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Sound issue on Philips 802

Anonymous user -  
baladur13 Posted messages 47328 Registration date   Status Moderator Last intervention   -
Hello,

I am reaching out to you because I am experiencing a problem with a PHILIPS 802 turntable.

I have no sound coming from the left output. I have a potentiometer to control the left/right balance. When it's turned all the way to the left I can barely hear the sound.

I have tested the speakers; it is indeed the left output that is faulty.

I have a multimeter, I have opened the turntable, and I also have the manual with the PCB schematics https://archives.doctsf.com/documents/feuilleter_document.php?num_doc=39148&ref=11845.

My knowledge of electronics is limited but I have a soldering iron, and I am not afraid to change a component.

The big problem is where should I start? Should I look towards the PCB connected to the balance potentiometer, or would it be simpler to first trace the left audio output and test each component one by one (I have noted the left and right paths that go from the PCB to the outputs)?

Can you give me two or three tips to help me find the fault?

Thank you





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9 answers

  1.
    fmq Posted messages 4899 Registration date   Status Contributor Last intervention   721
     
    Hello

    Is the radio working well?

    ciao ciao

    Can we have a photo of the sockets?
    Thank you

    --
    It's a good day to live today!
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    1. Anonymous user
       
      Hello, yes I didn't specify.

      The radio works fine. Both speakers are connected, if I keep the knob to the left of the pan and turn the volume up to the max, I can hear a little but it's very faint on the corresponding speaker.

      If I only connect the left speaker and move the pan to the right, the volume from the speaker increases but in poor quality... I don’t understand anything anymore, it feels like the pan acts like a volume knob... When I move it to the right, the sound should diminish since only the left speaker is connected... However, if only the right speaker is connected, the pan works logically.

      I feel like this is going to be a pleasure because having no sound at all on the left would have been simpler... I don’t understand the logic here...



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    2. fmq Posted messages 4899 Registration date   Status Contributor Last intervention   721
       
      we're going to take it step by step
      I wanted to know if the radio worked on both speakers
      or if the problem only appeared with a disc !!

      ciao ciao
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    3. Anonymous user
       
      Hi,

      The radio only works on the right speaker and the left one is as I've explained..

      The vinyl player hasn't emitted any sound for a few days now.. yet I haven't done anything ... I may have used it a bit longer than usual before the last restart.
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    4. baladur13 Posted messages 47328 Registration date   Status Moderator Last intervention   14 390 > Anonymous user
       
      Good evening,
      If we connect the right speaker to the left output and the left speaker to the right output, does the problem remain on the left output or does it follow the speaker?
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    5. Anonymous user
       
      Good evening,

      no, it’s not a speaker problem. I have tested it, unfortunately...
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  2. baladur13 Posted messages 47328 Registration date   Status Moderator Last intervention   14 390
     
    This is indeed the ON/OFF switch marked X on the diagram.
    Excerpt from page 6 (upper part) the switches X and XI are highlighted in yellow.
    Also see the switch marked XI named Laudspeaker (loudspeaker) which can also ground the signal.

    Note: A spray of contact cleaner on all accessible parts of the switches or push buttons won’t harm, quite the opposite.
    https://www.conrad.fr/p/nettoyant-de-contacts-kf-f2-special-contacts-1003-100-ml-065301

    A squirt in the male and female parts of the speaker jacks should not be overlooked either.
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    1. Anonymous user
       
      Hi,

      I have some contact cleaner that I'm going to use on this switch X and I'm also going to redo a ground solder point on the left output which seems weak...

      However, I don't know what switch XI looks like.

      I have a "mono" push button on the front panel, could that be it?

      Thanks a lot for your help.
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    2. baladur13 Posted messages 47328 Registration date   Status Moderator Last intervention   14 390 > Anonymous user
       
      The contact XI is actually a contact located in the headphone jack far left on the front panel.

