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Repair Sylvania Model 72032 LED Lite?

Discussion in 'Electronic Repair' started by KenO, Nov 2, 2012.

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  1. KenO

    KenO Guest

  2. hr(bob)

    hr(bob) Guest

    I am not familiar with that lite, but have you taken it apart to see
    what kind of batteries it uses? That is the first step.
     
  3. Franc Zabkar

    Franc Zabkar Guest

  4. whit3rd

    whit3rd Guest

    If the battery is bad, replace it. The typical
    'emergency lighting' appliance has to be tested
    from time to time, and commercial units recommend
    battery replacement every ten years, regardless of test.

    So, figure a battery has 10 year mean time between failure.
    There might be 10% of the batteries that fail in the first year,
    and another 10% that are good after fifteen years.

    Collecting anecdotes over the internet isn't going to be
    very useful in this kind of situation. Maintaining your
    emergency lighting, IS very useful. So, do it.
     
  5. KenO

    KenO Guest

    "I am not familiar with that lite, but have you taken it apart to see what kind of batteries it uses? That is the first step."

    Bob I Agree.

    Also would like to take it apart without totally destroying it.

    Do you have any suggestions, especially concerning de-bonding the plastic parts.

    There is a plastic ring around the main LEDs end and a clear plastic cover around the night lite LED end. Amazon has a good photo.
    http://www.amazon.com/Sylvania-72032-Sensor-Failure-FAILURE/dp/B000KJZNBW

    Was thinking of using a wrench to try to twist off but am afraid of shattering these parts.

    Am wondering about de-bonders?

    Ken
     
  6. hr(bob)

    hr(bob) Guest

    It's not that expensive at $14. I would take a very sharp/brand-new
    utility knife to the seams and carefully cut the unit at all the
    visible seams, like in a circle around where the clear lens fastens to
    the body, and elsewhere that you can find anything that looks like
    where two pieces of plastic were joined together. Superglue is great
    at re-attaching these separate pieces after you have fixed it.
     
  7. KenO

    KenO Guest

    Finally got the non working Sylvania Model 72032 LED Lite apart and checked the battery and fuse and they were OK but a component next to the fuse showed burn marks so am guessing this was what gave out.


    While it is sold in USA as the Sylvania Model 72032 LED Lite, it is actually manufactured by LOMAK and inside the plastic shell is marked T4-1.


    Did some searching using both Sylvania Model 72032 and LOMAK Model 72032 but to date have been unable to find either a parts list or schematic for it.

    Would be interested in any suggestions how to find either the parts list or schematic.

    Alternatively would be interested in trying to determine what the burnt component is.


    I have taken some photos and would be glad to post if there is interest.


    Thanks again for all your help.

    Ken
     
  8. Franc Zabkar

    Franc Zabkar Guest

    I'm interested.

    - Franc Zabkar
     
  9. KenO

    KenO Guest

    "I'm interested...Franc Zabkar...Please remove one 'i' from my address when replying by email."

    Franc,

    I did not see a way to post the Sylvania Model 72032 LED Lite Photos on the forum so tried sending them to you but got error message The message To: Cc: or Bcc: field contains a malformed email address.

    If there is a way to post photos on forum please tell me how.

    Thanks again for all your help!

    Ken
     
  10. Franc Zabkar

    Franc Zabkar Guest

    This is a text-only forum. You could upload your photos to a file
    sharing service.

    As for my email address, it is valid, but you need to remove one "i"
    ....

    - Franc Zabkar
     
  11. KenO

    KenO Guest

    If you are the only person interested in the photos, it would be easiest to send them to you.

    "As for my email address, it is valid, but you need to remove one "i" Franc Zabkar

    Somehow I am having problems with your email address even after removing an "i".

    Please send me a "test email" and will reply with photos.

    Thank you again for your help!

    Ken
     
  12. Franc Zabkar

    Franc Zabkar Guest

  13. Franc Zabkar

    Franc Zabkar Guest

    The component below the fuse looks like it may be a series resistor
    for the zener diode (ZD1). Together they would constitute a crude
    zener regulated DC supply.

    Measure the voltage across the zener and compare it against the
    markings on the zener's body. This should tell you if the supply is
    working correctly. I expect that there would be a filter capacitor on
    the reverse side of the PCB (could we see that as well?).

    - Franc Zabkar
     
  14. Franc Zabkar

    Franc Zabkar Guest

  15. KenO

    KenO Guest

    Franc,

    Thanks for all your help!!!

    "Measure the voltage across the zener and compare it against the markings on the zener's body. This should tell you if the supply is working correctly."

    Am a electronics beginner which is the reason I am interested in trouble shooting this LED Lite.

    How do I "Measure the voltage across the zener"?

    Ken
     
  16. Franc Zabkar

    Franc Zabkar Guest

    With respect, voltage measurement is a very basic task. If you have to
    ask this question, then you shouldn't be working on this device. There
    are lethal AC voltages inside.

