When the second chip popped, I thought maybe the board would need to be replaced. You do very good work. I always enjoy watching your videos.

Hi Peter, I feel bad for the OM as you, but sometimes you have to just make the most sensible decision, as I think you did. Enjoyed the video. 73

Sad to say I have been down that same road. Back in February my 50A linear supply suffered a series pass transistor fault that fed my radios nearly 24V instead of 13.8V. Unfortunately the crowbar circuit did not last quite long enough to blow he fuse either, so the radios saw the full rail voltage. Thankfully no major damage was done and most of the damage to the radios was confined to the TVSS diodes which ultimately took out the fuses after sacrificing themselves. For the initial power on test afterwards and after servicing I like to use my variable bench supply to control any fault current by dialing in a maximum amperage just above the normal expected idle/receive current for the radio combined with a reduced input voltage if 12V. That way if there is a terrible fault very little additional damage will be done. For the transmit test I do the same by increasing the current limit to an appropriate minimum level and then try transmitting, first at low power, then higher, to see if the piper amplifier stage suffered any faults. Then measure all your voltage rails to look for low or high rails while safely powered on. Thankfully, I lucked out since most of the more sensitive radio circuits were protected by inline linear regulators which safely limited the let-through voltage to the more sensitive lower voltage rails and allowed the TVSS diodes and fuses the necessary time to do their jobs and sacrifice themselves. To find the source of any shorted components, like the TVSS diode, regulators, ICs, etc, use a good multimeter with 4-wire Kelvin probes to measure the resistance across the voltage rails at various points, the areas of minimal resistance are either the faulted shorted components or is electrically very near the affected component. This allows you to track down the shorted component(s) without leaving the device powered on for an extended amount of time during fault finding.

Thanks Peter, it's always a pleasure watching you work.

Great video! I have an Icom 703 that won't power up and was trying to figure out a troubleshooting procedure. You just explained it to me! I'm new to radio repair so this was very helpful. Thanks again Peter.

GREAT troubleshooting as all ways Peter. Good call to put in a new board.

I think you made the right decision in the end Peter. Even after fixing the original board more problems could show up down the road at a later time. Specially since this was a brand new unit. You did do some awesome troubleshooting there, Thanks foe another great video Peter. 73

Thank you for a great video ! It made me check the specs. in the Icom IC-7100 Service Manual. It states the voltage is 13.8 Vdc +/- 15% e.g. 11.73 ~ 15.87 Vdc. As I intend to use an IC-7100 abord our little boat and use the 12 Vdc net, I measured the voltage there as well: when on shore-charge the maximum voltage (during wintertime) is 14.8 Vdc so no problem there, at anchor the voltage drops to a minimum of 12.2 Vdc before the generator kicks in to 14.3 Vdc so no problem there as well. Not a bad idea to measure the max. and min. voltages of say, your car or mobile home AND checking the specs. of your $$$ set before installing it, only to see it go up in smoke.

Excellent Peter, you can only go so far then it is better to replace. Another great video. 73 s from M3KQW

This is a fantastic video of clearness and even i am a beginner, I was able to follow you.

Peter it is a joy to watch and listen to an engineer at work :)

Great job Peter, my compliments, you are clear and precise, a great thumbs up

I was thinking that board is sure in bad shape, and you found the other board. That was the best way to go!! Another Awesome video!!

A great video Peter, well done! It was really interesting to see how easily maintainable the radio is!

I have done exactly the same with my FT-817ND... Forget to change from 28V which I have use previously to 13.8 when connecting Yaesu. Fortunately for me the only damages were the electrolytic capacitor (which exploded) and fuse at the very beginning of the circuit. More lucky then clever. Great video(s), I really enjoy watching for months. Huge knowledge sharing - thank you !

Love watching your videos brilliant methodical, the Sherlock Holmes of ham radio

excellent video i always learn loads from your videos keep you keep the good work going thanks again

Great troubleshooting Peter...thanks for the video

Love your work on the bench👍

This is better than any detective show on TV period!

Great video! Thanks for sharing.

That reminds me of a unit that has been hit by lightning. It may only need a fuse to get it going but soon after that weird things start happening. I knew that board was damaged further than you thought. You were being optimistic with the board but when the next component up the line failed you knew it was a losing battle. Good video and glad you got a new board. You can put a seal of approval on the radio and not worry about a call back to soon. Thank you for the video.

Again another educating video, thank You!

Great video. Really enjoyed the fault finding.

wow, the patience of a saint to go through all of that, halfway through the video I thought "I'd just buy a new board" absolutely brilliant and a spot on decision

Great video Peter.

Love your videos. Your camera work is fine. I'm looking forward to your next one.

Another great video Peter. Very costly mistake on power up. Thanks.

Thanks for taking the trouble for troubleshooting

Sad, I have a 7100. Great radio. Great video as always.,

great Works !! excellent video.

