Section 11 TECHNICAL INFORMATION
205
COMPONENT-LEVEL CIRCUIT DESCRIPTION and
TROUBLESHOOTING
General
Desoldering
While we socket the ICs that have the greatest potential for failure, many of the Zephyr’s
ICs are soldered in. That’s because most of the time the socket is more likely to cause
trouble than the IC. This is of no consolation when one of the soldered ICs appears to
have failed. When you need to replace a soldered in chip, the right tool is essential. We
use a vacuum desoldering system made by Pace (the MBT- 100) and highly recommend
it. Cost is about $450 - worth it if you do much PC board troubleshooting work. The
only other real alternative is to clip the leads from the top and remove the solder from
the holes with solder- wick. We’ve not had much luck with the non- heated, manual
vacuum desoldering devices like the ones from Radio Shack. We do not recommend
that newly- soldered connections be defluxed.
Active Low Notation
Whenever a slash ( / ) or a asterisk (*) is used after a signal designation in the text
or on the schematics, an active low is signified.
Circuit Description: Rev. F and Below
The revision level is screened on the motherboard on the edge closest to the front panel,
near the battery.
Motherboard Rev A-E: Audio Input
The signal enters the input buffer in balanced form. This is the common
“instrumentation amp” balanced input topology. The audio is extensively RF filtered by
the combination of ferrite beads, shunt capacitors, and special PI- filter components.
The stage gain may be set for either microphone or line level by changing the feedback
resistance using SW1A, B. Input audio is passed either to the send limiter, or directly to
IMPORTANT NOTE!
Zephyr memory backup is powered by Lithium battery BT-1.
The following precautions must be followed when working on
the Zephyr motherboard or when this battery is replaced:
1) Do not short the battery terminals (or traces connected to
these terminals) together.
2) Lithium batteries contain lithium and may be considered
hazardous. Local procedures must be followed when
disposing of used batteries. Do not dispose this battery by
burning.
3) Do not attempt to open the sealed battery container.
Summary of Contents for Zephyr
Page 13: ...Table of Contents 13 SECTION 1 QUICK RESULTS ...
Page 26: ...Section 2 INTRODUCTION 26 This page intentially left blank ...
Page 27: ...Section 2 INTRODUCTION 27 SECTION 2 INTRODUCTION ...
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Page 39: ...39 SECTION 3 ZEPHYR AT A GLANCE ...
Page 52: ...Section 4 INSTALLATION BASIC OPERATION 52 This page intentionally left blank ...
Page 53: ...Section 4 INSTALLATION BASIC OP 53 SECTION 4 INSTALLATION BASIC OPERATION ...
Page 84: ...Section 4 INSTALLATION BASIC OPERATION 84 ...
Page 85: ...Section 5 ISDN 85 SECTION 5 ISDN ...
Page 105: ...Section 6 NON ISDN NETWORKS 105 SECTION 7 AUDIO CODING ...
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Page 119: ...Section 8 DETAILED MENU REFERENCE 119 SECTION 8 DETAILED MENU REFERENCE ...
Page 157: ...Section 9 REMOTE CONTROL 157 SECTION 9 REMOTE CONTROL ...
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Page 177: ...Section 10 ADVANCED PROBLEM SOLVING 177 SECTION 10 ADVANCED PROBLEM SOLVING ...
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Page 197: ...Section 11 TECHNICAL INFORMATION 197 SECTION 11 DETAILED TECHNICAL INFORMATION ...
Page 219: ...Section 12 SCHEMATICS 219 SECTION 12 SCHEMATICS ...
Page 221: ...Section 13 MANUFACTURER S DATA SHEETS 221 SECTION 13 MANUFACTURER S DATA SHEETS ...
Page 223: ...Section 14 SPECIFICATIONS WARRANTY 223 SECTION 14 SPECIFICATIONS AND WARRANTY ...
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Page 229: ...Section 15 APPENDICES 229 SECTION 15 APPENDICES ...