Ham Radio - Yaesu FT-991 finals replacement repair

[@cuban9splat]

When you changed to CW mode, the frequency jumped down to 3.499 which is below the 80 meter band. I think that may be why you had no output on 80 meters during the preliminary testing. My FT-950 does the same thing. It has not been opened up to transmit outside the ham bands. Great job on the repair! Thank you for sharing it with us. 73 DE K7RMJ Frank

[@loughkb]

+cuban9splat I mentioned this in the description. I tested before filming, and had bumped it when I did the second pass for the camera..

[@tonyatnb]

I saw that too.... but think he my realize it eventually,,,,I still stumble on that once in awhile. I like the band stacking storing parameters for each stacked memory

[@ericlessard6653]

Agree 3.499 does work unless mars cap was done so why show this

[@chucknelson1676]

Thank you very much for this video. Recently one of the finals in my FT-991 failed, which I noticed when I failed to get into a local UHF repeater. This video helped a lot to assure me that doing the task wasn't too difficult. Fortunately I have access at work to a good quality de-solder station with suction and getting the part out wasn't too difficult though getting sufficient (but not too much!) heat on it to pull up the transistor wings once the solder was all removed was difficult I should have initially left a little more solder on the connection to help with getting heat to the pad. I chose to replace only the failed part and so far that has worked out well. I was able to balance the bias very closely between the old and new part. You are very correct about the adjustment being very touchy. It appears consensus on the correct working value is 950mA each and I was able to easily set that. The initial room temperature value on the one working device was 1.7A so if the failed one was similar this shows why it failed. Back to full power and getting good signal and audio reports so I think the surgery was successful. Thanks again! 73 NC7R

[@loughkb]

Good to hear of your success. Glad to know my vid helped.

[@OctavMandru]

wait a minute, Yaesu has not issued a recall for these units? I was considering getting one 991A but I am glad I went the 7300 route

[@clays5802]

Very informative and interesting. Fortunately my 991 was one of the later serials. Good view of inside and finals.

[@dougsmith4338]

Well after watching several times I think I'll take a stab at this and replace my finals. I have all the tools you showed in your video. It'll cast me 300 in change just to mail the radio. I just bought a new 991A to replace the bad unit. 😊

[@dxhunter5277]

Hello Kevin thanks for your video it is very helpful. I still have a question from which series number of the FT 991 was this error corrected by Yaesu?

[@Hillbillyshakespeare]

I have one that will not power on. What do I need to look for under the cover?

[@jeromegrzelak8236]

same with my rig 70 bucks used my mic ptt to key the rig put them in i found no heatsink compound on mine did add some on the new ones now the radio works tnx for the info kg6mn

[@loughkb]

There was a very thin film of heatsink compound on the factory finals, very thin. I painted some compound on the new finals before installing so they had a very uniform coating.

[@jeromegrzelak8236]

good the compound sb put on my fets are working very well i liked your repair looking foward to your other topics jg

[@hectorpascal]

This may well be the result of Yaesu getting sub-boards made in China. The mechanical inspection there is not as good as in Japan. The transceiver is almost certainly electrically tested in Japan before final assembly, but things like no heat sink compound can easily be missed.

[@johncliff5417]

Hi Kevin, Nice repair done there. I did a similar thing upgrading the output stage of a cb power amp some time ago. Ended up having to fit a large fan to sit on and over the cooling fins to keep the heat down. All worked out great I ended up with nearly 500 watts PEP out with the modification. I should have saved it for 10 m use. Got rid of all the cb stuff when I got my ticket. 73 de G0WXU -John.

[@ngemin1822]

Hello Sir I bought Yaesu FT-911A and when i joined with battery DC directly. It power never open. Please help.

[@jeromegrzelak8236]

GOOD JOB i think now the rig will work for a long time if the swr is low great job on the bias adjust 73 kg6mn

[@scottgarvy]

My rig is putting out about 21 watts on 2 meters with two watt meters. Have any idea if this is related?

[@HighFidelityFox]

Sounds like it

[@dougsmith4338]

can you read the power output with the ALC meter selected? I thought you would need the power setting.. I seem to have the same problem now with my 991 although I have used it now for 7 years.

[@matthewstravelers]

Thank you for the video, it will be very helpful. In the tech manual, it says to disconnect the coaxial cables from J4001 (PA IN), then terminate J4001 with a 50-ohm resistor. However, they don't say what power rating the resistor should have. Did you do this step, and if so, what size resistor did you use? Since it's an input to the PA, I'm guessing it's precautionary and doesn't need much.

