Service manual

Chapter 5 E01S Fault finding
FileStore Service Manual 78
The current drawn should be as follows:
The pcb:
+5V 0.9A to 1.2A min, 1.5A max
Following start up, after the EPROM has been copied into RAM, the current should drop by
about l00mA just before the discs are accessed.
The second output supplies the floppy disc drives. It is daisy-chained from the power supply
to the disc drive. Looking down on to the top of the disc drive with the bezel towards you, the
power supply pinouts are orientated as shown below:
* * * *
+5V Gnd Gnd +12V
Alternatively, some connectors are labelled 1 to 4, hence the supply would be shown:
1 2 3 4
* * * *
+5V Gnd Gnd +12V
The output can be tested by measuring the +5V and +12V voltage between the relevant pin
and ground. The allowable voltage ranges are as follows:
+5v 500V to 5.25 V
+12V 11.4V to 12.6V
In order to measure the currents drawn by the disc drives it would be necessary to make up a
small board that could be placed in-line between the power supply socket on the flying lead
and the disc drive plug. This board would need to have links which can be made or broken
depending on which line the current is being measured in. See- Fig 6 for details.
Figure 6: Board layout
Take care not to cause any short circuits between the power supply pins and also between the
board and the top of the disc drives and other components in the FileStore, i.e. the power
supply pcb.