Changing the main-board was the best option my friend.. You can never be sure what has suffered in an over voltage event such as this. At least now the customer knows his radio is as good as new again now. Regards John

Very interesting video. Keep up the good work Peter. A BIG thumbs up :)

Yes Peter, I too feel that you made the best decision to replace the whole board !! With a severe overvoltage like that, that voltage spike can destroy a large number of components unfortunately !! I feel bad for the owner too, but hopefully he will bea little more careful and thoughtful now too. !! good job on your part!! and good video!! John Bellas KC2UVN

Thank you very much for share the repair skill , VY 73 de BD7PA

I agree, sometimes its the only and better way to replace the whole mainboard. I hope a voltage overkill will never happen in my shack...Nice work and thank you very much for your very learnfull video presentation! 73 Ernest PA3DLP

Better late than never. I just came across this video, even though I have been scribed for some time. I too was using an external Liner type power supply. It was equipped with over/under voltage and current protection. However, the reaction time of my older supply apparently was not fast enough to overcome the problem to save my radio. The 24 VDC was directly applied to my ICOM 718 's 12 volt input supply. The result was it got toasted! and became a parts box. The good news is this was not connected to one of my newer more expensive Icom radios. There comes a point where you need to make a decision. How far do you go in investing time and money changing out components, or how much do you invest in new circuit boards before writing the radio off completely. A belated thank you for making a posting this video.

Impressive, i would have satrted crying. Good job.

I would really love to see you do the actual de-soldering and soldering of those surface mount components. I enjoy your videos

That would be the sum of all fears. I hope that never happens to me. My Yaesu 991a cost me a bundle; they've gone up since 2017. I cannot imagine frying my radio before even keying it up for the 1st time. Cheers & 73 from W Rusty Lane K9POW in eastern Tennessee

Good choice Peter. Too much problems on that board. It would not be a good idea to keep it. Nice work.

Great work, I can empathize with the owner. Puting too much voltage in the supply could cause heartache. It is a shame that you have to toss the original board after all of that troubleshooting.

Even though disheartning, sometimes complete replacement is the only logical answer. I'm sure the added cost is hard to deal with, but then again, it is not a total loss.

Nice troubleshooting. Shame on iCOM for not using a crowbar on the input. I think I would have gone with the original board and just repaired it if and when it failed.

You should limit the supply current, so you won't damage the PCB when a component blows up. I would replace any components that exceeded their maximum ratings, before even connecting the power back after replacing the first chip inductor. Probably, the regulator and the DC-DC converters took a hit from the 24V supply. Having said that, good repair.

A good call on replacing the entire PCBA. Component level repair not cost effective if there are multiple failures and possibly other components that were stressed

I don't know if you charge by the hour but I think you made the right call on this one. At some point the time involved would rack up a bill that would buy a new radio.

Something I noticed right away as soon as you took the cover off, the 5 amp fuse in the radio is blown

Your sprung multi-meter probes look very interesting.What make are they? Very informative video BTW.

Hi Peter, The 24V will have a cascade effect on all those IC's not rated for that voltage. I hope the radio came up to spec when you finished your testing. WB3BJU

Thanksss

Peter tnx, great Job, 73 Peter

In my days as a trainee radio/TV tech (47years ago), before any measurements were made, the three senses were used. Look over the board, smell, then heat check with a finger etc. Still holds true today.. GI0OTC

ijust came across this vid during my search for an IC-R7100. Both fascinating and depressing! All that money.....and the owner doesn't check the proper voltage! Very sad.

Good job

I love these videos. Additional benefit is I get to pick up a bit of German from the instruments at the back!! Spannung == Voltage! Great work. Question though - what is your thought on why the manufacturer doesn't put voltage protection on the input? Is it just a cost thing for them (as a commenter pointed out below) or is their some technical reason.

Ouch😥

Another enjoyable video from you - thank you. Is the replacement board readily available to the consumer? How much? I would think quite a lot!

Well Done!!!

I have a Yeasu FT-8900R which burns fuse when power is connected. This Radio was in my car and without eny use for few years, since my car had a serious main brakecylinder problem before we found what was wrong. My question is that could it be, forexample, dryed electrolytic capacitor in main voltage which causes short cut..? Certainly it´s not transmit unit because it´s not been used for meny years. I would be very greatful for eny information..

Hello, good Video, Thanks. Can You tell me how much such a Mainboarl will cost? I have to replace mine. Thanks, 73 de Willi

Very interesting, Thank you Peter how much did the replacement board cost ?

Just for curiosity what was the cost of the new board ??.............Ray H from the U.K.

Hey I really like your videos and I'm a subscriber also. My question is where do you get the schematics.

Have you heard of anyone who plugged an external speaker plug into the remote jack instead of the external speaker jack and now the tune button will no longer tune the external tuner on the IC-7100 ?

I would like to know your opinion on those inexpensive Chinese radios in terms of ease of service, ease of getting replacement parts, [clarity of instructions etc...

I find it quite amazing that i can understand him better when setting the playback speed to 2x ;)

how much did that new board cost ?

Excellent video as always Peter. I always learn something from listening to your methodical approach to troubleshooting and this video is no different. Great job. Out of curiosity, what was the cost of that replacement board?? That radio retails for nearly $1000 here in the US. 73 de N0BPS

Hi Peter, what kind of equipment and or trick are you using when removing components like the surface mounted dc-dc chip. Do you use a hot air soldering iron? , maybe you could make a video about this, when working in a close enviroment to ather components like the caps and coils around the chip. As always very good video, thank you for making them.

