Philips (Black Tulip) N5748 HI-FI Cassette Deck Power Outage

Discussion in 'Technical Repair' started by Michael 5of9, Dec 12, 2018.

  1. LesJones

    Well-Known Member

    Jan 8, 2017
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    It does not answer the question. If one end is - 0.8 volts with respect to ground and the other is -11 volts with respect to ground then there must be 10.2 volts BETWEEN those two points. Are you sure that you are not getting the two solenoids mixed up ? Check that you get a resistance reading of almost zero ohms between TS433 collector and one end of solenoid winding and you get almost zero resistance between the other of the solenoid winding and the emitter of TS434.

    Les.
     
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  2. Michael 5of9

    Thread Starter Member

    Dec 12, 2018
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    Resistance readings on slide solenoid RE476 winding to;
    TS433 collector, 0 no reading.
    TS434 emitter, 0 no reading.
     
  3. Michael 5of9

    Thread Starter Member

    Dec 12, 2018
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    I can confirm that these voltages are still correct.
     
  4. Michael 5of9

    Thread Starter Member

    Dec 12, 2018
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    I have taken a video of what happens when the unit is switched on, showing the voltage readings on RE476 slide solenoid winding, this is to ground.
    You can see this video on my OneDrive
     
  5. LesJones

    Well-Known Member

    Jan 8, 2017
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    Can you clarify your answer in post #82. When you say "no reading" do you mean that the display is blank ?
    With you meter set to the ohms range that you used to do the test what does the meter display if the test leads are touched together ? (This will be the resistance of the test leads which will normally be less than 1 ohm. For example my Fluke 114 displays 0.2 ohms.)
    With you meter set to the ohms range that you used to do the test what does the meter display if the test leads are are not touching anything. This display is when the resistance is greater than the meter can read. (My Fluke 114 displays OL as this meter can't read above 50 megohms.)

    Les.
     
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  6. Michael 5of9

    Thread Starter Member

    Dec 12, 2018
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    There was no resistance reading on my meter reads 0.L on either of those resistance tests.
    The two photos shows meter on ohms and in auto range, showing it in the ready mode, the next photo shows probes connected, giving a good reading of continuity.
     
    Last edited: Jan 10, 2019
  7. Michael 5of9

    Thread Starter Member

    Dec 12, 2018
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    I have removed U302 and undertook the same resistance tests; I have no continuity between pin 20 and collector on TS433, I do have 5.65 m/ohms between pin 21 and emitter on TS434, which is a breakthrough?
     
  8. Michael 5of9

    Thread Starter Member

    Dec 12, 2018
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    The board and block contacts needed cleaning.
    RE476 coil winding resistance, I now have a resistance of 33m/ohms and climbing between TS433 collector and the same between TS434 emitter to winding.
     
    Last edited: Jan 10, 2019
  9. LesJones

    Well-Known Member

    Jan 8, 2017
    1,797
    478
    O.L is NOT no resistance. It means a very high resistance greater than you meter is capable of reading. Probably greater than 20 million ohms. No resistance is zero ohms. The only thing that has no resistance is a superconductor. It is unlikely that you meter will be able to measure less than 0.1 ohms.If your test leads have a very low resistance then it would read zero when the ends were touched together.
    Try measuring the resistance of TS445 collector and TS446 emitter to the ends of the solenoid. If you get readings of less than about 2 ohms then you have been looking at the wrong solenoid.

    Les.
     
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  10. Michael 5of9

    Thread Starter Member

    Dec 12, 2018
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    I have been cleaning the 3 set's of connection blocks below and above U302.

    In post #71 working voltage across winding, when switching on the unit I can see around 50mv, it decreases sharply to 0.0mv.
    Post #61 repeated only actual voltages, they were still the same.
    Post #89 resistance values from slide solenoid RE476 motor winding; to TS445 collector, 0.4 ohms.
    To TS446 emitter, 58.5 ohms.

    I believe there is a problem with the resistance value on this TS445 collector, according to your expectation?
     
