Another Breville Dual Boiler Rebuild - leaky probes, disintegrated boiler bracket, rust everywhere

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
Johntron
Posts: 10
Joined: 5 years ago

#1: Post by Johntron »

In the spirit of Brian's Breville Dual Boiler Rebuild thread, I've decided to try repairing my BDB and document the process.

Links: Existing usage and maintenance:
  • 3-4 drinks a day
  • Filtered water - moderate hardness before filtration, slightly soft after filtration
  • Regular backflushes (at least 1x per day)
  • Descaling every month or so
  • O-ring replacement every ~1yr (obviously excluding inner o-ring on probes :( )
Background:
  • Original BDB was repaired after developing a leak, but was damaged during return shipment
  • The (clearly refurbished) unit Breville sent me arrived - I believe it already had a leak at the steam boiler probes (video linked below)
  • Back-and-forth trying to get unit repaired again
  • Life got busy, support issue was closed
  • Kept using the machine like an idiot
  • Months elapsed then machine stopped heating
Symptoms:
  • A leak from around the probes on steam boiler. Video of the leak.
  • Little to no heating according to temp on LCD
  • No steam (once or twice)
  • Before the above, pump didn't activate to fill boiler(s) (once) - any idea why?
The culprits: innermost o-rings on at least two probes allowed steam to escape from boiler by flowing between the ceramic/phenolic boss and metal probe


The victims:





Theory of failure:
  1. Steam escaping from probes corroded group head heater terminal
  2. Circuit for group head heater opened
  3. Machine was unable to heat. I don't see any voltage sensing on this circuit, so the machine would've attempted heating; however, the circuit failed open, so no heating would happen.
  4. I'm not sure why there was no steam, but it could've been related to the pump not turning on - thoughts?
Repairs needed (will update if/when I find more):
  • O-rings inside boiler probes (I'll replace all o-rings)
  • Bracket holding steam boiler - a good portion has disintegrated from rust
  • Tube clip on very top (center) of steam boiler
  • Group head heater terminal
  • Possibly the thermal fuse normally secured to side of steam boiler
  • Mica insulating washers on both sides of the boiler flanges where the bracket (above) attaches
  • Reattach grounding wires previously attached to steam boiler bracket
  • Rust removal and prevention
  • Screw extraction - the heads of a couple have rusted and stripped / broke
  • Replacement of many/most screws
Parts needed - please help me find them!
  • Bracket holding steam boiler - will attempt to 3D print with high-temperature filament - lmk if you know a source of the original!
  • O-rings - all of them. Help me compile a list?
  • Tube clip for top tube on steam boiler
  • Potentially the thermal fuse on steam boiler
  • Metal band for securing thermal fuse to steam boiler - currently considering stainless hose clamp for ease of tightening
  • Ring terminal connectors for grounding on steam boiler bracket
  • Some high-temperature coating to prevent new rust on all the terminal connectors - conformal coating, high-temp paint, or something else?
Changes to maintenance:
  • Regular inspections inside the unit
  • Replacement of inner probe o-rings (I've already been replacing rings with Viton every ~1yr)
Next steps:
  1. Document all the major components - names, types, specifications, etc.
  2. Create netlist of all major components (KiCAD)
  3. Test thermal fuse (in situ), pumps (in-situ?), and triac board (in situ)
  4. Reattach (solder) group head heater wire
  5. Turn machine on and see if it heats
  6. Assuming machine heats ...
  7. Order high-temp 3D filament, o-rings, tube clip, large stainless hose clamp, and ring terminal connectors for grounding
  8. Design, print, and test-fit new boiler bracket
  9. Re-attach thermal fuse
  10. Mount boiler
  11. Attach grounding wires to original steam boiler bracket (what's left of it)
  12. Temporarily assemble everything and test all functionality
  13. Disassemble
  14. Paint boiler mounting bracket to prevent future corrosion
  15. Clean rust, replace screws
  16. Apply anti-corrosion coating on all terminal connections
  17. Reassemble and enjoy some 'spro again

jkoll42
Posts: 105
Joined: 14 years ago

#2: Post by jkoll42 »

This is going to be a tough one especially as Breville has discontinued the model and I wouldn't expect much support as far as parts even if it was a current model.

If this is being done more of a hobby 'let's see if I can do it and it will be fun' project have at it. It would be cool to see everything fixed from the current sorry state it's in.

If this is being done as a practical 'let's fix this because it will be cheaper to fix than throw out and buy something new' I would heavily advise against it. You're in for a ton of work with a very uncertain outcome!

Either way, I'm here for it.

Johntron (original poster)
Posts: 10
Joined: 5 years ago

#3: Post by Johntron (original poster) »

Why do you say Breville has discontinued it? It should be a BES920XL, which is the current model, no? Regardless, I do realize only the most-frequently-replaced parts are obtainable - e.g. triac board, solenoids, pumps, some valves.

I enjoy hacking, so I figured I'd give it a shot. If the connection to the heater and some structural components are all that's wrong, maybe it's easier than it seems. The other parts don't look great, but most of the corrosion seems to be superficial, and the electronics look good.

For the record, I'm planning on buying a new machine. If I fix this one, then I'll either (try to) sell it to recoup losses, keep for parts, or build my own control board.

User avatar
lancealot
Posts: 1141
Joined: 7 years ago

#4: Post by lancealot »

Subscribed. I don't know why people keep repeating that the BDB has been discontinued. It has not.

Johntron (original poster)
Posts: 10
Joined: 5 years ago

#5: Post by Johntron (original poster) »

Yeah, to be clear, Breville has already offered a replacement at 40% discount. They're out-of-stock on website, but not sure about inventory otherwise. There have been multiple discussions around how frequently BDBs go out-of-stock for extended periods of time. It could be they're sending them all out as replacements for the broken ones :wink:

Johntron (original poster)
Posts: 10
Joined: 5 years ago

#6: Post by Johntron (original poster) »

First update

:!: See first post for links to useful schematic, spreadsheet, and photos.

