Yaesu FT-450 HF Transceiver Repair Update #2
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- Опубликовано: 13 сен 2024
- Well at least I now know what's wrong with this radio, and what I need to do to fix it. I appreciate the comments on the first video, and this video was more of a learning thing for me more than anything.
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Best thing about ham radio is learning... don’t stop
Amateur radio is a constant learning process. Good work.
hello Eric,.....nice video.and thanks for sharing with everyone.........and don't be concerned with all the nay sayers..........this is how we all learn.keep it up don't stop........its how well all become educated....I'm 80 years old and still learning...........I've been a ham radio operator for 44 years .....and I'm still amazed what is on the youtube channels.....keep on learning and someday I'm sure you will be a great radiophone license good luck you have the correct attitude you will do good......take care and good luck............Ray .....N1inv
Great job! Knowledge, common sense, patience and a willingness to listen to experts go a long way.
The PA board still looks repairable to me. If I dig a bit deeper, what we know is that the radio is getting an infinite SWR signal which kills the PA to protect it. The signal has to come from the directional coupler (a.k.a. the SWR bridge), which measures the forward and reflected power at the output of the PA. It's that little transformer in the left rear corner you hold your finger on at 4:05 and those little parts around it. So considering the placement of the coupler in the signal path, there are two possible problems here. One: the coupler and/or its detection circuitry is somehow damaged (blown diode would be my first guess) and provides the control board with a false reading. Two: the coupler isn't lying and it really sees an "infinite" SWR. That would mean there is an open circuit somewhere AFTER the coupler, which wouldn't be too hard to troubleshoot since there are only the ATU relays and I guess the TX/RX switch relay (I'm not familiar with this specific radio so I'd have to get the schematics to know for sure). In any case, from my point of view it looks like the problem is in one of these two things (it might of course go deeper and turn into a real PITA, but it's not always that bad). I'd test the signal path between the LPF and the antenna jack first. Look for cold solder joints or cracked PCB traces, you can also try unplugging a coax going to the ATU at the ATU side and plug it to the "from ATU" jack on the PA boad (if it is mechanically possible, of course), bypassing the ATU, which would allow you to test the ATU in/out relays in the ATU position but without the ATU in line. If there is no problem with the continuity between the LPF and the antenna jack, it's time to grab the schematics and have a look at the forward/reverse power detection circuit.
Also, be careful with the power transistors on the PA board (not just the finals, all of them). Reinstalling the board with these components soldered and then screwing them down to the chassis can mechanically stress the leads and leave them in constant tension, which might result in cracking and failures after some time. De-solder the parts before reinstalling the board back to the chassis, then put the transistors back, tighten the screws and then solder the leads back to the board. This way there is no stress in the leads.
Have fun. :)
73 de OK1VI Tom
Was thinking along the same line...
wow...very help and thanks for the feed back..don't forget to share it once you have working on the same issue for Yaesu FT-450D.
Thank you for your video. Here is what I learned from it today. My 450 is not only having trouble transmitting, but my AM broadcast band is also dead. I am damn glad I got my Icom 7300. You help me say to hell with repairing this radio because I am 81, have trouble seeing things and cannot remember where I just put my screwdriver. In the old days I fixed everything. I though for a moment , just a moment, that just maybe I could do the fixing, but just said forget about it. I love my icom 7300 and would probably never buy anything from Yaesu again.
I find it so amazing the things that men/women can do to create things and the process it takes to achieve the intended goals. There is so much complex thinking to make things work. Great job into learning how things are done. But for me I'm sure the mathematics are out of reach. Keep up the good work Eric you are an inspiration.
Better send it to Mr. Carlson's Lab LOL. At least you are learning.
I learn something every time I watch one of your videos Eric. Nice job again and I bet you will figure it out. Can't wait to see it up and transmitting that 10M beacon.
You passed 40k in a flash! Congrats!
I've got a yeasu 450, same problem. No transmit, great receiver!
Hello Eric 73 to you, I just found your channel. AWESOME STUFF keep up the good work. I've learned a lot watching your videos the past couple of days. Makes me want to get my radio stuff back out. Very 😎
Hey,
I like watching this type of video, the more that I do a similar job myself, I watch your films with great interest and will wait for the results of your actions.
I keep my fingers crossed for the success of your work, good luck.
Witek, SP5TAA.
Learning all this about your radio is great. Have you looked for a Yaesu FT 450 group? They might be able to help you. Thanks for sharing all your knowledge about this, it's good to learn more about our radios.
nice video .. i learned alot also . knowing you station equiment ins and out makes troubleshooting alot faster to resolve problems and save money . if ya don't try you'll never learn anything .
Thanks for the timely update on your project.
Take a look at R5074 and R5075 on the PA Unit. Grey metal film 22 ohm 1 Watt resistors. at 3:28 in the video, the one on the right looks like toast. I would suggest that you replace these with a 22 Ohm, maybe 5-10 Watt Resistor, maybe larger. These, (different component numbers depending on radio model), are notorious in Yaesu equipment for running near the thermal limit of the resistor, and failing. Sometimes carrying other more expensive components with it. I have even seen cases where they burn the board around the solder connections. I did the R2213 mod on my FT-840 and it runs much cooler, and is better all the way around. Did mine with chassis a chassis mount from Newark, and the resistor is mounted in a heat sink. Actually ran mine outside the back of the radio, through a rubber grommet. Rig (and board) loves the relief. Keep at it Sir, Education cannot be taken away from you! '73- de AC4YX.
