Before you start
This guide is for experienced repair technicians who can safely isolate and service mains electronics. It covers board access, inspection and the filmed optocoupler repair. The video does not show a triac being replaced, so it cannot supply a complete triac-fitting procedure.
Electrical safety comes first
Switch off at the outlet, unplug and prevent reconnection. The front-panel power button does not isolate the triac board.
Allow the machine to cool. A competent person must verify de-energisation and address stored electrical energy before work; a waiting period alone is not proof.
Use an appropriate electrical safety procedure. Do not probe the exposed board while following this written guide.
Refit every protective cover before a powered functional check. Refer the job to a qualified technician if safe isolation, component identification or soldering is outside your skills.
Tools and supplies
Suitable drivers for the actual casing and board fasteners
Temperature-controlled soldering equipment and desoldering tool
Flush cutters, as used in the optocoupler demonstration
Magnification for inspecting pads and solder joints
Matched repair components, verified against their markings and datasheets
Suitable PCB conformal coating where the original coating was removed; follow its product instructions
These are stills from the original workshop video. Some show wiring still attached; a photograph does not confirm that the equipment is isolated. Establish safe isolation before touching the board. The current kit advice is to replace the affected triac and optocoupler together, although the filmed repair replaces the optocoupler alone.
Part 1 of 4
Assess and isolate
01
Record the heating fault
Note what happened before opening the machine: temperature rising above the setting, heating that stalls, temperature drift, or continued heating long after the front-panel power is off.
If the machine is overheating or appears to keep heating while switched off, disconnect it from the outlet. Do not keep running it to reproduce the fault.
Record which heating circuit is affected where this has already been established. The Dual Boiler has separate coffee and steam boilers plus an actively heated group head.
These symptoms point to a fault-finding job. They do not, on their own, prove a failed triac, optocoupler or thermal fuse.
View the symptoms section1:51 Reference: Video 1:51–3:41 · Breville BES920 manual
02
Establish safe isolation
Switch off at the outlet, unplug and prevent the supply being reconnected while the machine is open. Allow the appliance to cool before handling it.
Have a competent person verify that the equipment is de-energised and safe to work on, including any stored energy. Treat it as energised until that verification is complete.
The front-panel power button is not an isolator. The original video includes live fault-finding; those measurements are not a step in this written repair workflow.
Reference: Video 4:16–4:42 · Breville BES920 manual · WorkSafe isolation guidance
Part 2 of 4
Access and inspect
03
Open the casing for board access
The access montage shows fasteners below the front of the machine and along the rear, followed by the rear panel being opened to expose the triac-board area.
Use these photographs to identify the filmed access points. Follow the casing procedure for the actual model and revision; this short montage does not establish a complete fastener count or removal sequence.
Keep the appliance isolated throughout access. Do not pull the panel against attached wiring.
View the casing-access montage3:53 Reference: Video 3:53–4:16
04
Inspect the board and find the cause
Locate the triac board under its protective enclosure. Inspect both sides for scorching, corrosion or contamination before deciding that component replacement is appropriate.
Check for the water or steam leak discussed in the video, particularly around the steam-boiler connections below the board. Repair the source of a leak before returning the electronics to service.
A clean-looking board can still have an electrical fault. Visible damage or a temperature symptom does not identify the failed part by itself.
View the board inspection4:31 Reference: Video 1:17 / 4:31 · Current Dual Boiler kit advice
The opened rear-panel area in the source footage. 4:15 in the video Board inspection view. Attached wiring is visible; this photo does not establish isolation. 4:33 in the video
Part 3 of 4
Plan and repair
05
Confirm the repair route and parts
For a component repair, BrevTech’s current Dual Boiler kit advice is to replace the triac and optocoupler together in the affected channel. The archive video replaces only the optocoupler on its example board.
Match the replacements to the actual board, supply version and device markings. Verify terminal assignments and orientation against the exact supplied-device datasheets before removing the originals.
The triac’s component fitting and thermal mounting are not demonstrated in this video. Use board-specific service information for that work, or have a qualified repairer complete it. A complete replacement board is the alternative discussed in the video.
Do not copy an Oracle-specific pin reversal or voltage-conversion instruction onto this Dual Boiler board. Product artwork is not a pinout reference.
