Thanks for the video.I know it must make you feel good when you troubleshoot the problem, find the fault, fix it. Then enjoy the results. Works for me. Keep up the good work. An old timer told me many decades ago, Do what you love and you will never work a day in your life. Thanks Brad
It was really very helpful how you found out the fault of the oscillator transistor. I have learnt a lot from this simple video. Thank you very much for sharing the basics.
Good Job OM. This is a good lesson for new people to repair on how to repair without a print, and that it can be done. Many Kids coming out of tech schools these days won't even try without a print. But Over my 52 years in radio you had to try, that was how you fed your family. Keep the videos comming. 73 Jimmy, ARRL TC, WX9DX
I know this video goes back a ways but I like your resistor trick. I've done that with capacitors but never tried resistor on the base of a transistor. Thanks for sharing your experience!
Well, another one found this “old” video. I started collecting radios about 2years ago. I have absolutely no knowledge of electronics AT ALL. Perhaps one day I will learn to work on these, but I am a slow learner. So when I stumble across one of these, I learn just a little bit more. Glad this is still floating around. Thanks. 📻👍🙂‼️
This is my FREE ebook. Password is allamericanfiveradio th-cam.com/users/redirect?event=channel_description&redir_token=QUFFLUhqa2hhVTRycWdJd1FUbTFCZWNmdGtQNlZCRmEzd3xBQ3Jtc0tuOFQ2bFhRcWdjdUdIcUREcnZFaHc0M2xURGhITVRuWDE2cGlDakdYUF9uODktNzc3TVRJTWdROUt6R3NLN2lla3hFS2lIM0RnOXR1dXFxMGx2cUNtWDhXb1Zvc2RCbGQxTThoendmN2E5R0lJdmI0Yw&q=https%3A%2F%2Fdrive.google.com%2Ffile%2Fd%2F1HHmaWYr7UMACfmS4W5uL6PADoem2KlRp%2Fview%3Fusp%3Dsharing
Your video about the FM signal path in tube radios actually helped me fix my transistorized Marantz 2015’s FM tuner. One day the stations just stopped coming in, all I could get was static. I was hoping it was a power supply problem. But the more I poked around, I knew the problem was in the FM tuner itself. Since I seldom see a tuner fail in a receiver, I’m really not experienced with tuners. After poking around more and reading the little description in the service manual, I was able to determine that it’s FM 10.7MHz oscillator stopped working. Later, I found an open base-emitter junction in the oscillator transistor (H103). Replacing the 2SC930 with one from an extra tuner board I bought on eBay, made the oscillator go again and all the stations came back! Now, I believe the FM needs to be aligned but it needed that since before the oscillator transistor failed. Thanks for your videos! I’m still wondering why the low-power oscillator transistor failed in the first place(?) Hopefully it failed on it’s own without the help of another bad part....
...Great, back again where I started, the " Old faithful School", made me go back, in the time capsule...Thanks for brought me back so good memories. My greetings and respects from PR.
Great timing Rick. I just acquired a Royal 150 and she's dead in the water. I was wondering where to begin and your video has got the wheels a spinning. Thanks as always. I can't believe how much I have learned from your generous sharing of knowledge. ( And I'm not alone ) 73
It was really very useful watching how you found out the failure of the oscillator transistor. I have learnt a lot from this simple video. Thanks very much indeed ,your lessons are simple wonderful for everybody interested how to restore old and new radios.
Thank You very much for the video as it has helped me in diagnosing a similar problem on a 1977/8 Ford AM/FM radio. Boy am I ever late to this video after seeing the comments from years ago. Better late than never!
Thanks Ron Pearson I use other methods for tubes because of the higher voltage. It have to be careful not to burn out the oscillator coil, or the primary of the IF
Hey Andy, It is unusual, first one for me. I have wanted to show the generator sub with a generator, and I knew an oscillator problem would happen sometime. When I resoldered the tracks and it played, I thought, that's great. And then when it stop again, I thought, even better. Regards, Rick
Hi Rick, well done on finding the ‘thermionic transistor.’ Oscillators can be the very devil as either an open circuit or closed circuit component simply kills it stone dead and it’s not very day you find a transistor on the edge of thermal stability is it. Nice one. Kind Regards ... Andy
The generator is taking the place of the local oscillator. So any frequency difference between the local oscillator and the incoming radio station RF that produces 455 KC will pass to the radio. Which is the normal operation of a superheterodyne.
You could inject a signal on the first transistors emitter base and or collector. I just found a convenient spot right at the antenna. If I would not have heard any stations I would move halfway up the circuit and found another test point. Cutting the circuit in half is common troubleshooting practice. There are many points for injection and for signal tracing, none of which will do you no good if you do not understand how a circuit works.
Rick... Great video. Would this same approach work on a tube radio? I still haven't finished the Revere 400. It has nothing coming out of the oscillator.
