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Behringer PMH2000 / PMX2000 Fuse blower

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  • #1

    Behringer PMH2000 / PMX2000 Fuse blower

    Hi everyone i hope you all had a great easter!!

    I'v just got a PMX2000 thats blowing the main fuse every time its switched on, but not the two fuses on the board. If i conect a light bulb in line on the 240 power supply and disconect the gray wires from the transformer to terminals X1 & X2 the light goes out !! so im guessing that this is the problem circut. I'v not gone much further then checking the board & components for any visual signs of a fault but all seens like new, 'like new' is a term i use very strong for this mixer as i dont think its ever worked in its life"factory fault maybe", There is not a speck of dust anywhere in the unit and all conections are scratch free!!

    If you guys know anything about the circut that you maybe abel to share with me i would be very greatful.

    I'v just put a multi meter across the (A1943)output transisters T1,T2,T7,T8 and they are showing a closed curcut across all three pins on any transister, and the other four transisters T3,T4,T5,T6 are giving a reading 440mv on terminals 1 & 3!! Could that mean the first four transisters are shorting? note i'v not removed any for the test.

    Nice1 guys take care
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  • #2
    Don't they use a complimentary pair for the outputs.
    2SC5200 (NPN) & 2SA1943 (PNP).
    I would start by removing all of the output transistors & the drivers (MJE15032 & 33).
    Check each one with diode check on your meter.
    Make darn sure the ballast resistors (0.33 ohm) are not open.

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    • #3
      Hi again
      Just an update on the PMX.

      I replaced one pair of 2SC5200 (NPN) & 2SA1943 (PNP) as these were the only components i could find faulty!!.

      After building it back up, i switched her on and she sprang back into life again and all was working fine for 3 hours i fed her some Guns n roses and she loved it!. Then after testing i turned off the i pod and switched off the PMX, 'thats when it got interesting....

      There was a very low hum starting to come from the speakers '''with power off''' and then it stoped. I tried to turn it back on again but the fuse had blowen, the PMX uses a 6.25A but i was only using a 1A fuse for testing so i poped a 2A in and it works again, happy dayz, but the hum still comes when i turn the power off so i have to remove the kettle lead incase it burns something out.

      Im just wondering is this hum normal for the PMX2000??? i also have a Peavey XR684F but that has no hum at power down, it just switches off and thats that!!.

      I have no idea whats causing the hum like i said its fine untill you switch it off and you get the hum. I dont know how long it lasts for iv pulled the lead out so as not to further damage the unit every time it hapend. ( Them parts are hard to get to on this amp so i dont wish to hurt them.)

      Thanks for taking the time to respond to my thread, Take care.
      Last edited by MARSHALL BUSTER; 08-01-2011, 03:38 AM.

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      • #4
        Do you still have the light bulb limiter connected?
        Education is what you're left with after you have forgotten what you have learned.

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        • #5
          Hi Enzo good to hear from you.

          The awnser is no! iv not tried it. To be honest i'v not even thought of it so il put it to the test in the morning.
          Thanks again
          Mark

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          • #6
            OK, I was just thinking if you had left it in there while the amp tried to make output power, it would confuse the amp. if you were not using it, then obviously that can;t be the problem.
            Education is what you're left with after you have forgotten what you have learned.

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            • #7
              Right! i see what you mean now, no i have the amp all back together now.
              Il have to get my meter out and try to find out whats drawing power after the switch is turned off and why, odd thing is when i reconect the power cable its not doing it until i turn on and then off again???

              Anyhow busy day today so i had no time for bellringing!!

              Thanks for reply
              Mark

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              • #8
                here you go
                Attached Files

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                • #9
                  That schematic has been floating around for a while.
                  Problem is, the power supply is missing.

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                  • #10
                    Ah yes, that is the mixer section, the power amp is a separate drawing.

                    The power amp is the P2502, and teh power supply is on that. The supply is linear and very basic.
                    Education is what you're left with after you have forgotten what you have learned.

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                    • #11
                      PMX1000 with power supply..... hope this is of help
                      Attached Files

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                      • #12
                        Thanks mozwell. I mentioned in the other thread, the 1000 is noting like the 2000. The 1000 has an SMPS, the 2000 a linear supply.
                        Education is what you're left with after you have forgotten what you have learned.

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                        • #13
                          Behringer PMH2000 Schematic

                          How close is the PMH2000.
                          Power supply is included.
                          Attached Files

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                          • #14
                            Reload of schematic: PMH2000.zip

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