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Kenwood TS-820s Troubleshoot no Rx,Tx.Digital display

Discussion in 'General Technical Questions and Answers' started by ROCK, Feb 5, 2010.

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  1. ROCK

    ROCK QRZ Member

    How do I check VFO output? What Instrument do you use?
    I have all the manuals & a 2'x3' main schematic.
    Also on troubleshooting symptom non-receiving:"Page 38" service point each transistor,must be an easier way.
    VCO: refer to PLL phase locked loop troubleshooting-- can not find it in the manual,except adjustments.
    The continuity checks are hard enough to get to.
    Checking voltage of each transistor would take awhile.
    I'm using the 9pin plug (8-9pin jumper wire)
    Bottom line I want to check out the easy & fastest ways,at least check out the right circuits first, if I hit rock bottom
    then turn it over to a pro. Probably will anyway. Thanks:)
  2. N8YX

    N8YX Ham Member QRZ Page

    First things first:

    Got 14vdc to the AF-AVR board?

    9vdc from the AF-AVR board to the balance of the radio's other circuits?

    14vdc to the 5v regulator assembly, and 5vdc from it to the counter assembly?

    You can verify these levels with a scope or a DVM.
  3. W9GB

    W9GB Ham Member QRZ Page

    What makes you think the VFO is dead?
    An RF Probe and/or frequency counter are 2 bench/test instruments you can use for your VFO testing.
    Do you even have a VOM or DVM and know how to use it?
    Have you seen some of the automobiles today, where you have to remove the engine -- to do simple repairs?? You spend at least 2 hours assembling and disassembling the engine compartment -- just to change out a bad alternator!

    Yes, troubleshooting and repairing radios can be time consuming. Even longer -- IF you don't have the basic bench equipment or know how to use it.

    Last edited: Feb 5, 2010
  4. ROCK

    ROCK QRZ Member

    I have a VTVM & DVM
    The 1957 T-Bird had a x frame and according to the manual you had to
    pull the Automatic transmission & Engine together in order to O/H
    the Trans, but if you pulled the tail housing & output shaft,then
    disconnect trans from the converter,you could drop the trans straight
    down & O/H it. Easy & fast.
  5. ROCK

    ROCK QRZ Member

    Yes I have the volt meters.
    Meant to say pull extension housing output shaft & disconnect
    trans from engine,then straight down to remove.
    Manual said engine & trans together.
    Always try the easy things first.
  6. AB8XE

    AB8XE Ham Member QRZ Page

    Start simple, check for 9 volts at your two pin jumper at the back, that sends the voltage to the VFO. If you pull the covers off, you have to beware of potentially lethal voltages. All the rest of the voltages should be printed on the transformer itself, follow those voltages across the rectifier board. Make sure your meter and cables are in good condition and rated for the appropriate voltages.
  7. ROCK

    ROCK QRZ Member

    To AF-AVR board =13.42 vdc from=6.12 vdc
    4.88vdc to counter board

    "14vdc to the 5v (regulator assembly)"
    My book:5v AVR unit (x43-1220-00) "Option"
    Main schematic shows a 4pin connector I can't find this board.
    Is it incorporated with the AF board?:)
  8. ROCK

    ROCK QRZ Member

    6.0 vdc with VTVM
    6.10 vdc with DVM Thanks:) BTW the HI-Voltage I'm very scared of,
    thanks for the reminder thou.:)
  9. AG3Y

    AG3Y Guest

    No callsign, and a low post count, so I am going to say it.

    "Rock", if you are not experienced with troubleshooting transmitters and transceivers, I highly recommend that you get someone who IS, to watch over and guide you through the process. As others have suggested, there can be very high ( deadly ! ) voltages present in the power supply area, which is what you should be checking out first. And if you are not familiar with troubleshooting techniques, you should NOT attempt to do it yourself.

    This is NOT an automobile that we are talking about here.

    Good luck! Jim
  10. ROCK

    ROCK QRZ Member

    I appreciate your advice, When I test live, I keep my distance from
    Electrolytic capacitors and power transformers,plus I look at the main circuit schematic for any hi-voltage.I have a heathkit IT-28
    and a Sprague TO-4 Capacitor analyzer which I test caps with,
    no power on of course and discharge them before-after I do any testing.
    I like the IT-28 for in-circuit test,the sprague you have to disconnect one lead. Thanks a bunch thou.:) And if it gets too scary:eek:, I'll send the Ts-820s to "O" one hand behind me and a glove on the other with a long probe on my VTVM. And no concrete floors for me,carpet is bad enough in the winter,static shocks LOL.:)
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