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help in fixing national panasonic stereo model RX - F80 - 2

Discussion in 'Troubleshooting and Repair' started by pharaon, Jan 24, 2016.

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  1. pharaon

    pharaon

    280
    3
    Oct 28, 2014
    i wish to run it at least as radio but i guess the power wire are connected to the wrong spot
    hope some one can guide me to the right place for the power wire connection spot
     

    Attached Files:

  2. 73's de Edd

    73's de Edd

    2,805
    1,176
    Aug 21, 2015
    .

    Sir pharaon . . . . . . . .

    Looking at your photos, but without further feedback from you, it looks like the long coiled up red (positive) and black (negative) wires would be your battery input to the board.
    You tell us the battery voltage now. ( *****)
    Is your thought, for the radio not working NOW is that possibly you or another person has placed one of those broken off wires back to the circuit board at a wrong place ?

    Looking at the black wire it looks like it is an original connection from the factory. looking at the red wire and its manner of connection and its brighter solder joint, looks like it ? might ? have been resoldered onto that point.
    Be it the correct place . . .or not.

    But, in looking at the circuitry in that immediate area, looks like there is a Schadow type of multi slide switch installed.
    That type of switch would be associated with a multi band ( AM-FM-Shortwave Bands) radio, and it would also incorporate the power switch for the radio.
    Other wise, if being a simpler radio you would just look down to the volume control and expect to find the power switch to be mechanically connected to and associated with it.

    (*****) So in looking at the limited available space, is that battery being the rectangular and common 9 V battery or is it consisting of a series of cells ?

    73's de Edd


    .
     
  3. HellasTechn

    HellasTechn

    1,497
    210
    Apr 14, 2013
    I doubt somenoe will be able to help just by looking at theese photos. Anyway what makes you think that the wires are misplaced ? did you accidently cut one of them ? that happens all the time in circuits like this.
     
  4. 73's de Edd

    73's de Edd

    2,805
    1,176
    Aug 21, 2015
    pharaon . . . . . . . .

    [​IMG]



    [​IMG]

    Now . . . .we see that your unit shown is being a Sony Walkman . . .wanna-be . . . as a Panasonic equivalent.

    So now the question is, if the problem is related to power ( I found to be two 1.5 V cells ) or its audio output.
    With there surely being a headphone jack as one of the three on top.

    PLUS . . . . there must be another set of pressure contacts on its back that connects R and L audio to the
    main amp unit when you place it down in its frontal cavity.

    73's de Edd
     
    Last edited by a moderator: Feb 24, 2016
  5. pharaon

    pharaon

    280
    3
    Oct 28, 2014
    73's de Edd that's the unit i have
    it's 1.5 two cells battery
    now the Walkman wont work on battery because miss attaching the power wire
    i would like to know where the right place to attach it
    the headphone jack it the one to the left
     
  6. 73's de Edd

    73's de Edd

    2,805
    1,176
    Aug 21, 2015
    .


    Sir pharaon. . . . . . . .


    The last time I encountered a like situation, was when I had a Longines radio . . .( I'm guessing a rip off of the name of the Longines watch fame).

    After many-many-many repeated battery replacements , I'm sure that 1 wire of the SEVERAL stranded wires was being flexed and breaking one at a time. Eventually, I ALSO, had a RED un-connected wire on my hands.

    The way I found the proper point of re connection was to initially know the general area and then use a very bright light and a magnifying glass to see if I could find a solder joint with some broken off strand ends embedded into it, and just barely showing, from breaking off flush.
    After it seems that I had found the correct one, I heated up the solder blob with a soldering iron, it was being readily apparent by all of the small wire shards, that I had found the old connection point.

    IF this doesn't work for you I will give you plan 2 but I need to know exactly which push button or slide switch action turns the radio and / or / cassette player on and off.

    And where it is located, on any picture already shown, as I am unable to read the all of the printed lettering on the units.

    As it is , there is the headphone jack on the very end and then two slide switches and then two microphone jacks.
    Your current RED battery connection being made is in close proximity of the slide switch, being the closest to one of the mike jacks.

    BTW what is your primary language, as I don't see a country shown on your profile.


    73's de Edd

    .
     
  7. pharaon

    pharaon

    280
    3
    Oct 28, 2014
    im Egyptian and my primary language is Arabic
    i'll provide you with all the picture you need and thanks you in advance for yu help
     
  8. pharaon

    pharaon

    280
    3
    Oct 28, 2014
    here is the pic
     

    Attached Files:

  9. 73's de Edd

    73's de Edd

    2,805
    1,176
    Aug 21, 2015
    .

    Sir pharaon . . . . . .

    By your good photo of the top of the unit , we are seeing that the the Tape /Radio switch is being our switch of interest.
    And that seems to be " in the area" which you are currently hooked up to.

    AND . . . I might now assume that after a VERY close inspection of that switch area, it revealed old no wire bits within a solder blob ?
    Next question is if the unit was playing properly up to the time when the battery wire broke off ?

