Printing Troubleshooting - ELCOM Euro-500 Handy Series Service Manual

Euro-500TX Handy
internal accumulator voltage is too low (external power supply disconnected)
incorrect VCC, VRAM values or NMI signal is in log. 0
incorrect RST and STBY signals
Q1 crystal vibrator doesn't function (ECR won't run at all)
EPROM memory (U3) is incorrectly inset or damaged (usu. the ECR won't run at all)
SRAM (U2) is damaged or random data were written into it (ECR will run, but its behaviour is random
and unstable)
ECR is reset cyclically
• system failure occurs during printing or turning on (external power supply disconnected)
almost flat accumulator
C9 and C16 capacitors lost capacity
• system failure occurs during printing or turning on (external power supply connected)
damaged accumulator
C9 and C16 capacitors lost capacity

6.3 Printing troubleshooting

If any printing error occurs, it is necessary to check the proper plugging of the PR&DISP1 and 2 into the
main PB and Intercon PCB, cable integrity for cables that connect main PCB to Intercon PCB. VCC1 and
VH voltages can be measured only during actual printing, best during the test #910.
• the printer is totally out of operation
incorrect or incomplete printer connexion
malfunctioning VH or VCC1 power supply
heavily damaged printer (head, cables...)
Service manual
– turn the ECR off, connect the external power supply;
continue work and charge the accumulator simulta-
neously.
– if this malfunction reappears after charging the bat-
tery, replace the battery, event. find the cause of
permanently high current consumption (constant
backlight, damaged semiconductive element...)
– check the voltage divider resistors R56, R57
– check the power supply circuitry according to chapter
6.1
– measure the signal levels according to the chapter
2.2.3; if they malfunction, replace them
– use the oscilloscope to measure the signal run on
vibrator outlets (approx. sine wave run with 3 V am-
plitude and 16 MHz frequency)
– check the capacity of C50, C51
– replace the vibrator
– if the vibrator replacement won't work, the microproc-
essor itself is damaged – replace it
– check the proper seating of the chip in the socket, pin
dirt contamination, proper chip orientation, or event.
replace for a new one.
– erase the SRAM (move JP1 jumper farther from the
NiCd accumulator for 10 seconds) and reinitialise the
ECR
– if problem persists, replace SRAM
– usu. VH voltage that is triggered also by the RST
signal is short-circuited (damaged semiconductive
part)
– increased consumption (damaged semiconductive
part) that causes the VCC voltage overshooting and
generates the RST signal cyclically.
– charge the accumulator, event. if it doesn't hold ca-
pacity for long – replace
– check the C9 and C16 capacity, event. replace
– charge the accumulator, event. if it doesn't hold ca-
pacity for long – replace
– check the C9 and C16 capacity, event. replace
– check the printer connexion
– using the test #910 determine if their voltages are
correct
– replace the printer
© Elcom, s. r. o.
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