Main Identify a component Help identify component

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  • #10550
    Grazvydas
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      Hello. Can somebody help me read this parts listing?
      What is the diffrence between xistor and transistor
      As i understand i need 2A. 3W smd transistor. Please explain me more about smd parts 😀 i have problems on amplifier is getting signal from channel 1 even if it is zero load.
      Amplifier qsc plx 3602

      #10620
      abrsvcs
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        I am not sure what you need here, but for starters: xistor is just a shortened way to indicate transistor. The X is used to mean “trans”.

        The circled components in the photo are for Zener diodes and they appear to be 1V at 1%.

        If you have the schematic for this amp, post the section with these parts and that might be a little more clear. How did you determine that these are the parts that require replacement?

        Dan

        #10639
        Grazvydas
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          Okay that was helpfull. I did not know that these smd transistors can be like zener diodes.
          I bought it faulty it has burned IC IR2110
          Ive changed nearby ic controller aswell
          I saw those parts was damaged or burned so i soldered out them and tested with simple transistor tester and showed me resistance not diodes 🙂
          The thing is amplifier was not turning on. Later on i found more components faulty in the power section ive changed them after that amplifier has a life, even one of channels was working but another one did almost blown ;D but my house fuse worked and i hope so amplifier still okay. So i need to find out shat are these parts and double check everything to not get singal on that channel. I dont want to get that spark again ;D

          Here is a link to this manual. Plx 3602
          https://www.manualslib.com/manual/513770/Qsc-Plx-Series.html?page=50#manual

          In the photo you will see lots of burned components i changed them all what i found shorted or damaged. But now im stuck with these smd parts
          Thanks for help!

          #10643
          Grazvydas
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            I can show you how its looking right now and please dont blame me about my soldering skills ;D

            #10652
            knw257
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              From that manual page, and the items you circled in the first screenshot, it appears that components D78 and D79 are actually QD-000108-30 SMT Switches, not Zener Diodes. It appears the site has both the source image and the OCR output overlayed, so it’s a little confusing to read, but pulling the image directly, this seems to be the case. I found a circuit schematic that indicates the same part number in the same positions, but I’m unsure if it’s for the same device – https://audio-circuit.dk/downloads/qsc1/QSC-CX702-pwr-sch.pdf. It’s much easier to read, and let’s me see the schematic so I can identify other components and how they connect. Between reviewing the schematic and looking closely at the board traces, it looks like they put a high-voltage, low-power diode in an SOT-23 package, and just left the bottom pin (as viewed from the image you provided) hanging. I’m not seeing any traces coming off that pad, and the schematic only has two lines connecting. Perhaps that was the easiest way to ensure the polarization was correct – can’t reverse a component that’s asymmetrical. In any case, it looks like you attached those diodes correctly. Based on the schematic, it looks like the positive side is on the left, the negative on the right, with R359 connecting both of those lines, and leading into pin 7 on the IR2110. If you test and the diode is bad, it looks like the only place to get replacements is from here: https://parts.qsc.com/qd-000108-30

              #11200
              Grazvydas
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                Thank you knw257 it will help me for sure.
                But still i just want make sure how to determine smd transistor values by marks on it?
                I have book of smd sot-23 of 60 types smd transistors. May there could be replacement for D78 and D79?
                I really need to know it because its stopping me now from my knowledge going forward 🙁

                • This reply was modified 1 month, 2 weeks ago by Grazvydas.
                • This reply was modified 1 month, 2 weeks ago by Grazvydas. Reason: Added more photos
                #11623
                cmagavilano
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                  mmbd1401a es el diodo busca su hoja de datos 3 pines sot-23 pin 1 anodo pin 3 catodo pin 2 nc

                  • This reply was modified 1 month, 1 week ago by cmagavilano.
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