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NOTE: Channels in MCM convention, 0 - 255.
This assembly went through the laser scan test on 27-Jan-00 and 15 channels
(6, 48-54, 70-76) were idenfied as dead. channel 6 is known to have broken wire
bond from Si+Kapton QA. For other dead channels, at the center of dead channels there
is a shorted channel.( Si short 51 --> dead 48-54, Si short 73 --> dead 70-76)
This is a common phenomenon for all assemblies, though some shorted channels shows
no fault.
| Assembly # | shorted ch | dead ch's around the shorted ch |
|---|---|---|
| OB-01 | 181 | 175-186 |
| OB-08 | 62(in fact, low capacitance) | 61-63 |
| OB-12 | 59 | 56-62 |
| OB-18 | 4 | 0-7 |
| IB-09 | 202 | 199-206 |
| OB-16 | 248,250?,251 | 244-251 |
| OB-23 | 51,73 | 48-54,70-76 |
| IB-03 | 140 | no problem here. |
| IB-04 | 254 | no problem here. |
| OB-19 | 87 | no problem here. |
It turned out that we can save these dead channels that is affected by a shorted channel. On 2-Feb-2000, this assembly was checked again, after preamp channel 51 and 73 disabled. We could save 12 channels by doing this.
last modified 4-Feb-2000
YoungGook Kim