Hi there, Not sure if you can help me since this is an old video.. I have a slight problem with the AM/MW band of my Eton FR-250 multiband radio This is an IC (Sony CXA1691) radio & my problem is the lower band on AM/MW, from 535KHz to around 1100KHz had gone deaf. All I hear are static noise. Above that freq I can hear the nearby station at much reduced gain. It is not loose contact since I already checked thoroughly the solder joints & tapped the board for any loose connection. Sometimes the reception would return to normal then suddenly go quite again (background static hiss remains) Can you give me an idea which stage (IF or RF) should I check & which part (capacitor, coils, etc) could be causing this. FM & SW are all ok from a fan in the Philippines
It sounds like the oscillator for the AM/MW band is not oscillating. You can use another AM radio to confirm if the oscillator is working. Oscillator Trouble Shooting Using Radios as Testers Demo th-cam.com/video/AuLP31cLBMQ/w-d-xo.html
Thank you for the video. What controls the power to the oscillator? I understand that the oscillator has to have pulses of power at the proper time to oscillate. Is this correct?
Download my free ebook. There is an explanation of the oscillator and much more. The Vacuum Tube Shortwave Radio www.richardmcwhorter.com/vacuumtuberadio/
Ha! Heating of that old transistor changed it's gain and made it work again, and of course as it cooled down some time later, gradually stopped working. Fantastic spot, not an easy repair AT ALL! 10/10
Not sure why. Usually a bad transistor will play until it heats up, then you cool them one at a time to find the bad one. Over the years the characteristics of the PNP transistor changed. Adding a little more negative bias on the base, caused it to function again. If this was a NPN transistor you would use a positive bias on the base.
Ok, my signal generator produces a sine and square wave which results in a single tone when I apply it to my radio's transistors. How are you getting broadcast signals out of yours?
I am just trying to square my understanding of what I think I understand (and may not, btw) with what you did. It seems that if you just injected a 455 kc signal at the collector of the transistor, wouldnt you hear a signal by tuning the tuning knob of the radio?
How do you select a replacement transistor when the specifics of the old one are unknown? I have a situation with proprietary part numbers and don't know what to replace it with.
That’s the first step, learn the circuit you want to troubleshoot first. My ebook has an active troubleshooting outline toward the end of the book. If you check on the outline it will suggest your next step, if you get to the last suggestion it sends you to the circuit for a review of how the circuit works.
One question: Since the IF stages are set up to pass 455 kHz (typically) is that the carrier frequency you injected into the antenna? If not, then I don't understand how it would get through to the audio sections and speaker if you wer injecting AM band frequencies and the local oscillator was not functioning. Perhaps you could clarify?
I just picked up an old realistic boombox style fm/am cassettplayer.. the radio worked awesome for about a half hour. next time I turned it on the radio sounded a little weak and in a matter of minutes it stopped receiving signal.. am and fm???...even the dial indicator lite stopped illuminating.???? thanks for you video here.. I might have to look into this oscillator thing
Where have YOU been,,! I needed this info last month before I made thing's worse with my attempt at two radio repairs! Perhaps I can give it another go if I can remember what else I messed up
I dug out my vintage Sony (ICF- A10W) clock radio that I bought used about 12 years ago. After I bought 12 years ago, I just tested quickly and not sure if I checked the am radio and just stored away. So when I came across it in my storage, I took it home, but heard something loose inside. So I took it apart with just 2 small screws. I found a long metal bar with 2 thin copper wire wrapped around lose and I believe came loose in shipping 12 years ago bc the eBayer left the battery in shipping and when I got it, the radio was playing inside the package. Lol! So bc I didn’t have any glue, I just put the loose bar near where it was attached to the inside corner. And it still shakes but seem not as much as before. But now I’m wondering if the am was already broken or if I had put the buttons back wrong? I managed to not break any of the plastic and careful taking it apart with snapping off anything. That’s the problem with handling something brand new and understanding without breaking it on how that part all go into place. Lol! I’m not that mechanical and don’t understand how things work or what each thing does what. So I get lost and usually don’t even go as far as taking apart or trouble shooting, I always hope for an easy fix or look on TH-cam for guidance. So if it having to replace the am part, are they all about the same or are there many? Can I take it jist from an old radio with am? This clock radio I have is a collectors item and I want it to completely work and including the am radio I never use. Lol! Anyway, thanks for the tutorial! Maybe if I re glue tgat metal bar, the Am will start working again. Also, I’ve looked at about 20 of these Sony clock radios used and most just have the fm wore port and not the wire that plugs into it. Perhaps most didn’t need or lost after 40 years and I only saw one unit with the original fm wire. Meaning if I find the fm fm wire, would that help make the am stations to come in? Oh and the end connection is much smaller than the end of the standard headphone jack. So it might be hard to find a replacement.
I guess there are ppl. like you that likes to fix these old radios and spend time trying to get them to work. Bc I see used radios at thrift stores, flea markets and garage sales and could easily find an old radio for under $10. I just picked up this Aiwa handheld emergency wind up option radio with even a light for $15. in like new condition. I should’ve gotten this top of the line Yamaha receiver from the early 2000s they were selling at Goodwill the day I was there first thing in the morning to get a record I saw the day before for only $24.99. I didn’t want to carry that 30lb. receiver on the bus and running late for work and in 7 minutes, I saw someone buying it when I was checking out.
