# Description

The interferometer consists of:

- Five antennas, each controlled by a VME microprocessor (the POINTING micro).
- One off-axis optical telescope per antenna, for pointing,
- 2 (4-6 on the long term, 2 simultaneous IF) receivers per antenna, controlled by the RECEIVER micro.
- The PHASER micro, which controls a 12-channel continuum detector, two HP-synthesizers for the LO frequencies, the phases and rates.
- The CLOCK micro, which controls the time distribution and also handles the meteo station.
- A 6-unit purpose spectral correlator. The digital part of each unit is divided in two VME crates, named the MASTER and the SATELLITE, which are linked by the “GigaLink”.
- A HP-J200 workstation named BURE1 for real-time command and acquisition,
- An HP-J200 workstation named BURE2 for data reduction, sharing NFS disks with the acquisition computer BURE1.
- A dedicated Ethernet link between BURE1, the PHASER and the correlator micros.
- A general Ethernet link between BURE1, the CLOCK, the antennas (POINTING and RECEIVER), BURE2 and all the other terminals/computers on the site.
- Many cables : low and high quality for the IF transmission, twisted pairs for specific signals, etc...

The instrument may be used in several basic modes: OPTICAL pointing, INTERFEROMETER observing, or TEST mode. In addition, within the OBS program, there is a CONFIGURE mode, which is used to specify and modify the array configuration parameters.

Any part of the instrument may fail, in any operating mode. The purpose of this guide is to pinpoint the most frequent failures, their effects and the remedies. It is assumed the reader has good knowledge of the “Users Guide”.