D0 Muon Scintillator Electronics Safety Review

C.  Rotolo

T. Fitzpatrick

T. Regan

February 9, 2000

Revised: February 21, 2000

# Introduction

The front-end scintillator electronic consists of 4 types of boards is
housed in 18 9UVME Euro standard crates located in the EF, CF muon
trusses for the A and B layers and in the EMC, CF trusses for the C
layer. VME crates are situated in locations where bundles of coaxial
cables are coming out of scintillation counters into trusses. Each of
the crates will contain a commercially built processor Omnibyte Model
VME40, 1 Fermilab designed Scintillator Readout Controller (SRC), 1
Fermilab designed Scintillator LED Pulser (SLP), 1 Fermilab designed
Scintillator Power Module, and up to 12 Fermilab designed Scintillator
Front End (SFE) modules. The system contains a total of 131 SFE modules.

# Muon Front-End 9UVME Subracks

Muon 9U VME subracks are manufactured by Schroff, Inc. The subracks were
completely assembled and tested by the vendor before they were delivered
to Fermilab. They consist of standard VME crate p/n 13890, VICOR power
supply p/n MP4-76517, standard J1/J2 backplane p/n 23007421, universal
J3 backplane p/n 10225-385 and 12U x 500 mm COMPTEC case. The power
supply has the following outputs:

-   +5V, 120 amps

-   -5V, 20 amps

-   +12V, 8.3 amps

-   -12V, 8.3 amps

+5V power supply output has overcurrent and overvoltage protection, +12V
and --12V outputs have overcurrent protection. The 115V AC subrack input
is protected by the Bussmann GMA 15A fast acting fuse. The VICOR power
supply is rated for the maximum output power of 1200 watts.@ 115VAC. The
COMPTEC case has two AC fan blocks of six fans each working in a
push-pull mode. A typical DC load in the crate does not exceed 75% of
the maximum power rating. The following components have been added to
the VME crate to satisfy D0 muon group requirements:

-   two active terminator boards at J3/P3 backplane (TTL signals
    termination)

-   flat ribbon cable with 18 DIN connectors at J2/P2 backplane (no DC
    power, TTL signals only)

-   22 uH choke between VME backplane ground and AC ground

-   magnetic shield on the power supply

# Scintillator Front End (SFE)

The SFE's power distribution scheme is shown in Figure 1. The maximum
current rating of each VME pin is 2 amps 0 °C. The VME specification
suggests derating the current carrying capacity of these pins at
elevated temperatures and multiple pins connected in parallel as is done
on the SFE. At 60 °C, each pin is derated to 1.2 amps.

## +5V Power

The +5 volt power comes on to the board via a total of 6 parallel pins
residing at the standard VME designated locations on J1 and J2. The
total derated current carrying capacity of all six pins is 7.2 amps. The
1N5908 is a 6 volt transient rated at 1500 watts peak power and 5 watts
of steady power. Three parallel inductor each with a single current
rating of 0.78 amps are used to filter the VCC to obtain +5V to power
the analog circuits. Using the 2/3 capacity rule the three parallel
inductors are capable of supporting the +5VA current draw of 1.5 amps.
The +3.3 volt regulator is rated at 1 amp and is not separately fused.
Power and ground planes are used to distribute power throughout the
board. A single front panel LED is used to indicate the presence of both
the +5V and --5V power.

## --5V Power 

The --5volt power is derived from three parallel pins on the custom J3
backplane and have a total derated current capacity of 3.6 amps. The VEE
transient suppressor and --5VA filter inductor are the same as those
used for VCC and +5VA.

## +/- 12V Power

The +12V and --12V each come onto the board with one VME with a current
capacity of 1.5 amps at 60 °C. Each of these voltages are fuse at
0.5amps and have 1N6373A transient suppressor rated at 1500 watts peak
power and 5 watts of steady power. A single front panel LED is used to
indicate the presence of both the +12V and --12V power.

# Scintillator Readout Controller (SRC)

The SRC's power distribution scheme is shown in Figure 2. The maximum
current rating of each VME pin is 2 amps 0 °C. The VME specification
suggests derating the current carrying capacity of these pins at
elevated temperatures and multiple pins connected in parallel as is done
on the SRC. At 60 °C, each pin is derated to 1.2 amps.

## +5V Power

The +5 volt power comes on to the board via a total of 6 parallel pins
residing at the standard VME designated locations on J1 and J2. The
total derated current carrying capacity of all six pins is 7.2 amps. The
1N5908 is a 6 volt transient rated at 1500 watts peak power and 5 watts
of steady power. Power and ground planes are used to distribute power
throughout the board. A single front panel LED is used to indicate the
presence of both the +5V and --5V power.

## --5V Power 

The --5volt power is derived from three parallel pins on the custom J3
backplane and have a total derated current capacity of 3.6 amps. The VEE
transient suppressor is the same as that used for VCC.

## +/- 12V Power

The +12V and --12V each come onto the board with one VME with a current
capacity of 1.5 amps at 60 °C. Each of these voltages are fuse at
0.5amps and have 1N6373A transient suppressor rated at 1500 watts peak
power and 5 watts of steady power. A single front panel LED is used to
indicate the presence of both the +12V and --12V power.

# Scintillator LED Pulser (SLP)

The SLP's power distribution scheme is shown in Figure 3. The maximum
current rating of each VME pin is 2 amps at 0 °C. The VME specification
suggests derating the current carrying capacity of these pins at
elevated temperatures and multiple pins connected in parallel as is done
on the SLP. At 60 °C, each pin is derated to 1.2 amps.

## 4.1. +5V Power

The +5 volt power comes on to the board via a total of 6 parallel pins
residing at the standard VME designated locations on J1 and J2. The
total derated current carrying capacity of all six pins is 7.2 amps. The
+5V is protected with a 5 Amp self resetting fuse. The 1N5908 is a 6
volt transient suppressor rated at 1500 watts peak power and 5 watts of
steady power. Power and ground planes are used to distribute power
throughout the board. A single front panel green LED is used to indicate
the presence of the +5V power.

## 4.3. +/- 12V Power

The +12V and --12V each come onto the board with one VME pin with a
current capacity of 1.5 amps at 60 °C. Each of these voltages are fused
with a 1.0 amp with self resetteing fuse. Each has a 1N6373A transient
suppressors rated at 1500 watts peak power and 5 watts of steady power.
Two green front panel LED's are used to indicate the presence of the
+12V and --12V power.

# Scintillator Power Module

The Power Module's power distribution scheme is shown in Figure 4. The
maximum current rating of each VME pin is 2 amps at 0 °C. The VME
specification suggests derating the current carrying capacity of these
pins at elevated temperatures and multiple pins connected in parallel as
is done on the SLP. At 60 °C, each pin is derated to 1.2 amps.

## +/- 12V Power

The +12V and --12V each come onto the board with one VME pin with a
current capacity of 1.5 amps at 60 °C. Each of these voltages are fused
with a 1.0 amp with self resetteing fuse. Each has a 1N6373A transient
suppressors rated at 1500 watts peak power and 5 watts of steady power.
The +12V line is regulated to +6V for use by the preamplifier module.
Twenty four (24) yellow front panel LED's are used to indicate the
presence of the +6V and --12V power at each output receptacle. Each
supply has to supply .06A to each output for a total current consumption
of .72A per supply. Each output is fused with 1A self resetting fuse.

Figure 1 -- SFE Power Distribution Scheme

Figure 2 -- SRC Power Distribution Scheme

Figure 3 -- SLP Power Distribution Scheme

Figure 3 -- Power Module Power Distribution Scheme