Epson LQ-2550 Technical Manual page 229

5.3 UNIT REPAIR
Unit repair is divided into three parts: ( 1 ) The ROPS/ROPSE board; (2) The ROMA board; (3) The Printer
mechanism.
This section will describe (l), the ROPS/ROPSE board unit repair. If (2) ROMA board or (3) Printer
mechanism should need repair, use the diagnostic tool introduced in Section 5.1.1.
5.3.1 ROPS/ROPSE Board
The power supply circuit ROPS/ROPSE board is divided into three blocks:(1) Input filter circuit, (2) Main
switching circuits, and (3) Secondary side (Refer to Figure 5-7.).
If trouble occurs, first determine the faulty block and then find the bad component, referring to Tables
5-7 and 5-8, and Figures 5-9 to 5-13. in addition, Tables 5-9 and 5-10 list the parts used in the
1. Before checking anything using the measuring instruments, check (that there are no metal chips
inside and that there are no burned components.).
2. Since this power supply is an isolated switching regulator, do not use a grounded measuring
instrument such as a multimeter or oscilloscope. If a grounded instrument is used, fuse F 1 may
burn out. Be sure that the measuring instrument is not connected to ground before using it on
this power supply circuit. In most cases, the line plug shown in Figure 5-8 will avoid this problem.
3. If your measuring instrument has multiple channels, measure the resistance value of each block
in the same way as described above and as shown in Figure 5-7. (Do not connect multiple
channels, such as channel 1 to the main switching circuit and channel 2 to the secondary side.)
4. Measure the resistance value on the circuit board after turn the power off.
MAIN SWITCHING
INPUT FILTER
CIRCUIT
,
Figure 5-7. ROPS/ROPSE Board Block Diagram
Figure 5-8. AC Connector for Measuring Instruments
SIDE
TRANSFOl?-
MERS
I
DANGER
5-17
REV.-A
+ 35 v
* 1 2 V