Reference: Video 0:25–0:45 · Video 6:51–8:14 · Current Dual Boiler kit advice
Component-side reference: triacs and the small optocoupler packages. This is not a fitting-orientation diagram. 7:17 in the video
06
Remove the old optocoupler
In the filmed example, the old optocoupler leads are cut, and the remaining lead material is desoldered from the board. The close-up shows the coated solder side and the desoldering work.
Before following that operation, positively identify the component and its footprint on your board. Preserve the pads and tracks; stop if the board is damaged or a connection cannot be confirmed.
This is the optocoupler-removal stage. It is not footage of a triac being removed.
View the optocoupler-removal demonstration7:18 Reference: Video 6:51–8:14
The archive’s close-up of the old optocoupler lead and coating area. 7:25 in the video Desoldering work during the optocoupler repair; not triac removal. 7:29 in the video
07
Fit the matched replacement and inspect
Fit the matched optocoupler only after verifying its orientation and pin assignments. Complete the soldered connections and inspect the repaired area under magnification.
Check for solder bridges, unconnected leads and damaged pads before reassembly. Complete the paired triac work required by the current kit advice using the verified board-specific instructions.
The photograph is a component-side reference from the optocoupler montage. It does not establish the new part’s marking or its pinout.
View the optocoupler-repair montage7:42 Reference: Video 6:51–8:14 · Current Dual Boiler kit advice · Technician sign-off requirements
Component-side context during the optocoupler repair. The replacement marking and pinout are not established by this view. 7:41 in the video Part 4 of 4
Refit and check
08
Restore protection and close the machine
The narrator calls for replacing the conformal coating removed during the repair. Use a suitable PCB coating and follow its application and curing instructions; do not treat extra coating as a substitute for fixing leaks.
Refit the board’s protective enclosure. Complete the model-specific reassembly and restore every cover and fastener before any powered functional check.
The still shows the protective board cover refitted. It does not show coating being applied or confirm that the complete machine has been reassembled.
View the coating note and board-cover refit8:14 Reference: Video 8:14–8:26 · Breville BES920 manual · Technician sign-off requirements
The board’s protective cover refitted. The complete machine is still open in this shot. 8:21 in the video
09
Verify the repair before handover
Have the repairer complete the appropriate electrical safety checks before returning the appliance to use. Check the repair, restored connections and protective parts as part of that sign-off.
With the machine fully reassembled, verify that the original heating fault has cleared and that there is no continuing leak. Stop and disconnect the supply if overheating or abnormal heating returns.
The original video ends with a brief powered check. It does not document a complete electrical safety test or a sustained temperature test; those checks still belong to the repair job.
Reference: Video 8:28–8:37 · Current Dual Boiler kit advice · Technician sign-off requirements
The original workshop film
Watch the repair in context
The archive includes live mains measurements from about 4:42 to 7:00. That section is for qualified technicians working under an appropriate electrical safety procedure. The written guide does not use those probe positions or readings as a DIY test.
Before returning the machine to service
This is a technician sign-off checklist, not a record of tests completed in the video.
The board and replacement parts have been positively matched to the machine.
The affected triac and optocoupler have been dealt with in line with the current kit advice.
Any leak that damaged or threatened the board has been repaired.
The repair, connections, protective enclosure and complete reassembly have been checked.
Appropriate electrical safety checks have been completed by the repairer.
A closed-machine functional check confirms the original heating fault has cleared.
Common questions
Does overheating prove that the triac is faulty? No. The symptom is a reason to investigate the heating control. The affected circuit and failed components must still be established. Do not use one voltage reading from the archive as a universal diagnosis.
Why does the video replace only the optocoupler? That is the repair demonstrated on the example machine. Current BrevTech kit advice is to replace both the triac and optocoupler, and repair the leak that caused the failure. The written guide makes that change in advice explicit.
Can I use this guide for an Oracle? This guide follows the Dual Boiler footage and BES900/BES920 kit scope. It does not establish the Oracle’s board layout, substitute-part orientation or regional board conversions. Use the correct Oracle information and parts for that machine.
Does the front-panel power button make the board safe? No. Disconnect the supply and have safe isolation verified before work. A panel light being off is not proof that the triac board is de-energised.
Sources and model notes
Written from BrevTech’s original video and current Dual Boiler kit advice. Stills are real video frames; their links open the matching source time. The source video is not a complete service manual.
Component-level mains repair is for suitably qualified repair technicians. Stop if the board, components or procedure cannot be positively identified. Read the BrevTech repair disclaimer .
