Cloud CA2500 Technical Bulletin - Page 12
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9.3. Replace the amplifier modules that have been removed, with new modules, following the procedure
to replace amplifier modules.
10. Where all channels on a particular PSU (or both PSUs) are in protect (all "odd" channels, all "even"
channels, or all channels) then it is necessary to narrow-down the fault to the specific modules causing the
issue, as well as ruling out an issue with the relevant PSU. This is a process of elimination, and is most
easily performed as follows:
10.1.
Follow the general PSU discharge procedure, to ensure that the amplifier power supplies are
fully discharged.
10.2.
Follow the procedure for removing an amplifier module, to disconnect all of the amplifier
modules connected to PSU1 ("odd" channels, or both channels in a CA2250) or PSU2 ("even"
channels, not present on a CA2250). Make a note of which branches of the wiring looms are
connected to which modules, so they can be reconnected later. There is no need to physically remove
the amplifier modules from the chassis, at this stage.
10.3.
Carefully re-connect the AC mains cable and power on the amplifier from the front panel.
10.4.
Apply signal to "wake" all of the channels from APD sleep.
10.5.
Observe whether the protect LEDs are still illuminated for the amplifier modules that have
been disconnected.
If they are all still illuminated, then this points to a potential issue with the PSU module – follow the
general discharge procedure a second time, and then remove and replace the PSU module at this
stage. Then continue with these steps.
If the protect LEDs for the disconnected channels, are no-longer illuminated, then one or more of the
amplifier modules have a fault and will require replacement. To determine which of the modules is at
fault:
10.5.1. Follow the general discharge procedure, to make the amplifier safe and prevent damage to the
modules
10.5.2. Reconnect a single amplifier module. At this stage, pay particular attention to any modules
which were found to have domed or bulging capacitors in the initial checks – it is reasonable to
eliminate these modules as early as possible in the testing process.
10.5.3. Carefully re-connect the AC mains cable and power-on the amplifier via the front panel.
10.5.4. Apply signal to "wake" all of the channels from APD sleep.
10.5.5. Check whether the relevant protect LED is now illuminated
If YES – this module is faulty and should be replaced. Follow the general discharge procedure, and
then disconnect, remove and replace the module.
If NO – this module is OK, and can be left in circuit. Repeat the above steps, from 10.5.1
onwards, to introduce the existing modules back into the amplifier, until all problematic modules
have been replaced and all working modules have been re-introduced.
Note: It is critically important to repeat the discharge procedure before connecting or
disconnecting any cables inside the amplifier. Irreparable damage may result if this procedure is
not correctly followed.
10.6.
Repeat the sub-steps for step 10 for the other PSU in the amplifier, if all the channels for that
PSU are showing a protect indication.