I also remember the days when there were many electronic repair shops and now gone like shoe repair shops bc of this disposable generation. This needs to change bc many now are getting into vintage aiduo equipment and many those units needs servicing and someone to care for these solid made equipment from the past, instead of filling up landfills. I remember buying this great JVC 80’s receivers with green lights and I think the spin radio dial from this guy who used to repair audio and worked at a few high end stereo stores in I think Portland or Seattle. He bought the troughs the receiver from a local theft store and cleaned it up and made sure everything worked. He told me he still knew places that sold parts for these older units and that this was a way to make some extra money flipping vintage stereo equipment to supplement his income while being retired and 12 years ago he was in his late 60’s and also told me he had cancer. I always love. Intake stereo equipment and not someone looking for one stereo to own. So I know now this vintage stereo collecting is trendy but that didn’t make a difference or change my love for vintage audio equipment Partly bc when o was a kid, I was fascinated by the adult buying stereos and how much that was a part of the culture in the 70’s and 80’s. I wish I was able to open a store 12 years ago buying and selling vintage audio equipment as some are doing now. Bc back then everyone thought I was nuts and didn’t understand my passion. I just a few days ago went to the SFMOMA museum in San Francisco and they had this great exhibition on vintage audio equipment and vintage concert/ music shows that were vibrant in color and fill up all the walls that made a huge impact. They even had 2 floors of independence used record sellers for the first time in the museum that USF normally has twice a year. It’s all coming back and the younger generation is responding hard to it, especially in the big cities across the US.
Your Sony radio is two radios with shard parts. I recommend to contact your local Ham Radio Club, for help. There will be someone in this club who repair radio or knows some who does radio repair. I did meet Mr. Carver when I was living in the Seattle area. Digital Time Lens by CARVER th-cam.com/video/eRNoUJcxQhY/w-d-xo.html
I think a very unusual fault, but with the illustrated method of diagnosis, giving detail of its function in a standard AM 'superheterodyne' radio, came to it in theory as well as practice. I looked up 2SA102, and found it to be a PNP point contact germanium transistor made by Matsushita, Japan, the company most known for making 'National Panasonic' radios, record players, amplifiers, etc. This radio might well have gone through the manufacture process (soldering), checked through final inspection, then tried in a cold atmosphere, and stopped playing. Thanks for sharing the information..
I have a general electric model 7-2825a am fm radio I'm pulling my hair out it works only in fm mode no am receive has 2 transistors ive replaced the caps I don't have any imfo on voltages I wished I had a signal generater I only have scope and volt meter not sure any ideas
AM and FM superheterodyne radios are set up with a separate front end for both AM and FM. This means that each has its own oscillator and I.F. cans, what is in common with both is the audio amplifier. I did look for a wiring diagram for your radio but have not found one yet. I would try and determine if the AM oscillator is working, I have done a few videos on how to do this using another AM radio. Oscillator Trouble Shooting Using Radios as Testers Demo th-cam.com/video/AuLP31cLBMQ/w-d-xo.html All American Five Radio Troubleshooting th-cam.com/video/clRQ0qxnA10/w-d-xo.html Digital PC Oscilloscope Signal Tracing th-cam.com/video/_fHAuzDIgEQ/w-d-xo.html AM Radio Demodulation Oscilloscope Demo th-cam.com/video/pKA0TPdnHg8/w-d-xo.html
I put the signal at the antenna for a number of reasons. If running through the AM frequencies nothing is heard from the radio speaker, this means a IF can may be open and the oscillator could still be bad. In this case we heard stations running through AM frequencies, the IFs are good, but I could not tune in a station with the radio tuner. This means the oscillator in the radio is not working.
I have a 1967 Mustang original radio. The radio lights up, has volume but the radio is oscillating. It varies as I tune across the AM band. I can't hear any stations just static with varying oscillation sounds. Any tips or forums that might be familiar with this AM only radio. I can't find a schematic.
@@AllAmericanFiveRadio after more tuning across the band I picked up a local station. Its not strong or clean sounding. If I connect my outdoor wire antenna the station drops out almost like the radio is being overloaded. I am wondering if a cap involved with AGC could be bad. Thanks for looking for a schematic. On the side of the radio it has the marking 7TPZ Its AM only. It appears to be the original radio with only a single speaker output
@@AllAmericanFiveRadio Thanks, the side of the radio has 7TPZ marked on it. Its AM only single speaker output and appears to be the original radio from a 1967 Ford Mustang. I checked the junctions of the only 3 transistors and the meter indicates the correct forward bias voltage. Emitter to Collector is around 1.4v The transistors are marked AR 103, AR 104, and AR 105 and they are germanium transistors. I also checked a germanium diode to be good too. This diode must be for audio detection or part of a AGC circuit. There are a few caps and one large cylinder cap that looks like its a multi-capacitor. Its corroded on the top and probably bad. I am going to have to remove the cap to get the values or if you can find me the schematic. I appreciate your help Thank you,
My Nobility 10 radio puts out full volume white noise-- volume control doesn't diminish it, and it does not tune any station. The pawn shop says it needs a new ant. It looked good to me and all the leads to the ant. are soldered in place.
