I'm equally intrigued each time you work through the circuits (and in detail) to troubleshoot these radios and thoroughly enjoy listening to your wisdom that has come from many decades of experience.. thank you again!
Fantastic! I own this radio and so I appreciate the peek into the schematic diagram and the beautiful problem solving process. Perfect! Well done! Thank you once again for all you do. It makes a huge difference! 73, de NZ5I OP Kenny (ex DJ0SI)
Thank you Peter. I feel further educated about fault finding, about finals adjustment and modern set reliability. I was thinking of buying the 7300, you have taken me a step closer. Regards Andy
I just love watching you repair these radios I am not good with electronics but its really great to see you work and explain what you are doing ..Thanks for another great video
Thank you for your video it really helped. As you know at the end of this video you showed us the proper way to adjust the idling current. That was very important can you also show use the receive adjustment, the TX power adjustment, TX amplifier adjustment and the frequency adjustment on the icom7300 I have learned a lot from you and to be honest your the only person that I trust with teaching and your attention to detail. Once again thank you from KG5ZLO
I have an Icom IC-7000 that was behaving the same way. The problem was also one of the finals. It is interesting to watch you troubleshoot the problem because we approached the troubleshooting process differently but both determined the finals needed replacing. I enjoy watching your videos, thank you!
Great Tutorial !! Just knowing where the different placement of the various boards are located, is a wonderful start to getting to the next step in place!! Your showing the physical locations of the PA driver board, and cables, will stick with me when I eventually purchase my own 7300. What a FANTASTIC tutorial!! Thank you TRX Labs!! Your statement of replacing BOTH PA's was interesting. I assume that was done because your logic is that the good PA was way over-stressed, (demonstrated because the 7300 got to NEAR max power-out, with just ONE PA ALONE, causing the life-expectancy of that good, single PA to be radically diminished). The latest firmware installation was ANOTHER point of interest as well!!. I am GLAD that Icom has provided diagnostic information/settings, as well, that is accessible on the front-panel readouts!! Thank you, AGAIN!!
Very interesting repair. I have a friend with a 7300. He has no problem with it yet but I will send him a link to this. Firmware update is more important than I thought. Learned alot from this. Thanks Peter!
Thanks Peter.. I love your thought process, analysis and explanations. It is a pure joy watching the repair videos. I actually have the same issue - different power levels on different bands with my vintage Yaesu FT757 GX2 !!. I applied same elimination process. The input (Base) of TX RF Amplifier on the RF board gets different levels while the level is almost the same on all bands at the Mixer and Buffer. In between is only the band pass filter with many, many switching diodes !! Receive is Ok but I guess some of the diodes might still be leaking - so will replace them all to be sure. Viele Gruesse aus Manila
Thanks Peter, that was a superb video, I have the IC 7300 and have done the 1.4 software upgrade. I am surprised the radio managed 90 watts with only one transistor working. 73 de Mike G4VQH
I like the way you went through the process of elimination, rather than just going straight to the finals and testing them, It made for a good video. Thank you for sharing! Also, the cord bouncing around the right side of the video is very distracting, lol it kept getting my attention and I would have to rewind what I missed.
Crazy point of failure, i never saw a final with that odd "reverse bias". Lucky enough that it did not destroy something around. Good thoughts and conclusions, Peter! Thank you for that video, you did another good job. 73 de Olaf
Thank you so much. As a novice license holder, you have highlighted a problem with my IC-7300 that I did not realise I had. it is disappointing when the issue has been identified after the warranty period has expired.
I agree with the prior comment. Watching Peter's videos makes me want to fix radios. But I would never conceive of the debug process Peter comes up with. Genius.
Show, very didactic and esplanade on how to correct a problem presented in the equipment in which it is maintained, I really like to follow your videos, they are very interesting, rich in details and help us to identify problems in our HF equipment, and vhf in an easy way which favors the technician who will do the maintenance because it is already over a north provided by the owner of the equipment. I like it because the images produced are high resolution and very sharp. Thanks or share, 73s to the friend and respectfully recommendations to family and friends.
