Good to see you got it repaired. Another case of crappy cap syndrome. I recently switched the type of SMD electrolytic can caps that I use. I have switched to the super high grade aluminum polymer capacitors instead of the liquid electrolyte type caps. They are a "dry" type capacitor so there's nothing to leak out. Cost a lot more but in my opinion well worth the expense. If there is one disadvantage it's that there isn't as large of a variety of values/operating voltage's to pick from but it's usually not a problem.
Thanks for the great video! I came accross EXACTLY the same issue with my TH-28 today. Suddenly, with no apparent reason, after I've turned the radio on, I've discovered there is no sound coming out. After initial investigation I found no 5C supply on emmiter of Q15 transistor! There was no continuity from Q1 indeed, but after connecting a test wire from Q1 to Q15 the sound has re-appeared. Furher investigation showed heavily leaked C17 cap, exactly as per your video! Unfortunatelly, the leak has damaged interPCB Q1-Q15 connection so I have to stay with a soldered wire on a 5C bus. Regards, Alex/EI4JY 73
That's a proper challenge ! No doubt that was a time consuming clean-up. Very nice. But this reminds me; I had a TH28a given to me new in the 90's...it failed and it's sitting in a box (for many years). I'm now curious to get it out and see if it's beyond repair or not. As I recall,it would not boot-up at all. Totally dead. This is inspirational!
Vintage handie.. When KENWOOD did maded pretty & good handies. I had the TH-48 and TH-78. I had lots of handies really. Some recurrents. Cheers from Spain, Peter
Well done Peter! Another triumph!! I guess that most older (and maybe not so old) electronic equipment is at a stage where electrolytic caps are a genuine cause of faults. So many repair videos from other sources seem to have this as a relatively common theme now. 20 years ago, these sort of faults were never really heard of, I suppose we can expect a lot more leaky cap causes in all older equipment from now on! Regardless, well done again, nice detective work Peter as always and you really sounded like you enjoyed this repair a lot. 73, Brian EI8EJB
Yes I really enjoyed this one, Brian! You are right with the electrolytic caps issues. It all started off with the upcoming switch mode power supplies in TV sets 25-30 years ago. I believe in the beginning all designers were not aware on the stress the caps were suffering from in early smps's. But the industry was focusing on this issue with new low esr types and high temperature types which was much better BUT more expensive. There I think all the trouble has started as a lot of cheap suppliers entering the market with crappy low quality products...and so it went on until today. It is always a question of money and quality....Thanks for comment! 73
That was fun to watch. Like always, i try to investigate it in real time while watching, and i giggle like a child if we come to the same conclusion after a few seconds. The moment you spot on the digi-transistor i just thought.."uhh..i there a cap on the other side?" ;-) Very good job. By the way, i use some epoxy or soldermask that i have in small syringes to repair and cover bare coppe trace or groundplanes, just to feel better before put it back together. Peter, 73 to you!
Hello, first please let me tell you I really enjoy your channel and your wonderful troubleshooting techniques. I’ve learned so much watching you! I only wish I had some of the nice equipment you have. Now this radio, I tried to find the age of this radio but just could find that it has been discontinued but it had been offered for a number of years. Do you happen to know how old this caps were? It’s really sad to see all these issues with capacitors that just don’t seem to have much age on them. I’m continually repairing televisions that are less that ten years of age that have bad caps in the power supplies. (I really want to work on antique radios and guitar amplifiers but folks keep bringing me TV’s.) :-) Thank You so much for you time and wonderful videos, Buddy
Another success well done peter caps seem to be a problem, peter what would the life span of caps be as a matter of interest? the leaking caps seem to have caused much damage to the PCB the leaking fluid of the caps seem to be very corrosive where the copper foil is concerned so hard to repair them !
hi, i need your help.. i already found 3 unit of QYT rig (different model) have the problem of always transmitting. power on, then straight full power tx..
Nice work Peter...did you dab a bit of conformal coating over the bare copper trace sections to stop any simple moisture related corrosion on the PCB? 73 - Dino KL0S
I have a TH78 (looks very similar) which got hit in the flood I had in January, I will open it up one day to see how badly damaged it is (along with the dozen or so CB's I had in boxes) but I suspect it is ruined.