The bench oscillator replaces the radio local oscillator. When the difference between the oscillator and the radio station equals 455KC we hear the station.
Great very informative video, thanks for sharing it. At minute 2.00 you used the signal generator but you can't see where you placed the probe, I think on the antenna but can you kindly explain to me where exactly? Thanks again, I follow your videos with a lot of interest.
By injecting RF at the blue arrow, aren't you approximating an rf signal coming into the antenna? Im not sure why that would show that would show the local oscillator wasnt working. It seems that in order to show that the local oscillator is at fault, wouldnt you have to inject an rf signal at the collector of that 1st transistor of precisely the correct freq and thus emulate the oscillator? Sorry but I dont understand
Exactly..so when you put in an rf signals (spanning the am broadcast band) into the antenna you are approximating the rf input derived from an on air signal, arent you? What I dont understand is that if when you put that signal in and you hear a signal out, doesnt it mean that the local oscillator stage is in fact working? Otherwise you wouldnt have the difference signal of 455 kc coming through.....and the if stage tuned to that freq wouldnt come through.
Rick, thanks. understand theory of mixer circuit from p 72. Just trying to take advantage of your ample experience. You are putting in an am signal at, say, 1000Kc. Local oscillator isn't working so mixing down to 455 kc shouldn't occur and like you said "nothing will come through the radio". If you suspect that lo isnt working, why not put lo signal from sig gen into emitter of the mixer stage? Just trying to understand 1) if that would work and 2) the advantage of your approach.
Thank you and God bless you for posting this. I am fixing my mother's old AM/FM radio. She listen to 1010 news AM. She lives in a high rise building and am reception is very bad up there. Do you have any suggestions on how to remedy this issue. The radio reception in my apartment is pretty good.
A tecsun loop antenna from amazon ,you just set it next to the radio ,and your A M will improve ,it has a tuning knob on the loop antenna too.,works good
It's hard to say from several hundred or thousand miles away. Since the FM is working there is a very good chance that the oscillator for your AM is not working. Below is one way to determine if your AM oscillator is working. Oscillator Trouble Shooting Using Radios as Testers Demo th-cam.com/video/AuLP31cLBMQ/w-d-xo.html
Search my channel for signal tracer. I've done several on making signal tracer's and on at least one of them threre is a close-up of the transistorized signal tracer.
Thanks for the video.I know it must make you feel good when you troubleshoot the problem, find the fault, fix it. Then enjoy the results. Works for me. Keep up the good work. An old timer told me many decades ago, Do what you love and you will never work a day in your life.
Thanks Brad
Yup and that’s the best policy.
It was really very helpful how you found out the fault of the oscillator transistor. I have learnt a lot from this simple video. Thank you very much for sharing the basics.
Thank you, and your welcome.
Good Job OM. This is a good lesson for new people to repair on how to repair without a print, and that it can be done. Many Kids coming out of tech schools these days won't even try without a print. But Over my 52 years in radio you had to try, that was how you fed your family. Keep the videos comming.
73
Jimmy, ARRL TC, WX9DX
I know this is an old video, but this is great information. Thanks.
Thanks
How old my videos are does not matter, the content is relevant.
It's a true pleasure to learn from you via your videos! Can't thank you enough!
I know this video goes back a ways but I like your resistor trick. I've done that with capacitors but never tried resistor on the base of a transistor. Thanks for sharing your experience!
THANK YOU!
Another Great Video,,,Thanks Rick!!! Everyone of your Videos teach ME Something!!! KEEP Them Coming!!!!
Well, another one found this “old” video.
I started collecting radios about 2years ago. I have absolutely no knowledge of electronics AT ALL.
Perhaps one day I will learn to work on these, but I am a slow learner.
So when I stumble across one of these, I learn just a little bit more.
Glad this is still floating around. Thanks.
📻👍🙂‼️
This is my FREE ebook.
Password is allamericanfiveradio
th-cam.com/users/redirect?event=channel_description&redir_token=QUFFLUhqa2hhVTRycWdJd1FUbTFCZWNmdGtQNlZCRmEzd3xBQ3Jtc0tuOFQ2bFhRcWdjdUdIcUREcnZFaHc0M2xURGhITVRuWDE2cGlDakdYUF9uODktNzc3TVRJTWdROUt6R3NLN2lla3hFS2lIM0RnOXR1dXFxMGx2cUNtWDhXb1Zvc2RCbGQxTThoendmN2E5R0lJdmI0Yw&q=https%3A%2F%2Fdrive.google.com%2Ffile%2Fd%2F1HHmaWYr7UMACfmS4W5uL6PADoem2KlRp%2Fview%3Fusp%3Dsharing
Your video about the FM signal path in tube radios actually helped me fix my transistorized Marantz 2015’s FM tuner. One day the stations just stopped coming in, all I could get was static. I was hoping it was a power supply problem. But the more I poked around, I knew the problem was in the FM tuner itself. Since I seldom see a tuner fail in a receiver, I’m really not experienced with tuners. After poking around more and reading the little description in the service manual, I was able to determine that it’s FM 10.7MHz oscillator stopped working. Later, I found an open base-emitter junction in the oscillator transistor (H103). Replacing the 2SC930 with one from an extra tuner board I bought on eBay, made the oscillator go again and all the stations came back! Now, I believe the FM needs to be aligned but it needed that since before the oscillator transistor failed. Thanks for your videos! I’m still wondering why the low-power oscillator transistor failed in the first place(?) Hopefully it failed on it’s own without the help of another bad part....
