Tait T889, Manual

Page: 53 / 66

M889-00
PCB Information 7.1.3
Copyright TEL 02/10/95
7.1 Introduction
PCB Identification
All PCBs are identified by a unique 10 digit number, the last 2 digits of which define the issue status.
The issue status starts at 00 and increments through 01, 02, 03, etc. as the PCB is updated. Some
issue PCBs never reach full production status and are therefore not included in this manual. A let-
ter following the 10 digit IPN has no relevance in identifying the PCB for service purposes.
Parts Lists
The 10 digit numbers (000-00000-00) in this Parts List are “internal part numbers” (IPNs). Your
spare parts orders can be handled more efficiently if you quote the IPN and provide a brief descrip-
tion of the part.
The components listed in this parts list are divided into two main types: those with a circuit refer-
ence (e.g. C2, D1, R121, etc.) and those without (miscellaneous and mechanical).
Those with a circuit reference are grouped firstly by PCB, then by component type in numerical
order. Each component entry comprises three or four columns: the circuit reference, variant
number (if applicable), IPN and description. A number in the variant column indicates that this
component is fitted only to that variant.
The miscellaneous and mechanical section lists the variant and common parts in IPN order.
Grid Reference Index
To assist in locating components and labelled pads on the PCB layouts and circuit diagrams, a com-
ponent grid reference index has been provided. This index lists the components and pads in alpha-
betical order, along with the appropriate alphanumeric grid references.
The first digit in the circuit diagram reference is the sheet number, and the last two characters give
the location of the component on that sheet.
The first digit in the PCB layout reference is a “1” or “2”, indicating the top or bottom side layout
respectively, and the last two characters give the location of the component on that diagram.
Using CAD Circuit Diagrams
Reading a CAD circuit diagram is similar to reading a road map, in that both have an alphanumeric
border. The circuit diagrams in this manual use letters to represent the horizontal axis, and num-
bers for the vertical axis. These circuit diagram “grid references” are useful in following a circuit
that is spread over two or more sheets.
When a line representing part of the circuitry is discontinued, a reference will be given at the end of