Repair Your Drayton Digitstat Wireless Receiver Repair Your Drayton Digitstat Wireless Receiver Repair Your Drayton Digitstat Wireless Receiver Repair Your Drayton Digitstat Wireless Receiver

Is your Drayton Digistat SCR or British Gas WR1 wirelss receiver not working?

If your Drayton Digistat SCR is not working correctly it may be due to a common fault where the capacitor inside the receiver becomes defective over the life of the product. The capacitor is soldered to the circuit board inside the unit and can be easily replaced to rectify the problem.

The resultant symptom is that the ‘Heating on’ light turns on upon demand but there is no audible click from the relay and the boiler fails to fire up. On combination boilers the direct hot water is not affected, only the central heating will not work.

The Iskra KNB1530 capacitor is a direct replacement for Drayton, British Gas and Iflo branded wireless thermostat receivers. Iskra are the exact supplier to Drayton and replacing with an original equipment manufacturer part ensures that the unit will operate as the manufacturer intended.

Detailed Fault Description

A capacitor is used to reduce the AC mains voltage from 230V down to approximately 24V. Over time the capacitor becomes defective and the voltage drop increases. There is then not enough voltage available to operate the relay on the receiver circuit board to switch the heating on. The resultant symptom is that the ‘Heating on’ light turns on upon demand but there is no audible click from the relay and the boiler fails to fire up. On combination boilers the direct hot water is not affected, only the central heating will not work.

This capacitor can be replaced by a competent DIY-er but it is recommended you use an electrician if you have any doubts.

This fix is a cost effective solution and extends the life of the receiver saving the need for an expensive replacement unit.

Depending on the year of manufacture Drayton used an Iskra KNB1530 or KNB1560 0.68uF capacitor. The difference between these two is the KNB1560 is slightly smaller but the unit was originally designed for the larger KNB1530 so it is a suitable replacement for all units.

Genuine Repair Capacitor part now available from our eBay store
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Drayton Digistat SCR & British Gas WR1 Wireless Receiver Repair Guide

This Drayton Digistat repair procedure details how to replace a faulty capacitor on the circuit board within the unit. This will fix the common problem where the unit indicates that the heating is on but the switching relay does not click to turn the heating on.

This fix can be carried out by a competent DIY’er and the tools can be purchased for a low cost online.

If you are following this guide you do so at you own risk.

Tools & Parts Required
1 x Digistat Receiver
2 x Flat head Screwdrivers
1 Replacement Capacitor (Iskra KNB1530 or KNB1560 0.68uF)
Basic Soldering Skills (Visit YouTube for tutorials on basic soldering)
Soldering Iron
Solder with flux core
De-Solder Braid (optional & not pictured)
Small wire cutters
Scalpel knife




Repair Procedure

Turn off your electric before removing the receiver from the wall back plate that is near your boiler. There should be an isolator switch near to the receiver or turn off all the electrics at the main fuse box for your house.
Remove the Digistat receiver from the wall plate by undoing the two small screws on the base of the unit and when loose the unit can easily be removed.





Turn the unit onto its front face. There are four tabs on the unit that need to be released to separate the two halves of the unit. The plastic is thin and so some light cosmetic damage may occur. This will not be a problem as when the unit is back on the wall it will never been seen.

With one screwdriver carefully push out the wall of the casing whilst at the same time using the second screwdriver carefully get it into the join of the two halves and leaver the back section of the casing upwards. When the back of the casing is above the locking tab you can move on to the next tab and repeat the process. Be careful not to insert the screwdriver in too far as on some versions of PCB the radio transmitter circuit is close to one of the tabs and damage can be caused.

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Do the same procedure for all four tabs and the unit shall be in two halves. The tabs will now catch on the circuit board so just flex gently the side of the casing with your fingers and then the plastic back plate and circuit board will come apart from the front section of the case.



There are now two more plastic clips holding the circuit board to the casing. Release the small clip first and then the larger one. Be careful with the exposed circuit board to avoid damage. Handle the board at the edges rather than the main surface.



With the circuit board free it can be turned over and the capacitor that requires replacement can be seen. Place the circuit board carefully on to your work surface.



Using a flat blade screwdriver gently prise the capacitor up from the circuit board. It is held with a sticky pad that is used to hold the capacitor in place during the manufacturing process of the unit and shipping.






Units may now have the capacitor glued solidly to the board which are harder to move. The screwdriver method will not be sufficient on its own in this case. You will need to carefully and gradually cut into the glue using a scalpel or Stanley knife. Start at the corners of the capacitor and gradually work towards the middle. It puts the PCB under some stress so be careful only to apply enough force to aid the cutting of the glue. Be very careful of nearby components and your fingers.
(Edited Jan 2014. Thank You to M.Bishop for this information and technique)

There are two methods for de-soldering the capacitor from the board. If you have solder braid or a solder sucker removal tool then you can remover the solder with these items and then remove the capacitor. If you do not have these items then there is a method that you can follow without using them.

Turn the circuit board over and identify the two connections that are for the capacitor. Apply heat with the soldering iron to the connections whilst applying light pressure with the screwdriver to pull the capacitor out. You will have to alternate between the two connections moving it a little bit at a time with each. The capacitor will eventually come free from the board.





