I see America isnt the only country with people who take the golden screwdriver to perfectly good radios... most techs wouldn't even touch a radio that was jacked up this way. Kudos do you Peter Peter you went well Way Beyond the Call of Duty on this one. We all can tell that you know how to accept a big challenge . The best tech on KZfaq in my book

A man's got to know his limitations. The owner of this radio didn't know his.

Hi Peter. That was an amazing video. I have many years experience and I would not have gone as far as you did. Your videos and so informative that I have watched most all of them. you are one of the best I have ever learned from. I am retired now but i still dabble a little from now and then. thank you for your effort.

Peter, you don't give up easily! That radio was terribly abused. Thanks for the video!

Great video. I learned some troubleshooting from you and I have been repairing for many years. You are one of the VERY best. Thank you

Wow! That repair work on the vias was really amazing!

Thanks a million Peter for all your help and patience with the messed up radio. Great video with learning aspects

I feel that you were very kind to the person who tried to "fix" the radio before--as if they were your in-laws. It's a self-esteem radio, to make you feel good about the quality of your work. The resistor was added for added inductance : )

I used to do electronics repairs some years ago in my spare time and I truly loved the process.... watching your videos brings back great memories and it also reminds me that there never really was enough money in component repair to earn a living wage because of the costs of time. I think it's impossible to "Make A Living" at it unless a person buys equipment that doesn't work, then repairs it and resells it on eBay/Online or to a Pawn shop. Take a car into the garage for repair and it's like $100 an hour plus parts for service work. Even working out of the home to repair electronic equipment, the repair costs would exceed the value of the equipment in just a few hours of repair work and most people wouldn't be willing to pay more to repair something than to purchase something new or buying even Used in Working Condition... I can see you have a lot of quality test equipment there and I know that it didn't come cheap so I can't imagine that you "Repair Electronic Equipment" for a living. This must be a hobby or a side job / second job for you. Keep making great videos, they are quite detailed and very informative and I appreciate watching them....although...a little lengthy...

I bought an FT-847 the first year they came out and I remember there was a recall for the power switch and I really didn't want to have to ship my 847 to Yaesu just to replace a silly power switch. My radio wasn't exhibiting any kind of problem but after talking with Yaesu they sent me the replacement switch, which I happily replaced on my own.

I so much admire your skills and equipment to fix things. However, your willingness to share knowledge one step at a time overshadows it all. Thanks

I really enjoy the videos when you repair hack jobs and fried board traces. It really demonstrates your skill and gives me something to work towards in my own abilities. Thanks fir putting this together even though the repair wasn't successful.

How can ANYBODY treat a radio that STILL sells for ~$1000 like that! It almost physically hurts me to see it! I know Peter loves a challenge, but surely this one was always well beyond the call of duty!

The conclusion is send your radio to a professional to make the modification. Great video Peter thanks for posting

Excellent video, very informative. Just a suggestion, press the fast and lock buttons together at the same time and turn the radio on this will reset the micro, it’s just a suggestion but it might be that at boot up, some of the initialize code is corrupted, leading to an ‘unknown-status’. There is probably enough code available to ‘force-shutdown’ rather than enter a possible ‘burn-out’ status. One final suggestion, this is from my early PC service days, when a ‘486DX2-66’ was a fast processor. My original IBM PC has directional detection on the CPU Cooling-Fan, if the fan was seized, and not running, the system would lock-down rather than overheating, if the Fans on the FT-847 are not running, could that force the fault you are seeing? Great video again, Bye-4-Now - Neil G1OVH - UK-QTHR.

I never seen do that before I have same radio since 2001 and still works to this day works great for me so far never have any problem with great video Peter !

I said that like number 67 was mine here in Brazil! Very good work and knowledge, congratulations TRX Bench.

I worked for years at a major electronics manufacturer. My first day on the job they made me take a class on proper soldering (and unsoldering) techniques. Even though I knew how to solder, I still learned a lot in that class! It's scary to see the mistakes that some people make: dirty tip on the soldering iron, wrong flux, not wetting the tip first, wrong tip shape for the task at hand, using an iron that is too hot, blowing on the liquid solder joint to "cool it down faster", not recognizing a cold solder joint (or not knowing how to prevent it), etc. etc. There's a lot of metallurgy and chemistry involved as well which can adversely affect the properties of the solder joint after it solidifies from the molten state. Just solder it correctly and let it cool at its own rate.

