I have to thank you again Peter, Because of your #118 I was able to work on my TS450s following you leadership and repair the same problem although my problem was the capacitor #104 had failed and it burnt off the trace between the + terminal on that capacitor and the output terminal #4 of the amp. Thanks again for all the help. Both radios work fine.
I had no audio on my old Kenwood TS-430S and found the speaker was not properly connected. I never fixed it because I always used headphones or an external speaker. I also noticed that the 1/4 inch jack for headphones on the front panel would hang and not let the audio to the external speaker. I'd have to plug/unplug to get it to switch. I prefer headphones when operating my radio, 'cause the wife don't want to hear my radio since it is in the living room. I've got to relocate to the bedroom when we get it cleaned out. Cheers & 73 from W Rusty Lane K9POW in eastern Tennessee
Im with you. The scope does not lie. Many things are seen with the scope that the tracer wont pickup. Thank you for the wonderful video. You are the best radio tech on youtube.-+
I saw that burned inductor in the first part of the video at about 1:41 minutes. Of course had I been working on it myself I probably wouldn't have seen it. That's usually the way it works, lol! Great troubleshooting! Enjoy your videos!
Great diagnostic process as always. I'm glad you did not see the open coil early on, it would have spoiled the fun. I appreciate that you take the time to show the schematic.
Trouble shooting is an art. Nicely done sir. I'm a nubee at all of this and really enjoy all of the time and effort you put into your videos. Big thumbs up, and Thank you for Sharing! Joel
How timely and wonderful Peter! Great video and you must be reading my mind. I wish I had a TS850 to follow along with, but instead, I have a TS450 with weak audio, but the line level out to an external speaker is still okay. I should probably part it out. I do have someone willing and begging to pay me as much as I paid for the radio, just for the auto-tuner, which works fabulously well. I do use the old audio tracers with the speakers or sometimes I just pop trace. That is really just a quick and dirty shortcut, but it works. When the fault is that close to the speaker, it makes it a lot harder, but an electrolytic capacitor and a coil on a board that is that smokey and cooked looking, what are the odds? What color code does all black and grey represent? Oh toasted. Yes indeed! I have other words, I tend to use, but not on RU-vid comments. Personally I don't like seeing electrolytic caps adjacent to Pentawatt audioamp ICs, power resistor and other things that get hot, but what can you do? We did not design it, we just fix them. A 30 cent inductor. Not bad, oh and $50 in labor. Happy Christmas, Peter. 73s KI7AQJ
Hi George, yes me too when I was editing the video. So the camera angle is different to what you see when you are in front of the radio :^) Thanks for stepping in 73
Very nice troubleshooting Peter. I also think he may have plugged in a bad speaker. Wonder if he has an amplified speaker that failed and put voltage back into the rig. It is hard to believe that there is enough current in the system to cook that 1uH choke. And leads me to think that voltage entered the external port. Keep up the great job my friend, 73 Buddy
Hi Buddy, thanks for stepping by my friend! Well I'm not entirely sure if an external voltage which may be coming from an defective active external speaker can fry the choke as there is no close dc circuit loop until the 470yF cap is intact. Depending on the reverse voltage I see more the cap jeopardized which may fail first and will than take the choke as well. But you never know :^) Take care 73
+The Radio Shop An external voltage would need a path so cap would also need to be shorted. And if this unlikely combination happened, the audio amp would have been damaged. I vote for a short inside the speaker plug.
Cool, I did not pull the schematic and look but you are probably spot on. And like Davecc said below a short on the in the speaker plug could be the culprit. Great video as always my friend and 73
Thank you Peter for this one, You have given me the imfo to start on my own pair of 450 SAT radios that have the same problem. I have never plugged in any external speakers into them but they have many many hours of receive time on them almost no transmit time , again thank you very much for the lessen . I will let you know how i made out.