    That said, here is the zener regulated supply:

    Vin o-- R --|----|---o Vout
    | |
    Z C
    | |
    0V o-------|----|---o

    Z = zener diode
    C = electrolytic capacitor on reverse side
    R = series resistor

    Measure Vin with respect to 0V, and also measure the voltage between
    Vout and 0V.

    Examine the markings on the zener.

    - Franc Zabkar
     
  17. Franc Zabkar

    Franc Zabkar Guest

    Here are you measurement locations:
    http://www.users.on.net/~fzabkar/Sylvania_LED_light/FS-2ed2863_reg.jpg

    - Franc Zabkar
     
  18. KenO

    KenO Guest

    Franc,

    "With respect, voltage measurement is a very basic task. If you have to
    ask this question, then you shouldn't be working on this device. There
    are lethal AC voltages inside."

    Agree, which is why I have not plugged in this LED Lite to AC.

    Had hoped I could do the measurements without plugging it in!

    "Examine the markings on the zener." What am I looking for? From your looking at the photos I sent what are the possible variations?

    Thanks again for your detailed explanations and help!

    Ken
     
  19. KenO

    KenO Guest

    Franc,

    "Examine the markings on the zener."

    Forgot to ask, do you recommend trying to clean the zener diode to better see any band markings?

    If yes, what do you suggest?

    Thanks

    Ken
     
  20. KenO

    KenO Guest

    Franc,

    Was going to ask you about testing the zener diode but what I found said you need an analog meter which I do not have.
    http://www.electronicrepairguide.com/testing-zener-diode.html

    I did find an article on How to Read Zener Diode Code
    http://ezinearticles.com/?How-to-Read-Zener-Diode-Code&id=40081

    Also found a basic zener diode test and wonder how accurate it is.
    http://www.learningaboutelectronics.com/Articles/How-to-test-a-zener-diode
    "If you want to check a zener diode is whether it is good or defective, there are two simple but effective quick tests that you can do.

    We will discuss both tests in this article.
    Test a Zener Diode with an Ohmmeter of a Multimeter

    A very good test you can do is to check a zener diode with your multimeter set to the ohmmeter setting.

    This is a simple test we can do to check whether it is good, open, or shorted.

    So we take the ohmmeter and place it across the leads of the diode. The orientation is very important.
    Anode-Cathode Diode Resistance Test

    We first take the ohmmeter and place the positive probe on the anode of thediode (the black part of the diode_ and the negative probe on the cathode of the diode (the black strip), as shown above. In this setup, the diode should read a moderately low resistance, maybe a few hundred thousands of ohms. For example, you may read around 450KΩ.

    Zener Diode Anode to Cathode Resistance Test
    Cathode-Anode Diode Resistance Test

    Now take the ohmmeter and switch the probes around so that the positive probe of the multimeter is now on the cathode of the diode and the negative lead on the anode. In this setup now, the diode should read a much higher resistance, well over 1MΩ. A typical reading may, for example, be 2.3MΩ. The multimeter may even indicate 'OL' for an open circuit, sincethe resistance is so high.

    Zener Diode Cathode to Anode Resistance Test

    If you read a moderately low resistance with the leads on the zener diode one way and a high resistance with the leads the other, this is a sign that the zener diode is good. A zener diode should read relatively low resistance in the forward biased direction and very high resistance in the reverse biased direction.
    Open Diode

    If a zener diode reads high resistance in both directions, this is a sign that the diode is open. A diode should not measure very high resistance in the forward biased direction. The diode should be replaced in the circuit.
    Shorted Diode

    If the zener diode reads low resistances in both directions, this is a signthat the diode is shorted. A diode should not measure low resistance in the reverse biased direction. The diode should be replaced in the circuit.
    How to Test a Zener Diode with a Voltmeter of a Multimeter

    A second test you can do to check to see whether a zener diode is defectiveor not is to measure its voltage with a voltmeter of a multimeter (or simply just a voltmeter if you have one.)

    In order for this test to work, we must feed voltage to the zener diode in reverse bias in series with a resistor. The voltage must be higher than therated zener voltage of the zener diode. In the circuit below, we feed the zener diode and a 1KΩ resistor 9 volts from a 9-volt battery. The zener diode is rated for 5.1V, well below the 9 volts, so the test will workwtih this diode. When measuring the voltage across the zener diode, it must measure a voltage near its rated zener voltage.

    Zener Diode Voltage Test

    If a zener diode reads a voltage near its rated zener voltage, VZ, then it is good.
    Open Diode

    If the diode reads a much higher voltage, of or near the voltage of the supply voltage feeding it, it is open and, thus, defective. It should be replaced.
    Shorted Diode

    If the diode is reading a much lower voltage than its rated voltage, such as near 0V, it is shorted internally and, thus, is defective and must be replaced."

    What do you think?

    Ken
     
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