electrovoice_zlx_15p up in smoke

Collapse
X
Collapse
 
  • Page of 1
  • Time
  • Show
Clear All
new posts
Previous template Next
  • DukeWadd
    Member
    • Apr 2022
    • 11
    • Canada
    #1

    electrovoice_zlx_15p up in smoke

    one of electrovoice speaker stopped working the other day pulled it apart and found a whole section burnt up. replaced q1(mosfet) and a bunch of resistors around it. turned it on and it worked all voltages are there (+12 +15 -15) but then it started smoking again in a different area resistors R57 and R37. cant find anything else shorted but if i replace those burnt resistors they just get smoking hot and burn not sure why. added the schematic with whats bin done any help would be appreciated about to throw in the towel on this one
    Attached Files
    Tags: None
    • CapLeaker
      Leaking Member
      • Dec 2014
      • 7980
      • Canada
      #2
      Re: electrovoice_zlx_15p up in smoke

      Check the gate drives, maybe one is stuck on. What is VCC doing on the 3845? If the FET was totally short on all pins, it dumped full power to the gate drive.

        Comment

        • DukeWadd
          Member
          • Apr 2022
          • 11
          • Canada
          #3
          Re: electrovoice_zlx_15p up in smoke

          finally had time to look at this again
          the 3845 vcc was 8.3vdc

            Comment

            • check12
              Senior Member
              • Nov 2012
              • 103
              • UK
              #4
              Re: electrovoice_zlx_15p up in smoke

              I repaired two of these with similar problems a few months ago.

              As well as replacing all the burned resistors & Q1 I also checked all components around the TL3845 and ended up replacing:

              I2 = Gate driver IC TL3845
              R62 - R71 = 1ohm resistors (replaced with single 3W 0.1ohm)
              Q1 = Mosfet 17N80C3 replaced with Toshiba TK31E60X,S1X
              R26 = 100ohm
              C48 = 100nF
              R120 = 180ohm fusible
              C49 = 0.1uF
              R28 = 150ohm
              R100 = 100ohm
              R121 = 680ohm
              D10 = Bat54 (replaced with Bat54C)
              Q8 = 6B = BC817 (2N3904)

              One also had problems on the pre-amp board that was sorted with some new MC33178 op-amps and a new gain pot.

              Both speakers back in service again ... one last thing to watch for is I found that one of the TDA8953 woofer amp chips was not making good contact with the raised heatsink platform for it (check with a torch from several angles when bolted down) ... I sorted this by replacing the original 1mm thermal pad with a 2mm pad.

                Comment

                • DukeWadd
                  Member
                  • Apr 2022
                  • 11
                  • Canada
                  #5
                  Re: electrovoice_zlx_15p up in smoke

                  Finely got the TL3845 in mail and that fixed it, stopped R57 and R37 from burning up.

                    Comment

                    • CapLeaker
                      Leaking Member
                      • Dec 2014
                      • 7980
                      • Canada
                      #6
                      Re: electrovoice_zlx_15p up in smoke

                      Congrats! Another device saved from the bin!

                        Comment

                        Previous template Next

                        Related Topics

                        Collapse
                        • TinkerTron
                          Schematic vs. Reality: Where Are the Resistors on My Sharp Clock Radio? Model FY-70CH
                          by TinkerTron
                          Hey everyone,

                          I'm currently working on a mid-70s Sharp Electronic Digital Clock Radio, Model FY-70CH. I found the service manual online, printed it out, and have been studying it for a while. My main reasons for tackling this are: (1) I want to learn electronics and figured I'd start with something I had on hand, and (2) I want to fix its issues. Right now, the radio sounds awful, has about 5V DC at the speaker terminals, and the alarm time setting doesn't work. But I'm not asking how to fix these problems.

                          Instead, here's what's been bugging me so far:
                          The schematic...
                          3 Photos
                          03-06-2025, 02:03 PM
                        • brightest_z
                          Hot Air Blew Away Resistors Near Bios
                          by brightest_z
                          Hi All - I'm in the midst or reprogramming the bios on my gen1 Surface Laptop Studio and I accidentally blew away 2 resistors nearby the bios. I don't have another board to measure values of the missing resistors and schematics aren't available, bbut the bios is a 6x5mm Winbond WSON8, W25R256JWPQ model. The traces are conductive to Pins 3 and 7 (IO2 & IO3 respectively) so I have reason to believe they are 10k pull up resistors since IO2&3 pins are used for Quad SPI instructions.

                          Does anyone with more knowledge, and experience than I, know if this is the case?

                          ...
                          12-11-2024, 08:34 PM
                        • karatzdi
                          Denon AVR 1908, High pitch noise on Surround back Left channel after long overhaul
                          by karatzdi
                          Hello,

                          I know some might say... just buy another one. Sell it as parts..!

                          So had this AMP for quite some time. Recently I saw light smoke coming out of the AMP. Had my fire extinguisher close by. Just kidding. Turned immediately all devices off from mains.
                          Let things cool a bit, and opened up the amp device. I clearly saw on the main board which hosts the 5X amp (5.1), 3 10 ohms 1W resistors had their leads looking black, while the rest of the remaining 2 x 10 ohms were brownish as being installed from factory.

                          Spent some time downloading the Service...
                          06-11-2024, 08:38 AM
                        • jinu_j
                          LED driver circuit. Burnt Resistors
                          by jinu_j
                          Hi Folks
                          This has to do with a LED light driver rated for Output - DC36-65V 300mA. This is used to drive a 15W LED panel light.

                          Now this does not work so opened up and found 2 resistors burnt to crisp. Sensing a learning moment, i looked around the circuit to figure out that it is built around the OB2538 chip. The circuit to a large extent follows the sample application circuit mentioned in the data sheet. I have traced the actual circuit and the same is also attached for reference.

                          But i have some queries on this circuit
                          1. The resistors that burnt to crisp...
                          08-26-2020, 01:24 AM
                        • repair-it
                          Pioneer VSX-40 ,Trying to ID these resistors
                          by repair-it
                          I am trying to determine why these two resistors are the colors that they are. This is a Pioneer amp. The ones I am concerned about are the RED & GREEN colored resistors. I need to replace them and want to be sure to use the properly rated component....
                          12-16-2024, 02:08 PM
                        • Loading...
                        • No more items.
                        Working...