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Micron 30FF - 50FF Engineer Support (Pektron)

Micron 30FF – 50FF Fault Finding

Pektron PCB Versions

NEON KEY

These Neon’s will light up on the PCB to indicate the appliance status:

Neon 1 = Switched Live Input (From External Controls)

Neon 2 = Demand On (Thermistor & Control Knob Set Point)

Neon 3 = Fan Running & Air Pressure Switch Proved

Neon 4 = Burner Lit (Flame Rectification)

Neon 5 = Overheat (The Overheat Thermostat Has Activated)

Neon 6 = Flame Failure (Ignition Lockout)

Schematic Wiring Diagram (Pektron PCB)

Component Tests - Micron 30FF – 50FF with Pektron PCB)

NTC Thermistor

Test with the power to the boiler turned OFF and the Thermistor disconnected from the PCB if necessary

It should read 10Kohms -12Kohms at 20 – 25 degrees Celsius. The Resistance Range is 14Kohms (cold) to 2.5Kohms (hot). There were 2 styles of NTC Thermistor used on the Micron 30FF and both are interchangeable (See Below)

Fan

230vac across the Purple (L) and the Blue (N) wires at the Fan with demand. The Fan motor can also be tested for resistance, and with the power to the boiler turned OFF it should measure approximately 50ohms.

Air Pressure Switch

With the Fan running it should read 230vac on the Red Wire (Common Contact) to a Neutral, and 230vac on the Grey Wire (Normally Open Contact) to a Neutral.

The Air Pressure Switch can also be checked for operation with the power to the boiler turned OFF in the following manner: In the rest position it should read continuity across the Common (Red Wire) and Normally Closed (Yellow Wire) contacts. When the Air Pressure Switch is “made” it should read continuity across the Common (Red Wire) and the Normally Open (Grey Wire) contacts. The minimum switching pressure for the Air Pressure Switch is approximately 1mbar.

Overheat Thermostat (Safety Temperature Limiter)

With the power to the boiler turned OFF you should read continuity across the 2 connections on the overheat thermostat itself (Brown wires) The Overheat Thermostat will trip to an open circuit at approximately 94 degrees Celsius. The Overheat Thermostat will automatically reset itself once it has cooled down, but the appliance will still require resetting via the Control Knob on the front after an overheat fault to clear the fault light.

Gas Valve

During spark ignition there should be 230vac across the Brown and Blue wires off the PCB to the Gas Valve Solenoid EV1, and 230vac across the Black and Blue wires off the PCB to the Gas Valve Solenoid EV2 (Both solenoids are powered at the same time and there is no adjustable ignition burner pressure on the Micron’s 30FF – 50FF range).

The resistance of the individual Gas Valve Solenoids can be measured as follows. With the power to the boiler turned OFF, remove the square black electrical connection plug off the Gas Valve and measure the resistance across the corresponding pins on the Gas Valve as marked below:

EV1 to COM = 800 – 900 ohms

EV2 to COM = 800 – 900 ohms 

Points to note on a Micron 30FF – Micron 50FF with a Pektron PCB

1 - The Micron 30FF – 50FF range of boilers do not have a Pump over-run function, so therefore it does not require a permanent mains live supply, nor does it require the system pump to be wired in to the boiler.

2 – All versions of the Micron 30FF – Micron 50FF PCB’s (Pektron, Pijnenburg & Ritter) are all interchangeable - E.G a Pijnenburg could replace a Pektron or a Ritter can be fitted in place of a Pijnenburg etc. The Pektron PCB was used in production on these Micron’s from 2000 to 2002.

3 – When the Micron 30FF to Micron 50FF range of boilers is fitted to a thermal store unit (e.g. Gledhill Boilermate) then a specially calibrated replacement NTC Thermistor should be fitted into the boiler in place of the original factory fitted NTC Thermistor. This specially calibrated NTC Thermistor will allow the boiler to satisfy the heat requirements of the Thermal Store. The Part Number for this specially calibrated NTC Thermistor is 2000802653.