1. You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
    Dismiss Notice

Icom 756pro III got zapped

Discussion in 'Ham Equipment' started by 357, May 26, 2018.

  1. 357

    357 Walkin' the dog

    Joined:
    Sep 12, 2009
    Messages:
    882
    Likes Received:
    255
    Anyone familiar with Q25, D22, D23 on the CTRL unit?
    Mine got smoked by a close lightning strike.

    I repaired it but its only partially fixed.
    Apparently there are some shorted diodes on the RF-B unit.



    History: The radio wouldn't make power, only a 50w carrier on all modes.
    It did 100w with only 18db att. on oscillated at 0,6 and 12db, receive was 50% what it should be with 0 Att on the 24mhz up bands..

    After fixing the CTRL unit, it would only make power in 6, 12 or 18db att. oscillated 50w on 0db.
    Receive still low, nothing on the lower bands, no wwv, no broadcast stations at all, deaf.
    Digging further I found shorted diodes on the RF-B unit. Mainly D104, D851 but others are leaky too.
    (maybe just do them all?)

    Anyone dealt with this before?
    I've scoured the net I'm looking for some first hand knowledge.



    Thanks.

    IMG_3079 (2).jpg 97a9d7c00ebf0e90227937032ba5618f.jpg 2017060.jpg IMG_3h088.jpg
     
    #1 357, May 26, 2018
    Last edited: May 26, 2018

  2. Captain Kilowatt

    Captain Kilowatt Professional Amateur
    Staff Member

    Joined:
    Apr 6, 2005
    Messages:
    14,761
    Likes Received:
    6,160
    Sounds like maybe the first RF amp is gone and possibly one or more bandpass filters. Check for open inductors in the different bandpass filters and make sure they are being switched when they should be.
     
  3. 357

    357 Walkin' the dog

    Joined:
    Sep 12, 2009
    Messages:
    882
    Likes Received:
    255
    Well I'm just gonna do all the diodes on the backside and a few on the front that look suspicious.

    RF-B BACKSIDE BOTTOM.jpg RF-B BACKSIDE TOP.jpg IMG_3092.JPG IMG_3091.JPG IMG_3090.JPG RF-B FRONTSIDE TOP.jpg RF-B FRONTSIDE BOTTOM.jpg IMG_3093.JPG
     
  4. 357

    357 Walkin' the dog

    Joined:
    Sep 12, 2009
    Messages:
    882
    Likes Received:
    255
    2017088.jpg 2017089.jpg
     
  5. 357

    357 Walkin' the dog

    Joined:
    Sep 12, 2009
    Messages:
    882
    Likes Received:
    255
    please excuse my language but.....FUCKING A IT WORKS I FIXED IT HALLELUJAH!!!!!

    [​IMG]
     
    ShadeTreeMechanic likes this.
  6. 357

    357 Walkin' the dog

    Joined:
    Sep 12, 2009
    Messages:
    882
    Likes Received:
    255
    Heres the results.
    I melted a cap a bit but otherwise no problems.
    The last pictures are it transmitting with no oscillation, mission accomplished.



    IMG_3106.JPG IMG_3107.JPG IMG_3108.JPG IMG_3109.JPG IMG_3110.JPG IMG_3111.JPG IMG_3112.JPG IMG_3113.JPG IMG_3114.JPG IMG_3115.JPG
     
  7. 357

    357 Walkin' the dog

    Joined:
    Sep 12, 2009
    Messages:
    882
    Likes Received:
    255
    IMG_3116.JPG IMG_3117.JPG IMG_3118.JPG IMG_3119.JPG
     
  8. 357

    357 Walkin' the dog

    Joined:
    Sep 12, 2009
    Messages:
    882
    Likes Received:
    255


    special shout out in the video description....you know who you are.
    (nobody from here)
     
  9. Klondike Mike

    Klondike Mike Well-Known Member

    Joined:
    May 31, 2010
    Messages:
    634
    Likes Received:
    237
    Congratulations on your repair. You sure learn a lot about your radio when you go though repairs such as that.
     
    357 likes this.
  10. 357

    357 Walkin' the dog

    Joined:
    Sep 12, 2009
    Messages:
    882
    Likes Received:
    255
    thanks!
    While the pro 3 was down I've been drooling over the 7610...I was gonna sell my car and buy a POS to get one.
    Now I'm not jonesing so bad I'll wait.

    :cool:
     

Share This Page

  • About Us

    The WorldwideDX Radio Forum was originally established in 2001. We pride ourselves on welcoming Radio Hobby enthusiasts of all types, while offering unbiased, informative, and friendly discussion among the members. We are working every day to make sure our community is the best Radio Hobbyist's site.
  • Like us on Facebook

  • Premium VIP Member

    The management works very hard to make sure the community is running the best software, best designs, and all the other bells and whistles. Care to buy us a beer? We'd really appreciate it!

    Donate to us!