November 07, 2010

Fixing Yaesu FT 411E audio problem.

It has been a long time that I updated my blog. Thought of putting up some information about my latest tinkering on one of my VHF radio.

It has been quite some time that my Yaesu FT 411E had developed a weird malfunction. ever since I had bought from my friend the audio was coming on and off from the rig's speaker and upon that one of the fellow ham opened up the rig without my permission (this is one quality of VU hams that I dislike) and screwed it up. when ever I open the squelch it was automatically transmitting, Shees that was a nightmare. I search every where on the net about Yaesu FT 411E problems, but not a single piece of information about the problem which I am facing.

Today on Deepavali day 6-Nov-2010, I thought of putting one of my favorite Radio Yaesu FT411E, under the knife. I am a novice in servicing radio's and this was my first attempt to tinker with radio's.

For such kind of operation you need the right tools, Fortunately I had the tools handy. Removing all the three Knobs SQL, VOL and DIAL knobs was easy. There are 5 Star screws on the top plate and 4 on the back plate (including the one's on the steel clip. Also below near the battery pack steel plate there are 4 tiny screws which needs to be removed.

After removing all the screws a slight nudge separated the back and front end sections. Both the section's are connected by a thin strip of wire which is very new and I haven't worked with such setup before so it was bit tricky for me. On the front section you have the Speaker,Mic & and the PTT switch's, strip of wire connects both the PCB's boards together. Connected the Ni cad battery and switched the rig on, Thank god it was still alive. Connected my VOX head set to check the audio via connectors it was loud. Now got down to the delicate and risky part, separating the board from the front shell.

Using the smallest of phillips screw driver I removed 3 tiny screws and tried to lift the board but the board refused the come out of the shell.  keen inspection led me to another screw on to the left side of the board just below the strip of wire, Even then the board was not parting. I was seeing 1 inch by 2 inch copper plate which must be some kind of heat sink, I was afraid to lift it as the copper plate was soldered at two places. I just slowly lifted the copper plate and saw fifth screw hiding beneath the plate. I had to lift the copper plate fully which broke the soldering, but I had an access to the last screw which was holding the PCB to the shell.

Now I fired the rig again, It was still breathing. touching the Speaker and mic socket some times made a hiss noise from the speaker, It was a sure case of Dry solder. Took out my old faithful soldering iron and delicately soldered off the dry solder, fired the rig again Voila the squelch hissing was blasting from the rig speakers. Reassembled the rig back in the reverse order. connected my external Yagi antenna it was time for evening R3 net. VU2QNY Ismail was taking the net, Heard the net for some time while tapping and fiddling with SQL knob. Auto transmission had stopped and audio was coming from the speaker. Now connected Yeasu YH2 Headset and checked into the net, 59 was the report both ways. At-last my rig is back in action.

Note: Don't ask me to fix your rig problem,  never know I might screw it up !! :)

Handle: NEO


  1. Beautiful technical exertion!

  2. Anonymous8:29 PM

    I know it's been a while... My FT-411 had the same problem. The next time I turned it on: only red LED for 1 sec. Not coming up, like if the battery was dead. Any idea? Tnx, 73, OE3VBU Martin

    1. Hi Martin

      Thank you for visiting my blog. Sorry to hear that you FT-411 has developed a problem. I will give you few suggestion to isolate the problem ( Hope you read the NOTE at the end of the blog post :)
      1. Check if the battery pack has enough juice (power) to trigger the rig. Connect an external power source to isolate the battery issue.
      2. Open the Squelch to check if you can hear white noise, if you hear try step 3 else step 4
      3. Connect a SWR meter in between your Rig and Antenna to check if your rig is transmitting if you press PTT.
      4. Open carefully and check the ribbon tape connectors and soldering contact which connects to antenna socket.
      5. Inspect for any abnormal blown outs and dry solder.
      6. Beyond this it will difficult to troubleshoot remotely. May be you have to give it for Repair with some experts.