QUESTIONS ABOUT THE OPERATION OF MY RAM SYSTEM

RAM-10000 Systems

Q. Why does the yellow overload light keep turning on my RAM-10000 system?

A. The overload light will be turned on when the current drawn from the high- voltage supply exceeds a preset limit. This limit is set at the factory to a value, which depends on the maximum duty cycle of the amplifier and the maximum power available. The duty cycle is determined by the burst width and the repetition rate. For low-power systems, the maximum duty cycle is 1%, and higher duty cycles will activate the overload light and shut down the high voltage power supply. For high-power systems, the maximum duty cycle is 0.3%. Current versions of the software adjust the repetition rate so that the duty cycle is always below these maximum values. If the system is set to a very low duty cycle and the overload light is still turning on, then it is possible that there is a problem on the gated amplifier module. One method to identify if the problem is in the amplifier module or in the power frame itself is to remove the high-voltage rectifier fuse, typically a Bussman GBB-8 8 ampere 250V fuse, from its holder on the rear panel of the instrument. Turn on the high-voltage switch. If the yellow overload light is on, then there is a problem in the power frame and it will have to be returned to RITEC for repair.

Q. The line fuse has blown on the RAM-10000 but I can only find the round fuse holder marked "High Voltage Rectifier Fuse"?

A. The line fuse is located inside the power entry module on the rear panel. It is hidden by a cover place that also indicates the line voltage. The fuse is typically a Bussman MDL-3 3 Ampere 250V slow-blow fuse, for systems set for use with 100VAC to120 VAC mains or a Bussman MDL-1.5 1.5 Ampere 250V slow-blow fuse for systems set for use with 220VAC to 240VAC mains. The cover place can be removed by using a small screwdriver to lever the cover out from the power entry module. The Bussman GBB-8 rectifier fuse should not be used as a replacement.

Q. I've replaced the line fuse twice but it blows whenever I turn on the unit?

A. First, please check if the high-voltage switch is in the "ON" position. It should be in the "OFF" position when the power switch is turned on. There are several possible failure mechanisms in the high-voltage section of the power supply or in the gated amplifier module, which could cause one to suspect there is a problem with the low-voltage section of the power supply. If the line fuse blows when the high-voltage switch is in the "OFF" position, there may be a short in one of the power supply transformers or on the power supply board. Please contact the factory for a return merchandise authorization (RMA) number.

Q. Why does the line fuse blows when I turn on the high-voltage switch?

A. There are four possible failures that would result in the line fuse opening. The primary cause is a transistor failure in the power supply module in the high voltage section. Another cause could be a short in the high-voltage circuitry in a clamped diplexer such as the RCDX-2. There could be a short in the cable connecting the RAM-10000 external power output to a peripheral device such as the pre-amplifier. Finally, there could have been a device failure in the gated amplifier. If there has been a device failure in the gated amplifier, typically the high-voltage, fast-blow rectifier fuse will open. Sometimes however, when the system is turned on, immediately after replacing the open rectifier fuse, the line fuse can open instead of the rectifier fuse. To identify a possible cause, please disconnect any peripheral power supply cables from the external power output connector and check if the fuse still opens when the switch is turned on. One method to identify if the problem is in the amplifier module or in the power supply is to remove the high-voltage rectifier fuse, typically a Bussman GBB-8 8 ampere fuse, from its holder on the rear panel of the instrument. Turn on the high-voltage switch. If the yellow overload light is on, then there is a problem in the power frame and it will have to be returned to RITEC for repair.