Hi, has anybody had trouble building the ELENCO 108 AM/FM RADIO KIT

In summary, the conversation was about someone seeking help with a radio they were building. They accidentally swapped the battery and speaker, but eventually figured out their mistake. They were asked to provide a schematic and DC voltages measured at various points in the circuit to help troubleshoot the issue. The person also mentioned trying to connect a different speaker to no avail. The conversation then shifted to asking for more information and eventually the person provided a link to the schematic they were using.
  • #36
michael1978 said:
Goodmorning Tom are you here somewhere….
Yes. It is ten minutes before midnight here and I was looking at your latest results.

michael1978 said:
FM voltage is 8.6V at the battery, the TP2 AND TP15 stay at 2.6V,
Something is not right. TP15 should be Ground, 0V. Where was the other voltmeter lead when you measured 2.6V at TP15?

The following was typed before I noticed the TP15 voltage. I will leave it here in case the TP15 voltage was just a measurement error. (That way I will not have to type it again.) Please check the TP15 voltage, and correct any errors, before doing the below tests.

There seems to be a problem with either the power supply (battery and C39) or something around the LM386.

Please check that C39 is the correct value (470uF) and installed in the right direction. If it is wired backwards that would be a problem. Also make sure the solder connections are good.

Check all the parts around the LM386. Make sure they are the correct value and in the right spot.
C42 = 10uF, C43 = 470uF, C44 = 0.047uF. C42 and C43 must be installed the correct direction.
R44 = 47 Ohm (Yellow Violet Black), R45 = 10 Ohm (Brown Black Black)
Check jumpers J2 and J3 that they are in the right location and soldered.
Check soldering of the socket for LM386.

Sometimes when an IC (LM386) is put in a socket, a pin will bend and not plug into the socket. Check that all the LM386 pins are in the socket. You may have to unplug the LM386 to see if a pin is bent.

(The time here is now 30 minutes after midnite.)

Cheers,
Tom
 
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  • #37
Tom.G said:
Yes. It is ten minutes before midnight here and I was looking at your latest results.Something is not right. TP15 should be Ground, 0V. Where was the other voltmeter lead when you measured 2.6V at TP15?

The following was typed before I noticed the TP15 voltage. I will leave it here in case the TP15 voltage was just a measurement error. (That way I will not have to type it again.) Please check the TP15 voltage, and correct any errors, before doing the below tests.

There seems to be a problem with either the power supply (battery and C39) or something around the LM386.

Please check that C39 is the correct value (470uF) and installed in the right direction. If it is wired backwards that would be a problem. Also make sure the solder connections are good.

Check all the parts around the LM386. Make sure they are the correct value and in the right spot.
C42 = 10uF, C43 = 470uF, C44 = 0.047uF. C42 and C43 must be installed the correct direction.
R44 = 47 Ohm (Yellow Violet Black), R45 = 10 Ohm (Brown Black Black)
Check jumpers J2 and J3 that they are in the right location and soldered.
Check soldering of the socket for LM386.

Sometimes when an IC (LM386) is put in a socket, a pin will bend and not plug into the socket. Check that all the LM386 pins are in the socket. You may have to unplug the LM386 to see if a pin is bent.

(The time here is now 30 minutes after midnite.)

Cheers,
Tom
Thank you very much Tom, i will check it and i will let you know, Have a nice sleep:wink:
 
  • #38
Tom.G said:
Something is not right. TP15 should be Ground, 0V. Where was the other voltmeter lead when you measured 2.6V at TP15?
@michael1978 -- Apologies if I missed it, but could you please attach the negative lead of your voltmeter to TP15 (ground), and post the voltages that you measure at all of the other test points when you attach your positive lead to them? Thanks.
 
  • #39
berkeman said:
@michael1978 -- Apologies if I missed it, but could you please attach the negative lead of your voltmeter to TP15 (ground), and post the voltages that you measure at all of the other test points when you attach your positive lead to them? Thanks.
But i desoldeer now, and i soldeer again, the volume is more high, where i rotate is for low to high but not so much high, and i have no signal, only the part of AM, but no problem i going to measure again, because i change all capacitor lytics
 
  • #40
michael1978 said:
Thank you very much Tom, i will check it and i will let you know, Have a nice sleep:wink:
Hi Tom, i desoldeer all the party of AM and i soldeer it, and i change all capacitor lytics, and i buy new LM386 and i change it, but now the voice is working beter and i hear when i rotate its goes down and love noise but no so much and no signal, i going to send you now the test
 
  • #41
Tom.G said:
Yes. It is ten minutes before midnight here and I was looking at your latest results.Something is not right. TP15 should be Ground, 0V. Where was the other voltmeter lead when you measured 2.6V at TP15?