Temporary shower head heater connection
I've soldered the lead back on the shower head. Warning: this is just a temporary solution to allow me to test that it turns on (for a brief period). I'll be finding screw-down terminal to attach these long-term - a suggestion from r/AskElectronics.

Now:


For reference, this is what it looked like initially (broken / open circuit):


Re-attaching thermal fuse on steam boiler
I picked up a 1/2in (12.7mm) wide, 2-4in (51-101mm) diameter hose clamp from the hardware store, and used it to reattach the thermal fuse on the steam boiler:



For all my projects, I try to use readily-available parts in case I need to repair or someone else wants to replicate my work. Brian used zip ties, but I didn't see these at the hardware store; they also can't be re-tightened if needed AFAIK. Hose clamps are readily available, and I think it's sufficient with a little modification.

The diameter is good, but I'll need to modify around the thermal fuse; after initially attaching the band right over the top of the thermal fuse and tightening a little (not too much!), it's clear there's still a bend in the hose clamp. I think with thermal cycling, these bends could loosen. I don't want to have to constantly be opening the machine to check and tighten this, so I'll modify it to minimize slack in the clamp. I'll do the modification after some initial testing - trying to minimize effort until I know the machine can be fixed.

Documentation
I've also taken some photos of the main PCB and started a schematic in KiCAD. Links will be added to the first post for discoverability, but here's some low-res photos - including the back!



At a high level, AC power is supplied from wall outlet to the main PCB. There's some crude protections there, then AC line is routed through the triac board to the various heater elements before returning to AC neutral on the main PCB via blue wire. :!: All wires for the heaters pass through a section at the back of the unit. There you'll find a bunch of crimp-on connectors and a plastic clip securing everything to the chassis. This would be a great place to test connectivity, resistance, etc. without taking everything apart.



Wires from traic board to heaters are labeled with these colors on my machine (your may not be):
Red: coffee boiler
Orange: shower head heater
Rust (orange/red): Steam boiler

All wires returning from heaters to AC neutral (via the PCB) are blue.

The thermal fuse on the steam boiler seems to be normally on, turn off at 152C, and turn back on at 27.5C. This is what I could deduce from these markings: 36TMH01 566484 L152-27.5C-Z2119 (also included in spreadsheet - link in first post).

I've also found a PDF of the parts diagram - I'll include this among the files linked in the first post.

Progress:
  1. [started] Document all the major components - names, types, specifications, etc. - links added to first post
  2. [started] Create netlist of all major components (KiCAD) - links added to first post
  3. [started] Test thermal fuse (in situ), pumps (in-situ?), and triac board (in situ)
  4. [started] Reattach (solder) group head heater wire - temporary; will replace with screw-down terminals
  5. Turn machine on and see if it heats
  6. Assuming machine heats ...
  7. Order high-temp 3D filament, o-rings, tube clip, large stainless hose clamp, and ring terminal connectors for grounding
  8. Design, print, and test-fit new boiler bracket
  9. Re-attach thermal fuse
  10. Mount boiler
  11. Attach grounding wires to original steam boiler bracket (what's left of it)
  12. Temporarily assemble everything and test all functionality
  13. Disassemble
  14. Paint boiler mounting bracket to prevent future corrosion
  15. Clean rust, replace screws
  16. Apply anti-corrosion coating on all terminal connections
  17. Reassemble and enjoy some 'spro again
Parts needed:
  • [NEW] Screw-down terminal for securing wire from triac board to shower head heater conductor
  • Bracket holding steam boiler - will attempt to 3D print with high-temperature filament - lmk if you know a source of the original!
  • O-rings - all of them. Help me compile a list?
  • Tube clip for top tube on steam boiler
  • Potentially the thermal fuse on steam boiler
  • [acquired] Metal band for securing thermal fuse to steam boiler
  • Ring terminal connectors for grounding on steam boiler bracket
  • Some high-temperature coating to prevent new rust on all the terminal connectors - conformal coating, high-temp paint, or something else?

Johntron (original poster)
Posts: 10
Joined: 5 years ago

#7: Post by Johntron (original poster) »

Fun-fact: rust converters can create super nasty by-products when heated. Don't use these in your machine! I'm thinking of using a brass brush on rotary tool to remove as much rust as possible, then coating things in some high temperature paint with a rust inhibitor. I'll probably leave the boilers uncoated, since they're supposed to be stainless and not something with a galvanized surface (which would be damaged by rust removal).

jkoll42
Posts: 105
Joined: 14 years ago

#8: Post by jkoll42 »

Johntron wrote:Why do you say Breville has discontinued it? It should be a BES920XL, which is the current model, no? Regardless, I do realize only the most-frequently-replaced parts are obtainable - e.g. triac board, solenoids, pumps, some valves.

I enjoy hacking, so I figured I'd give it a shot. If the connection to the heater and some structural components are all that's wrong, maybe it's easier than it seems. The other parts don't look great, but most of the corrosion seems to be superficial, and the electronics look good.

For the record, I'm planning on buying a new machine. If I fix this one, then I'll either (try to) sell it to recoup losses, keep for parts, or build my own control board.
The discontinued part was based on a prior post on HB as well as reddit where Max Stoiber received a response from Breville that the DB was discontinued.

mangoie
Posts: 67
Joined: 2 years ago

#9: Post by mangoie »

Unless this discontinuation message was posted in the last two months, the myth that Breville discontinued the Dual Boiler has already been debunked.