the 6D6 shows 10 volts instead of 20; the plate of the 6D6 shows 63 instead of 20. The 42 shows minus 8(-8) on grid 1, pin 4 instead of plus 8. Would these values affect the volumne? I checked the output of the power transformer and the center tap reads minus 250 (-250). The CT is linked through 2 resistors to the grid of the 42 which may be why it is showing negative. Any thoughts? Thanks for the help and for helping me through so many project radios in the past. Al

Hi Al

Minus 8 rather than + 8 would be correct for and output tube grid #1. Difference in screen voltage on 6D6 may be due to series resistor being high in value? Check #40 resistor.

Try peaking the two adjusting screws on IF Transformers. You could use a signal generator. If you don't have one a radio station will do..

Norm

:Hi: I am working on a Delco 1107. I've replaced the caps and several open or out of tolerance resistors. It works but the volume is very low. The voltages on all the tubes are similar to what is shown on the voltage charts except for the 6D6 AF and 42 output tubes. Grid 2 of the 6D6 shows 10 volts instead of 20; the plate of the 6D6 shows 63 instead of 20. The 42 shows minus 8(-8) on grid 1, pin 4 instead of plus 8. Would these values affect the volumne? I checked the output of the power transformer and the center tap reads minus 250 (-250). The CT is linked through 2 resistors to the grid of the 42 which may be why it is showing negative. Any thoughts? Thanks for the help and for helping me through so many project radios in the past. Al
:

Hi Norm: Thanks for the help. I did replace #40 after checking it and it was high. It brought the voltage up to 12 but still weak volume. I tweaked the IFs by ear and it helped a little. The speaker's voice coil was rusted when I got the set and I got it to free up but it still may not be right. I'm curious if that could a cause of the weak volume? Thanks again. Al

Hi Al
:
: Minus 8 rather than + 8 would be correct for and output tube grid #1. Difference in screen voltage on 6D6 may be due to series resistor being high in value? Check #40 resistor.
:
: Try peaking the two adjusting screws on IF Transformers. You could use a signal generator. If you don't have one a radio station will do..
:
:Norm
:
::Hi: I am working on a Delco 1107. I've replaced the caps and several open or out of tolerance resistors. It works but the volume is very low. The voltages on all the tubes are similar to what is shown on the voltage charts except for the 6D6 AF and 42 output tubes. Grid 2 of the 6D6 shows 10 volts instead of 20; the plate of the 6D6 shows 63 instead of 20. The 42 shows minus 8(-8) on grid 1, pin 4 instead of plus 8. Would these values affect the volumne? I checked the output of the power transformer and the center tap reads minus 250 (-250). The CT is linked through 2 resistors to the grid of the 42 which may be why it is showing negative. Any thoughts? Thanks for the help and for helping me through so many project radios in the past. Al
::
:
:

The voice coil pole piece being rusty could hold the cone from traveling. This would cause a raspy sound. Or a low volume hollow sound. Try to bridge a PM speaker across the existing speaker. See how that sounds.

:The voice coil pole piece being rusty could hold the cone from traveling. This would cause a raspy sound. Or a low volume hollow sound. Try to bridge a PM speaker across the existing speaker. See how that sounds.
:

Thanks Warren I'll give that a try. I need to pick up a PM speaker. Would a 4 ohm work?

::The voice coil pole piece being rusty could hold the cone from traveling. This would cause a raspy sound. Or a low volume hollow sound. Try to bridge a PM speaker across the existing speaker. See how that sounds.
::
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For a temporary test yes it will. You could also disconnect one side of the old speaker, connect the test speaker to the audio output secondary.

Thanks. I did a temporary connect to a PM speaker and the results were the same. After tracing a strong RF through the IF tube I noticed it did not switch to AF on the detector plate. It still had a fairly strong RF and a distorted and weak AF signal at that point. I checked the continuity of the IF trans. and that appears to be ok. Looks like the RF was carrying all the way through the audio section along with a very weak audio signal which was being picked up at the speaker. Any thoughts? Thanks. Al

:For a temporary test yes it will. You could also disconnect one side of the old speaker, connect the test speaker to the audio output secondary.
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Just a quick followup on the low volume problem. It was the voice coil after all. I had a bad PM speaker that I was using but was able to find a good field coil speaer and it works great. Thanks again for all the assistance. Al

:Thanks. I did a temporary connect to a PM speaker and the results were the same. After tracing a strong RF through the IF tube I noticed it did not switch to AF on the detector plate. It still had a fairly strong RF and a distorted and weak AF signal at that point. I checked the continuity of the IF trans. and that appears to be ok. Looks like the RF was carrying all the way through the audio section along with a very weak audio signal which was being picked up at the speaker. Any thoughts? Thanks. Al
:
::For a temporary test yes it will. You could also disconnect one side of the old speaker, connect the test speaker to the audio output secondary.
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