9
£
DIAGNOSTIC MESSAGES - TROUBLESHOOTING GUIDE
PLUG-IN DAUGHTER BOARD
Description
A plug-in board is pre-installed in the MEC320TS chassis to provide local reset, remote alpha-
numeric display, serial communications and normally closed relay contacts.
FIGURE 4.
PLUG -IN BOARD LOCATION AND INSTALLATION
POSSIBLE CAUSE
SOLUTION
Check Programmer
Voltage on Terminal 5 at improper time.
Inspect wiring to main fuel valve
Welded watchdog relay
Replace chassis
Internal diagnostic failure
Replace programmer
Check Chassis
Voltage on Terminal 3 or 4 at improper time.
Inspect wiring to pilot valve and igniter.
Welded watchdog relay
Replace chassis
Chassis Opto
Opto-Coupler(s) short circuited
Replace chassis
Amplifier High Count Fail
Amplifier signal level high
Replace Amplifier module
Amplifier Auto Check Fail
Flame signal too high
Use orifice in sight pipe
Internal Amplifier diagnostic fault
Replace Amplifier module
Check Scanner
Defective shutter
Inspect scanner wiring, replace scanner
UV tube false firing
Replace UV tube or scanner
Check Blown Fuse
No power detected on terminal 3
Inspect defective pilot valve or igniter
Defective fuse
Replace fuse
Line Frequency Noise Detected
Spikes detected on AC mains
Check for SCR motors or DC drives
Inspect ground system
Fuel Value State Change
Terminal 5 (main fuel) detected on during TFI
Check external wiring or replace chassis
Check Amplifier
Amplifier not passing diagnostic tests
Replace Amplifier module
System Error
Noise transient
Check high energy ignition noise location. Be
sure it is not arcing to chassis or wrapped with
scanner wiring.
STANDOFF
PLUG-IN BOARD
RELEASE
DIRECTION
SERIAL COMMUNICATIONS
REMOTE DISPLAY
RJ45 JACK
RELAY CONTACTS
(RS485)
B
A
MED8