Peter, I am beginning to ‘not like’’ the Aluminium Surface mount capacitors. They obviously corrode the Vias and other components. Very obvious as viewed by your microscope Nice work troubleshooting -Bob. KQ2Q. Athens. GA.
Hey Peter, I see you chose to use a tantalum cap in place of the electrolytic did you just have it already because you could have put a newer solid aluminum or even a ceramic. I'm curious about your choice, I always think about a current limiting circuit when using a tantalum. (or I used to, I don't do any of this any more) K5AZE
Hi Bud, fully understand your concern. In the past tantalum caps were known for burning off and nobody trusted those caps. Still I have the same bad feeling but latests products have improved a lot and the advantage is they are dry and don't leak. We only can hope that the newest stuff don't explode like we have seen it in the past...73
Question ?? Acidic or base electrolyte?? I in my old time experience thought they used a base electrolyte, still corrosive, but requires different neutralization methods?
Bagaimana kabarmu? Saya harap baik baik saja... Lama sekali tak ada unggahan video yang baru.. Mungkin sedang sibuk begtu? Salam Elektronik From Indonesia.....
Hi, I have found your video very interesting. Thanks for sharing this one. Got the same issue but with the chip marked G2, UMG2N package SMT5.( in fact Q3 on the schematics ) I cannot find this one with the same package and pins (FM2GA) . Any idea where i can find this chip? (A dual common emitter NPN ). (.....Just next to the one you have replaced.) Of course, I have got also the same issue with the electrolytics cap. Thank You christian
Hello. I have a TH28E that can't hear anything as shown in your video. I have not been able to find anyone in Spain who can repair it for me. It would be possible to send it to you and try to repair it. Obviously I would pay you what you estimate for it. This was a Christmas present from many years ago and I really appreciate the person who gave it to me. Thanks in advance, whatever your decision. All the best.
Hi brother, greetings healthy I'm from Indonesia, I want to ask? HT kenwood th234 does not emit RX sound, mic sound also does not come out and if TX is normal. how to solve it? Thank You.
Hallo Peter, vielen Dank für die tollen Videos. Das inspiriert mich für eigene Videos und Projekte. Zum Glück muss ich aber nicht so viel reparieren wie Du .. wie Du immer nur an diese Geräte kommst!? Kannst Du mir auch noch verraten, mit welcher Kamera Du die Aufnahmen machst? vy 73 de Lothar
I have an th28 as a souvenir of my youth and last year I replaced all caps, power unit, jacks ,coils. because of the caps corrosion the little fellow now changes channels alone it is very temperamental . I can't find the issue.
Over the past 12 years, I have replace nearly a thousand bad caps on motherboards, power supplies, and other equipment. The manufacturers all want to discard the entire units and sell a new unit costing thousands of dollars, when the only problem are the darn caps. In some cases the manufacturers no longer supply the units installed, and the customer is faced with tens of thousands of dollars to "upgrade". This is criminal! I wonder if the manufacturers of capacitors have deliberately lowered quality, at the request of builders in order to have built in repeat sales?? I certainly hope not, but I do wonder.
Well Jerome I know what you mean but to be honest a Bofang can't be fixed after all that years..With all the China crap we will lowering our standards and quality requirements. So it is up to us what we want in the future more electronic waste witch will be harmful to human being and our environment or repairable and thus sustainable products...
I usually can easily follow your meticulous diagnoses without missing anything but you got me confused this time. At 9:32 you say "there is no audio in the input" to the AF amp, but that can't be correct since it turned out to be a power problem. Also, I did not understand what made you find out that the problem was not with Q13 & Q14 and jump to the Q15 (digital transistor)... You replaced the digital transistor, but later (I think) it turned out to be a via problem due to corrosion. Maybe the digital transistor you replaced was not faulty?. Nevertheless, I always enjoy your videos, including this one but I really could not follow your logic this time... All the best from Ankara / Turkey. TA2AWX, 73.
It looks like you did not replace the solder mask? If you don’t have the real mask material, just put instead some nail polish! Nowadays it looks like you can get ANY color, probably including green...