[@richardp5161]

Any suggestions for the best method of removing the mounds of solder on the finals without damaging the board or close by components?

[@loughkb]

I sucked most of it up with a de-soldering iron and then used solder wick for the remaining. I think I remember using the tip of a razor knife and heating the tabs while gently prying them up to get them released initially. Cleaning the pads with solder wick after.

[@MrAdy1306]

Who else was shouting "out of band" at the screen !!

[@justinhellyer8892]

Lol I. It was making me so aggravated. The TX light is blinking of course its not putting out power

[@philnyc]

9:15 You omitted The most important aspect of filming how you are desolder the transistor. You don't have to talk while doing precise work, but don't skip on filming it because that is why ppl actually watch these vdos.

[@Westy-1]

philnyc its probably because he never done the work himself and someone else done it then started filming again saying he's replaced the parts himself. I meen why couldn't he have filmed it its not like he had to hold the camera and try and solder at the same time. As u said this is why people watch these videos in the first place, me included. It's annoying and a complete waste of time.

[@stevemobile1]

excellent well presented.....thanks

[@jamesoleary8687]

I have watched the video several time's , my Bias will not adjust, what am I doing wrong?

[@Starbuckin]

Thanks a LOT for this video! It encouraged me to swap out my own finals on my FT-991 instead of sending it off and I saved a ton of money. It was easy to do and it's nice that the F.E.T.Finals are so accessible and easy to swap out. Also easy to set the bias on the new Transistors to where they should be. Thanks again, SUBBED. -73 KJ4JAE.

[@joelflam]

Kevin who ever hired you is NOT paying you enough

[@keneley8055]

love watching you at work its all very interesting you are a wealth of information

[@keithryant5779]

On my ft991a I checked my finals after finding out that I was using a bad antenna for about a week. Each side was set to 1.2 amps and seemed to be working. The only thing I found that is different is I am getting 7amps out when testing both together instead of the expected 2.4amps. Would you know why it would be reading higher, maybe an incorrect setting on the radio?

[@jeromeGrzelak]

check idel current kg6mn

[@jeffdwyer6105]

Question : The manual says to remove the exciter cable and put in a 50 ohm resistor and tune each Final Bias to 1.5A , you are tuning to .800A , which is it ?

[@loughkb]

I thought I mentioned it in the video. I read from more than one radio engineer that the default 1.5A bias is too high and the finals run hot even at idle. The consensus of the articles was that around 800ma seems best.

[@panzerdivizzion]

cool you fixed it.Any chance someone tx with wrong antenna?

[@stevenlawhon3695]

5w over? finals getting hot?

[@flatfrog69rr71]

Hi-can I ask ! did you put it on the tester and check its spectrum output before giving back to the costumer?

[@loughkb]

No. Only because it seems to be such a common and well known problem that it was a direct fix.

[@puretoronto]

Yaesu should be repairing all units with this issue at no cost.

[@Hax0rZ1]

This is not just a problem with the old model. I have a less then a year old ft-991a at Yaesu right now for a “pa” finals being replace and rebalanced. Smoked up my whole ham shack with electrical smoke. It’s a factory defect that they are definitely not dealing with and forcing consumers to send in their equipment to fix on warranty or not warranty for some people.

[@NealBailey]

I just found out my like new 991A has a bad final too. going to be sending it off to get repaired. I'm not so sure that Yaesu fixed the issue completely with the newer models.

[@clivewi9103]

tab with the cut oou is the drain, the tab opersit is the gate.

[@jeromegrzelak8236]

Anyone knows what yeasue charges for this kg6mn

[@raykiii]

Kevin, did you use a vacuum pump on all that solder or did you use wick or was there another option that was more scalpel accurate?

[@loughkb]

I have one of those radio shack desoldering irons with the squeeze bulb on it. It took awhile!

[@WaterWhiteTuber]

sold-a-pults work pretty good. you can get knock offs cheap enough. I usually throw them away after the tip cracks or melts (even though you can buy new tips). Tips are available in nylon or ceramic.

[@gertkok2113]

Hi Kevin, I have a Yeasu FT1802E/M My transmit filters are kaput on it and I am battling to find the part number. Could you perhapse see if you can point me in the right direction. Thank you so much and keep up the awesome videos - Gert de ZS2GHK 73

[@joelflam]

So knowing this why didn't Yaseu cover the costs?

[@loughkb]

From what I've read, they did, during the warranty period. I didn't run across any 'official' yaesu announcement about it, but lots of forum and blog posts about it from techs.