Wow. So much easier than back four decades ago working on R.L. Drake factory production lines ;-) Make me feel a lot better about my ‘7300. Thanks for this video! 73 de W8IJN
To Icoms credit these radios do not seem to be breaking down. I'm one of a very small handful of shops in the US northeast that does ham radio repair and I haven't seen one yet. And I have one that I love. I nearly lost my mind when I saw how the bias was adjusted. Im used to the desolder a jumper, insert ammeter, adjust pot. This is awesome! Kudos to Icom for a truly amazing design. Best part is it's not really ground breaking from a technology stand point. It's an evolution of the trend and a truly brilliant design and execution. I don't know if there is even now a radio that compares from a performance and design at a given price perspective.
Nice work, excellent procedure. I have that same radio (Icom IC-7300) and already on the second set of final transistors. The first set appear to have been destroyed when my Astron 35 power supply crow-barred, shorting the power supply but also allows a brief reverse current in the radio as it discharges the capacitors inside the radio back through the crowbar. MOSFET's actually operate in reverse bias most of the time; if you reverse the voltage it looks like a big diode and basically a short circuit. Kaboom. Anything that can crowbar the power supply is dangerous for an IC-7300.
@@ukrainehamradio Mosfet family are very sensitive, it's enough a little bit spike of RF or static and oxide gets in fault !!! I repaired radios like IC-706MKIIG, IC-7300, IC-7000 and so on with finals with gate in fault. Regards.
Thanks for the video Peter, great troubleshooting as usual. No mention in the v1.4 firmware release notes about the biasing unfortunately. Looking forward to the next video already!! 73 Brian EI8EJB
Awesome fault finding again as always Peter. Nice to see such a new radio being repaired. I wonder what caused it to fail. The setup for the new finals seemed very easy compared to the old school methods. Let’s hope the software is accurate. Thanks for sharing the repair. Regards Graham
Thank you Graham! Well what the fail caused is really in question as the radio was handled with care so I really hope there is nothing wrong with the setup...
Hi Peter, as an RF engineer I found your troubleshooting method to be excellent. With only ~1dB delta in drive to the final stage, it became apparent that one of the RD70HVF1C n-channel enhancement mode MOSFETs were likely damaged, but it was good to then check biasing of the final stage pre-drivers. As soon as you compared biasing, my thought was one of the push pull pairs was in question. How the fault occurred would be interesting to dig into. The positive gate voltage made the MOSFET operate in full enhancement mode, which means that the good transistor was doing the work. Your recommendation to replace the finals in pairs is extremely good, and it is also important to note that optimally the pairs should be from the same date code so that their operating characteristics are therefore as identical as possible. I appreciate the physical design by ICOM with respect to final layout, but question the choice of Mitsubishi RD70 which is designed for VHF, not HF. There is a note in Mitsubishi's datasheet that comments about this. S11 parameters are centered around 175MHz. "4. In the case of use in below than recommended frequency, there is possibility to occur that the device is deteriorated or destroyed due to the RF-swing exceed the breakdown voltage." So, did this occur? Was the radio being used to cause the referenced breakdown to occur, or did improper idle biasing occur from the microprocessor?
Great video as always Sir. I really enjoy your explanation while troubleshooting issues. It helps me so much in understanding how things work. Question... Is the RD70HVF1C the same as a RD70HVF1? Sorry for not knowing!
I have fixed plenty of IC-7300 with similar problems and almost ever, it is one of the finals which is KO. I will watch the video to see if I am right... Yes, they were bad!. Good reasoning and very instructive. Why do they fail is still an obscure thing... Maybe you are right and the firmware is the culprit. I use to update it also. Another thing which is faulty on that unit is the clock battery, this is the reason it starts at 0:00. It uses a rechargeable battery but goes bad. I use to replace it with a different model, which hope lasts a bit more.
Thanks for the troubleshooting video. It's good to see your thought process. Can you describe what's inside the diagnostic jack? I presume it enables the diagnostic mode to be used? Something on the lines of a loop back plug I'm guessing. When there was full power on 20m and not on the others, I was expecting the problem to be around the LPF or LPF relays. If you monitored the RF output on 20m would it be grossly distorted as the bias was out or perhaps the stars were aligned for 20m so it appeared to "sort of" work?
