CAEN power suppliesThe neverending story

Jennifer PursleyJohns Hopkins University

Silicon Workshop II, May 10-12, 2006University of California, Santa Barbara

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System overview:

Diagram courtesyof J. R. Mumford

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Infrastructure: the SY527Universal 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)

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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/L00Diagram courtesy

of M. Stanitzki

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Crate Naming Conventions

Crate Reset Panel PS Interlocks

Crate 1 SVX NW Top 1 NW Top Top

Crate 2 SVX NW Top 2 NW Top Bot

Crate 3 SVX SW Top 1 SW Top Top

Crate 4 SVX SW Top 2 SW Top Bot

Crate 5 SVX SW Bot 3 SW Bot Top

Crate 6 SVX SW Bot 4 SW Bot Bot

Crate 7 SVX NW Bot 3 NW Bot Top

Crate 8 SVX NW Bot 4 NW Bot Bot

West Side

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Crate Naming Conventions

Crate Reset Panel PS Interlocks

Crate 9 SVX NE Top 1 NE Top Top

Crate 10 SVX NE Top 2 NE Top Bot

Crate 11 SVX SE Top 1 SE Top Top

Crate 12 SVX SE Top 2 SE Top Bot

Crate 13 SVX SE Bot 3 SE Bot Top

Crate 14 SVX SE Bot 4 SE Bot Bot

Crate 15 SVX NE Bot 3 NE Bot Top

Crate 16 SVX NE Bot 4 NE Bot Bot

East Side

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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

Layer 0 1 2 3 4

VMax (V)

170 170 60 140 60

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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 cablesLayer 00,01 10,11 20,21 30,31 40,41

VMax FWD

60 140 60 140 60

VMax CNTL

140 140 140 140 140

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Finally: L00 Modules (A509H) Occupies 2 slots in SY527 1 board powers 1 wedge

4 + 1 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

Layer 0 1 2 3a,3b

VMax (V) 90 90 90 160

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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

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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 courtesyof J. R. Mumford

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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

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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

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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!

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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

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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