The following was typed before I noticed the TP15 voltage. I will leave it here in case the TP15 voltage was just a measurement error. (That way I will not have to type it again.) Please check the TP15 voltage, and correct any errors, before doing the below tests.

There seems to be a problem with either the power supply (battery and C39) or something around the LM386.

Please check that C39 is the correct value (470uF) and installed in the right direction. If it is wired backwards that would be a problem. Also make sure the solder connections are good.

Check all the parts around the LM386. Make sure they are the correct value and in the right spot.
C42 = 10uF, C43 = 470uF, C44 = 0.047uF. C42 and C43 must be installed the correct direction.
R44 = 47 Ohm (Yellow Violet Black), R45 = 10 Ohm (Brown Black Black)
Check jumpers J2 and J3 that they are in the right location and soldered.
Check soldering of the socket for LM386.

Sometimes when an IC (LM386) is put in a socket, a pin will bend and not plug into the socket. Check that all the LM386 pins are in the socket. You may have to unplug the LM386 to see if a pin is bent.

(The time here is now 30 minutes after midnite.)

Cheers,
Tom
T15:TP1=4.11V
T15:TP2=0.54V
T15:TP3=7.33V
T15:TP4=7.33V
T15:TP5=1.32V
T15:TP6=7.92V
T15:TP7=1.32V
the coil red green black white are not like in show in book, they have other resistance(maybe here is problem)
greetings.
 
  • #42
michael1978 said:
T15:TP1=4.11V
T15:TP2=0.54V
T15:TP3=7.33V
T15:TP4=7.33V
T15:TP5=1.32V
T15:TP6=7.92V
T15:TP7=1.32V
the coil red green black white are not like in show in book, they have other resistance(maybe here is problem)
greetings.
Goodmorning, i contact elenco, they say maybe problem with tuning? i don't know, they say send me the picture of kit
 
  • #43
michael1978 said:
Thank you very much Tom, i will check it and i will let you know, Have a nice sleep:wink:
Tom i did my best, but still the problem i check it , all what you say, i don't know anymore what to do
 
  • #44
You did a lot of work! Resoldering everything, replacing the electrolytics, replacing the LM386 and contacting Elenco.
The voltages at the TP look a little bit low. Maybe the battery is low. Did you use that battery a long time?
michael1978 said:
but now the voice is working beter and i hear when i rotate its goes down and love noise but no so much
When you say "its goes down" do you mean the noise is quieter or does it go slower?
Does the noise sound like 'ssssss' or does it sound like 'tap tap tap tap'?
 
  • #45
Tom.G said:
You did a lot of work! Resoldering everything, replacing the electrolytics, replacing the LM386 and contacting Elenco.
The voltages at the TP look a little bit low. Maybe the battery is low. Did you use that battery a long time?

When you say "its goes down" do you mean the noise is quieter or does it go slower?
Does the noise sound like 'ssssss' or does it sound like 'tap tap tap tap'?
no no like normal not nymore tap tap tap or ssssss, i think norma volume down and high, i desoldeer also the fm, and i solder i pick up just one station and i don't hear anymore, but there is no sound at speaker i hear with earphone, in am with speaker, i was so happy when i catch one station i thougt is working, what do you think what's the problem?what to do
 
  • #46
VERY GOOD! YOU GOT IT TO WORK.

If radio stations are far away they are hard to hear. Are you in or near a city with many stations?

The instruction book for the radio tells how to adjust (tune) it on pages 34, 35, 36. Did you do that?
 
  • #47
Tom.G said:
VERY GOOD! YOU GOT IT TO WORK.

If radio stations are far away they are hard to hear. Are you in or near a city with many stations?

The instruction book for the radio tells how to adjust (tune) it on pages 34, 35, 36. Did you do that?
Tom.G said:
VERY GOOD! YOU GOT IT TO WORK.

If radio stations are far away they are hard to hear. Are you in or near a city with many stations?

The instruction book for the radio tells how to adjust (tune) it on pages 34, 35, 36. Did you do that?
Tom.G said:
VERY GOOD! YOU GOT IT TO WORK.

If radio stations are far away they are hard to hear. Are you in or near a city with many stations?

The instruction book for the radio tells how to adjust (tune) it on pages 34, 35, 36. Did you do that?
I did, but i don't understand that magic wand, i rely don't understand, there come in kit one small metall and one plastic like antena, but i don't understand what to do with that?
 