That's great! Glad you got your radio working again. Hope the video helped. Thanks.
Rick..thank you so much for your time....great book by the way...
I Always find your videos informative and learn something every time.
Great Job.
...Great, back again where I started, the " Old faithful School", made me go back, in the time capsule...Thanks for brought me back so good memories. My greetings and respects from PR.
Thanks and your welcome.
Great timing Rick. I just acquired a Royal 150 and she's dead in the water. I was wondering where to begin and your video has got the wheels a spinning. Thanks as always. I can't believe how much I have learned from your generous sharing of knowledge. ( And I'm not alone )
73
It was really very useful watching how you found out the failure of the oscillator transistor. I have learnt a lot from this simple video. Thanks very much indeed ,your lessons are simple wonderful for everybody interested how to restore old and new radios.
Thanks
Nice troubleshooting, fun to watch. Very informative.
Me gusta su manera de trabajar, lo hace con método y observar sus vídeos me hace aprender. Gracias por enseñarnos por aquí sus trabajos. Felicidades.
Thanks you and you are welcome.
Thank You very much for the video as it has helped me in diagnosing a similar problem on a 1977/8 Ford AM/FM radio. Boy am I ever late to this video after seeing the comments from years ago. Better late than never!
Thanks and your welcome.
I see. Thank you!
Love your channel.
Great Video, and Great Fix, Thanks for uploading.
Thanks Rick you are the best .
Thanks skycarl
Hope you get it working!
Great job. Thank you for sharing.
THANKS
Thanks Ron Pearson
I use other methods for tubes because of the higher voltage. It have to be careful not to burn out the oscillator coil, or the primary of the IF
AllAmericanFiveRadio
Hi Rick: Good methodology divide and conquer. I have never seen the bias trick. That worked well.
Very interesting and educational video, Thank you very for your effort, Best regards from Venezuela.
Thanks
Hey Andy,
It is unusual, first one for me. I have wanted to show the generator sub with a generator, and I knew an oscillator problem would happen sometime. When I resoldered the tracks and it played, I thought, that's great. And then when it stop again, I thought, even better.
Regards,
Rick
Hi Rick, well done on finding the ‘thermionic transistor.’ Oscillators can be the very devil as either an open circuit or closed circuit component simply kills it stone dead and it’s not very day you find a transistor on the edge of thermal stability is it. Nice one.
Kind Regards ... Andy
Thanks MrHarveyluke
me gustan tus videos, estoy aprendiendo a reparar mi radio con problemas recepcion en la banda AM.gracias y saludos desde Bs As. argentina¡¡¡
I appreciate your comment very much! I hope my videos can help you in repairing your radio. Thank you!
Very useful video thanks!
Thanks and your welcome.
@@AllAmericanFiveRadio ... let’s keep an eye on each other :-)
Very usefull video,love the transistor radio repair video's
Thanks!
Thanks John,
The highest frequency the generator produces is 1MHz. I avried the generator from about 700KHz to 1MHz.
Rick
The generator is taking the place of the local oscillator. So any frequency difference between the local oscillator and the incoming radio station RF that produces 455 KC will pass to the radio. Which is the normal operation of a superheterodyne.
Indeed very interesting!! This is a tricky transistor fault, as it lost its bias with working shifted bias range during the resitor test.
Thank you, and your welcome.
Thank you and appreciate your effort. Greetings to you from Turkey .
Thank you! I appreciate that you watch and comment.
Thanks for the video, good information, I learned something new today :)
Thanks
Another great video.
The transistor prob had a thermal fault, which by heating, bought its characteristics to spec.
Thanks
Good video as always, Rick.
73, KM4JA
It really shows what a,skilled man you.are I enjoyed that a lot.
Thanks,, and your welcome.
Thanks dmottern1952
Sure you can use the video. I have no restrictions and I hope you find it useful.
You could also listen on a RX for the Oscilator Freq.
73
Jimmy, ARRL TC, WX9DX
You could inject a signal on the first transistors emitter base and or collector. I just found a convenient spot right at the antenna. If I would not have heard any stations I would move halfway up the circuit and found another test point. Cutting the circuit in half is common troubleshooting practice. There are many points for injection and for signal tracing, none of which will do you no good if you do not understand how a circuit works.
Thank you for your good video
Thank you, and your welcome.
Thanks RadioHamGuy
Many many thanks.
Thank you, and your welcome.
Rick... Great video. Would this same approach work on a tube radio? I still haven't finished the Revere 400. It has nothing coming out of the oscillator.
nice repair
Very useful !
Thank you, and your welcome.
Thanks ACatal1
Hi there,
Not sure if you can help me since this is an old video..