Welcome to my world. The world of butchered and hacked up radios. I swear there are days I spend half the day just shaking my head in disbelief. The sad thing with this radio is before someone started butchering the radio it was probably a easy repair. People need to learn their limits. Good attempt on the repair.

I just got mine back from a shop in Texas. I bought it used as a newly licenced ham from a reputable shop. There was a few months delay before I started using it on HF since I was only on UHF and didn't realize there was an issue. It had terrible receive quality on HF and I didn't realize the volume was very low. They did several mods including the power switch, found the short causing the issue and brought everything into compliance of spec. It works wonderfully now and its much louder..

I really appreciated and enjoyed this video. It brought back horror memories of my Kenwood TH-F6A that went into meltdown because the "ON/OFF" "switch" was not an actual switch but a "soft switch" which would not allow me to turn it off as it went into meltdown. The protective covers on the right side (mike, speaker, etc.) were missing and some jerk nearly hit me causing the contents of a coffee cup to be spilled into the rig via the jacks on the right side. The battery would not come off unless I removed the belt clip, and since I was driving down the interstate I had no screwdriver to do so. I do wish I could get it working again, but I fear that like the one you worked on in this video, it is simply not cost effective. There were a couple of times that I thought I saw a problem that you may have missed. One such item is at 38:24 in the video. In the upper right part of the screen is a bit of debris that it appears that you didn't see since it didn't show you removing it. There was also a bit of debris above the trace of the bottom left resistor between the trace and the ground plane. You may have taken care of both of those, but I didn't see it, so I couldn't know for sure. Keep up the excellent work!

I own two FT-847's and to see this makes me very sad and a bit angry... I had a similar problem on one of mine but it was the power switch itself. If I held down the switch it stayed on. Eventually temporarily did the mod for the switch and then replaced it... Great video and keep up the work !

Those damaged pads next to xtal and the wrongly fitted 2k2 resistor are where the padding capacitor (along with another "select on test" SMD capacitor) is fitted which forms part of the main reference oscillator. What a mess! Big 👍👍 up to Peter for keeping his cool !!!!

Now we know why you keep your hair so short Peter. It's so you don't grab handfuls of hair and pull it out when working behind people that make such a mess of the radios.

I know it's a 5 years old case, but anyway... I got similar fault in very fast, 2x9pin needle printer with huge power supply unit. The PS unit was switching off after about two seconds from Power On. All voltages were OK (I had to measure them with oscilloscope), no symptoms of shortage in the mainboard, motor drivers etc. The PS was receiving an "emergency power shutdown" signal from CPU. The problem was caused by one of the resistors in voltage divider measuring one of the PS output lines. It changed the value from 20k to 40k, so the measured voltage seen by CPU was 3V instead of 1.5V. So it looked like an overvoltage and CPU immediately halted the PSU. It took me 3 days to find this resistor as at first glance 3V looked quite a good value for a 5V Z80 based CPU, until I made proper calculation ;).

Great video Peter, much patience and great skill. Thanks for sharing your videos. 73s Pasquale IW0HEX

Excellent video too well done and very imformative, sad to see someone destroy a great radio. No sure why someone would do such a thing. Peter is really one of the best of the best lots of knowledge and patience and very kind and helpful.

I have no knowledge of this radio. But is that an RS232 port on the back of the radio? Hook up a breakout box and see if the UART initializes (built into the processor?). If it does, is there anything on the TD or RD leads? I say this because as a programmer from this era it was very common to squirt out status messages during initialization of the system and to send error codes (in ASCII) if something goes wrong. Just a crazy random thought....

Oh man.....1hr 20min video from Petr and at 6:00, we already see this is going to be another case of "The man with the Golden Screwdriver." This is going to be good, I already know it!

