CAEN%20power%20supplies%20The%20neverending%20story

1
CAEN power suppliesThe neverending story

• Jennifer Pursley
• Johns Hopkins University
• Silicon Workshop II, May 10-12, 2006
• University of California, Santa Barbara

2
System overview
Diagram courtesy of J. R. Mumford
3
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)

4
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
5
Crate Naming Conventions
West Side
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
6
Crate Naming Conventions
East Side
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
7
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
8
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

Layer 00,01 10,11 20,21 30,31 40,41
VMax FWD 60 140 60 140 60
VMax CNTL 140 140 140 140 140
9
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
10
L00 Crowbars
Automatic crowbar tester! No light blown fuse

• 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

11
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
12
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

13
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 cant get to the set voltage
• Common PS failure (esp. of ISL supplies), NOT
  fixable at FCC
• Software protection trips
• Voltage/current doesnt 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

14
Less Common Failure Modes

• Transistor regulating the Bias voltage blows
• Symptoms ladder voltage ramps up to VMax (250V
  or 500V) and doesnt trip
• Cant 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 doesnt recognize power supply
• Not fully connected to backplane, X28HC256 prom
  is garbled
• None of the other supplies in the crate will work
  if theres one in there the crate cant
  recognize!
• Supply wont work in one particular slot/crate,
  but is fine in another
• Usually require expert diagnosis!

15
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!)

16
Backup Slides
17
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