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

  • #1
434
19

Main Question or Discussion Point

Hello, i build the radio like they say in the book, and i did everything with VOM(testing with only multimeter),
everything was like in book , but when i finish, i switch to am or fm, i just hear high noise
:doh:
 

Answers and Replies

  • #2
berkeman
Mentor
56,923
6,891
When I built it, I accidentally got the battery and the speaker swapped. It took me a while to figure out my mistake. o0)

But seriously, how are we supposed to help you with so little information? Post the schematic and label it with the DC voltages you measure in your circuit -- that will give us a starting point to try to help you...
 
  • #3
434
19
When I built it, I accidentally got the battery and the speaker swapped. It took me a while to figure out my mistake. o0)

But seriously, how are we supposed to help you with so little information? Post the schematic and label it with the DC voltages you measure in your circuit -- that will give us a starting point to try to help you...
You had the same, i can tell you the value, you mean the TEST POINT(TP)? i dont know, which value you are interessed? just tell me and i will do it
 
  • #4
berkeman
Mentor
56,923
6,891
You had the same, i can tell you the value, you mean the TEST POINT(TP)? i dont know, which value you are interessed? just tell me and i will do it
I was kidding in my first paragraph, making fun of the fact that you posted with so little information and wanted help. Sorry if my humor wasn't obvious.

In my second paragraph, I asked you to Upload a copy of the schematic (as a PDF or JPEG file), and be sure to mark the DC voltages you measure at each node of the circuit on the schematic. That will help us to look for obvious problems (like if you measure a zero voltage at a place in the circuit where the voltage should be non-zero). Mark up the voltage you measure on the schematic that you have, and use the UPLOAD button to Upload a PDF or JPEG copy of that marked-up schematic. Here is an example without the measured voltages marked on it yet...

http://electroschematics.com/wp-content/uploads/2010/07/fm-radio-receiver.gif
 
  • #5
berkeman
Mentor
56,923
6,891
You had the same, i can tell you the value, you mean the TEST POINT(TP)? i dont know, which value you are interessed? just tell me and i will do it
I was kidding in my first paragraph, making fun of the fact that you posted with so little information and wanted help. Sorry if my humor wasn't obvious.

In my second paragraph, I asked you to Upload a copy of the schematic (as a PDF or JPEG file), and be sure to mark the DC voltages you measure at each node of the circuit on the schematic. That will help us to look for obvious problems (like if you measure a zero voltage at a place in the circuit where the voltage should be non-zero). Mark up the voltage you measure on the schematic that you have, and use the UPLOAD button to Upload a PDF or JPEG copy of that marked-up schematic. Here is an example without the measured voltages marked on it yet...

http://electroschematics.com/wp-content/uploads/2010/07/fm-radio-receiver.gif
 
  • #6
434
19
When I built it, I accidentally got the battery and the speaker swapped. It took me a while to figure out my mistake. o0)

But seriously, how are we supposed to help you with so little information? Post the schematic and label it with the DC voltages you measure in your circuit -- that will give us a starting point to try to help you...
I Measure, Test Point, without connection a speaker(because i thought the speaker was bad, so i desoldeer, and i connect with wire other speaker 8ohm but the same problem stays),
so
i switch to FM
tp15 and tp2=2.74V
tp15 and tp13=1.4V
tp15 and tp11=6.59V
tp15 and tp10=1.20V
tp15 and tp9=7.08V
tp15 and tp8=6.43V
tp15 and tp12=6.74V
i switch to am
tp15 and tp2=0.02V
tp15 and tp3=7.77V
tp15 and tp1=4.21V
tp15 and tp4=8.13V
tp15 and tp5=1.34V
tp15 and tp6=0V
tp15 and tp14'=0.02V
TP15=GND
 
  • #7
berkeman
Mentor
56,923
6,891
I Measure, Test Point, without connection a speaker(because i thought the speaker was bad, so i desoldeer, and i connect with wire other speaker 8ohm but the same problem stays),
so
i switch to FM
tp15 and tp2=2.74V
tp15 and tp13=1.4V
tp15 and tp11=6.59V
tp15 and tp10=1.20V
tp15 and tp9=7.08V
tp15 and tp8=6.43V
tp15 and tp12=6.74V
i switch to am
tp15 and tp2=0.02V
tp15 and tp3=7.77V
tp15 and tp1=4.21V
tp15 and tp4=8.13V
tp15 and tp5=1.34V
tp15 and tp6=0V
tp15 and tp14'=0.02V
TP15=GND
Please upload the schematic or link to a copy of it on the Internet. Thank you.
 