  • #48
michael1978 said:
I did, but i don't understand that magic wand, i rely don't understand, there come in kit one small metall and one plastic like antena, but i don't understand what to do with that?
Long story here. It tells how this radio works and why you have the Magic Wand.

Maybe you know that to tune in a station the radio needs a coil and a capacitor of the right value. To tune a different station you change the value of the capacitor (the tuner). You can also tune a different station by changing the value of the coil, but changing the capacitor is easier.

Your radio has 5 different tuned circuits made of a coil and a capacitor.
Three of those are the "IF transformers", T6, T7, T8. They are tuned by turning the screw on the top. Turning the screw changes the value of the coil inside of them. After these are adjusted they do not need to change again.

The other two tuned circuits are the Oscillator and the Antenna. When you tune to a different station both of these circuits change because you turned the tuning knob on the tuner. The Oscillator and Antenna circuits must follow each other when you change stations. To make sure they follow each other, the coil and the capacitor in both circuits must be adjusted.

This is what pages 34, 35, 36 do.

The Oscillator is adjusted with the Oscillator Trimmer on the tuner and coil L5.
The Antenna is adjusted with the Antenna Trimmer on the tuner and by sliding the coil (L4) on the antenna rod.

Now the Magic Wand.
When a piece of metal is put near a coil, the value of the coil changes. A piece of Iron will make the coil value bigger. A piece of Brass will make the coil value smaller. The Magic Wand has a piece if Iron in one end and a piece of Brass in the other end. It is an easy way to test if the Antenna coil needs a higher value or lower value to follow the Oscillator circuit.

That is what page 36 in the instruction book is doing. If the station gets louder when the Brass end of the Magic Wand is put next to the Antenna, then the coil value needs to be smaller. Then the book says to move the Antenna coil closer the the end of the Antenna rod.

If the station gets louder when the Iron end is put near the Antenna Coil, move the coil towards the middle of the rod to make the coil value bigger.

If the station gets quieter with both ends of the Magic Wand, the Antenna coil does not need to change.

30 minutes after midnite again. Goodnight.

Cheers,
Tom
 
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  • #49
Tom.G said:
Long story here. It tells how this radio works and why you have the Magic Wand.

Maybe you know that to tune in a station the radio needs a coil and a capacitor of the right value. To tune a different station you change the value of the capacitor (the tuner). You can also tune a different station by changing the value of the coil, but changing the capacitor is easier.

Your radio has 5 different tuned circuits made of a coil and a capacitor.
Three of those are the "IF transformers", T6, T7, T8. They are tuned by turning the screw on the top. Turning the screw changes the value of the coil inside of them. After these are adjusted they do not need to change again.

The other two tuned circuits are the Oscillator and the Antenna. When you tune to a different station both of these circuits change because you turned the tuning knob on the tuner. The Oscillator and Antenna circuits must follow each other when you change stations. To make sure they follow each other, the coil and the capacitor in both circuits must be adjusted.

This is what pages 34, 35, 36 do.

The Oscillator is adjusted with the Oscillator Trimmer on the tuner and coil L5.
The Antenna is adjusted with the Antenna Trimmer on the tuner and by sliding the coil (L4) on the antenna rod.

Now the Magic Wand.
When a piece of metal is put near a coil, the value of the coil changes. A piece of Iron will make the coil value bigger. A piece of Brass will make the coil value smaller. The Magic Wand has a piece if Iron in one end and a piece of Brass in the other end. It is an easy way to test if the Antenna coil needs a higher value or lower value to follow the Oscillator circuit.

That is what page 36 in the instruction book is doing. If the station gets louder when the Brass end of the Magic Wand is put next to the Antenna, then the coil value needs to be smaller. Then the book says to move the Antenna coil closer the the end of the Antenna rod.

If the station gets louder when the Iron end is put near the Antenna Coil, move the coil towards the middle of the rod to make the coil value bigger.

If the station gets quieter with both ends of the Magic Wand, the Antenna coil does not need to change.

30 minutes after midnite again. Goodnight.

Cheers,
Tom
Hey my friend i change the battery, AM i don't pickup nothing, but fm i pick up 8 stations good, but speaker don't wrok also AM
have a nice sleep
 
  • #50
Tom.G said:
Long story here. It tells how this radio works and why you have the Magic Wand.

Maybe you know that to tune in a station the radio needs a coil and a capacitor of the right value. To tune a different station you change the value of the capacitor (the tuner). You can also tune a different station by changing the value of the coil, but changing the capacitor is easier.

Your radio has 5 different tuned circuits made of a coil and a capacitor.
Three of those are the "IF transformers", T6, T7, T8. They are tuned by turning the screw on the top. Turning the screw changes the value of the coil inside of them. After these are adjusted they do not need to change again.

