Yaesu FT-840 intermittent RX/TX repair.

[@rondellschuyler7074]

This was my first full-blown amateur rig wish I still had it it was simple but mighty

[@bblod4896]

I thought that radio model looked familiar. I learned from you and Buddy. Changed the two Chernobyl resistors and all the electrolytic capacitors on that board. Worked great. Thanks Mike. p.s. The solder on the external speaker jack was cracked.

[@TheRadioShop]

Great troubleshooting on that one Mike. Lots of bad solder connections. Man those caps were cooked until golden brown!

[@bg8fairpoint610]

Great video thank you very informative

[@dougtaylor8735]

Good info. Thanks. How do I remove the regulators from the chassis? They are stuck.

[@MM0SDK]

My first HF radio..... 1993

[@BobACNJ]

Imagine Mark Sherman of Fine Tune CB Shop even being able to understand what Mike does;-)

[@randythurman3185]

I have 575gt that in losing its receive . What would you charge to fix.it.

[@KEYSTONE223mobile]

As Always , Another great Vid.And I Thank YOU

[@baghdadiabdellatif1581]

Thank you

[@cfpau]

Great job!

[@robcole332]

Great video

[@rondellschuyler7074]

How do we contact you to have radio work done ?

[@thesavo]

Do you still take repair orders?

[@Rattletrap-xs8il]

Hey there Mike I have a question about one of these radios. I have one that I have been using for FT8 digital. Mine still has the "Chernobyl" resistor and it has almost no discoloring. It has no additional modules in it. And the caps "visually all look good". I'm sure some of them have to be iffy by now. It was working ok, but it seems every now and then I can't get full power out of it. Then today when the radio was keying up to send, the TX relay seemed delayed, the radio came up to it's lethargic 35w (even though it was set much higher) then another delayed click and the radio jumped to 122w (I had turned everything up in the software but the power stayed at 35w till that other relay threw) and the SWR and Reflected power came back down to normal levels. I noticed when the power was limping at 35w the SWR's and Reflected power were almost double when the radio was running at full power. Normally at about 60w SWR is 1.25 to 1.59 and reflected is 1.0 to 2.4 depending on the band. (I have a 10-80m End Fed Dipole EFHW-8010). Does this thing have a two stage relay or two separate relays that trigger at the same time and one is sticking? Or old caps causing this. Of course I mean based on what you know about these radios, I would never expect you could diagnose it here. I'm just wondering if it should go in for a look see. Thanks Rich ~W1SPS

[@masterpainter12]

I HAVE TWO OF THESE FT-840 RADIO. ONE NEEDS A NEW HEADER FOR THE TWO REGULATORS THAT PLUG INTO IT. CAN YOU TELL ME WHERE I CAN FIND ONE.

[@user-su5sq5ib3i]

Hi Mike, which manufacturer do you like to use for cap replacememts?

[@CarNRadio1]

where did you get that 470uF on the board? i am repairing this radio at the moment. done the chernobil section with all the caps around it.

[@mikesradiorepair]

Any electronics parts supplier on the planet. There is nothing special about it.

[@CarNRadio1]

ther eis a 330uF at audio amplifer, 47, 2 10uF and 2,2uF in that section. that is why i was wondering where did you change it on the board.

[@rondellschuyler7074]

@@mikesradiorepair how do we contact you to have radio work done. I have a uniden HR2510 that needs a tune up. new electrolytic capacitors and all of the corrosive glue removed. Thanks

[@jcradiosandiego96]

Hi Mike, where are you? I have a Yaesu ft 840 and my memory runs out.

[@q95oldies57]

Always excellent, very interesting videos, but as Brian asked below, HOW do you contact Mike if you wanted to send a piece of gear to him?? Tnx, 73, Bill KC4KMG

[@paulshepard3438]

Does anyone in these comments know how to help mike become a better engineer! He is quite the auto-motivator. I find it interesting to watch and listen to his KZbin videos. I have had a passing interest in radios. Whenever I looked inside of one, and tried to tweak things like improvement mods, I think that I have done more harm than good. A very disappointing experience and I get impatient with myself. Mike, here, really keeps going and on some of his videos he explains where things can get expensive. I am not sure, but I think that I can relate to Mike's comments because expensive could mean paying attention when things are not always simple to do... That is where it is possible where I get frustrated. I know that I may not be being clear in what I am typing here. At any rate, I have made a small donation to his channel through Patreon and KZbin to his electronics course at a risk. I may not really understand how long it really takes to become an engineer. At my age a real risk. Probably should stick with Business Administration. My understanding is that Business is easier and makes more money and engineering is harder and makes less money. Does anyone here have any ideas if a KZbin course in electronics is a substitute for school?

[@mikex691]

Why replace electr caps if not tested ? Never seen yellow caps before.

[@EngineeringVignettes]

They may be Nichicon "Gold" series caps. Those are high end though... Used in audio

[@RadioWhisperer]

You replace them without testing because when they are that cooked, even if they work today, they are not long for this world. They will be dead soon. Heat is very bad for electrolytic caps. And those are literally cooked. If a miracle happens and they test ok, why risk it. They're well under $1 each, why not replace them and be sure. Prevent a bring-back and an unhappy customer.

[@ELTROQUERO44]

hi mikes my name carlos k5otd and i have a problem with my yaesu ft 840 .and the problem is the display of my radio it blinking and stop recieve and transmit i like to send my radio to you shop but the telephone number it.s not the you shop.

[@bryanlippard6286]

Does anyone know how to get in touch with Mike? I would like for him to look at a radio I have. Thanks.

[@ShainAndrews]

For any channel that allows/want's communication. Go to the channel home page. Then select the about tab. If they want to post that info that is where you will find it.

[@francismcclaughry3794]

most of these were done three to six years ago.. I'm just wonder if you are still doing radio and gave up on these videos

[@jcradiosandiego96]

Mike hi

[@robschlotterbeck2566]

125 watts, doesn’t sound like something an amateur radio operator would ask for.

[@RadioWhisperer]

Just about every HF ham radio is a 100 watt radio. Why would a ham not want 125? Granted it's not enough extra power to get excited about, it's roughly 1.9dB, so roughly 2/3 of one S unit. Probably not going to make a huge difference in link balance, but, it's a little help when you need it. I've been a ham for more than 40 years, I would not turn my nose up at a 125w radio just because it had the extra power.