  • #8
434
19
Please upload the schematic or link to a copy of it on the Internet. Thank you.
 

Attachments

  • #9
434
19
I was kidding in my first paragraph, making fun of the fact that you posted with so little information and wanted help. Sorry if my humor wasn't obvious.

In my second paragraph, I asked you to Upload a copy of the schematic (as a PDF or JPEG file), and be sure to mark the DC voltages you measure at each node of the circuit on the schematic. That will help us to look for obvious problems (like if you measure a zero voltage at a place in the circuit where the voltage should be non-zero). Mark up the voltage you measure on the schematic that you have, and use the UPLOAD button to Upload a PDF or JPEG copy of that marked-up schematic. Here is an example without the measured voltages marked on it yet...

http://electroschematics.com/wp-content/uploads/2010/07/fm-radio-receiver.gif
i post schematic
 
  • #10
berkeman
Mentor
56,923
6,891
i post schematic
Thank you, that helps a lot. I think I'll move this thread to the EE forum, to get more specialized help.

It looks like there are several adjustable components in the schematic. Was there an "alignment procedure" included in the instructions? Also, did you assemble this from a kit with a PC board included?
 
  • #11
berkeman
Mentor
56,923
6,891
I Measure, Test Point, without connection a speaker(because i thought the speaker was bad, so i desoldeer, and i connect with wire other speaker 8ohm but the same problem stays),
so
i switch to FM
tp15 and tp2=2.74V
tp15 and tp13=1.4V
tp15 and tp11=6.59V
tp15 and tp10=1.20V
tp15 and tp9=7.08V
tp15 and tp8=6.43V
tp15 and tp12=6.74V
i switch to am
tp15 and tp2=0.02V
tp15 and tp3=7.77V
tp15 and tp1=4.21V
tp15 and tp4=8.13V
tp15 and tp5=1.34V
tp15 and tp6=0V
tp15 and tp14'=0.02V
TP15=GND
It looks like TP17 (lower right of the schematic) is Ground. Can you please measure the voltages of the other test points with respect to TP17 Ground? That would be helpful. Just keep you meter's negative test lead on TP17, and measure the voltages of the other test points with your meter's positive lead. Thank you.
 
  • #12
434
19
It looks like TP17 (lower right of the schematic) is Ground. Can you please measure the voltages of the other test points with respect to TP17 Ground? That would be helpful. Just keep you meter's negative test lead on TP17, and measure the voltages of the other test points with your meter's positive lead. Thank you.
It looks like TP17 (lower right of the schematic) is Ground. Can you please measure the voltages of the other test points with respect to TP17 Ground? That would be helpful. Just keep you meter's negative test lead on TP17, and measure the voltages of the other test points with your meter's positive lead. Thank you.
I dont use transistor amplifier, but i use lm386,
 
  • #13
berkeman
Mentor
56,923
6,891
I dont use transistor amplifier, but i use lm386,
Please post the schematic for what you have built, and post the test point voltages. Thank you.
 
  • #14
434
19
Please post the schematic for what you have built, and post the test point voltages. Thank you.
I show you tomorow maybe, because i go to sleep, here is 24:10 goodnight berkeman
 
  • Like
Likes berkeman
  • #15
Tom.G
Science Advisor
3,082
1,827
It looks like TP17 (lower right of the schematic) is Ground.
TP15 is also GND; that's below Q5 in the FM section.

@michael1978
I have only looked at the AM section because that part is easier. Let's get that and the earphone working first.
Page 34 of the manual says the battery should measure 8.5V or more with the power switch turned on. Your measurements show around 7.8V to 8.1V. Please replace the battery.

This test can be done with the old battery. It will give you something to do until you get a new one.
There is a problem at TP6, it reads 0V but should be about 8V or higher (about the same voltage as at TP4).
Check the wiring at the primary (left) side of T6, around L5 and around Q7. There is probably a bad or missing connection to T6.

Let us know what you find.

Cheers,
Tom
 
  • #16
434
19
TP15 is also GND; that's below Q5 in the FM section.

