Table of contents
- 1. 2011 June 30
- 1.1.1.1.1. 1) Re-connect pulled RCUs:
- 1.1.1.1.2. 2) Checked RCUs
- 1.1.1.1.3. 3) Exchanged HBA Frontend Modules
2011 June 30
A. Horneffer and K.Schlich did the following:
1) Re-connect pulled RCUs:
30: -> 10638002094
31: -> 10638002062
64: -> 10638002001
65: -> 10638001026
178: -> 10638001092
179: -> 10638002005
2) Checked RCUs
The spectra from channels 30, 31, 178 and 179 look O.K.
The HBA-led of RCU 64 is always "half-lit". The in rcumode 5 and 7 the channels 64 and 65 show only the receiver noise. In rcumode 3 the two channels show mostly a normal spectrum, except that channel 64 has a higher noise-floor. Exchanging the RCU module does not change that behavior. Measuring the output voltage (the antenna power supply) gives:
| rcumode 5 | rcumode 3 | |||
|---|---|---|---|---|
| HBA | LBH | HBA | LBH | |
| RCU 64 | 2.9 V | 0.01 V | 2.9 V | 7.8 V |
| RCU 70 | 48.1 V | 0.06 V | 0.0 V | 7.8 V |
My (AH) assumption is, that there is something more serious wrong. (E.g. on the backplane.)
3) Exchanged HBA Frontend Modules
The impedance of the cable of channel 31 was 80 Ohm (a opposed to ca. 5 kOhm).
Testing at the tile showed that FE module 12 (counting starts at 1) was broken, replaced this FE module.
We also replaced FE module 12 in tile 50/51.
