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Yaesu FT101EX... where should I start looking for these 2 problems?

Discussion in '"Boat Anchor" & Classic Equipment' started by KD0YSX, Sep 17, 2021.

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  1. KD0YSX

    KD0YSX Ham Member QRZ Page


    I have an old Yaesu FT101EX boat anchor that I have methodically been replacing the electolytic capacitors on. It was DOA when I got it, but now has a very quiet recieve on 20 meters - so, I have made some progress. It is quiet on all bands and LSB/USB but if I switch it to AM the blast of static would wake a dead Bison. So the audio amp works for AM but for everything else, it's barely audible. I can hear people's voices so it's discriminating the signals. It's just too quiet.

    Second problem: When I key to transmit, nothing happens. I mean nothing. It doesn't stop recieving. I've cleaned the relay but I'm not sure that's the issue. I've tried a couple of different Microphones, known good.

    Any suggestions as to which areas of the rig to check would be much appreciated.
  2. G3YRO

    G3YRO Ham Member QRZ Page

    Firstly - have you had this rig for a while, but the the faults suddenly occured? Or have you just acquired it, and it came with the faults you describe?

    Best to always start checking things on 80m, as everything is less critical.

    Can you hear the Crystal Calibrator on 3.7 MHz? How strong is it on the S Meter? (you obviously need to peak the Preselector control)

    When you flick the front panel switch to MOX, do the relays go over?

    (by the way, the electrolytic capacitors in these rigs very rarely need changing . . . I have worked on hundreds, and never had to replace a single electrolytic!)

    Roger G3YRO
  3. G3YRO

    G3YRO Ham Member QRZ Page

    Also . . . you've already said you have cleaned the Relay contacts . . . but have you cleaned the Mode switch? Spray a good combined Switch Cleaner/Lubricant on all the wafers and rotate it back and forth.

    In fact, clean ALL the switches and pots, if you haven't already.

    Similarly, unplug each of the boards, wipe the edge connections with a rag soaked in the same cleaner, and plug them back in.

    This is all Routine Maintenance that should be carried out every 5/6 years. And BEFORE looking for faulty components (very rare with these rigs).

    Roger G3YRO
    N4FZ likes this.
  4. KD0YSX

    KD0YSX Ham Member QRZ Page

    Thanks Roger! I bought this rig a year ago, and it was DOA (as I had been warned). Replaced some electrolyics, and got (weak) sound out of it. Put things on hold over the summer, and am now getting back to it.

    I have NO response from the relays either keying the mic or using the MOX switch. Nothing. S meter does nothing. I can't hear the calibrator.

    I've cleaned the switches but not the edge of the plug-in boards. I'll try that tomorrow. Also I will start checking voltages and current again. I trued all that up last winter but I've changed some stuff out since, and need to verify.
    N4FZ likes this.
  5. G3YRO

    G3YRO Ham Member QRZ Page

    It sounds like there is no 12V rail getting into the set . . . I presume you have the correct Power Plug in the back - it needs various pins connected together, depending on whether you are running on mains or 12V.

    Do the dial lights work?

    Does the VFO LED light up?

    Roger G3YRO
  6. KD0YSX

    KD0YSX Ham Member QRZ Page

    Yup, all lights work. Could these symptoms be caused by dead sweep tubes? I have replacements but I've been hesitatiung to put them in until I know the rig is basically sound. Is there a way to pop them in and run the rig in some mode that won't damage them for setup and test?
  7. N4FZ

    N4FZ XML Subscriber QRZ Page

    Look for broken wiring? Sounds like a contact or connection is not being made.
  8. KD0YSX

    KD0YSX Ham Member QRZ Page

    OK, I put in the rep[lacement tubes and brought them up gradually over the course of an hour with a Variac.
    2 developments: The relays now work when using the MOX switch, but not with the mic key. Also: about the third time I cycled the MOX switch, I suddenly got full audio on USB and LSB. So that one needs to be cleaned again, and cleaned better.

    Hoping I'll get relay action from the mic key once things are cleaner. We'll see.

    I have to say, the sensitivity on this rig is impressive. I can hear stuff clear as a bell when I'm scanning the 20m band, now that the amp is working.
    NG0L and N4FZ like this.
  9. W9GB

    W9GB Ham Member QRZ Page

    Dirty Switch Contacts OR Intermittents.
    Q-TIPS/Foam Sticks, CAIG LABS Cleaner, PATIENCE, and TIME

    CAIG LABS (Poway, CA)
    Product Demonstration Videos — Using CAIG products
    DeOxit D-Series
    DeOxit F-Series for Rotary Pots and Faders (safe for conductive plastic faders)
    Yaesu FT-101EX is the same as the FT-101E ,
    BUT without the RF Processor, DC power supply, some range crystals.

    Yaesu FT-101 HF Transceiver Web Page (FoxTango)

    Yaesu FT-101E HF Transceiver : Schematic Diagram Schematics.pdf

    Yaesu FT-101 SERVICE MANUAL (33 MB PDF) 101 Service.htm
    Last edited: Sep 19, 2021
    W1TRY likes this.
  10. KI4ZNV

    KI4ZNV Ham Member QRZ Page

    Agreed, the sweep tubes are a red herring and have nothing to do with the relays now working. You have contact issues. DeOxit will help.

    Don't throw out the old tubes yet.

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