Nice job keep up the good work I wish I had your knowledge if I ever need a radio worked on I will be contacting you you definitely know what you're doing when it comes to working on electronics and check circuits and making sure everything goes right 73's and God bless from kc9cjc
I really admire and fascinated by your RF skill, I was wondering if you have a specific video which explains component and subsystem of a typical VHF radio, so we have better understanding while we watch your performance and repair show
Great video! A guide for the ID calibration on a IC-7610 would be most welcomed! I'm curious, having been an electronics technician myself (in another life), I find it interesting we never really saw you wearing the ESD strap during repair, however, it appeared that you were wearing it during calibration. I've always been taught to NOT wear ESD when circuits are live (you do not want to present a good ground path)
What a very nice radio! And a good job fixing it. I'm glad you didn't check the finals first. Those first few test's were good to see as you narrowed the problem down. Hey have you compared your Multi-Function Tester TC1 against very expensive equipment? Thanks!
Thank you for making this incredible video. It was a wealth of information to me. I was curious why you didn’t test with continuous wave instead of FM unless you wanted to make sure voice works well.
no not periodically but an old radio +20 years are developing bad pots which might be replaced to prevent a final crash. See the Yaesu FT-817 which is not 20+ years but the pots are bad and creating a lot of trouble....
Hallo Peter, wieder einmal so ein schönes repair Video von Dir!! Interessant ist wie ICom in der IC7300 FW den Bias Abgleich selbständig durchführt. Den bias Abgleich mit der neuen FW noch einmal auszuführen scheint mir sinnvoll. Schaden kann es ja nicht und so wie die FW den Abgleich autonom ausführt ist es ja auch sehr einfach und sicher durchzuführen. Klasse Video - PY2BND - 73
Another great video and the first I've seen on the IC-7300. Thanks as always for everything you put into these videos, I always learn something. I am curious about one thing, since the beta of the new pair is likely not exactly what the old pair had, would adjusting the output power have been a good thing to do? Or is it that the beta were likely close enough and since the output was in spec it wasn't needed?
Thank you. The only point to do is the perform the bias setting because we need to make sure the both transistors are working equally and we don't have a matched pair. Problem I see is the fact that we can not verify the bias current after setting. The output power was all over 100watt so no need to align..
Note in video +30 dBm at 50 ohms is 1 watt, so measured drive levels at around +10 dBm would be 10 milliwatts and so forth. that's why in trouble shooting u need a sensitive RF level meter that works at the frequency in question plus down to low milliwatt levels.
I had in for repair a TS850 a few years ago that had issues with power output , Traced the fault to the IC that to the control signal and switched the relays , It was stuck on one frequency range , from about 4 MHz to 6.5 MHz .... In this range the radio did what it was meant to do , But outside this range as the low pass filters wernt being switched the radios protection circuits cut in and reduced power , As well as seeing a high input vswr due to the wrong filter for that band ..... Just a single IC worth a few £ and it was back up and running again .... Nice 😁
The adapter cable you used to bypass the antenna tuner so you could directly measure PA output at tuner input, is this cable commercially available or did you build it? If commercially available what is technical name for coax connector on adapter cable so I can search for it? Great video, your channel is a wealth of practical knowledge.
Very clever work and detailed videos thank you. My problem I just encountered with my rig, the MULTIKNOB just started to become tight to turn and LOST the push knob play of it. Any advice for me? Thank you and looking forward to your reply
Lovely video many thanks. You say the service jack was plugged into the back port when you made the bias adjustments, will the service menu not appear without the service jack plugged in. Its a lovely radio, my old FT767 used to be my favourite but the 7300 has surpassed it. Thanks again.
Peter, I enjoy your extremely detailed videos very much. I have learned a great many things as a result of watching your excellent presentations. But, In this particular video #221, involving a failing final transistor exhibiting the leaking problem. I was struck with a puzzling question. Since the pair of final transistors are common providing output power to all bands, why do you suppose the fault was primarily evident on some bands, and not on others. Just wondering why that would be the case. Best Regards, and Thanks for your great service to the radio community.
Peter hi ! Great advice thank you Sir. Would you advice to align the bias current even from a new radio? Or just leave it? I have noticed there are some differences between bands. WRT power delivery using a dummy load for testing, but never knew why or how to fix
I'll go out on a limb here, when I got my 7300, I looked at the issue of the audio amp getting into the RX especially on the AM band as it does but what I did discover was that the screws that hold the PCB's and the screws that hold said transistors to the chassis/heatsink weren't tight. Now I am not saying tightening them until the screws go loose and back off 1/2 a turn :) but pretty much all the screws could do with 1/2 to maybe 3/4 of a turn or more (some where on the verge of being loose) to make them firm. The PWM audio amp in the 7300 (poor design) still is an issue but I solved that with a 7610.