I have a slight problem with the AM/MW band of my Eton FR-250 multiband radio
This is an IC (Sony CXA1691) radio & my problem is the lower band on AM/MW, from 535KHz to around 1100KHz had gone deaf. All I hear are static noise. Above that freq I can hear the nearby station at much reduced gain. It is not loose contact since I already checked thoroughly the solder joints & tapped the board for any loose connection. Sometimes the reception would return to normal then suddenly go quite again (background static hiss remains)
Can you give me an idea which stage (IF or RF) should I check & which part (capacitor, coils, etc) could be causing this. FM & SW are all ok
from a fan in the Philippines
It sounds like the oscillator for the AM/MW band is not oscillating. You can use another AM radio to confirm if the oscillator is working.
Oscillator Trouble Shooting Using Radios as Testers Demo
th-cam.com/video/AuLP31cLBMQ/w-d-xo.html
Rick,
Thank you. Great job. Very, very informative. What frequency did you inject?
Regards,
John
Thank you for the video.
What controls the power to the oscillator? I understand that the oscillator has to have pulses of power at the proper time to oscillate. Is this correct?
Download my free ebook. There is an explanation of the oscillator and much more.
The Vacuum Tube Shortwave Radio
www.richardmcwhorter.com/vacuumtuberadio/
Ha! Heating of that old transistor changed it's gain and made it work again, and of course as it cooled down some time later, gradually stopped working. Fantastic spot, not an easy repair AT ALL! 10/10
Thanks
Not sure why. Usually a bad transistor will play until it heats up, then you cool them one at a time to find the bad one. Over the years the characteristics of the PNP transistor changed. Adding a little more negative bias on the base, caused it to function again. If this was a NPN transistor you would use a positive bias on the base.
Ok, my signal generator produces a sine and square wave which results in a single tone when I apply it to my radio's transistors. How are you getting broadcast signals out of yours?
No. AM station is close to my house
I am just trying to square my understanding of what I think I understand (and may not, btw) with what you did. It seems that if you just injected a 455 kc signal at the collector of the transistor, wouldnt you hear a signal by tuning the tuning knob of the radio?
How do you select a replacement transistor when the specifics of the old one are unknown? I have a situation with proprietary part numbers and don't know what to replace it with.
Determine if it is PNP or NPN, than us a beta of at least 200
That’s the first step, learn the circuit you want to troubleshoot first. My ebook has an active troubleshooting outline toward the end of the book. If you check on the outline it will suggest your next step, if you get to the last suggestion it sends you to the circuit for a review of how the circuit works.
Great repair! very in site full, a lot of these transistors burn out. This 2sb102? is very VEY! old. Sometimes they use Fets instead.
Yeah Jordan, I think I'll have to swap out a few.
Thanks famossfla
Yes that is the transistor I used 2N3906
I wonder what heating the heat trace was doing to improve the reception? Interesting find.
It wold not last the transistor is bod/
One question: Since the IF stages are set up to pass 455 kHz (typically) is that the carrier frequency you injected into the antenna?
If not, then I don't understand how it would get through to the audio sections and speaker if you wer injecting AM band frequencies and the local oscillator was not functioning. Perhaps you could clarify?
The answer is simple. The signal generator acts as a replacement for the (broken) internal oscilator.
Thanks 321reh
Good luck sir 🎉FROM IRAN...
Thank you, and your welcome.
Thanks tectalabyss
I just picked up an old realistic boombox style fm/am cassettplayer.. the radio worked awesome for about a half hour.
next time I turned it on the radio sounded a little weak and in a matter of minutes it stopped receiving signal.. am and fm???...even the dial indicator lite stopped illuminating.???? thanks for you video here.. I might have to look into this oscillator thing
Thanks
Could have had some growth on the inside. No, I did not change the bias, I just replaced the transistor.
Where have YOU been,,! I needed this info last month before I made thing's worse with my attempt at two radio repairs! Perhaps I can give it another go if I can remember what else I messed up
Hope you got it!
I dug out my vintage Sony (ICF- A10W) clock radio that I bought used about 12 years ago. After I bought 12 years ago, I just tested quickly and not sure if I checked the am radio and just stored away.
So when I came across it in my storage, I took it home, but heard something loose inside. So I took it apart with just 2 small screws. I found a long metal bar with 2 thin copper wire wrapped around lose and I believe came loose in shipping 12 years ago bc the eBayer left the battery in shipping and when I got it, the radio was playing inside the package. Lol!
So bc I didn’t have any glue, I just put the loose bar near where it was attached to the inside corner. And it still shakes but seem not as much as before.
But now I’m wondering if the am was already broken or if I had put the buttons back wrong? I managed to not break any of the plastic and careful taking it apart with snapping off anything. That’s the problem with handling something brand new and understanding without breaking it on how that part all go into place. Lol!
I’m not that mechanical and don’t understand how things work or what each thing does what. So I get lost and usually don’t even go as far as taking apart or trouble shooting, I always hope for an easy fix or look on TH-cam for guidance.
So if it having to replace the am part, are they all about the same or are there many? Can I take it jist from an old radio with am?
This clock radio I have is a collectors item and I want it to completely work and including the am radio I never use. Lol!
Anyway, thanks for the tutorial!
