2011/03/09
| 1600 | Remove side coax and recheck detector directly: LED2 on DIB1 still open to chassis. |
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| Remove bottom lid and source holder. Photograph LED2 wire bonds: looks like they are intact. |
| Figure 1: Photograph of wire bonds from DIB1 on side 2. LED2 is is located above pin 9, and wire bonded to pin 10. Connection looks intact. | |
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| Larger image: 2048 × 1536 | Larger image: 2048 × 1536 |
| 1700 | Reassemble tower: attach source holder and bottom lid. |
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| Heads of two out of 6 brass screws fastening bottom lid to source holder are knackered. Use three screws instead, keeping one spare. This should be more than enough with the 6 threaded rods. | |
| Perform detector level continuity checks of LEDs with Fluke 87 DMM. It looks like this model also applies a 1 μA bias current. It is likely that Fluke has standardised this across its range. However, conductance can be measured directly. |
| Table 1: Detector level continuity checks of LED channels. | ||
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| Signal | DIB1 | DIB2 |
| LED1 Rforward | 768 kΩ | 788 kΩ |
| LED2 Rforward | open | 783 kΩ |
| LED1 Vforward | 1.060 V | 1.061 V |
| LED2 Vforward | open | 1.061 V |
| LED1 Rreverse | 0.4 nS | <0.1 nS |
| LED2 Rreverse | N/A | 0.2 nS |
| 1800 | Attach side coax to tower, and place structure in N2 purge cabinet. |
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