    Here is a blow up of your concerned slide switch function.

    [​IMG]


    Its having four separate single pole double throw positions, I have each switch pair being color coded.

    E can swing between D or F.
    B can swing between A or C.
    2 can swing between 1or 3.
    5 can swing between 4 or 6.

    We can expect 3 switches to be doing tape -radio CIRCUIT changes and one set of contacts being for power switching.

    When we slide out switch towards the earphone jack power should be made to the radio.
    I've got this blown up so much I can't see that direction but confirm for me that direction is closing
    E-F . . .. B-C . . . .2-3 . . . . .and 5-6.
    With 5 and 6 seeming to be our suspect power switch area.AREA.
    Don't CHANGE anything yet, as I have marked up some YELLOW connections (vias) that are making interconnections from one side of the boards foil path to a foil path on the boiards other side..

    OHM out and tell us if there is a direct connection between BLUE XXX and the nearby YELLOW ? connection .
    I don't expect it.
    Also the foil path goes up and passes between all of the switch contacts and finally ends up at the other YELLOW ? and the XXXXXX area.
    I do not believe that any connections are being made over to any of those contacts . . . . .am I correct ?

    Lets locate larger electrolytic capacitors which are typically going to be connected across the + 3V supply line and a common ground
    Main interest are units A-B-C on the markup:

    [​IMG]

    With no power to the set . . . . .confirm ohmically that the - negatives of ABC electrolytic capacitors are all being connected together.
    Now, a bit more tricky, see how the resistance between the different possible readings between the + positive connections vary between ABC.

    Standing by . . . .





    73's de Edd


    [​IMG]

    .
     
  10. pharaon

    pharaon

    280
    3
    Oct 28, 2014
    no there is not


    they are connected together

    what do you mean?? the 3 capacitors have the same values 470 uf / 6.3 v
     

    Attached Files:

  11. 73's de Edd

    73's de Edd

    2,805
    1,176
    Aug 21, 2015
    MINOR CORRECTIONS . . .

    When you're ripping along at 100 wpm . . .mistakes occur, and you usually miss them on the first proof and
    sometimes even on the second . . . .with your old mind easily accepting :

    Aoccdrnig to a rscheearch at Cmabrigde Uinervtisy, it deosn't mttaer in waht oredr the ltteers in a wrod are, the olny iprmoetnt tihng is taht
    the frist and lsat ltteer be at the rghit pclae.
    The rset can be a total mses and you can sitll raed it wouthit porbelm. Tihs is bcuseae the huamn
    mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe.
    Amzanig huh?


    When we slide out (our) switch towards the direction of the earphone jack (+3VDC )power will be made (switched) to the radio.


    Main interest are units A-B-C on the markup: (add ). . .With A being of particular interest, since its sitting right in the middle of the units

    radio section.



    Now, a bit more tricky, see how the resistance between the different possible readings between the + positive connections vary

    between ABC.
    Now, in making testing a bit more tricky, check out the resistance readings between the possible interconnects between AB and C.
    E.G.
    A+ to B + and then A+ to C+
    Then test B+ to C+

    Additionally, replying to your NEW entry just above . . .of.

    What do you mean?? the 3 capacitors have the same values 470 uf / 6.3 v



    When you tested the NEGATIVE electrolytic cap leads, all were being directly interconnected to each other as was expected, but when running through a test of the caps positive leads :
    A+ to B + and C+
    B+ to C+

    I'm expecting different values of resistance being between them by separate circuitry.





    73's de Edd
     
    Last edited: Feb 2, 2016
  12. pharaon

    pharaon

    280
    3
    Oct 28, 2014
    how can i measure it???
    my multimeter resistance scale is 200 - 2k -20k-200k-2m-20m-200m
    but when i put the multimeter connectors on the A+ or B+ or C+ numbers keep changes till it become 0

    is there away to measure it?
     
  13. 73's de Edd

    73's de Edd

    2,805
    1,176
    Aug 21, 2015
    .

    Sir pharaon . . . . . .


    Great feedback, you are fine on that measurement, with what you have already done, the type of response that you are getting, is telling us that there is no very low value of resistance being between the + terminals of the three capacitors.
    Lets bet on capacitor A being the one that will be across the RADIO power supply leg of the radio.
    Put your ohmmeter in the lowest 200 ohm scale and have one of its probes going to the + of the A capacitor, making GOOD connection and then use the other probe to see if there is being a direct connection (low ohms or short) between any of the ABCDEF or 123456 terminals of the slide switch.
    If none is found, then move the first probe to the place where the RED battery connector wire is currently soldered onto the PCB, and use the other probe to test for a connection between it and the slide switch ABCDEF or 123456 terminals, to see if there is being a direct connection (low ohms or short) .

    Awaiting to see what is found.


    73's de Edd

    .
     