This video was quite useful to see how you try to repair such a mess. The work rebuilding the vias and traces was amazing. And I must be really interested, because I watched to the very end :)

You have so much patience. Great video. Show the owner a red card in the future! 73’s Lynton

This is a painful video to watch on so many levels. No other comment necessary.

Thanks for that, nicely done. I have this radio so was even more interested than usual to see it repaired. Pitty about the outcome. I hope some sacrificial spares come available!

I've been looking for any FT 847 boards...but 800 to 1200 USD for a 20+ year old radio...got to love the US ham market . :)

Another FANTASTIC video!! Congratulations Peter from Brazil. 73 from PY5MM- Mauricio

Moral of the story. Do not open the case if you don't know what you are doing. A good tech is worth the price.

Hi Peter. I had a similar problem with a stereo receiver. I would push the on/off button and the relay that provided power to the whole unit would vibrate. At first I thought the problem was the filter caps in the power supply but replacing them did not solve the problem Finally I started reading about how the reset of microprocessors worked and how the capacitors around the reset chip were a problem. I used the shotgun approach and replaced all of the capacitors around the reset chip and that fixed it. This seems to go along with Nikki Copper’s more rigorous analyses. Hope this helps. Also, thank you for the detail you presented about how processors control radio circuits. John C

That was a great effort! Thanks for sharing it with us. Greetings from Arizona. Mike K8MB.

If you have access to an infra red camera you may be able to see the offending component at power on. Jeff.

I'm only at the point where you found the 2.2K resistor. I bought a broken radio for $300 that was dead. I troubleshot the radio only to find the 100ohm resistor was open. I thought that the resistor was too small and had too much current running through it and decided it needed to be larger. I replaced it with a 2.2K resistor and the radio came to life. I then happened to google the problem (after the I fixed it) and found this to be a common problem and Yaesu made an engineering change to replace the resistor with a 2.2K resistor :-) That may be why it was replaced...poorly so unfortunately.

I would try using an logic analyzer configured to trigger when the reset goes low. I would also set the LA so that there is a healthy pre-buffer before trigger, so you can connect many inputs of the LA to various test points on and around the processor, and then be able to go back and see what happened right before the processor reset. I would also make sure to monitor any interrupt type of pins in relation to the reset line. Could be an additional fault that is generating an interrupt signal that the firmware is decoding to be a power off condition. Last resort would be the "shotgun" approach and simply test all pins in relation to reset, again seeing if anything is happening right before the reset goes low. My last ditch effort would be to freeze the board real good and see if you have any caps or other components that have failed short. Ceramic caps of that era are known to fail short, so you might see that if any device instantly heats up. Should all that fail, I would suggest the owner buy a donor board like you suggested (that and revoke his soldering iron license till he takes a certified soldering class!). (edited to remove suggestion of tying the battery switch one way or the other, as i failed to notice your comment on the subject)

I am more amazed how people do something really bad, then try to undo and destroy more, and than just downplay their works. "I cannot understand why it doesn't work anymore" I hope you made him pay a pretty penny for this

As far as I'm concerned, the owner can do whatever he wants to his own radio. It's no skin off my nose if he bricks it. I am more distressed by people who decide it is helpful to heap criticism on top. That is contrary to the mission of amateur radio in that such criticism can discourage people from experimenting. It is amateur radio, not professional radio and I try to always be welcoming and encouraging to anyone who wants to participate. It is not a place to play "King of the Mountain".

These guys with the endless modifications to these radios, they can't seem to leave anything alone. It's amazing how much of this you see, and just say to yourself when one is in front of you, "hammy-bones strikes again."

Great video!!! I have the same radio that I bought in 1999 for $1500, I've never used it, it's brand new, still packed in the box! Is there anything I should do with the new one that's been packed away for 20 years before I start it for the first time? Thank you in advance! Currently living in 🇬🇧 KE6MFK Merry Christmas 🎄

The golden screw driver strikes again soldering with a hot nail

O like número 67 foi meu aqui no Brasil !Muito bom o trabalho e conhecimento,parabéns TRX Bench .