      Also clean the speaker jacks.
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    3. Pierr10 Posted messages 13831 Registration date   Status Moderator Last intervention   5 840
       
      Hello,

      And especially a blast of contact cleaner on the L/R balance potentiometer if it's accessible. It's equipment that isn't new and there may be some oxidation.
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    4. Anonymous user
       
      Hello, I did what you told me.. unfortunately no change. The left output is still almost inaudible and distorted when I turn the volume all the way up.
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    5. baladur13 Posted messages 47328 Registration date   Status Moderator Last intervention   14 390 > Anonymous user
       
      Sorry... but right now... without special equipment to see where the signal becomes abnormal on the left track... it's hard to say more.
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  3. fmq Posted messages 4899 Registration date   Status Contributor Last intervention   721
     
    Hi

    Thanks to Baladur for taking over
    I’m not at my best

    Well, apparently the issue comes from the amplifier
    or the preamp

    You need to connect a low-end pair of powered speakers
    to the headphone output of the preamp.. apparently

    to find out where the problem lies

    a sort of signal tracer

    See you later

    --
    It's a good day to live today!
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  4. Anonymous user
     
    Well, too bad, my last message doesn't seem to want to be published by the moderators, maybe it has too many internet links in it...

    To get back to the point, I was saying I'm a bit lost with the pins B, C, and E of the transistors and how they can be tested with a multimeter... I realize, on the one hand, that there are quite a few, but they are also different in terms of pin order...

    I was mentioning that buying an oscilloscope is possible through a well-known online store for 20 euros, it's a Tech DS0150... I don't know if that could do the trick and help me in my quest for a malfunction.

    I took a few photos; the first one concerns the PCB connected to the pan, I was able to locate the left and right tracks, but 2 of the capacitors on each of the tracks seem a bit blackened in the same way on the top... so it probably isn't that.



    On the main PCB, the resistors have their coating cracking here and there...
    There is also a component (marked C on the diagram, I believe a "trimmer" capacitor) that seems to have leaked a bit from the top...



    Finally, I looked for any "dry" soldering; tomorrow morning I will try to re-solder 2 or 3 points...
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  6. baladur13 Posted messages 47328 Registration date   Status Moderator Last intervention   14 390
     
    My last message doesn't seem to want to be published by the mods
    No, it's the automated systems of CCM that really don't like URL shorteners. (Why not just put the link directly?)
    I restored one of the two messages.

    How do you test transistors... directly without unsoldering them?
    The method given is for bare transistors
    on a circuit, you need to check that the voltage values given on the schematic are correct

    No, not all transistors have their pins arranged the same way
    Excerpt from the pdf page 4

    Checking with the oscilloscope requires knowing what you are going to see... it's more of a specialist's job in my opinion. But anyway.
    With a multimeter on AC, you can see if there is a signal or not.
    It's a comparison between what you find on the right channel versus the left when you run the radio, for example.

    Regarding the capacitors, you mainly need to look at those that are part of the audio output. These are the electrolytic ones that can cause issues... like C913 and C914 (1000µF).
    The others (low values <1µf) and especially the trimmers (they have nothing to do with the audio output).
    The left channel is in the upper part of page 6 and for a transistor in the upper part of page 5.
    -- 
     Very difficult to catch a black cat in a dark room.
                                  Especially when it's not there...
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    1. Anonymous user
       
      Hi Baladur13,

      so I desoldered the capacitors C913, C914 and C1013, C1014

      I followed the steps provided on Google to test a capacitor with a multimeter.

      When I set it to OHM, I get:

      C913: no value displayed
      C914: it starts at 30 then goes up 31,32,33...

      C1013: it starts at 70 then 71,72,73...
      C1014: it starts at 49 then 50,51,52,...

      when I switch to alternating current, I get:

      C913: no value displayed
      C914: 11.8

      C1013: 35
      C1014: 20.2

      I'm going to solder the capacitors on the right in place of those on the left, if I get the sound back on the left, it will confirm that the problem is there. Nothing simpler, right?

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    2. Anonymous user
       
      Well, it's a failure, I swapped the pairs of capacitors but the problem is still the same... Sound on the right but not on the left... I don't understand, I had the capacitor C913 that showed no value...
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    3. baladur13 Posted messages 47328 Registration date   Status Moderator Last intervention   14 390
       
      Chemical capacitors have a polarity... and one does not become a repairman as easily.
      Try to limit yourself to checking the collector voltages of the transistors as shown in the diagram on page 6.
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    4. Anonymous user
       
      By "sense," do you mean + and -? Because I paid close attention to the polarities.

