MEMORY PLUS Manual By Lee Davison
Page 17
MEMORY PLUS Testing and Field Repair
Your MEMORY PLUS board has been burned in and tested before shipment. If,
after following the steps outlined in the "Setting Up MEMORY PLUS" section,
the board does not seem to work properly, or if it ever seems to stop
functioning correctly, then the following steps should be taken.
1. Check that the board is receiving adequate power.
Place the ground lead of a voltmeter or 4scope on any convenient
ground on the board (the left lead of the large capacitor at the
upper left hand corner of the board is handy) or on the connector
(A-1, E-1, E-22, E-A, or E-Z).
Measure the +5 volts at each of the four jumpers on the Header
located near the voltage regulators. If you are providing
unregulated +8 to +10 volts, then the top jumper should have this
value. If you are using regulated +5 volts, then the top jumper
should show +5V. The bottom three jumpers should show +5V in any
case. If not, check your supply. If one of the three shows a
voltage other than +5, it indicates a problem with the associated
voltage regulator which might require replacement. The bottom jumper
comes from Q6, the next jumper from Q5, and the next to top jumper
from Q4 (See diagram on page 25).
Measure the +25 volts at pin A-22 of the MEMORY PLUS application
connector. If you are providing unregulated +27 to +30 volts, the
output of the +25 volt regulator circuit should show about +24.7V.
If you are providing regulated +25 volts at this pin, it will show
the output of your power supply. If the value for the unregulated
situation is not +24.7, then check your unregulated voltage at pin
E-2 of the MEMORY PLUS expansion connector. It must be +27 to +30V.
2. Check that all IC chips are firmly in their sockets. It is possible
for chips to come loose during handling and shipping. Push each chip
firmly into its socket.
3. Check that the Header is in the proper position for the method of
providing +5 volts. If you are providing +5 at pins E-21 and E-Y,
then the Header should have its notched corner at pin 9 and the
jumper wires should go from pins 2 - 15, 4 - 13, 6 - 11, and 8 - 9.
If you are providing unregulated +8 to +10 volts at pins E-19 and
E-20, then the Header should have its notched corner at pin 1 and the
jumper wires should go from pins 1 - 16, 3 - 14, 5 - 12, and 7 - 10.
4. Check all of the connections between the MICRO, MEMORY PLUS, and the
power supplies.
5. Follow the instructions in the "RAM Memory Test" section if the RAM
Memory appears to be having problems.
6. Check the MICRO or try MEMORY PLUS with a different MICRO. For EPROM
Programming it is absolutely essential that bits 0, 1, and 2 of the MICRO
Port B are functioning properly (PBO, PBl, and PB2). A quick test of
Port B may be made by putting FF in location PBDD and then trying to
write 07 in location PBD. If this does not work, then you have a
problem and should not attempt to program any EPROMs until you have the
MICRO serviced.
Page 17
Last page update: 8th December, 2002. |
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