Another great repair video Peter. If you don't mind me asking a dumb question is 24 volts a standard voltage where you are? In the US about the only place you see higher voltages is the military and aviation. Just wondering how the owner accidentally hooked up to 24 volts. Mike

Hi my real time clock battery backup on my IC7100 is not holding much charge anymore as it dies after a few days switched off. I was trying to see how easy it would be to swop and wanted to know is it soldered into place? I think it's near to the SD card slot. any chance you could have a quick look on the broken pcb and let me know. Thanks!

thanks for reply but what is WEB 73????? pls tell me the link

Excelente trabalho, parabéns!

Hi Peter, as always great video, even if have not been able to fix it by changing some little components (it's the 1st video of this kind isn't it?) But if it is toasted too much, even the "wizard" has no chance ;) 73's

What was the cost of a new board? Always discuss the costs of parts (when they are expensive) so we can learn economics of your decision to get the board rather than continuing diagnosis. What if there were further problems (on other boards)? What would you do then?

I own a Icom 7300 and it was *UNHOOKED from the power supply* . I was going to move the radio to another location and when I picked it up, the power supply leads touched together and I heard a loud snap! It was like there was stored voltage in the radio. When I went to hook it back up again, it wouldn't turn on. I checked the circuit fuse on the board and it was O.K. and the other fuses are all good. What do you think it could be? It still draws a little power when connected, though. Probably the power amp section drawing the power.

Danke für ein wieder mal tolles Video. Gruß aus München

Even if 24V ended up finally at the 7808 it wouldn't had blown it up; these typically have a voltage range up to 30 volts.

ANOTHER JOB WELL DONE. SOMETIMES YOU JUST HAVE TO BITE THE BULLET. AT LEAST THE PARTS ARE AVAILABLE.

Hi Peter, i wonder if you had found this defect quicker with the thermal Camera. Just replacing the 2nd Coil and slowly bring up the Voltage until you see the shorted part. 73 de DK3JF Jörg

Great video what did the board cost to replace ?

Are you going to post any videos of the 7300?

How did you manage to get a new board from icom?

Good decision to replace the main board.

really discouraged with icom. i literally order approx $22,000 a year in gear with the icom name on it ... i order from gigaparts which is excellent... one time i have a problem and icom will not stand behind it .. i order 2 icom 718 radios at a time, one time recently i get a case that is dented, " not the box the case" so i know it happened at icom , i do not blame it on gigaparts, there is no way it happened at gigaparts, it happened at the factory . was told i had to purchase a new case lid for $36.00 .. nice staff at icom but when it comes to customer service i am really truly disappointed. over not making it right they are willing to lose a customer that spends so much money on their product. .amazing......Attn icom. This will be posted in every area of the web i can find to copy and paste..

Hi sir, I am your avid follower, may I know how/where do you order the PCB? thanks..

Hi, is it normal to have a 30 amp in line fuse there? Thanks

What sad moments...maybe a little varistor as power supply protection, could save or reduce risk for that kind of radio. Have you used one for the 2nd new icom board !? By the way..what do you think, why icom or other usually not used a cheap overvoltage protection ?! '73 :)

A friend of mine once did the same thing... the radio made a warranty call and got a new operator...poor guy... wonder wat they did with him...

Stupid disign, In older vhf (Marine) radio,s a zener diode is placed over the suplly, behind a fuse.. Higher then the zener voltage the fuse will blow, and the zener, But the rest of the boards wil be fine (Forinstance Sailor RT 144, and the Sailor RT2048 marine radio,s have this..) Saves a lot of damage! Hopfully the processor is still fine, and dident get any overvoltage...

WERE DID YOU GET THE schematic diagram LET ME KNOW PLS

Hello Sir, My ICOM IC-706MK2 VFO encoder is faulty and the part has been discontinued..so u know which part for this replacement?

Icom should have installed a 12/24 voltage ragulator at the power input with a reverse polarity protection

Where was the Fuse ?

Had I designed that radio the 13.8 volt input would have a fuse and 14 volt zener, If you applied 14 volts or more it would blow the fuse,. the fix would be to replace the fuse or at worst the fuse and zener diode, negligent of Icom not to have simple protection like that

nice video ... 73 from PY7DJ - NETO

I was thinking it might be a good idea to add an anti-static pad to your work desk. Not only would it help with static discharge, but it would provide a slightly soft surface so as not to scratch cases when moving them and sliding them around the desk.

Peter now I relook and see radio supply has 30A fuse. Why would this be? This seems crazy? You could have 5kJ (5kw) inside the radio momentarily during fault conditions. I am curious on peak current measurement for 100W radio with maybe 25 ohm load over 10mS. Because RMS should still always be ~100W maximum which would only be near 8A. This seems could even be fire risk potentially from being such a wrong size.

I can't believe you applied power after replacing the coil chip without checking for shorts first. mistake