Mamiya C28, C32, C24 manual Fault Finding

FAULT FINDING

FINDING

77 FAULT FINDING

WARNING

Care must be taken when conducting fault finding tests to guard against the risk of electric shock.

230 Vac is the nominal UK supply voltage. This may vary between 253 Vac and 196 Vac.

When checking continuity ensure power is off to the appliance.

With a fast pulse showing on LED 1 the boiler will continue to operate with a reduced performance in some fault conditions.

Before commencing fault finding please check the following:

Are all wiring connections OK ?

Are the function selector settings correct (Refer to frame 35, 36 and 39)

Pay attention that if the boiler locks out five times in an hour, it is not sufficient to press the reset button to re---start the boiler but it is necessary to disconnect the boiler from the main supply and, after reconnect it, to press the reset button.

FAULT

START

Ensure the room thermostat (if fitted) and programmer are calling for heat

Also that all services are on and the selector switch is set to heating*

Are only the two

no

no

Is there at least one of

Is there 230V between

no

green leds on front

fascia flashing together or alternately?

yes
	no
Are only the two green		Wait 60 seconds
leds on front fascia
flashing alternatively?
yes

With the boiler in heating	no		no
mode, what is the		Is the gas inlet
maximum burner
		pressure > 17 mbar?
pressure with boiler and
system cool ?		yes
(pressure values are
			no
given in Table 2 page 4		Adjust the burner
yes
		pressure. refer to
Continued		frame 35. Can the max
		burner pressure* be
from page 56.		achieved?
yes		yes
	no	no	no

the led flashing?

yes

Continued on page 54 of fault finding.

Rectify gas supply fault

no

Is there at least 15V dc at the connections on modulator coil?

yes

Adjust max ’stop’ on Gas Valve to achieve the max burner pressure*

no

Live and Earth at the mains connection in the control box?

yes

Is there continuity across the fuses on the PCB?

yes

Is there 230V at the

Live connection to PCB

pin 4?

yes

Replace faulty PCB

Is modulator harness

continuity O.K?

yes

Replace faulty PCB

no

no

no

no

Rectify external

wiring fault

Replace faulty fuses and check for wiring fault

Repair or replace

wiring fault

Repair or replace

faulty wiring

no

Does the heating

Is it a

Is there a

Disconnect DHW

Is there 230V

Is the continuity

Repair or

flow pipe become

system

DHW tap

flow sensor wiring.

between Blue

of the 3---way

replace

warm quickly?

boiler?

open?

Does the heating

and Brown at

valve harness

faulty

flow pipe now

the 3---way

O.K?

wiring

yes

yes

yes

become warm?

valve

connection?

yes

yes

yes

Replace faulty PCB

Close

DHW

tap

no

Remove the motor

Replace faulty

assembly, with 230V at

motor assembly

the connections is the

spindle visible? Refer

to frame 76.

yes

Replace faulty valve

body assembly

Replace the DHW flow

no

no

detector sensor body.

Replace the faulty

Does the heating flow

Dismantle the DHW

become warm?

detector valve. Refer to

DHW detector

frame 66 and clean.

valve

yes

When re---assembled

with DHW taps closed,

Faulty sensor now

does the heating flow

pipe become warm?

replaced

yes

Continued on page
53 of fault finding.	* see Table 2 at page 4 for the correct value

52 mini HE --- Installation & Servicing