Great video as always! Thumbs up! I had a peek at the schematics and had one far-fetched thought: What if the undefined state of the broken backup battey switch (S1001) confuses the CPU? Since that switch looked molten to death by a soldering iron and it is close to where the "mod" was done, I thought it might be a possibility even if it might not be a likely explanation. The backup battery switch leads straight to one pin on the CPU. In off state that pin is grounded via 10k and in on state it has 3V from the Lithium cell.

Nice video Peter. I did have one of these rigs. It worked fine for a while and then did the exact same as this one. I think i saw i was loosing 5v signal down to 2.4 or something. After some troubleshooting just like you did, it lead me to a small smd regulator on the bottom side of the bord. It was near the relay area . I replace it and the rig would work real good for 19 out of 20 power ups. So once in a while it would not power up. I never did git it working any better than that. Hope this helps you or someone else.

Ich würde als erstes nochmal den Ein/Aus-Schalter überprüfen ob der auch wirklich noch im gedrückten Zustand den Kontakt schließt und nicht nur während des drückens.. Wie du schon sagtest ist der bei dem Gerät anfällig, deswegen wurde die zweite Schalterhälfte ja schon mit Kabeln dazu geschaltet. Als zweites dann den defekten Backup Schalter neben dem Prozessor ersetzen, dadurch das der obere Teil fehlt wird ja jetzt gar kein Kontakt geschlossen, dadurch könnte der Prozessor vielleicht blockiert sein. Und natürlich die Batterie wieder anlöten nicht vergessen.

it's not the processor. keep digging. (reheat the soldering of the processor, with hot air, without removing it from the board. The solder Yaesu used tended to crystallize and make intermittent or no contacts after 20 years of use.)

Great job, that radio was a mess.

Have you tried doing a factory reset on the radio? when I have done this kind of mod on other types of radio sometimes the CPU gets confused.

Hello Peter,I can only tell you about an experience I had with a MEOS TV I have it did the same as your radio, I checked the capacitors, and the diodes in the power supply, all was well, board looked clean nothing showed up no smells, so I put freeze spray on section of the board at a time and switched on, eventually I went to one section powered on and immediately one component thawed out, it was one of those smd caps, so I got the part number off the schematic and I swapped it out, bingo the TV fired up, wife was happy I was relieved , so as the board your working on has been messed about with, could this method help you out. 73 Paul M0BSW

I have been using this radio for a very long time. for comfortable work on the VHF bands, I installed TCXO

hf transceiver repair is a lot fun, you must have a ball doing it.

Wohl mit dem Brotmesser auf der Herdplatte gelötet, so ein Murkser. Gut dass du die Sauerei wieder hinbekommen hast.

All I can say is BRAVO.

Good of you to show us even when it is not fixed. I would recommend focusing on the destroyed vias etc. in the mode area 1, 2, 3 and 4 at 7:41. Most of the time, it is the last thing that "changed" that is the culprit. The processor is booting up and even running long enough to switch modes and receive. So the processor is probably fine. It has to be some input to the processor, analog or digital input, if it is the processor shutting it down. I am sure you checked that any DC to DC power supplies are not causing the shutdown. Are there any protection circuits/blocks? Did they mess with the bias settings?

Yaesu Christ, it's a wonder the person who did the messy damages, found the right screwdriver to open the case.

very informative, well done

Hi! Nice video and explanations how different parts of the radio communicate to each other. And yes, this video should be a warning what can happen to all those who will take the old 100W big soldering iron that they used with great success in the 1960's. I have seen stuff like this. And if you still have the radio around, I would give you a hint to try. I have an FT-847 and I did a MARS mod to it, or tried to do. It was bought from German Ebay back around the 2010, so I think it came with your area software and settings. I followed the info on the internet and it didn't work, if I remember right I was on a same kind of situation where it just rebooted itself like that radio. I returned those "jumpers" to original and it worked again. I think there might be different versions of the processor or memory that will not work with MARS-modification settings or with info of the original settings you find from internet. But if you are really sure what pads were connected at factory this might be not the case. But still an easy one to try. By the way, excellent job with repairing those missing traces! I have a working FT-847 here so if you want some info to compare, you can message me.

The radio is on for a few time. Solution: replace the on switch with a 555 timers ;-)

Acid core solder and a 500 watt iron works every time!

