ISA Backplane

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MicroATX ISA Backplane - Version 1.1

This backplane supports bus width up to 16 bits. It has onboard POST code indicators as well as a -5V regulator allowing you to use it with modern power supplies.

Isa-backplane.jpg

Available For Sale

[For sale at my eBay store]

  • Bare PCB
  • Individual Components
  • Full Component Kit

Features

Required Tools

  • Soldering Iron,
  • Wire cutters
  • Pliers
  • Rosin core solder
  • Multimeter (optional: if you want to check for shorts)

Assembly Steps

Start with the shorter components first. This way you can lay the board down flat on the table and be able to solder them in. The taller components go next. The recommended order is as follows.

1. IC Sockets

component type reference Name Qty
socket U5, U6, U7 14 pin 300 mil DIP socket 3
socket U1, U2 16 pin 300 mil DIP socket 2
socket U3, U4 20 pin 300 mil DIP socket 2

2. Capacitors

component type reference Name Qty
PCB PCB 1
Capacitor C1 - C51 10 uF ceramic, 5.08 mm lead spacing 51
Capacitor C52 1 uF ceramic, 5.08 mm lead spacing 1
Capacitor C53 - C59 0.1 uF ceramic, 5.08 mm lead spacing 7

Polarity doesn't matter unless you are using electrolytic ones.

3. ISA Slots

component type reference Name Qty
Connector BUS1 - BUS8 Edge Connector 98 Pin 8

4 LED Lights

component type reference Name Qty
Diode D1 - D5 5 mm LED 5

5 ATX Power connector

component type reference Name Qty
Connector P3 ATX Connector 1

LED Display Configuration

7-Segment Decoders and Matching Displays

The ISA Backplane board supports a variety of 7-segment decoders and common anode / common cathode type LED displays. Please use the following table to determine the proper configuration.

74LS48, 74LS248 Limited - Displays distinct figures for codes A-F Common cathode 1-2 2-3 2-3 No
7-Segment Decoder Type Hexadecimal Support Matching Display Type J2 J3 J4 Built in current limiters
74LS47, 74LS247 Limited - Displays distinct figures for codes A-F Common anode 2-3 2-3 2-3 No
CD4511, MC14511, 74HCT4511 No - Displays nothing (blank) for codes A-F Common cathode 1-2 2-3 1-2 No
Mitel MD4311BE Yes Common cathode 1-2 2-3 1-2 No
DM9368 Yes Common cathode 1-2 1-2 2-3 Yes
DM9370 Yes Common anode 2-3 1-2 2-3 No
DM9374 Limited - Displays distinct figures for codes A-F Common anode 2-3 1-2 2-3 Yes
D345D Yes Common anode 2-3 1-2 2-3 No
D346D Yes Common anode 2-3 Trim2 2-3 Yes
D347D Limited - Displays distinct figures for codes A-F Common anode 2-3 1-2 2-3 No
D348D Limited - Displays distinct figures for codes A-F Common anode 2-3 Trim2 2-3 Yes

POST Codes and what they mean

[Reference information available here]

Power On and Test

The goal is to identify any short circuits that would cause problems. Before powering on the device check to see if there are shorts across any of the rails of the PCB.

  1. Turn on the backplane and use a volt meter to check voltage across the PCB including the expansion slots.
  2. Plug in the ATX power connector and the PCB and the standby light should go on.
  3. Then click the power button and the power lights should go on.
  4. The -5V regulator is option and if your power supply does not provide -5V then you can solder that in as well. Once the regulator is installed the -5V light should go on as well.