Excellent job of trouble shooting, following along I was suspecting the electrolytic. And got a surprise that it was the inductor..hihi Great job Peter. Lloyd - W9NLA
Here's wishing you a Merry Christmas and a Happy and Prosperous New Year. Don't get too drunk on the strong German lager though! LOL!! :O (From Wayne and Nina, from Ipswich, Suffolk).
LOL yes okay not too much German lager haha! Thanks for the x-mas greetings and of course for you and Wayne the very best Christmas and a happy new year! 73
Great video! I know many years have passed but I followed along with my TS-850 which had audio out but very weak. Turns out also my inductor was toasted (although it still measured 750 uH on the tester) but I believe the culprit is the electrolytic cap near it (C187) which decouples the output of the amplifier. My guess is that mine was shorted so the inductor (and speaker because there is no decoupling at the input of the Kenwood speaker) had the full DC voltage + the audio voltage on them and the inductor gave up.
Very good Peter ... I think: in market have a external speaker with amplifier inside .. maybe this is a reason ... return of voltage in speaker jack ... All the best
@@TRXLab...Thanks and I have a Kenwood TS-450S with audio issue. TX and everything else working fine but I hear the audio sound very very little even i plug in my head phone into radio phone jack audio is so little with volume all the way to the right. any idea ??.. thanks in advance
Looking at the circuit, I wonder if C187 is leaking some DC which would heat L37 if the speaker output line became shorted or if it was used to drive a low impedance speaker for a long time...Something cooked L37 badly...!
Good morning, colleague, would you have or could I get the eprom of the Control Unit of the coupler ICOM 746 pro?, Because here in Brazil I can not find
Doesn't it seem that the old man has a lot of problems with his equipment? Do you think it might be misuse of the equipment on the other hand it does keep you busy and us entertained. Thanks
my 735 had no audio remember? Turns out the previous owner tried to remove the vco box cover that is soldered and dropped a blob of solder on the board....after replacing capacitors and tapping on the board, I finally found it. Radio is working. So it could be any possibility sometimes.
Well done Peter. On the bottom of the PCB there appeared to be a mod of some sort with a long wire, a couple of diodes and a resistor tack soldered onto the board; the solder looked a little ugly, may have been just a video artifact. May have been a factory kludge; did it look ok to you in real life? 73 - Dino KL0S
Hi Dino, yes the soldering was not fancy but it seems to be intact so I didn't touch it. It may have been a kind of factory kludge as I have seen it a several times..but never found it documented. Thanks for stepping in 73
I doubt if the amplifier would have enough drive current to fry that inductor. Maybe the series cap from the amp to the inductor went intermittently short? Most likely someone has applied power to the speaker jack.
I have a similar problem .. when I turn on the radio do not hear the sound, after a few seconds (10 or 20) it starts to work. What could be my problem?
I Spotted that Burnt Inductor @2:04😉☺😁...I did watch the video to the end too see how long it would take you to spot it.....Just show's how a good eye or in my case a cheap pair of £1.99 Spectacles come in Handy.
A shorted speaker wire is what killed the audio in my Stryker 955. 1 tiny strand of positive got soldered to negative on a jack repair and I did not see it. It took out the audio amp, roasted and cracked open a trenchfet in the PCB on the ground side of the speaker circuit. They dont make either part so had to cross reference them and still waiting on the trenchfet to arrive. 21 days to get that little guy.
@@TRXLab I have all the bad parts replaced in my radio now but still no sound. My audio amp looks just like the one in this radio. With an audio tracer I hear receive and audio all the way to the positive terminal of the speaker jack and the on board speaker but external or on board speaker does not work.
I notice there is a Phone jack in the front of the radio. Might he have used headphones and caused an issue from there? I know some radios use 1/4" jacks for CW keys. Might he have plugged a CW key in the jack in the front? Just a few ideas. Thanks for another great detective story! '73, Mike / KD2EAT
Hi Michael, yes all is possible so it is always important to discuss it. The owner will probably read all this here and may be we get a feed-back.. Thanks for watching 73
Depends. Not usually with solid state, but it could make the chip run hotter. A dead short, yes! I can't see a 4 Ohm speaker cooking the inductor, though. I had a vac tube Epiphone model 100 with a shorted voice coil, that read about 1.2 ohms rather than 8 Ohms. That made a nice light show on the noval tube socket for the EL84 tube, but it did NOT cook any parts inside the amp. A new speaker from Weber and it is mean sounding little guitar amp. Had I tried to use it for 20 minutes the transformer would have probably burned open, and been ruined.
