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
Dismiss Notice
This forum does not allow a single user to have more than one username. If anyone wants to change their username contact an admin and it will be done. Multiple accounts belonging to the same member will be deleted without warning.

Ts-940s dots or display problem

Discussion in 'General Ham Radio Discussion' started by Robalo, Jan 1, 2009.

  1. Robalo

    Robalo Well-Known Member

    Joined:
    Aug 21, 2006
    Messages:
    521
    Likes Received:
    183
    One of my locals got this radio on ebay with power supply problems and after fixing (avr) the power supply replacing Q13, Q6, D1, D2, D14, D3, and D9, the radio starts and after testing on a dummy loan the radio swings about 80 watts. but heres the trick, the radio transmits about 5-20 minutes and the frequency display goes out and all i see are dots. after a while the radio comes back sometimes/sometimes not. and then i decided to search online and i got some ideas on how to go about fixing this problem. after i started pinpointing, and testing all the connections, this is what i got. can someone help me out fixing this problem?

    i think Q31 and 32 is the problem but i cant find it in any stores, what do you think?


    kenwood ts-940s serie708xxxx
    pll 50-2020-00 board

    ic19>pin2=4.82v
    ic8>pin2=1.37v not working (1.8vworking)
    d16 ok
    d8 ok
    r75=2.34v (4.8v)
    ic9>pin2=4.76v
    ic9>pin3=1.46v
    ic17>pin7=5.10v
    ic17>pin1=2.28
    ic19>pin3=1.59
    d9=4.75v
    con 5 pin4(ul)=0 (4.8v working )
    con 2 pin5(ul)=2.49
    d16 ok 2.50v/4.84v

    Q 31 = DTC124ES NPN(NTE2357)
    IN | OUT | GROUND |
    3.90 V | 0.02 | GROUND | NOT WORKING
    0 | 4.84 V | GROUND | WORKING




    Q 32 = DTA124ES PNP(NTE3258) DIGITAL TR
    IN | OUT | VCC |
    2.49 | 4.92 | 4.9 V | NOT WORKING
    4.91 | 0 | 4.95 | WORKING
     
    #1 Robalo, Jan 1, 2009
    Last edited: Jan 2, 2009

  2. Robalo

    Robalo Well-Known Member

    Joined:
    Aug 21, 2006
    Messages:
    521
    Likes Received:
    183
    I managed to fix the radio, if you have any questions PM me.
     
  3. ve7waz

    ve7waz Member

    Joined:
    Mar 26, 2011
    Messages:
    1
    Likes Received:
    0
    Please help!

    I got a TS-940S in Serial # 603XXXX series that has the "dot" problem. When I turn it on, the freq. momentarily displays then disappears.

    When I press the bandswitch buttons, the freq. shows again even when rotating the dial. But stopping, the "dots" displayed and PLL not locking.

    Could you advise me what to do?


    Skie
     
  4. Shockwave

    Shockwave Sr. Member

    Joined:
    Sep 19, 2009
    Messages:
    3,639
    Likes Received:
    2,845
    Search the internet a little more an you will find information about an IC chip mounted in a socket that often causes this problem. The socket itself will develop poor connection to the IC pins. They recommend removing the socket and soldering the IC directly to the board. Definitely not something to do unless you are very experienced with desoldering. An alternative may be to try and reseat the IC in it's socket while using contact cleaner.

    These intermittent connections can also corrupt the information stored in the memory and may require a hard reset. Hold the A=B key on power up to clear any corrupt data. As I recall there are also two locations in this radio that require 3 volt lithium batteries. When they start going bad it can cause the display to do strange things.
     
  5. TonyV225

    TonyV225 W9WDX Amateur Radio Club Member

    Joined:
    Apr 18, 2005
    Messages:
    5,824
    Likes Received:
    305
    The TS-440S also was known for the PLL not locking after time resulting in showing dots on the display. I repaired one that I had by reseating the chip. make sure if you do this that you ground yorself so any static on your body is cleared.

    Radio Shack sells wrist straps for grounding and there inexpensive. All it takes is a simple shock or transfer of static in some of these chips and poof you have junk.
     
  6. Robalo

    Robalo Well-Known Member

    Joined:
    Aug 21, 2006
    Messages:
    521
    Likes Received:
    183
    Ve7was di you see my videos part one and part two search under ts-940s dot's repair
     

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!