Hi Peter at 7:37 it looks to me like there are two vias on the traces from the processor to solderbrigde 1 and 3. It doesn't look like these vias are conected to the traces anymore. And yes you are right, this mess is something anyone can do without special skills :-)

I’m sure you covered these but the screw terminals even with power connected went dry joint and I had re-flow these. I had an issue where headphones were once plugged into CW socket in a clients radio and it went into TX as power on and over current. Obviously not what’s going on here but the surface mounts caps are normally 45c working from factory..... yes honestly they are as I worked on camcorders in the 1990s and must have changed 10,000 of the caps for 85c and 105c to give the camcorder a better future. Canon E90 especially. I had this problem on my C2 and trying really hard to remember how I fixed it. See my videos as my C2 is alive and working the birds. Let me check my notes but I’m sure I re-flowed something near the power section. 5 years ago or more....

i am watching this at 2am as i cant sleep but i am hooked on your video now i am wide awake totaly enjoy you video de gm0ioa

Now on Craigslist: Ham radio for sale. Does not work, do not know whats wrong with it but was tuned for maximum smoke the last time it worked. No lowballers! I know what I have. It is worth lots of money when working and can be easily fixed with the proper tools.

Jeezo! someone has rap*d that lovely radio :(

Since even the panel lights shut off, I would assume that the power supply is receiving a disable command from somewhere. What supplies that command and can you monitor that control input to the power supply? Can you disconnect that line and maybe force the power supply to be enabled (or not disabled)? How about finding an FT-847 support group on Yahoo or Facebook where you can discuss this problem with hard-core enthusiasts? These groups often have community files with factory service manuals and a wealth of undocumented knowledge. The odds are high that you are not the first person to experience this auto shutdown condition.

Measure the base of Q1122. After hitting the power switch, Q1118 holds it low for a short amount of time, then it should get a hi signal from IC Q1106. Find out why that signal disappears. (and de-energizes relay RL1001) As you said, there are no PSU overloads, so I would even force that signal hi. (cut the trace before)

Somehow disappointing that there was no rescue. But I learned a lot what can be done and a lot more what you should never do.

what about the loose yellow wire ,near the lithium, that was the first thing i would fix , communication of the switches worked , because de dial changed the frequency during the first second,

I want to use SMD 0201 size, 0 ohm jumpers for the JP1 001 - JP1 006. I was wondering if this would be the correct size. BTW, I'll make sure I'm wearing a ESD Wrist Band. these jumpers are connected directly to the CPU. Very nice Videos...

Hey Peter... One of your longer videos but because of the content and the valid step by step analysis, the time flew watching this!! It is so unfortunate that FOR NOW, the radio must be put to one side. As you say, the radio seems to be operational, receiving, audio amp OK, mode switching, it just seems for some reason that the DC is not latching. I have no doubt that the owner is not fully forthcoming with the details attempted or the history of attempted repairs. Why would that through hole resistor be changed in the oscillator stage as well as damage to the long track beside it? I guess that there has been a million angry soldering irons attempting mods in that radio long before you were given it. If you cannot repair it, then not much hope of anyone else curing the issues. 73 as always Peter, Brian

very good video from Gary in the UK.

I have one of these rigs and have done a few mods but used a soldering iron not a poker! 73's One rig QRX

It's like a tornado picked up a bunch of chisel tipped soldering irons and then went over the board. Horrendous!

Call or email Yaesu UK - they may be able to provide that chip for you. They helped me find an obsolete part for another rig.

Hi Peter - what a messy service You picked up!! May be CPU is reading a corrupted setup data on booting and shuts down. To reset CPU and config on radio startup make sure the radio is OFF, then press and hold the and button's and turn the radio ON. (!!Warn the customer that all the contents of the memory channels will be reset and lost. :-!!) - Did You replaced the messed up battery switch? Did You checked the supply close to the processor during power on? (Nominal value and max ripple)

configuration selection jumper wires dectructed and u checked an told that they are true and left them but the vias on that lines simply should be connected to pull up resistors I think. The via on th "3" line is destructed too, so the line might be floating instead of being pulled up

Check the POR of the cpu. The power rails. The cpu can be found and be replaced ( in the worst case ) if the program memory is outside of it.