      As for the transistors, I swapped the TS633a and the TS733a... and no improvement..

      Can you tell me the procedure to test the collectors of the transistors? I put black on the collector and red on the emitter?

      Thank you
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    5. baladur13 Posted messages 47328 Registration date   Status Moderator Last intervention   14 390 > Anonymous user
       
      No ...
      You put the black probe of the multimeter on the ground and the red one on the collector to be tested...
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  7. baladur13 Posted messages 47328 Registration date   Status Moderator Last intervention   14 390
     
    0 volts on the base of the TS401?
    The resistor divider R405 (1Mohm) R406 (120Kohm) should provide 1.4 volts (about 1/10 of the 14.5 volts supply)
    How much do you find on the base of its counterpart TS501?

    -- 
     It's very difficult to catch a black cat in a dark room.
                                  Especially when it isn't there...
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    1. Anonymous user
       
      on the b of TS401 I have 0.9v
      on the b of TS501 I have 0.8v
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  8. baladur13 Posted messages 47328 Registration date   Status Moderator Last intervention   14 390
     
    Have the measurements changed again???
    Now 0 on the TS401 transmitter? With 0.9 on the base it should conduct.
    When testing with the ohmmeter on the disassembled TS401 (red lead on the base, black lead on the transmitter), what do you find?
    By crossing the red lead on the transmitter and the black lead on the base, what measurement do you get in Ohms?
    Swap TS401 and TS501.
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    1. Anonymous user
       
      No, the measurements haven't changed; there may be a misunderstanding somewhere.

      The emitter of the TS401 gives me 0 while the collector gives me 13.2.
      The emitter of the TS402 gives me 13.4 while the collector gives me 0.

      On the ohmmeter, on the TS401 no value is displayed in red on base and black on emitter.
      Whereas on the TS501, I get about 15.

      I will swap them and provide the result.
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    2. Anonymous user
       
      Great! I now have sound on the left but not on the right, so we can now identify the culprit, i.e., the TS401? In that case, finding a BC149 transistor online is enough for the repair?

      The TS401 is a BC149B and the TS501 is a BC149... is there a significant difference between the two?

      Thank you very much for your help.
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    3. baladur13 Posted messages 47328 Registration date   Status Moderator Last intervention   14 390
       
      Ok... Finally, the left track is the TS401, but after the swaps...
      Yes, you just need to find a BC149B transistor or equivalent and put it in place, and it should work.

      Note: with an ohmmeter, red probe on base and black probe on emitter, an NPN transistor (arrow pointing out on the emitter) should conduct in the direction from base to emitter (it's like a diode, with the arrow indicating the conductive direction of the diode) and not when reversing the probes.
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    4. Anonymous user
       
      Alright, is there a difference between the BC149 and the BC149B?

      After reading this document http://pdf-html-new.icpdf.com/pdf_html/PdfOld_html/icpdf_datasheet_5/BC147_datasheet_5804/pg_0001.png

      there seems to be no difference.
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    5. Anonymous user
       
      After research, the TIP3055 seems to be equivalent to the BC149.
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  9. Anonymous user
     
    Hello Baladur,

    I received the BC149B transistor, I installed it and everything is fine for the radio part but there’s something incomprehensible for the vinyl part, I’m facing a similar problem.

    I have sound on the right when I turn the pan pot to the right, but when I turn it to the left, the sound is very weak and, interestingly, there’s a loud buzz in the speaker... Could it be possible that the TS401 and TS501 handle the radio part while the TS402 and TS502 take care of the vinyl part?

    Thank you.
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  10. baladur13 Posted messages 47328 Registration date   Status Moderator Last intervention   14 390
     
    For the PU (Pick Up) section, see the preamplifier side on page 6
    TS701, 702 and TS 601, 602.
    Same type of control, check the E, B, C voltages of these transistors

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