@michael1978
I have only looked at the AM section because that part is easier. Let's get that and the earphone working first.
Page 34 of the manual says the battery should measure 8.5V or more with the power switch turned on. Your measurements show around 7.8V to 8.1V. Please replace the battery.

This test can be done with the old battery. It will give you something to do until you get a new one.
There is a problem at TP6, it reads 0V but should be about 8V or higher (about the same voltage as at TP4).
Check the wiring at the primary (left) side of T6, around L5 and around Q7. There is probably a bad or missing connection to T6.

Let us know what you find.

Cheers,
Tom
GoodMorning, i was wrong, because now between T6 is 8.7V, now is not anymore so high noise, but low noise, and when i rotate the VARcapacitor
i dont hear nothing changes, i cant pickup any fm or am radio station?
what do you think where is problem?
have a nice day
 
  • #17
434
19
Thank you, that helps a lot. I think I'll move this thread to the EE forum, to get more specialized help.

It looks like there are several adjustable components in the schematic. Was there an "alignment procedure" included in the instructions? Also, did you assemble this from a kit with a PC board included?
yes
 
  • #18
434
19
TP15 is also GND; that's below Q5 in the FM section.

@michael1978
I have only looked at the AM section because that part is easier. Let's get that and the earphone working first.
Page 34 of the manual says the battery should measure 8.5V or more with the power switch turned on. Your measurements show around 7.8V to 8.1V. Please replace the battery.

This test can be done with the old battery. It will give you something to do until you get a new one.
There is a problem at TP6, it reads 0V but should be about 8V or higher (about the same voltage as at TP4).
Check the wiring at the primary (left) side of T6, around L5 and around Q7. There is probably a bad or missing connection to T6.

Let us know what you find.

Cheers,
Tom
I see one video, all collector of fm have the same value, he show in the video and i tested my the same they have,
but like in am and fm sometimes is high noise, sometime little bit noise, but i cant catch any signal,
 
  • #19
434
19
now is low NOISE like in am or fm but i can get any signal, what do you think , where is problem:bow:
 
  • #20
Tom.G
Science Advisor
3,082
1,827
Does anything you do make a change in the high noise or low noise?
If yes, tell use what you do to make that change.
 
  • #21
434
19
Does anything you do make a change in the high noise or low noise?
If yes, tell use what you do to make that change.
I think maybe, i soldeer it one more lm386 WITH bypass capacitor at pin 2 and 6, and also i change the battery little bit old,
and also i can hear nothing from earphony, totaly nothing,
 
  • #22
Tom.G
Science Advisor
3,082
1,827
WITH bypass capacitor at pin 2 and 6
That should be pin 4 and 6.

Do you have any test equipment besides the voltmeter?
 
  • #23
434
19
That should be pin 4 and 6.

Do you have any test equipment besides the voltmeter?
how not, how i measure til now?, but in the book is between pin 2 and 6 capacitor, how come now pin 4 and 6(are you sure)?
 
  • #24
434
19
how not, how i measure til now?, but in the book is between pin 2 and 6 capacitor, how come now pin 4 and 6(are you sure)?
i have dvm
 
  • #25
Tom.G
Science Advisor
3,082
1,827
how not, how i measure til now?, but in the book is pin 2 and 6, how come now pin 4 and 6(are you sure)?
The image below is from the datasheet for the LM386 made by National Semiconductor. As you can see, the supply voltage is on pin 6, Ground is pin 4, and -Input is pin 2. Your circuit has pin 2 connected to Ground, probably as a short circuit trace between pins 2 and 4. I said pin 4 for the bypass capacitor just to be very safe (conservative). If there is a bad connection on the board between pins 2 and 4, the bypass might not connect to Ground if soldered to pin 2.

If the connection between pins 2 and 4 are good, for your circuit it probably will not make much difference. For other circuits it can make a difference, so we all get in the habit of connecting bypass capacitors to the power and Ground pins just to avoid problems.

OK, you have DVM. What make and model is it?

upload_2018-7-15_15-14-38.png
 

Attachments

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

  • Last Post
Replies
3
Views
3K
  • Last Post
Replies
9
Views
3K
  • Last Post
Replies
3
Views
1K
  • Last Post
2
Replies
31
Views
64K
Replies
12
Views
4K
  • Last Post
2
Replies
25
Views
46K
Replies
16
Views
3K
Replies
11
Views
2K
  • Last Post
Replies
6
Views
2K
  • Last Post
Replies
10
Views
15K
Top