A great video Peter, you showed remarkable patience. I put a suggestion about comparing the serial protocol between a working radio and the dead one. I2C or SPI would make that easier. I also wonder is there a message into the processor right before the shutdown? I wonder if that came from the front panel, or something else.

Late saturday evening, without my tea...unususal...but i could not resist! Just hammering down some car jumper cables with a torch and huge amounts of lead isn´t fixing a problem..may we should produce an sell some stickers with that hint. I wonder, what triggers the unit to shout down, and what to do to bypass that behaviour. Ok, normally it should protect the unit to fail / burn/ lift off, but as you said, it works fine for 2 sec, no exessive current draw or things like that. So maybe it is possible to hard wire and do some rerouting to eleminate this shutting down? Problem is: How much time could you spend to this thing? There are many hours left to check every bus and voltage, every cap etc. Anyway: Fine job again so far, i like it very much. And be sure: You will get the Luis Rossman diploma for SMD and via-bridging repair! Thats for sure! 73 de Olaf

Yaesu has most of the times a kind of reset or init function of a radio by holding a key combination while powering up. For the FT 847 it's this procedure: If you wish to reset the FT-847's microprocessor to its original factory default settings (all memories and customized Menu settings will be lost), use the follow-ing procedure: Press the [MENU] button to activate the Menumode of operation. Rotate the SUB-TUNE knob to select Menu #39("ALL INIT "). ƒPress the [MCK/W] key.„ Press the [MENU] key to exit the Menu mode But given the short time that the system has power this might not work. maybe try to disconnect the eeprom chip from i2c bus, it might hold wrong values that confuses the CPU. Good luck 73 de pa3fus.

Well what can I say Peter, I am senior service engineer for a very famous guitar amplifier company here in England and I see terrible work that causes damage and mods that cause oscillation and all sorts of nasty faults. All I can say is 'I feel your pain'! Electronic circuits are designed like that for a reason and personally I find that all these mods I see generally cause problems. Best wishes my friend. 2E0EEH 73

might have been worthwhile to re-flash the firmware to see if that cleared the problem

"This is something anyone can do. You don't need special skills....", but sometimes it is helpful to have at least "some" skills? That PCB is really one sick puppy... :(

Perhaps the power supply is providing the correct voltage but it can't for some reason provide current and as the current tries to surge the processor shuts down? Or some other short pulling the power supply down?

excellent video with you hints tips thank you

Was this mod done with a blowtorch? Another great vid, 73 de Malc 2E0EZP.

Great video as always!

Radio acts as though it's going through a POST routine, finding something missing and shutting down before more damage is done. If that is a multilayer PC board, perhaps one of the feed throughs was damaged in the original modification and not making contact in a middle layer.

Thanks Peter! I would try reflowing the processor and other IC's. You may have mentioned that you did and I just missed it.

My comment has more than likely already been covered, And this video is fairly old now, But all the time watching this i was thinking "I'm sure the backup battery has to be connected for it to power on" And when you first opened it there was a backup battery someone bodged in, but the backup switch was broken so the battery wasn't actually in circuit, Did you ever try a new battery and replace switch, Or solder the two tabs of the switch together so its on ?

Peter I know it's a long shot but have you tried the Processor reset procedure..I would also suspect the Guy with the Hot Poker has also fried some of the Capacitors, you only have to look at all the plastic that be has melted with his Iron to realise he hasn't got a clue how to do basic electronic soldering.

Did you check the on/off switch as there was a mode out to put a relay in line so that the switch was only turning on a relay that supplied the power instead of going through the switch.

Hi Peter, When the radio shuts down, I hear a relay click, can you trace back from the relay to see what is shutting the relay down. Thanks for all the great videos.

Why would you not check the power switch and power supply first? Find out why the radio is not staying powered whether it is a supply problem. It sounds like the latch on the switch is releasing or a relay is dropping out when it shuts down. Solder one side of the resistor to one of the pads then extend the other pad to the resistor with a wire. Again fix the flipping reason that. The power goes off first¡ Is that a multilayer PCB!

I never understand how some people can be so inept with a soldering iron