    Last edited: Feb 3, 2016
  14. pharaon

    pharaon

    280
    3
    Oct 28, 2014
    when i put multimeter to 200m C+ - B+ = 00.9 //// C+ - A+ = 00.9 //// B+ - A+ = 00.9

    Direct coonection between A+ and D

    i tried it any way there's short between where the RED battery connector wire is currently soldered onto the PCB and E - F - 2 - 3
     
  15. 73's de Edd

    73's de Edd

    2,805
    1,176
    Aug 21, 2015
    .




    Sir pharaon . . . . . .

    On the last statement . . . . I am reading . . . .

    73's de Edd said: ↑
    If none is found, then move the first probe to the place where the RED battery connector wire is currently soldered onto the PCB, and use the other probe to test for a connection between it and the slide switch ABCDEF or 123456 terminals, to see if there is being a direct connection (low ohms or short) .



    i tried it any way there's short between where the RED battery connector wire is currently soldered onto the PCB and E - F - 2 - 3


    Now with that reading you found, it looks like you must have the Tape-Radio slide switch in the tape position.

    If that is true, go ahead and leave it that way and insert a known good cassette tape and plug in some headphones and see if the unit will then play for you.

    73's de Edd


    .
     
  16. pharaon

    pharaon

    280
    3
    Oct 28, 2014
    its true but tape unit dos not work i guess some thing wrong with it's motor

    i redone the test again with switch switched to radio

    there's a short Between + of the A capacitor And D ,E, 2

    there's a short between where the RED battery connector wire is currently soldered onto the PCB and D,E,1,2
     
  17. pharaon

    pharaon

    280
    3
    Oct 28, 2014
    73's de Edd will you help me to make it run as Radio?
     
  18. 73's de Edd

    73's de Edd

    2,805
    1,176
    Aug 21, 2015
    pharaon . . . . . .

    Its certainly looking like that when when the Tape - Radio slide switrch is moved in the direction of the earphone jack, that 3 VDC being switched to connector 2 from 1 is what makes the radio play.

    Unfortunately, as you have found, the tape player didn't work, to confirm tape operation in the Tape position.

    Without any batteries in the unit can you now confirm that whan you put a meter probe to switch terminal E that a shorted connection being made to terminal D and then move the switch in the direction of the two central mike jacks, that the short disappears.
    Keeping the probe on E and testing with the moving probe to the F terminal sjhould show the short moving to it.
    I'm expecting all of that test to pass.

    Then you now move over to slide switch terminal 2 and test to terminal 1 with the slide switch moved towards the headphone jack I am hoping to find a short between 2 and 1. Then it opens as you move the slide sw towards the mike jacks.
    Finally test between switch terminals 2 and 3 for a short when the slide switch is towards the mike jacks and an open connection when the slide switch is moved towards the headphone jack.

    If all of these tests pass then we know that that A-B-C and 1-2-3 switch actions are proper.
    Now if the 1-2 contacts short out in the Radio position, we need to inspect the copper foil path going out from 1 and see where it goes and what other connections or parts are now being connected to it .

    Next testing:
    Do you have a pair of 100 ohm resistors or a 100 and 47 as some of your parts or can be can found in old electronic equipment of yours or borrowed from a better equipped friends parts stock ?


    73's de Edd
     
    Last edited by a moderator: Feb 24, 2016
  19. pharaon

    pharaon

    280
    3
    Oct 28, 2014
    when the switch is to tape = no short between E & D
    when the switch is to radieo = Short between E & D

    when the switch is to tape = no short between 1 & 2
    when the switch is to radieo = Short between 1 & 2

    when the switch is to tape = short between 2 & 3
    when the switch is to radieo = no Short between 1 & 2

    consider it done
     
  20. 73's de Edd

    73's de Edd

    2,805
    1,176
    Aug 21, 2015
    pharaon . . . . .


    I was being very careful with checking out the wiring.
    I am able to find the specs on the C1217G small flat pack I.C.s. which are associated with the tape recorders /players pre amp stages.
    However, I can not find any info on the 20 pin 102?0 ( RED wire blocks view) small flat pack I.C. which is providing all of the functions of your AM-FM radio ,built within it.
    Your tests have almost confirmed our power connection to probably be switch terminals 1 or E.
    When I look at E I see no copper foil connection, but since this is a double sided board, all of the connections and copper foil routings could be on the OTHER side of the board.
    It is being the same way with 2.
    Can you track down all foil paths connected to E or 1 and see if there any solder connection points where the red battery wire might have been soldered onto.
    them.

    Before we attempt reduced power application through the two protective resistors that I requested earlier.

    Can you go to the 20 pin radio I.C. 102?0 and have one ohmmeter connected to the A capacitors + and probe each of the I.C. pins, to see which pin(s) that capacitors + might be connected to.

    Its #1 pin is the corner one closest to the volume control and then down at pin 10, 11 is being the closest one across the board at that end of the IC
    then the count continues until 20 which is ending just across from 1..
    .
    .73's de Edd
     
    Last edited by a moderator: Feb 24, 2016
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