Transcript CAEN power supplies

CAEN power supplies
The neverending story
Jennifer Pursley
Johns Hopkins University
Silicon Workshop II, May 10-12, 2006
University of California, Santa Barbara
System overview:
Diagram courtesy
of J. R. Mumford
J. Pursley - Silicon Workshop II
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Infrastructure: the SY527
Universal Multichannel Power Supply system
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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
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Diagram courtesy
of M. Stanitzki
J. Pursley - Silicon Workshop II
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
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Crate Naming Conventions
West Side
Crate
Crate 1
Crate 2
Crate 3
Reset Panel
SVX NW Top 1
SVX NW Top 2
SVX SW Top 1
PS Interlocks
NW Top Top
NW Top Bot
SW Top Top
Crate 4
Crate 5
Crate 6
SVX SW Top 2
SVX SW Bot 3
SVX SW Bot 4
SW Top Bot
SW Bot Top
SW Bot Bot
Crate 7
Crate 8
SVX NW Bot 3
SVX NW Bot 4
NW Bot Top
NW Bot Bot
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Crate Naming Conventions
East Side
Crate
Crate 9
Crate 10
Crate 11
Reset Panel
SVX NE Top 1
SVX NE Top 2
SVX SE Top 1
PS Interlocks
NE Top Top
NE Top Bot
SE Top Top
Crate 12
Crate 13
Crate 14
SVX SE Top 2
SVX SE Bot 3
SVX SE Bot 4
SE Top Bot
SE Bot Top
SE Bot Bot
Crate 15
Crate 16
SVX NE Bot 3
SVX NE Bot 4
NE Bot Top
NE Bot Bot
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The Workhorse: SVX Modules (A509)
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Occupies 1 slot in SY527
1 board powers 1 wedge
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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)
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Occupies 2 slots in SY527
1 board powers 1 wedge
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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
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Finally: L00 Modules (A509H)
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Occupies 2 slots in SY527
1 board powers 1 wedge
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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
VMax (V)
J. Pursley - Silicon Workshop II
0
1
2
3a,3b
90
90
90
160
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L00 Crowbars
Automatic crowbar
tester!
No light = blown
fuse
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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
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Junction Cards
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Same junction card used for SVX, ISL, and L00
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Cables in CH run from PS racks down into the bore
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Extra LV and Bias connectors to accommodate ISL
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 II
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Common Failure Modes – SY527
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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:
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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 II
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Common Failure Modes – PS
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Overcurrent trips
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Overvoltage/Undercurrent trips
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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
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Maybe the current is going high – try raising limit, watch plots
Also a common PS failure, usually fixable at FCC
Supply can’t get to the set voltage
Common PS failure (esp. of ISL supplies), NOT fixable at FCC
Software protection trips
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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 II
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Less Common Failure Modes
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Transistor regulating the Bias voltage blows
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Large current offsets
Erratic or oscillatory voltages/currents (seen on DVDD
and Bias)
Crate doesn’t recognize power supply
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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!
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
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Love ‘em or hate ‘em, CAENs are here to stay
Increasing frequency of failures may be due
to radiation exposure or aging
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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!)
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Backup Slides
Loadbox testing
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J. Pursley - Silicon Workshop II
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
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