The low voltage for the repeater boards and the Beetle chips is supplied by two CAEN modules (left A3009, right A3009B) located in the lowest crate in the first rack in the cage. They are controlled via a SY2527 CAEN HV-controller just above. The controller should evidently be on, which can be performed by turning the key as far as possible clockwise.

To operate the SY2527 controller:

  • After a power up a login-window appears. Username/password is: admin/admin. Then, an ASCII menu appears on the screen.
  • Select main -> channels by means of the arrow-keys and hit the enter-key. This gives you access to the settings of 2x12 channels. With the Tab-key you go back and forth the top menu bar. With the space-bar you toggle between on/off. If a channel is ON, its corresponding red light should burn on the front panel.
  • While the channel is OFF you can change the nominal voltage and the maximal load current. After you turn the channel ON you can only observe the measured voltage and the load current.
  • The same screen can be obtained on a WIndows machine by choosing: Start -> All Programs -> Accessoires -> Command Prompt and giving the command: telnet caenepfl06 1527. You can as well execute this command from any telnet-capable machine. The display will be easier to operate when you make it higher than the standard 25 lines: try 40 or more.
  • Channels names can be chosen to reflect their actuall function.
  • Both modules are switched off when the front-panel interlock from the control board becomes active. When the interlock is gone you need to turn all the channel back ON.
  • LV channels are organized in groups of four, each group supplying two hybrids. The +/-6.0V is shared by both repeaters while +4.2V is separated. Thus we have six groups that can supply twelve repeater boards.

In case of an interlock:

  • All channels will normally go off
  • Make sure that the voltages and currents measured (Vmon and Imon) go down to zero. The right power supply used to show channel status "Off" but the voltage and current were still there. This behavior has been corrected by updating the firmware but you never know, thus it is good to check. In case of a doubt turns both power supply off manually with the switch in the upper left corner.
  • When the interlock signal is removed (it is latched in the temprature board) you need to clear the alarm condition by going to the main menu (Tab-key) and choosing Utility -> Clear Alarm and they confiming Yes. Use the Tab-key to go back to the channel control display.


  • Right after you turn on the SY2527 controller it receives fake characters from the keyboard. You may try to stop it by pressing any key on the keyboard. For same reason the first attempt to login may fail.
  • The power connection on the back of the lower crate labeled "Service 48V" is very fragile: it is enough to touch it and it can make the lower crate inoperable (observe the red LED's above the connector). Thus, please do not touch it but if you see there is something wrong (like the lower crate appears dead), try to gently fiddle this connector.
  • The A3009B on the right side is known to give problems: some channels may refuse to turn on for example. If that happens try to turn it off (a switch on top) and then turn it back on. You don't need to power cycle the controller (this takes much longer).
  • It was observed that the controller did not remember well all the settings: for example once the name of channel changed to standard "CHxx" and another time a voltage setting changed from 5 to 3 V. Thus, each time you (re)power the controller or a power supply do a quick check for the settings: there should be the pattern 6.0, 6.0, 4.2, 4.2 for voltages and 1.5, 1.5, 4.0, 4.0 for the current limits.
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Topic revision: r6 - 2006-11-09 - JanBuytaertSecondary
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