Da haste fast alle Messgeräte von Rohde & Schwarz und kommst dann mit einem Rigol Oszilloskop an. =) Du machst super Videos, ich schaue sie mir gerne an, mach weiter so! Vy 73 de DL7LL
LOL, tja Leon so ist das wenn man sich nicht alles leisten kann was man gerne hätte...Danke fürs vorbeischauen, freut mich das dir die videos gefallen... 73
change C187 (470 mikroF / 10V) to 470 mikroF / 16 volt. This capacitor becomes leaky because of voltage stress, and starts to conduct. In many times this capacitor starts leaking physically. This is the cure, a capacitor rated to minimum 16 volts DC. 73 :)
lol he would have had to have that thing on a dead short and at max level to burn that thing up.... i know some power supplies use a head phone jack if he plunged some thing like that in that would smoke that in short order... sucks when things just inexplicably burn up... my kenwood TS-2000 just stopped transmitting out of nowhere. i was using it to talk to a friend 20 miles away on 15 meters after we where done we cleared the freq and 2 days later I powered it up and it would not transmit at all... "it was working on the last shift!!"
Super: i have an Kenwood TS450S and no Audio :) Have open the radio after watch this vid, and found the PA, same condition Pin5 13.5V Pin1 6.5V and Pin4 has full Audio - seen on Oszi and via test.Speaker. Found desolate Capacitor and have remove em from topside .. but after replace this one : no Audio will be come out, only direct on PA 4-Pin i have the signal. I think now, all capcitors in the line i must renew.. it's a bit dificult to remove all the neighbor -capacitors on the board.. the little black cube is an LC-Filter : there are here unknow, this type would be serch to replace this ones too. Have any one a Link to the Type of black LC-Filterbox behind the PA IC ? (never seen this formfactor befor) www.flexxvision.de/PublicImg/ken1.jpg www.flexxvision.de/PublicImg/ken2.jpg Thanks for nice Video , looking forward now :)
Ah sehr lehrreich, ich legte am Pin 4 der PA ein Tonsignal 1.8khz ~2V an, und wollte dies nun verfolgen.. haha.. da ist auf allen Board -punkten das Signal zu hören, jetzt versuche ich es mit einem 8 Ohm Dummy und folge dem Wiederstand. Das sieht sehr einfach aus im Video, aber die die Vorarbeit über den Bestückungsplan (grauenhafte Qualität) verbraucht viel Zeit.. Du hast Dich "verraten" als Du die Drossel lachend gefunden hast, denn Du wusstest gleich die Henry zahl :) Meine Drossel ist leider noch IO .. Man braucht sehr viel Erfahrung um sowas zu fixen.. mal sehen ob ich das Problem noch finde C104 war ausgelaufen..
Na das wollen wir doch hoffen :^) Ja in einem Punkt gebe ich dir recht, es sieht im Video manchmal recht einfach aus. Aber du bist auf dem richtigen Weg.. Viel Glück
Danke Meister! Das macht Mut.. Habe einen Short auf der Ext-Pa -Dose. Aber okay.. Ich werde das schon noch finden :) www.flexxvision.de/PublicImg/ken4.jpg Ups ein Bilder Link war kaputt.. :)
Du ich habe hinter der Drosselspule einen Elko ersetzt der auslief nun muss man sich vorstellen das Pin4 der PA direkt drauf geht auf den Elko gefolgt von der Induktivität. Das ausgelaufene Elektrolyt hat den Kontaktring der Leiterbahn zerfressen, das war sehr schwer zu sehen, es geht wieder ! Danke .