    Last edited: Jan 10, 2019
  11. LesJones

    Well-Known Member

    Jan 8, 2017
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    You have wrongly identidied the slide solenoid. The one you have been doing the tests on is the pressure roller solenoid. (RE475) From the way you said that a very high resistance reading (Greater than your meter could read.) was "no resistance" I.E zero ohms you seem to have no understanding of resistance. I will explain the readings you got in post #90 The collector of TS445 is connected to ONE side of the solenoid winding by some wire (And some connectors.) As you got a reading of 0.4 ohms this would be the resistance of the wire and connectors in series. If you look at the schematic you will see that TS445 collector is connected to terminal 22 on the solenoid. When you did the test from TS446 you must have had the probe still in terminal 22 of the solenoid. So as TS446 emitter is connected to terminal 23 on the solenoid you were measuring the resistnce of the wire between TS446 emitter and terminal 23 on the solenoid PLUS the resistance of the solenoid which you measured previously as 58 ohms. If you had moved the probe to terminal 23 the the reading to TS446 emitter would have been about 0.4 ohms and the reading to TS445 collector would have been about 58.5 ohms.
    You will have to repeat the earlier tests manualy pressing the correct solenoid and measuring the voltage across that solenoid winding.

    Les.
     
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  12. Michael 5of9

    Thread Starter Member

    Dec 12, 2018
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    I am very sorry if; I have not undertook exactly as you have requested, I think the misunderstanding started in post #71 when you asked me to “connect across RE476 and confirm that there is 10 volts across it” this I did, and the results were 0mv, there was no voltage on my meter reading, now if you had asked me to take a reading to ground that could of given a different result, if you would kindly look at post #47 after your later quote, I took reading on each of the winding to ground.

    Post #78 second paragraph you said “The results in post #75 agree with the results in the table from post #65. They do not agree with the result in post #72. Did you do anything different in post #72 to what you did in post #75 ? You will see that in post #65 and post #75 the difference in voltage between the ends of the slide solenoid was 10.2 volts yet when you measured directly between the ends of the solenoid in post #72 you got a reading of zero volts.”

    The results in the table in #65 and #75 were taken to ground; in post #72 the results were taken across the windings.

    The uploaded files shows RE476 the slide solenoid on the schematic drawing and identified in photo; this is the one you have asked me to take reading from the coil winding.

    Post #86 I now realise that I had made an error in my statement, of which I have amended, my apologies for that regarding O.L meter reading.

    Post #89 you kindly asked for readings from TS445 and TS446 which is on the other side of the schematic drawing which is associated with the pressure roller RE475, I took these reading from the winding on RE476 because you didn’t say otherwise.

    I honestly thought we were getting to the source of the problem with my last results.
     
  13. LesJones

    Well-Known Member

    Jan 8, 2017
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    I think I assumed that you had more electrical knowledge than you have, For example your statement "The results in the table in #65 and #75 were taken to ground; in post #72 the results were taken across the windings." I expected it to be obvious that the voltage across the winding should be the difference between the readings to some other common reference point. (Ground in this case.) Around post #82 I began to suspect that you might be testing the pins on the wrong solenoid. The test in post #89 was to confirm this. (Which it has done.)
    Connect your meter (Set to a DC voltage range) directly across the pins on the THE OTHER SOLENOID (Which will be RE476). Power the unit on but do not press any buttons. Note the voltage reading. Try pressing this solenoid in manually and note if it stays in.
    It is very difficult diagnosing a fault remotely on something you have never seen. Tests that take seconds when you have the unit in front of you can take days when done remotely.

    Les.
     
    Last edited: Jan 10, 2019
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  14. Michael 5of9

    Thread Starter Member

    Dec 12, 2018
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    Post #72 these readings were taken across RE476 slide solenoid, from the ends of the windings.
    RE475 pressure roller, which would be pins 22 and 23, l certainly have not been on those pins, for quite some time.

    I have just undertook these tests again RE476 slide solenoid readings, across it's winding, switch on, I brefly get 50mv, but if you blink you miss this, then the reading is a constant 0.0mv.

    If I push this slide solenoid across, it just unwinds the tape, in to the pressure roller area, causing a mess

    I took a reading from this winding to ground, to assist with this issue, it is 356mv.

