CAEN power supplies The neverending story Jennifer Pursley Johns Hopkins University Silicon Workshop II, May 10-12, 2006 University of California, Santa Barbara

J. Pursley - Silicon Workshop II2 System overview: Diagram courtesy of J. R. Mumford

J. Pursley - Silicon Workshop II3 Infrastructure: the SY527 Universal Multichannel Power Supply system CAEN mainframe, has 10 board slots NOT custom-made, also used for plug power supplies Communicates via serial connection (RS232 port or CAENET coaxial cable) Control power supplies (settings and on/off) from front panel NOT radiation hard, but located in the collision hall! These are what you hockerize (reboot the crate CPU)

J. Pursley - Silicon Workshop II4 Collision Hall Map: 16 crates Mounted on CH walls, with fib racks 4 crates in each corner, numbered clockwise (sort of…) Roughly, 2 PS crates = 1 fib Even number fib is SVX, odd is ISL/L00 Diagram courtesy of M. Stanitzki

J. Pursley - Silicon Workshop II5 Crate Naming Conventions CrateReset PanelPS Interlocks Crate 1SVX NW Top 1NW Top Top Crate 2SVX NW Top 2NW Top Bot Crate 3SVX SW Top 1SW Top Top Crate 4SVX SW Top 2SW Top Bot Crate 5SVX SW Bot 3SW Bot Top Crate 6SVX SW Bot 4SW Bot Bot Crate 7SVX NW Bot 3NW Bot Top Crate 8SVX NW Bot 4NW Bot Bot West Side

J. Pursley - Silicon Workshop II6 Crate Naming Conventions CrateReset PanelPS Interlocks Crate 9SVX NE Top 1NE Top Top Crate 10SVX NE Top 2NE Top Bot Crate 11SVX SE Top 1SE Top Top Crate 12SVX SE Top 2SE Top Bot Crate 13SVX SE Bot 3SE Bot Top Crate 14SVX SE Bot 4SE Bot Bot Crate 15SVX NE Bot 3NE Bot Top Crate 16SVX NE Bot 4NE Bot Bot East Side

J. Pursley - Silicon Workshop II7 The Workhorse: SVX Modules (A509) Occupies 1 slot in SY527 1 board powers 1 wedge  5 Bias channels  5 Low voltage (AVDD & DVDD)  2 portcard (2V & 5V DOIMs)  Total: 18 channels 73 supplies in CH (72 for SVX wedges, 1 for a L00 wedge) VMax = 250V, IMax = 5 mA Cable pinouts designed for SVX Layer01234 VMax (V)

J. Pursley - Silicon Workshop II8 Next up: ISL Modules (A510) Occupies 2 slots in SY527 1 board powers 1 wedge  10 Bias channels  5 Low voltage (AVDD & DVDD)  2 portcard (2V & 5V DOIMs)  Total: 23 channels 30 supplies in CH VMax = 250V, IMax = 5 mA Bias Adapter, double LV cables Layer00,0110,1120,2130,3140,41 VMax FWD VMax CNTL 140

J. Pursley - Silicon Workshop II9 Finally: L00 Modules (A509H) Occupies 2 slots in SY527 1 board powers 1 wedge  Bias channels  4 Low voltage (AVDD & DVDD)  2 portcard (2V & 5V DOIMs)  Total: 15 channels 11 supplies in CH VMax = 500V, IMax = 36/23 mA Sense, LV, and Bias adapers! Extra feature: crowbar on bias line Layer0123a,3b VMax (V)90 160

J. Pursley - Silicon Workshop II10 L00 Crowbars Protect Si from PS failure 2 mA fuse on each bias line Now frequently blown in beam incidents (eg kicker prefires or nasty quenches) Blown fuse = no bias on sensor Most L00 sensors draw measurable current now; check for blown crowbars by biasing L00, look for 0 current Automatic crowbar tester! No light = blown fuse

J. Pursley - Silicon Workshop II11 Junction Cards Same junction card used for SVX, ISL, and L00  Extra LV and Bias connectors to accommodate ISL Cables in CH run from PS racks down into the bore  And across the COT face… This is the closest we can get to the silicon! Diagram courtesy of J. R. Mumford

J. Pursley - Silicon Workshop II12 Common Failure Modes – SY527 Crate CPU gets in a funny state  Some symptoms: “Crate xx lost communication” (or you see anything turn blue in IMON) All supplies in one crate spontaneously turn off Garbled readback of voltage/current of a ladder (could lead to trigger inhibit)  Solution: hockerize! Fan failures: frequent in plug crates, but none of ours (yet…) 1 damaged backplane (not fun!) Remember: must turn crate off for ~10 mins before removing power supplies, or could blow a PS fuse

J. Pursley - Silicon Workshop II13 Common Failure Modes – PS Overcurrent trips  Maybe the current is going high – try raising limit, watch plots  Also a common PS failure, usually fixable at FCC Overvoltage/Undercurrent trips  Approx. the same thing – if the voltage is set above the limit, the supply clamps it down before tripping  Usually a PS failure Undervoltage trips  Supply can’t get to the set voltage  Common PS failure (esp. of ISL supplies), NOT fixable at FCC Software protection trips  Voltage/current doesn’t trip the hardware  Software limits stricter than hardware, but requires the value stay above the limit for several mins before tripping  Usually denotes a readback problem, check values in IMON

J. Pursley - Silicon Workshop II14 Less Common Failure Modes Transistor regulating the Bias voltage blows  Symptoms: ladder voltage ramps up to VMax (250V or 500V) and doesn’t trip  Can’t be turned off, have to cut power to the whole crate  This is the failure mode crowbars were introduced to prevent! Large current offsets Erratic or oscillatory voltages/currents (seen on DVDD and Bias) Crate doesn’t recognize power supply  Not fully connected to backplane, X28HC256 prom is garbled…  None of the other supplies in the crate will work if there’s one in there the crate can’t recognize! Supply won’t work in one particular slot/crate, but is fine in another Usually require expert diagnosis!

J. Pursley - Silicon Workshop II15 Summary Love ‘em or hate ‘em, CAENs are here to stay Increasing frequency of failures may be due to radiation exposure or aging  9 PS swaps in 2005; 4 in first 3 months of 2006 Do our best to:  Work w/ FCC to minimize downtime from common failure modes (eg hockerization)  Hassle CAEN to make more spare crates and PS (and to fix the broken ones faster!)  Get creative (such as, put a PS with failure on one ladder in for a wedge where that ladder is out of the HWDB for other reasons!)

Backup Slides

J. Pursley - Silicon Workshop II17 Loadbox testing Must test a new PS before hooking it up to the detector Do this by cabling it to a junction card with a loadbox attached Loadbox uses constant and variable resistances to mimic a silicon wedge