Hi Eric,
That coupler between the two relays I think is for the SWR circuit. The resistor that is burned may mean the transistor nearby could have a problem. 73 WB3BJU.
Did you end up fixing and finding what was wrong with this radio ?
When you reinstalled the PA board and fastened it down, and the transmitter stopped working. Maybe the stress of fastening the board down has stressed a small crack in the board, or changing the stresses on the board is creating a connection issue somewhere...
did you ever fix this radio? do you still have it? thank
Nothing wrong with increasing your knowledge at all, I suspect it blew a diode or two out, Maybe you could find someone who has the ability to repair it and they would let you assist and/or film it so we can all see process and maybe some safety tips when working on transceivers.
Did you try holding down the "band up" and "band down" switches while pressing the On/Off button to clean the relays?
You might want to turn the power supply off before poking around inside
google Navy Six Step Troubleshooting. Great guide for figuring stuff out.
Sent mine to Yaesu. 159 bucks and back in action. Mine was just a low power issue
anyone know how to scramble voice FT450D ? need help and refreence about this, many thanks..
Eric - how old is this radio? Are you the original owner? Keep probing - you get an A+ for effort. If you've owned this radio since new, I would highly suggest trying to figure out how the board ended up in the condition it was, that you showed us in your last video. That was definitely something you don't want to happen to your shiny new IC-7300! Also - I'd question why there is a big lump of thermal paste just sitting there on the transistor on the right. Typically this is used as a bridge between the transistor and a heat-sink, not just lumped on top of a transistor all by itself.
BTW - your channel is by far more entertaining the other few radio guys out there :D
@@bruehlt Thank you my friend. Not the original owner, about 9 years old.
My first MAJOR CRINGE on this channel. Wow, even though I am late to this party. The 'white' toroid with a single turn through the center in the upper left is your directional coupler for SWR. You disconnected the output transformer to check for output? Big no no. Even no antenna this radio will attempt small power like 3 to 5 watts. I wanna ramble, oops already did, lol. Still watching though. Plus do not give up. Since radio is not working it is good learning radio. It is easier to fix transmit than it is receive believe it or not. Is a straightforward design.
Many people are having FT450 breakdowns. Mine has a bad CPU. Ham repair guy said it would be cheaper to buy a new radio. 45 dollars for that.
you keep saying it has a tuner, but its not a 450D or AT? FT-450's dont have an ATU, or so I thought....
@@CrisisGuildWOW THIS IS AN FT450AT
I'm afraid its way over my head. I wish I understood more, but electronics are not my thing.
I think that you know more and are smarter than you think, or what you've been told by others. Try gently tapping on each of those relays as you hit the transmit button. The Tx just MIGHT kick in. I always suspect mechanical problems and dirty switches and such FIRST.
As part of this: See if any voltage or heat or smoke(!) suddenly appears in the vicinity of that resistor.
Find out if there are any technicians diagnostic "soft button" hidden menus.
Look for any interlock safety switches. Carefully... Caveat Emptor.
The (Fluke) VOM finds the majority of problems (I see you chose to bite the bullet there and pony up for a good meter... I own the Fluke V Model 28 type and have never regretted my choice) , and a cheap Entry Level Oscilloscope will get most of the rest. The new Entry Level Oscilloscopes are AWESOME CRAZY GOOD, with specifications that we could have never dreamed of fourty years ago at ANY Price Point, and you can get an Abritrary Waveform Generator again with crazy awesome specs for about the same price as the Oscilloscope. (I am going to recommend Siglent on both accounts based on my experience. Your mileage may vary... There are others out there that I am SURE are as good but Siglent is what THIS Radio Rip Van Winkle purchased.) Good Luck! P.S. I have never owned one of those Service Monitors but always wanted to try one... hope in a future video you will show that.
My experience is that the TX section of any radio is usually easier to fix than the Rx section.
Good Luck! 73 DE W8LV BILL
All right take the Icom 7100 over to Patrick's house and you can take the 9:40 Kenwood and do a video on that or maybe use it as avakin is that Workhorse puts out 150 watts and it will be an open end loan the icon will and just think when I go SK you're not going to have that much to to load back to your house over and plus I'll be able to do CW we will be brass fish Brothers I said fist are you go
Keep working on it ...
Want you replace the whole PC board we will work and after you replace the board
Once you replace the PA board
The best thing you could do is send your radio to someone to fix it, because your opening statement is wrong. When the finals die, you get nothing out.
Send it to Yazoo if the estimate is to too much tell Yoshi hey you got to l u Yankee Memorial Yaesu as featured in hundreds of ham radio concept videos was that provenance I believe
BOOM... first!
Nah.. The radio said boom first.
My 450d has all pixels on on the lower right display, so I can only run the menus thru hrd.... Any ideas?
N0RDC DE Dutch
rule 1 never work on a radio while plugged in
I would not "experiment and learn" on an expensive radio.
That's actually a cheap radio mate.
73
You don’t have the right equipment, knowledge or experience to fix this. Hire a professional.
Nor intuitive troubleshooting ability, which is pretty much formed by our mid-teens
I see he has the spirit of amateur radio, a place for anyone to play and learn.
This is waaaay too harsh. Ease up, brothers.
He will do fine, He's taking his time and learning each step before doing it. he will learn a lot and will likely fix this rig.......