Testing reset IC ncp803sn293 & 2sc3052 NPN Transistor

Collapse
X
Collapse
 
  • Page of 1
  • Time
  • Show
Clear All
new posts
Previous template Next
  • Chaks
    Senior Member
    • Sep 2015
    • 115
    • India
    #1

    Testing reset IC ncp803sn293 & 2sc3052 NPN Transistor

    I am trying to trouble shoot the power-detect part of the circuit see attached images and my readings are as below. can anyone suggest me if the IC and NPN transistor is working properly. The TV resets automatically when switched on.

    Q7502 2sc3052 npn transistor has the following readings.
    Base +lead to emitter -lead = 0.6v
    Base +lead to collector -lead =0.6v
    Emitter +lead to base -lead =over limit
    Collector +lead to base -lead = over limit

    Collector +lead to emitter -lead = 0.98 volts
    Emitter +lead to collector -lead = 0.68 volts

    POWER DET circuit:

    IC 7509 ( ncp 803 sn293)

    Pin 3 vcc to ground of PCB is 3.5 volts
    Resistance between pin vcc and reset pin 2 is 100k ohms
    The TV resets when pin 1 gnd or pin 2 reset is touched by multimeter leads pos or neg.

    IC 7510 (ncp 803 sn293)
    Pin vcc to ground of PCB is 0.9 volts
    Pin 3 vcc to gnd pin 1 is 1.9 volts
    Resistance between vcc and reset pin is 355k ohms
    Pin 1 gnd and pin 2 reset pin (+lead) is 3.6 volts
    Reset pin to ground of PCB is 1.2 volts

    Is there anything faulty here? Power-det circuit is on page 35 of the service manual.
    The service manual of TV is also attached.
    Attached Files

    if you find these attachements useful please consider making a small donation to the site

    Tags: None
    Previous template Next

    Related Topics

    Collapse
    • Superbee_dad
      Sharp 80” long short flash backlight error - Help
      by Superbee_dad
      Hello Sharp TV experts
      Our Sharp LC-80LE642U displays one short one long flash error code which is a backlight error. I went into service mode and there were 8 lamp error counts recorded. I reset the count to 0 and did a reset. The last monitor error cause was 16 B00014639:12. 16 is the code for backlight error. I tried to power the tv up but went back into error mode.

      > I checked voltages on the power supply board and they all check out .. including 3.28 volts at the error pin.
      > There is power to the cpu and T-CONN and no faults found there. The cpu has a flashing...
      01-24-2025, 11:51 PM
    • u666sa
      HP Envy x360 13-bf0013dx (i7, 8gb) ipa32 la-m024p rev 1b short near PJ1802, type-c not switching to 19 volts
      by u666sa
      Laptop is HP Envy x360 13-bf0013dx, hp website link, it's an i7-1250U with 8 gig onboard ram.
      Platform: ipa32 la-m024p rev 1b



      Originally you'd plug power supply into it and it would take up to 1.2 amps and then drop to 200 milliamps and then go back up again to 1.2, staying all the while at 5 volts. Pressing power button would results in power LED blinking amber 3 times. 3.3 volt rail, 5.1 volt rail present, main power rail 8.8 volts. Power button test pads near EC chip 2.7 volts.

      I found a short on the other side:



      ...
      10-04-2025, 05:03 PM
    • Mcfeetroy
      Fishing bite alarm drains battery
      by Mcfeetroy
      Good day to all. The bite alarm drains 9-volt Krona batteries. Current consumption when switched on is about 50 mA. I wiped the board from oxides, I will attach a photo (on the board there is a j3y transistor and a 7533 stabilizer, the microcircuit is erased = (the 3.3-volt stabilizer heats up weakly. I replaced it, nothing changed. I unsoldered the microcircuit, the consumption disappeared. The resistance on the pins of the unsoldered microcircuit from the point clockwise is more than 2 megaohms, the 11th leg is presumably ground. I warmed up the microcircuit, the consumption does not change....
      08-01-2025, 03:52 AM
    • sheffieldyorky
      ZAB/ZAB A,B/ZYJA BLOCK DIAGRAM Acer Aspire
      by sheffieldyorky
      Hey there people
      While working on my Acer Aspire with the OS failing to load, I encountered a motherboard number of DA0ZHQMB6E 0 REV: E. I was getting nowhere fast or slow, for that matter.
      This is what I tried, but not in any order.
      Google
      YouTube
      BIOS
      Command Prompt (administrator privileges)
      >
      On Google AND YouTube, I was getting mixed messages, try this and try that, but when you cross reference the advice it is either the wrong model (even though you enter the correct search term) a YouTube case in point, with the search term "how to...
      10-25-2025, 02:22 AM
    • supermattch
      HP 15dy-2021nr wont power on mystery volts
      by supermattch
      Hi everyone.

      I am diagnosing my personal laptop, because it wont power on and no leds light up.

      At the dc-in there are 8 pins, 1 and 2 shows healthy 19.66 volts. The next three are ground, but the 6th one shows .283 volts. This is strange to me, it should be 3.3 or 5 or aome volts not 0.283v. As I am new to this, I would like some guidance. Please someone advise me on what to check next.

      Oh the boardview and schematics I am using is for a similar model as I cannot find the proper one anywhere. Quanta DA0P5HMB8F1 rev F. Nowhere on the internet.
      09-23-2025, 12:13 PM
    • Loading...
    • No more items.
    Working...