Maybe if I re glue tgat metal bar, the Am will start working again. Also, I’ve looked at about 20 of these Sony clock radios used and most just have the fm wore port and not the wire that plugs into it. Perhaps most didn’t need or lost after 40 years and I only saw one unit with the original fm wire. Meaning if I find the fm fm wire, would that help make the am stations to come in? Oh and the end connection is much smaller than the end of the standard headphone jack. So it might be hard to find a replacement.
I guess there are ppl. like you that likes to fix these old radios and spend time trying to get them to work. Bc I see used radios at thrift stores, flea markets and garage sales and could easily find an old radio for under $10.
I just picked up this Aiwa handheld emergency wind up option radio with even a light for $15. in like new condition. I should’ve gotten this top of the line Yamaha receiver from the early 2000s they were selling at Goodwill the day I was there first thing in the morning to get a record I saw the day before for only $24.99. I didn’t want to carry that 30lb. receiver on the bus and running late for work and in 7 minutes, I saw someone buying it when I was checking out.
I also remember the days when there were many electronic repair shops and now gone like shoe repair shops bc of this disposable generation. This needs to change bc many now are getting into vintage aiduo equipment and many those units needs servicing and someone to care for these solid made equipment from the past, instead of filling up landfills.
I remember buying this great JVC 80’s receivers with green lights and I think the spin radio dial from this guy who used to repair audio and worked at a few high end stereo stores in I think Portland or Seattle. He bought the troughs the receiver from a local theft store and cleaned it up and made sure everything worked. He told me he still knew places that sold parts for these older units and that this was a way to make some extra money flipping vintage stereo equipment to supplement his income while being retired and 12 years ago he was in his late 60’s and also told me he had cancer.
I always love. Intake stereo equipment and not someone looking for one stereo to own. So I know now this vintage stereo collecting is trendy but that didn’t make a difference or change my love for vintage audio equipment Partly bc when o was a kid, I was fascinated by the adult buying stereos and how much that was a part of the culture in the 70’s and 80’s.
I wish I was able to open a store 12 years ago buying and selling vintage audio equipment as some are doing now. Bc back then everyone thought I was nuts and didn’t understand my passion.
I just a few days ago went to the SFMOMA museum in San Francisco and they had this great exhibition on vintage audio equipment and vintage concert/ music shows that were vibrant in color and fill up all the walls that made a huge impact. They even had 2 floors of independence used record sellers for the first time in the museum that USF normally has twice a year.
It’s all coming back and the younger generation is responding hard to it, especially in the big cities across the US.
Your Sony radio is two radios with shard parts. I recommend to contact your local Ham Radio Club, for help. There will be someone in this club who repair radio or knows some who does radio repair.
I did meet Mr. Carver when I was living in the Seattle area.
Digital Time Lens by CARVER
th-cam.com/video/eRNoUJcxQhY/w-d-xo.html
I think a very unusual fault, but with the illustrated method of diagnosis, giving detail of its function in a standard AM 'superheterodyne' radio, came to it in theory as well as practice. I looked up 2SA102, and found it to be a PNP point contact germanium transistor made by Matsushita, Japan, the company most known for making 'National Panasonic' radios, record players, amplifiers, etc. This radio might well have gone through the manufacture process (soldering), checked through final inspection, then tried in a cold atmosphere, and stopped playing. Thanks for sharing the information..
Thank you, and your welcome.
I never seen 2SA102 transistor about 42 years ago, what is push/pull audio output transistor number?
I no longer have the radio. Any germanium PNP audio output transistor will work.
Is the transistor bad a germanium type? is there any equivalent sustitution of this transistor?, thanks.
Yes it is germanium Type. You can still get germanium transistors.
I have a general electric model 7-2825a am fm radio I'm pulling my hair out it works only in fm mode no am receive has 2 transistors ive replaced the caps I don't have any imfo on voltages I wished I had a signal generater I only have scope and volt meter not sure any ideas
AM and FM superheterodyne radios are set up with a separate front end for both AM and FM. This means that each has its own oscillator and I.F. cans, what is in common with both is the audio amplifier. I did look for a wiring diagram for your radio but have not found one yet. I would try and determine if the AM oscillator is working, I have done a few videos on how to do this using another AM radio.
Oscillator Trouble Shooting Using Radios as Testers Demo
th-cam.com/video/AuLP31cLBMQ/w-d-xo.html
All American Five Radio Troubleshooting
th-cam.com/video/clRQ0qxnA10/w-d-xo.html
Digital PC Oscilloscope Signal Tracing
th-cam.com/video/_fHAuzDIgEQ/w-d-xo.html
AM Radio Demodulation Oscilloscope Demo
th-cam.com/video/pKA0TPdnHg8/w-d-xo.html
Thank you so much for the hard work ,and please what transistor did you use?
Thank you. I used a 2N2222. Hope this helps.
I put the signal at the antenna for a number of reasons. If running through the AM frequencies nothing is heard from the radio speaker, this means a IF can may be open and the oscillator could still be bad. In this case we heard stations running through AM frequencies, the IFs are good, but I could not tune in a station with the radio tuner. This means the oscillator in the radio is not working.