[@pudiful]

Good video and good multimeter. I had one of those.

[@joedebaer2265]

I had the same issue on my FT991. Find out that one of the final stage have a short circuit between Gate and source (like yours). How many power out you get on 80m with 12,5 V after repair? btw Thank for the detailed video of the repair :)

[@loughkb]

Thanks for watching. It gave a full 100W on all bands with the new finals and proper biasing.

[@rafaelpaulino462]

How can i contac you,im in Tampa

[@loughkb]

My email is good on my QRZ page.

[@oxfd611]

How much are those parts?

[@loughkb]

About $33 each

[@johnhiggins4698]

Hi Kevin, Any experience with Yaesu FT-7100 Dual Band Mobile? Mine worked fine for years then suddenly began to distort VHF audio on transmit. Hmmmnnn....seen this before?

[@loughkb]

+John Higgins no, sorry. Have you tried a different mic?

[@johnhiggins4698]

Kevin Loughin Yep! Got abt 13 good years on it...not ready to consign her to "parts". Might try the somewhat delicate final transistor replacement K3478...Quite a solder pond! TNX for the quick reply. 73, John/N6VTS

[@loughkb]

Get ahold of an ESR meter and check the electrolytics in the audio chain. You might have one failing.

[@johnhiggins4698]

Good Morning! I just ordered one and should be able to make those checks...thanks for the suggestion!

[@propagating-radio]

Great video! Thanks!

[@carolmartin7042]

Great repair. Thanks. Glen M

[@ne2i]

they should have used a 10 turn pot for the adjustment.... cost cutting strikes again....

[@loughkb]

Would have been easier by far.

[@yucliffecuffie2005]

My radio has a probably not working good it a ft991a

[@ericalbert6954]

Merci beaucoup l'Ami !!!

[@ericlessard6653]

Buddy unless mars cap 3.499.30is not 80 its below 80which mean the radio is set to not transmit. 73

[@loughkb]

Yeah, obviously. I was so focused on the menus at that point I didn't notice the freq.

[@jeromegrzelak8236]

Did mine works now 1.2 amp works ok kg6mn

[@terryjohnson5925]

A great way the remove the RF transistor would be to use a Chip Quik kit ,it is mainly used for SMD Removal watch the video link below! kzbin.info/www/bejne/bZzckq1qj9eXbZo

[@kendellinger7473]

Kevin, maybe you are paying more attention to making a video than watching what you were doing but in your testing phase you failed to notice that you had tried to transmit out of band and an un-modified ft991 won't do that. You may have replaced finals that were perfectly good.

[@marcinmichigan2772]

Good advertising for IC-7300's :)

[@M0WFC]

It''s about time Yaesu stopped being so tight and stingy with the amount of solder they use.

[@PachaTip]

Great VDO GOOD JOB

[@TheSlowpC]

Got to do this to my 857 here ... Lost 2m/440 power sadly :(

[@paulhealey2984]

You missed out the most important bit of the video, which was the desoldering and resoldering of components.!!

[@kg5pte]

This radio reminds me of the first-generation XBOXES with the processor ring of death. My warranty just expired on May 20th and Yesterday May 22 my HF transmit went out. This shack in a box is junk. I never buy another one or any Yaesu product ever again.

[@paulhastings3109]

That had to be adjusted carefully. So if FTDX-1200 gets crazy I know who to call Lol 73 gd dxing

[@Japik79]

I just burned my one... :(

[@jeromegrzelak8236]

Path yourself on your back kevin

[@ERICtheLATE]

3.499 mhz....no watts out....😎

[@chucknelson1676]

Thank you very much for this video. Recently one of the finals in my FT-991 failed, which I noticed when I failed to get into a local UHF repeater. This video helped a lot to assure me that doing the task wasn't too difficult. Fortunately I have access at work to a good quality de-solder station with suction and getting the part out wasn't too difficult though getting sufficient (but not too much!) heat on it to pull up the transistor wings once the solder was all removed was difficult I should have initially left a little more solder on the connection to help with getting heat to the pad. I chose to replace only the failed part and so far that has worked out well. I was able to balance the bias very closely between the old and new part. You are very correct about the adjustment being very touchy. It appears consensus on the correct working value is 950mA each and I was able to easily set that. The initial room temperature value on the one working device was 1.7A so if the failed one was similar this shows why it failed. Back to full power and getting good signal and audio reports so I think the surgery was successful. Thanks again! 73 NC7R