Bend the leads on the new capacitor at 90° to the plastic casing and cut the leads to approximately the same length as the old ones. A few millimetres longer is ideal to give sufficient lead length to solder to. You don’t want to cut the leads after they are soldered as this can cause the solder joint to crack.





Offer the capacitor to the circuit board contacts and if the holes are clear push the leads in and the put the capacitor in place flat to the circuit board. If solder is blocking the holes you will have to heat the solder in the holes whilst applying a little pressure to the capacitor to push the leads in. You will need to alternate again between the two contacts until the capacitor leads are in sufficiently.

You may then need to add a little solder to each contact depending on which removal method you followed.





This is an example of a good solder joint. There is not too much solder and it is volcano shaped. To achieve this heat must be applied to the lead and then the pad for the solder to stick to both surfaces.

Please visit YouTube for basic soldering technique.



With the capacitor now replaced the unit can now be reassembled. Insert the circuit board back into the back plate with the clips and then offer that assembled half to the front casing. Be careful to ensure the buttons are correctly seated in the casing. When they are together push the two halves until all four casing clips are fixed.





The receiver unit is now fixed and it can now be replaced on the wall mounting plate next to the boiler. Once the two fixing screws are done up the power can be restored to the boiler and you can enjoy your now working central heating.



Genuine Iskra KNB1530 0.68uF Repair Capacitor part now available from our eBay store

Component Technical Data

Manufacturer --  Iskra Kondenzatorji d.d.
Construction --  Polypropylene film, metallized
Part number --  KNB1530
Capacitance --  0.68uF
Operating Voltage --  275 VAC
Class --  X2
Tolerance --  ±10%
Length --  32mm
Height --  20mm
Width --  11mm
Terminal Pitch --  27.5mm

Genuine Iskra KNB1530 Repair Capacitor
available from our eBay store.


CLICK HERE TO SEE OUR EBAY ITEM


Fault Diagnosis Tips

If you are experiencing problems with your Digistat wireless thermostat and the red LED stays on continually it means that the SCR is unable to receive a radio signal from the thermostat controller. This may be caused by the batteries being dead or some temporary interference with the radio signal.

Radio Signal Test

1. To re-sync the units and test the radio signal, open both battery drawers of the thermostat controller and wait for the display to fade.
2. Close the right hand drawer first, then the left.
(It must be done in this order)
3. On the controller set your desired temperature.
4. If the radio signal has been successfully transmitted and received, the red LED will flash for 7 seconds then go off. If you turn up the temperature setting so that the flame indicator is showing the ‘Heating on’ green LED should appear on the SCR and you should hear a click from the switching relay. The boiler should now fire up and provide heating.

If you do not hear the ‘click’ of the relay it is likely that your SCR unit requires the capacitor to be renewed as per the instructions on this website.


The Drayton Digistat SCR is used with the following wireless thermostat systems:

Drayton Digistat RF1 Wireless Thermostat
Drayton Digistat RF2 Wireless Thermostat
Drayton Digistat RF3 Wireless Thermostat
Drayton Digistat + RF Wireless Thermostat
Drayton Digistat +C RF Wireless Thermostat
Drayton Digistat +1 RF Wireless Thermostat
Drayton Digistat +2 RF Wireless Thermostat
Drayton Digistat +3 RF Wireless Thermostat
Drayton Digistat RF601 Wireless Thermostat
Drayton Digistat RF701 Wireless Thermostat

The British Gas WR1 is used with the following wireless thermostat systems:

British Gas RC2 Wireless Thermostat
British Gas RC5 Wireless Thermostat
British Gas T4 RF Wireless Thermostat

The Iflo Digistat SCR is used with the following wireless thermostat systems:

Iflo Digistat + RF Wireless Thermostat RF603
Iflo Digistat +2 RF Wireless Thermostat RF700
Iflo Digistat RF702 Wireless Thermostat

 

Click to download a PDF of this Repair Guide

Repair Guide PDF

 

 

 

 

 

 

 









 

 

 

 

 

 

 

 

 

 

 

 



Click to download a PDF of this Repair Guide

Repair Guide PDF

 

 

 


Genuine Iskra KNB1530 Repair Capacitor
available from our eBay store.

CLICK HERE TO SEE OUR EBAY ITEM






































 

 

 

 

 

 

 

 













Click to download a PDF of this Repair Guide

Repair Guide PDF

 

 

 



Genuine Iskra KNB1530 Repair Capacitor
available from our eBay store.

CLICK HERE TO SEE OUR EBAY ITEM

































 

 

 

 

 

 

 

 




Click to download a PDF of this Repair Guide

Repair Guide PDF

 

 



Genuine Iskra KNB1530 Repair Capacitor
available from our eBay store.

CLICK HERE TO SEE OUR EBAY ITEM



























































































Click to download a PDF of this Repair Guide

Repair Guide PDF

 


Genuine Iskra KNB1530 Repair Capacitor
available from our eBay store.

CLICK HERE TO SEE OUR EBAY ITEM



























































Click to download a PDF of this Repair Guide

Repair Guide PDF

 


Genuine Iskra KNB1530 Repair Capacitor
available from our eBay store.

CLICK HERE TO SEE OUR EBAY ITEM