    Do you think that there is some sort of safety fitted that is stopping this RE476 from working?
     
  15. LesJones

    Well-Known Member

    Jan 8, 2017
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    In post #94 when you say RE476 is it the solenoid that you were originally calling RE476 or the one you were originally calling RE475 ?
    I have traced the solenoid drive signals using drawings G & H on page 15 of the manual. This is the path the signals take through the connectors.
    Screen Shot 01-11-19 at 12.28 PM.jpg
    Can you confirm the pin numbers 20 to 23 that you were testing were the pin numbers on board U302 ? Can you do an end to end resistance test from the connections on the board G on page 15 to the driver transistor connections. (The signal paths run vertically in the above table.)

    Les.
     
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  16. Michael 5of9

    Thread Starter Member

    Dec 12, 2018
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    I think maybe you are trying to wind me up with this question? This is a photo of the printed paper that I use to keep me from going astray, with regards to which solenoid to refer to.
    Slide and Pressure solenoids.jpg
    Will the same pin be alright on each winding coil; RE475 is a little difficult to get at, but doable?
    Yes I confirm that the pin numbers 20 to 23 were the pin numbers on board U302 that I use for testing; I have preferred to use the winding coil pins on RE476 slide solenoid as an easier alternative. Your chart is understandable and correct, thank you.
     
  17. LesJones

    Well-Known Member

    Jan 8, 2017
    1,797
    478
    In post #90 you say "Post #89 resistance values from slide solenoid RE476 motor winding; to TS445 collector, 0.4 ohms." This would mean that TS445 collector was connected to the pin on the solenoid that you are calling RE476. From the schematic and the table I posted in post #95 (Column B) you can see that it is connected to RE475. This is why I am convinced that you have the two solenoids mixed up.
    With not being able to see the unit I have no idea how the wires from the solenoid get to connector 12 (Block H on page 15) It looks like they may go via block G on page 15. If you can trace the wiring on the unit between the solenoids and connector 12 it will prove if I am right or wrong about you having the solenoids mixed up.

    Les.
     
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  18. Michael 5of9

    Thread Starter Member

    Dec 12, 2018
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    First of all; please accept my apologies; I am very sorry for my assumptions regarding the identification of RE475 and RE476 solenoids, you were correct all along.

    Whilst undertaking these resistance tests I couldn’t get any readings what so ever, the brake through came when I got a reading on the plug that houses the wires from the coils, when I realised, I was getting a reading on different pin numbers.

    I opened the cassette door and manually operated the solenoids and this was an eye opener; the pressure roller solenoid not only does as it suggests, it also moves/slides the cam that brings the gears into play mode, I am sure of the latter.

    The slide solenoid; in my opinion, does not do as it suggests, it lifts the play and recording heads into position only and vertically, the definition of word slide, to move or cause to move smoothly along a surface, I take this to be horizontally not vertically, this has been misleading to me, causing much wasted time and effort, again I am truly very sorry.

    Resistance tests

    RE476 slide coil pin to;
    TS433 collector 0.8Ω
    TS434 emitter 0.5Ω

    RE475 pressure coil pin to;
    TS445 collector 0.4Ω
    TS446 emitter 59.5Ω

    Is there anything I need to retest or amend to keep the records straight? Thank you.
     
    Last edited: Jan 12, 2019
  19. LesJones

    Well-Known Member

    Jan 8, 2017
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    The resistance tests in post #98 do not tie up with the schematic or the table I posted in post #95. If you swapped over the naming of the solenoids "RE475 pressure coil" with "RE476 slide coil" they would tie up with the schematic and the table in post #95 It would also make them tie up with their function. So "RE475 pressure coil" would put the head in contact with the tape and press the tape against the capstan.

    Les.
     
    Last edited: Jan 12, 2019
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  20. Michael 5of9

    Thread Starter Member

    Dec 12, 2018
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    My hand written notes were correct; I was just connecting to the wrong solenoid! Thank you.
    So have I got my results to the correct solenoid; to make sure I will recheck!
     
    Last edited: Jan 12, 2019
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