The other two tuned circuits are the Oscillator and the Antenna. When you tune to a different station both of these circuits change because you turned the tuning knob on the tuner. The Oscillator and Antenna circuits must follow each other when you change stations. To make sure they follow each other, the coil and the capacitor in both circuits must be adjusted.

This is what pages 34, 35, 36 do.

The Oscillator is adjusted with the Oscillator Trimmer on the tuner and coil L5.
The Antenna is adjusted with the Antenna Trimmer on the tuner and by sliding the coil (L4) on the antenna rod.

Now the Magic Wand.
When a piece of metal is put near a coil, the value of the coil changes. A piece of Iron will make the coil value bigger. A piece of Brass will make the coil value smaller. The Magic Wand has a piece if Iron in one end and a piece of Brass in the other end. It is an easy way to test if the Antenna coil needs a higher value or lower value to follow the Oscillator circuit.

That is what page 36 in the instruction book is doing. If the station gets louder when the Brass end of the Magic Wand is put next to the Antenna, then the coil value needs to be smaller. Then the book says to move the Antenna coil closer the the end of the Antenna rod.

If the station gets louder when the Iron end is put near the Antenna Coil, move the coil towards the middle of the rod to make the coil value bigger.

If the station gets quieter with both ends of the Magic Wand, the Antenna coil does not need to change.

30 minutes after midnite again. Goodnight.

Cheers,
Tom
Tom one more time me ho does not work AM, but FM is working perfect also with speaker, how to fix am,
 
  • #51
Tom.G said:
Long story here. It tells how this radio works and why you have the Magic Wand.

Maybe you know that to tune in a station the radio needs a coil and a capacitor of the right value. To tune a different station you change the value of the capacitor (the tuner). You can also tune a different station by changing the value of the coil, but changing the capacitor is easier.

Your radio has 5 different tuned circuits made of a coil and a capacitor.
Three of those are the "IF transformers", T6, T7, T8. They are tuned by turning the screw on the top. Turning the screw changes the value of the coil inside of them. After these are adjusted they do not need to change again.

The other two tuned circuits are the Oscillator and the Antenna. When you tune to a different station both of these circuits change because you turned the tuning knob on the tuner. The Oscillator and Antenna circuits must follow each other when you change stations. To make sure they follow each other, the coil and the capacitor in both circuits must be adjusted.

This is what pages 34, 35, 36 do.

The Oscillator is adjusted with the Oscillator Trimmer on the tuner and coil L5.
The Antenna is adjusted with the Antenna Trimmer on the tuner and by sliding the coil (L4) on the antenna rod.

Now the Magic Wand.
When a piece of metal is put near a coil, the value of the coil changes. A piece of Iron will make the coil value bigger. A piece of Brass will make the coil value smaller. The Magic Wand has a piece if Iron in one end and a piece of Brass in the other end. It is an easy way to test if the Antenna coil needs a higher value or lower value to follow the Oscillator circuit.

That is what page 36 in the instruction book is doing. If the station gets louder when the Brass end of the Magic Wand is put next to the Antenna, then the coil value needs to be smaller. Then the book says to move the Antenna coil closer the the end of the Antenna rod.

If the station gets louder when the Iron end is put near the Antenna Coil, move the coil towards the middle of the rod to make the coil value bigger.

If the station gets quieter with both ends of the Magic Wand, the Antenna coil does not need to change.

30 minutes after midnite again. Goodnight.

Cheers,
Tom
Hi tom i fix it, there was two problems which they did not show it in book, first on wire to connect that fix the fm, second am, they say to make red and green coil together, but i make greeb and black together fix am

THANK MY FRIEND FOR TIME AND HELP, MAYBE I BORING YOU, BUT SORRY:wink:
 
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  • #52
Awesome troubleshooting @Tom.G. Fun thread.
 
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  • #53
dlgoff said:
Awesome troubleshooting @Tom.G. Fun thread.
+1.0 Nice work, @Tom G :smile:
 
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  • #54
michael1978 said:
Hi tom i fix it, there was two problems which they did not show it in book,
Good work! I'm glad you fixed it.

Now that the radio is working, what did it help you learn?

Tom
 
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  • #55
Tom.G said:
Good work! I'm glad you fixed it.

Now that the radio is working, what did it help you learn?

Tom
I want just to know the steps, where to start and where to end, i still have to study when i buy oscillscope generator signal in future:wink:
 
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  • #56
berkeman said:
+1.0 Nice work, @Tom G :smile:
Thanks
 

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