Hi Peter, great videos as usual. I really enjoy these types of videos, they make me think outside the box. If the RF Amp is good, your videos gave me three additional places to troubleshoot. Looking at the bias on the RF Amp, APC circuit, and switching circuit as well. Your videos make me think way beyond the RF Amp as other circuits may be causing this type of issue. Keep up these great videos.
Interessantes Video , habe das gleiche Problem mit den Kenwood TH F7 , habe gedacht die Pin Diode wäre hinüber aber jetzt kann Ich es versuchen zu Wechseln, der Endstufenaufbau ist gleich wie bei den TH D72, sicher der Mosfet ist sicher ein wenig Tricky, LG aus Südtirol
No we do not need to summarize what we have done up to this point. We need to go on down the line and check the transistor at the final beings the preamp and the driver are good. Go on down the line of the circuit please. Please stop being redundant. What a waste of time.
Would have been nice to see the new FET on the curv tracer too. Also I'd have probably measured the driver output power right at the gate of the final transistor aswell. The transistor datasheet specifies a 500mW input power for test condition.
If you can give me a hint on where to find this FET, I will run the same test and post the graph. Need one for my d72 but having a hard time finding one!
When I power on the radio everything works perfectly. I can hear the bands just fine, except if I turn the vfo knob. As soon as I turn that knob the radio will go deaf. I am no longer able to recieve signals, but if I turn it off then turn it back on it is completely normal again. For instance, I will be listening to someone and turn the adjustment knob, then when I adjust back to that frequency, I can no longer hear them, nor anything else on the band. All it takes is a power cycle and it is back to operational. I check the ribbon cable and they were all fine and properly connected. Then I check the knob again and it seems to me that if I turn the knob very slow I can creep away from the frequency that I am listening to and continue to recieve. But if it turn it fast, it instantly goes deaf. To me this sounds like a software issue and looks like it in practically every way. I tried resetting the radio but it did not take care of the issues. Is there firmware or software updates out there for this radio? Thank you, KD9VSG
Hi Peter I had to smile when I saw the results on the curve tracer. Somehow that seemed familiar to me. As always, very professional work and further proof of how important a curve tracer is. 73, DG3JA, Jörg
Great repair Peter & thanks so much for showcasing these techniques you use. Most of us see these tiny HTs & are way too scared to even touch them. Always learn so much from your videos. God bless & 73s
Great video. I really like how you put it to bed, showing the (terrible) engineering margin of the original design and also the curves of the failed part.
thank you, educational content. i suspect its more probable Kenwood were buying these selected for higher gain by Toshiba prior to shipping pretty much how with led you can or could order based on certain perimeters so you order the part number and get a selected colour band as all the green of one part number will not all be the same, if that makes sense and if you are making a display you want the frequency of the color to be as close as possible.
Thank you, Yes, most probably they directly ordered the parts with a higher gain originally. Most likely the overall BOM was too high, because the radio was only sold for a short while.
Nearly missed that video, glad to find it, that was a very good video, Peter. Very good conclusions and explanations how to check and go ahead for young players, especially how to read the truth behind datasheets ans product designs. I did not had a semi-working mosfet like this, so first thought (that thing delivers to much power to be dead) is sometimes proven wrong. Hat mir gut gefallen, wie immer, Peter! Der Daumen hoch ist bereits gesetzt! 73 de Ole
Thank you, Olaf! Da der Durchbruch nicht sofort passierte, sondern erst nach ein paar Volt, hat wahrscheinlich die APC den exzessiven Stromanstieg unter Kontrolle gehalten und der Transistor hat damit dann ein bisschen funktioniert. Anders kann ich es mir nicht erklären. 73 Peter
Amazing video on diags and repair! Great repair.
Great work peter . Thank you
Great job as usual. Always enjoy watching your repairs and especially your troubleshooting. Thank you.🙂
Thank you
Hi Peter, great videos as usual. I really enjoy these types of videos, they make me think outside the box. If the RF Amp is good, your videos gave me three additional places to troubleshoot. Looking at the bias on the RF Amp, APC circuit, and switching circuit as well. Your videos make me think way beyond the RF Amp as other circuits may be causing this type of issue. Keep up these great videos.
glad that you liked it
Interessantes Video , habe das gleiche Problem mit den Kenwood TH F7 , habe gedacht die Pin Diode wäre hinüber aber jetzt kann Ich es versuchen zu Wechseln, der Endstufenaufbau ist gleich wie bei den TH D72, sicher der Mosfet ist sicher ein wenig Tricky, LG aus Südtirol
Sei vorsichtig, es ist nicht einfach, die Endstufe zu wechseln, speziell wenn du nicht die richtigen Werkzeuge haben solltest. Viel Erfolg
@@TRXLab ne habe das schon , wenn kennst die Klasse A von vortreiber von Icom 7000 ähnlich... ne von der Endstufe zwischen TH F7 und D72 identisch
Peter is a genius ... thank's for the nice video ... best 73s de DL6RDE / AA1KD, Charlie
Thank you, Charlie
You are a great teacher Peter. Appreciate your hard work in making these videos and keeping the hobby alive.
Best 73's de ND1B
Thank you!
Surprised that you didn't measure the Rec & Xmit voltages on the Final.
I did, and it is documented in the video..
