Acorn Products Z80 SECOND PROCESSSOR 409 用户手册
Fig. 9 Position of +5V Trimmer on Power Supply PCB.
If the current is zero, the second processor PCB has gone open
circuit. Check fuse FS1 and connectors and tracks.
circuit. Check fuse FS1 and connectors and tracks.
If the fuse is blown, the fault is a short circuit on the PCB.
If the current is higher than it should be, measure the voltage. If
the voltage is greater than 5.25V, adjust it to 5V using the trimmer-
see fig. 9. If the voltage is in spec., then one or more of the
components on the second processor PCB is faulty. Switch off the
power supply and feel which of the components is hot.
the voltage is greater than 5.25V, adjust it to 5V using the trimmer-
see fig. 9. If the voltage is in spec., then one or more of the
components on the second processor PCB is faulty. Switch off the
power supply and feel which of the components is hot.
WARNING TAKE CARE WPEN CPECKING FOR 'POT' COMPONENTS` - TPEY MAY BE
HOT ENOUGH TO CAUSE INJURY.
6.3.10 Checking the Tube power supplies
The Tube (IC1) is powered both from the BBC Microcomputer and from
the second processor. If either of these supplies fails then the
second processor wi11 not work.
the second processor. If either of these supplies fails then the
second processor wi11 not work.
With the second processor switched off (ON/OFF switch down), switch
on the BBC Microcomputer (ON/OFF switch up). Check that there is a
potential of approx. 5V between pin 4 (+ve) and pins 1 and 5 (ground)
of IC1. If not, check the ribbon cable and connectors.
Now switch off the BBC Microcomputer (ON/OFF switch down), and switch
on the second processor (ON/OFF switch up). Check that there is a
potential of 5V between pin 2 (+ve) and pins 1 and 5 (ground) of IC1.
Also, check that there is a potential of between +2v and +3v between
pin 3 and both pins 1 and 5. If not, investigate components R2 and
Ll, replacing if necessary.
on the BBC Microcomputer (ON/OFF switch up). Check that there is a
potential of approx. 5V between pin 4 (+ve) and pins 1 and 5 (ground)
of IC1. If not, check the ribbon cable and connectors.
Now switch off the BBC Microcomputer (ON/OFF switch down), and switch
on the second processor (ON/OFF switch up). Check that there is a
potential of 5V between pin 2 (+ve) and pins 1 and 5 (ground) of IC1.
Also, check that there is a potential of between +2v and +3v between
pin 3 and both pins 1 and 5. If not, investigate components R2 and
Ll, replacing if necessary.