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A100

My A-100 system does no longer work

Preface: The A-100 modules require only +12V and -12V, i.e. they work also without +5V, +5V is required only by a few older A-100 modules (A-113/old version, A-190-1, A-191). But some modules from other manufacturers require +5V.

If your A-100 system does no longer power up or the installed modules do not work as they should please follow these instructions:

  • Remove one of the modules at the right side of the case. Then you will see the bus board mounted at the rear panel of the case. Each bus board is equipped with three control LEDs at the right side of the board:
    • -12V (lower LED)
    • +12V (middle LED)
    • +5V (upper LED)
  • Please check these control LEDs of the bus board:Provided that the A-100 case is equipped with an A-100PSU3 power supply all three LEDs have to light up.
    Provided that the case is equipped with an older supply (A-100PSU2 or A-100NT12) only the two LEDs for +12V and -12V will light up because these power supplies had +5V not available. Only if the additional 5V Adapter (A-100AD5) has been installed on the bus board even the +5V will light up in case of these older power supplies.
  • If all control LEDs are dark after power on please continue with (1)
  • If only one control LED remains dark after power on please continue with (2)
    • (1)
      • Check if the cable used to connect the A-100 with mains is not broken (e.g. try another cable)
      • Check if the mains voltage specified for the A-100 case corresponds to the mains voltage in your country (115-240V AC for A-100PSU3, 115V or 230V AC for A-100PSU2/A-100NT12). The voltage is specified on a sticker at the rear panel of the case next to the mains inlet.
        Check if the mains fuse of the A-100 case is not blown. The fuse is located at the IEC mains inlet on the rear panel. One simply has to disconnect the mains cable and remove the fuse holder from the outside (e.g. with the aid of a small slotted screw driver). The fuse holder is a small black plastic part that is inserted into the mains inlet. This picture shows the position of the fuse holder in the IEC mains inlet.
        The fuse values are specified here. Please replace the fuse only by the correct value. Never use a fuse with a higher current ! Pay attention to use only time lag/slow blow fuses.
        Note 1: An optical inspection of the fuse is not sufficient (i.e. wire visible inside the glass tube). Even if the wire inside the glass tube seems to be OK the fuse may be defective !  
        Note 2: In case of the A-100LC3 and the A-100 DIY kit the fuse in located on the power supply board inside a small green box. This is not a mains fuse but a fuse in the secondary circuit. A-100LC3 and the A-100 DIY kit are equipped only with this fuse (i.e. no mains fuse).
      • When the fuse has been replaced by a new one with the correct value/type and the fuse blows again after power on please check if the sum of the currents of all modules installed in the case does not exceed the max. current of the power supply that is used in the case (e.g. A-100PSU3 or A-100PSU2). For details please refer to the chapter Current specifications of A-100 modules and power supplies. Some modules from other manufacturers have a high inrush current which is not specified clearly. If the system does not power up even though the calculated value of the total current if below the maximum value of the power supply this might be the reason (especially when an A-100PSU3 is installed because the supply will not turn on if the total current during power on exceeds the specified current) .
      • If the sum of the currents of all modules does not exceed the max. current of the used power supply please remove ALL modules, install a new fuse and turn the power on. Then the control LEDs should turn. If this does not happen something is wrong with the power supply or the bus board and the case has to be repaired (or at least the power supply). Please look also at the pin headers used to connect the modules to the bus board. Maybe two touching pins generate a short circuit (e.g. caused by unsuitable installation a bus connector).
      • If the control LEDs turn on without any module installed the power supply seems to be fine and the problem is caused by one of the modules. Maybe one of the modules is faulty and takes too much current which causes the fuse to blow. Even if a module is installed in the wrong way (reverse or displaced bus connector) this may happen. We recommend to re-install one module after the other to find out the culprit (i.e. turn power off, install the next module, turn power on and look at the control LEDs).
        Module re-installation in detail:
      • 1. Switch off the power
      • 2. Mount the next module and connect it to the busboard
      • 3. Switch on the power and check whether on all busboards the control LEDs are lit and if the installed module is working as it should. If one or all LEDs remain dark one has probably found the culprit. Even the fuse may have blown again and has to be replaced.
      • 4. If everything is fine leave the working module in the system and continue with the next module (back to step 1) until all required modules are installed or the culprit is found.
        It is recommended to install the modules in the most right position as the last modules. Otherwise you won't be able to see the control LEDs of the bus board.
    • (2) 
      • If only the control LED for +5V does not turn on the case is equipped with an older power supply (e.g. A-100PSU2) or the fuse for +5V is blown provided that the A-100PSU3 is installed. The +5V fuse is located on the power supply board. For details please refer to the short form manual that came with case.
      • If the control LED for +12V or -12V does not turn on please check for the voltage in question (+12V or -12V) if the sum of the currents of all modules installed in the case does not exceed the max. current of the power supply that is used in the case. For details please refer to the chapter Current specifications of A-100 modules and power supplies. Pay attention that some modules from other manufacturers may have a high inrush current which is not specified clearly.
      • If the sum of the currents of all modules does not exceed the max. current please turn off the power, remove ALL modules and turn the power on. If then the control LED in question turns on the problem is caused by one of the modules. Maybe one of the modules is faulty and takes too much current or a module is installed in the wrong way (reverse or displaced bus connector).We recommend to re-install one module after the other to find out the culprit in the same way as described above (section Module re-installation in detail).
      • If the control LED in question does not turn on without any module installed probably somemething is wrong with the power supply or a bus board and the case has to be repaired (or at least the power supply). Please look also at the pin headers used to connect the modules to the bus board. Maybe two touching pins generate a short circuit (e.g. caused by unsuitable installation a bus connector).  


Additional note for all cases equipped with A-100PSU3: If all control LEDs of the bus boards are dark the reason is almost certainly a blown fuse because each of the three voltage has it's own circuitry and it's very improbable that all three circuits are defective at the same time.