No we do not need to summarize what we have done up to this point. We need to go on down the line and check the transistor at the final beings the preamp and the driver are good. Go on down the line of the circuit please. Please stop being redundant. What a waste of time.
Can I send you a radio to fix...? I have a Kenwood TS60 50-54 MHz. Has eratic power output. Tim W8RNG Ohio.
Would have been nice to see the new FET on the curv tracer too.
Also I'd have probably measured the driver output power right at the gate of the final transistor aswell.
The transistor datasheet specifies a 500mW input power for test condition.
Agreed, but we could not risk putting a very sensitive ESP part to the tester...
If you can give me a hint on where to find this FET, I will run the same test and post the graph. Need one for my d72 but having a hard time finding one!
Thanks Peter another great repair, I always learn something from your videos
The faulty MosFET has a negative differential resistance like a tunnel diode. Could be used for such purposes.
yes, on a kind of reverse way axis wise lol
Well done, thank you, this is a classroom for me.
your techniques are great nice to see someone showing this kind of repairs great content again thanks keep up the great work.
Thank you
Hi Peter Tnx fer another great video. 73s
Great job, nice to see as a mosfet can die with breakdown voltage ! Very interesting, thanks Peter. Best 73 de Pasquale IW0HEX
Always glad to see you, my friend! Thank you 73
Hi Peter. Again a great video. My compliments! I Learn every time. Thanks for taking the time and for all your enthusiasm. Br pa1ant
Thank you
Real nice video, Peter. Thanks, and 73 de Earle / WB3EFE
I need help with my Icom 7000. Something really wierd has been happening.
When I power on the radio everything works perfectly. I can hear the bands just fine, except if I turn the vfo knob. As soon as I turn that knob the radio will go deaf. I am no longer able to recieve signals, but if I turn it off then turn it back on it is completely normal again. For instance, I will be listening to someone and turn the adjustment knob, then when I adjust back to that frequency, I can no longer hear them, nor anything else on the band. All it takes is a power cycle and it is back to operational. I check the ribbon cable and they were all fine and properly connected. Then I check the knob again and it seems to me that if I turn the knob very slow I can creep away from the frequency that I am listening to and continue to recieve. But if it turn it fast, it instantly goes deaf. To me this sounds like a software issue and looks like it in practically every way. I tried resetting the radio but it did not take care of the issues. Is there firmware or software updates out there for this radio?
Thank you, KD9VSG
Awesome diagnosing , I wish I could find schematics and service manuals of that style ....
Great Service Manual - where can we find them?
We got it from Kenwood
Hi Peter
I had to smile when I saw the results on the curve tracer. Somehow that seemed familiar to me. As always, very professional work and further proof of how important a curve tracer is.
73, DG3JA, Jörg
Hi Jörg, yes I can believe that since I know your transistor collection of oddities! We don't want to be without our curve tracers...
Great repair Peter & thanks so much for showcasing these techniques you use.
Most of us see these tiny HTs & are way too scared to even touch them.
Always learn so much from your videos.
God bless & 73s
Thank you
Now thats what i call small ,must be very difficult to see all the components .
That is why we need a microscope for SMD work. For our eyes much too tiny...
Very good catch. Few techs would catch that. It's so nice to see electronics videos from people like you who actually KNOW electronics. Thank you.
Thank you!
Great video. I really like how you put it to bed, showing the (terrible) engineering margin of the original design and also the curves of the failed part.
Thank you!
Informative as always Peter, always love to see you and Mr Carlson
73 de WD8JM
Thank you, Jeff ! Yes, Mr Carlson is fantastic!
Thanks for another interesting video where as usual I learn so much. Those components are way too tiny for my eyes these days; 73s Bob
Thank you, Bob! Yes, for my eyes too! Without a good microscope, no way....
thank you, educational content. i suspect its more probable Kenwood were buying these selected for higher gain by Toshiba prior to shipping pretty much how with led you can or could order based on certain perimeters so you order the part number and get a selected colour band as all the green of one part number will not all be the same, if that makes sense and if you are making a display you want the frequency of the color to be as close as possible.
Thank you, Yes, most probably they directly ordered the parts with a higher gain originally. Most likely the overall BOM was too high, because the radio was only sold for a short while.
Thanks Peter so much for showing a great repair and faulting finding techniques you use so interesting
Thank you!
Peter still the best teacher on You tube learn the most. Very professional
That is a very high honor! Humble, thanks!
Nearly missed that video, glad to find it, that was a very good video, Peter. Very good conclusions and explanations how to check and go ahead for young players, especially how to read the truth behind datasheets ans product designs. I did not had a semi-working mosfet like this, so first thought (that thing delivers to much power to be dead) is sometimes proven wrong. Hat mir gut gefallen, wie immer, Peter! Der Daumen hoch ist bereits gesetzt! 73 de Ole
Thank you, Olaf! Da der Durchbruch nicht sofort passierte, sondern erst nach ein paar Volt, hat wahrscheinlich die APC den exzessiven Stromanstieg unter Kontrolle gehalten und der Transistor hat damit dann ein bisschen funktioniert. Anders kann ich es mir nicht erklären. 73 Peter
Do you drink coffee, tea, or watch football? Your hands are very steady for such small work! de Wb8yqj
lol, yes all of that...