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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 Ham Member QRZ Page

    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.:)
  11. ROCK

    ROCK QRZ Member

    I finally found it, you said AF-AVR duh
    the AF-AVR board connector AF1
    pin 1 reads 6.12 vdc :)
  12. ROCK

    ROCK QRZ Member

    I forgot, I can't find the 5v regulator assembly other than
    5v AVR unit (x43-1220-00) "option" in my service manual.
    Web site I look at said it was on the bottom w/4 screws
    and 3 connectors. The only thing I could find was the
    AF AVR unit,but the main schematic shows 5v AVR with a 4 pin connector
    1pin is grd 1 is 5v 1 is 14A (A ) amps? that does not make sense.
  13. ROCK

    ROCK QRZ Member

    Ok I think I'm waking up, The 5v AVR unit feeds the counter assy
    Only problem now is I can't find the dang thing.
    Counter assy is getting 0 vdc from it.
    My chart and manual says it is 5v AVR unit (43-1220-00) Option
    I take it I should have one because I have the display unit.
    happen to know where it is located? Thanks:(
  14. ROCK

    ROCK QRZ Member

    I spent so much time I lost my notes.
    15.16vdc to AF-AFR board
    5.97vdc from AF-AVR board
    15.16vdc to 5v regulator board (Finally found it) pulled connectors
    and cut some ties to trace the wire
    Now I have 4.91 vdc to the counter assembly, I think before I had 0 volts.
    Now I have 5.97vdc AF-AFR board instead of 9VDC
    5.97 @ IF board IF1 pin 5 Is there a fault with AF-AVR board? Thanks
  15. ROCK

    ROCK QRZ Member

    I finally got 9.05vdc from the AF-AVR board was reading 5.97
    My guess is the capacitors sprung back to life because at first
    I tried to discharged them after disconnecting the set and there was no spark.
    After hours messing with it like I said 9.05 vdc from the AF-AVR
    and when I shut it down and went to discharge the hi caps they cracked
    energy. Now that my rig is working again,my thought is to replace
    the Electrolytic capacitors.Are the Hi Caps for tx only? Could it have been the connectors?I spent a lot of time messing with them. BTW thank all of you for the help.:D
  16. N8YX

    N8YX Ham Member QRZ Page

    Look at the Relay board - there are two big electrolytics and the antenna changeover relay mounted to it, as well as a number of single-row male connectors. The big caps are 2200uF at 35WVDC.

    Remove board and replace both of those, then resolder the male connectors.

    Now remove the AF-AVR board and resolder all of those male connectors.

    Then get some DeOxIt (Caig Labs) and apply a bit to each of the pins in the headers on those two boards Clean off the DeOxIt with a Q-tip, then replace each board and attach each of the wiring harness plugs to its appropriate male connector. Ensure the mounting screws are snugged down evenly and securely, thus giving the boards a good ground to the chassis.

    That'll cure 99% of the low voltage power-distribution problems you're likely to find with an 820-series rig.

    If I have a rig apart for rebuild or maintenance, I replace the HV electolytics - especially if the 'original' caps are still installed in the rig. You can probably get away with not changing them for now but give some thought to doing so in the future.

    FWIW, both of my TS-820S transceivers still have their original power-supply components installed, and both have ripple-free HV. However, your mileage may vary. ;)
  17. ROCK

    ROCK QRZ Member

    Thanks for the tip.:)
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