Nice save
Thanks and your welcome.
If the fail is present in other circuit do you use the same way to find the fail?
For oscillators
I have a 1967 Mustang original radio. The radio lights up, has volume but the radio is oscillating. It varies as I tune across the AM band. I can't hear any stations just static with varying oscillation sounds. Any tips or forums that might be familiar with this AM only radio. I can't find a schematic.
All the capacitors are bad. The electrolytic capacitors are polarized and must be installed correctly. I see if I can find the schematic.
@@AllAmericanFiveRadio after more tuning across the band I picked up a local station. Its not strong or clean sounding. If I connect my outdoor wire antenna the station drops out almost like the radio is being overloaded.
I am wondering if a cap involved with AGC could be bad. Thanks for looking for a schematic. On the side of the radio
it has the marking 7TPZ Its AM only. It appears to be the original radio with only a single speaker output
@@AllAmericanFiveRadio Thanks, the side of the radio has 7TPZ marked on it. Its AM only single speaker output and appears to be the original radio from a 1967 Ford Mustang. I checked the junctions of the only 3 transistors and the meter indicates the correct forward bias voltage. Emitter to Collector is around 1.4v
The transistors are marked AR 103, AR 104, and AR 105 and they are germanium transistors. I also checked a germanium diode to be good too. This diode must be for audio detection or part of a AGC circuit. There are a few caps and one large cylinder cap that looks like its a multi-capacitor. Its corroded on the top and probably bad.
I am going to have to remove the cap to get the values or if you can find me the schematic. I appreciate your help Thank you,
@@n1kkri I Just talk to a friend in the St. Louis area. He is going to look for the schematic. Hoope he can find it.
@@AllAmericanFiveRadio Thanks,I really appreciate the help. Ken
My Nobility 10 radio puts out full volume white noise-- volume control doesn't diminish it, and it does not tune any station. The pawn shop says it needs a new ant. It looked good to me and all the leads to the ant. are soldered in place.
No, I’m replacing the local oscillator. Download my ebook and read page 72. You can find the download link on my TH-cam Channel.
AllAmericanFiveRadio
The bench oscillator replaces the radio local oscillator. When the difference between the oscillator and the radio station equals 455KC we hear the station.
Great video Rick - May I use this in my troubleshooting class? Doug
Great very informative video, thanks for sharing it. At minute 2.00 you used the signal generator but you can't see where you placed the probe, I think on the antenna but can you kindly explain to me where exactly? Thanks again, I follow your videos with a lot of interest.
Inuit is at the base of the transistor.
i learneeeeddd!!!
Thanks.
So the heat changed the transistor..I guess you could check it with a lighter...or match..to see right???
By injecting RF at the blue arrow, aren't you approximating an rf signal coming into the antenna? Im not sure why that would show that would show the local oscillator wasnt working. It seems that in order to show that the local oscillator is at fault, wouldnt you have to inject an rf signal at the collector of that 1st transistor of precisely the correct freq and thus emulate the oscillator? Sorry but I dont understand
Exactly..so when you put in an rf signals (spanning the am broadcast band) into the antenna you are approximating the rf input derived from an on air signal, arent you? What I dont understand is that if when you put that signal in and you hear a signal out, doesnt it mean that the local oscillator stage is in fact working? Otherwise you wouldnt have the difference signal of 455 kc coming through.....and the if stage tuned to that freq wouldnt come through.
Rick, thanks. understand theory of mixer circuit from p 72. Just trying to take advantage of your ample experience.
You are putting in an am signal at, say, 1000Kc. Local oscillator isn't working so mixing down to 455 kc shouldn't occur and like you said "nothing will come through the radio".
If you suspect that lo isnt working, why not put lo signal from sig gen into emitter of the mixer stage? Just trying to understand 1) if that would work and 2) the advantage of your approach.
Nice
Thank you, and your welcome.
Thank you and God bless you for posting this. I am fixing my mother's old AM/FM radio. She listen to 1010 news AM. She lives in a high rise building and am reception is very bad up there. Do you have any suggestions on how to remedy this issue. The radio reception in my apartment is pretty good.
Exactly!!
A tecsun loop antenna from amazon ,you just set it next to the radio ,and your A M will improve ,it has a tuning knob on the loop antenna too.,works good
And the transistors are also.
I've never had much luck replacing germanium transistors with silicon...
Rick why would the heat make the transistor work for a while
Why you didnt test the oscillator transistor before removing it from the pcb?
I did measure tha voltages on the transistor.
Nice bit of fault-finding.
Thank you and your welcome.
Thanks wx9dx
In my case my vintage cassette fm.is working but the am station is no signal whats wrong thanks bro
It's hard to say from several hundred or thousand miles away. Since the FM is working there is a very good chance that the oscillator for your AM is not working. Below is one way to determine if your AM oscillator is working.
Oscillator Trouble Shooting Using Radios as Testers Demo
th-cam.com/video/AuLP31cLBMQ/w-d-xo.html
Search my channel for signal tracer. I've done several on making signal tracer's and on at least one of them threre is a close-up of the transistorized signal tracer.