Coffee | One Roast at a Time

Roast Interruption – Gene Café CBR-301 (E4 Error)

This note documents a recent interruption during roasting and the steps taken afterwards. It sits outside normal roast analysis, but is important from a system and reliability perspective.

What Happened

During a standard roast, the machine began as expected, with temperature rising normally. Shortly into the roast, an unusual buzzing sound was noticed from the right-hand side of the roaster. Immediately after this, temperature began to fall rather than continue rising.

At the time, no error was displayed on the machine.

The roast was stopped and the machine powered down. Initial checks were carried out:

  • Power cycle
  • Full chaff path clean
  • Visual inspection

The issue persisted.

Re-Test and Error Identification

On re-running the following morning, the behaviour became repeatable and clearer:

  • Roast starts normally
  • Approximately 1 minute into the roast
  • Machine displays E4 error
  • Heating does not recover

This occurred consistently across three separate attempts.

The image below shows the error as displayed on the machine.

(Insert image of E4 error here)

Observation vs Interpretation

Observation

  • Temperature rise initially normal
  • Audible buzzing from right-hand side
  • Temperature drop mid-roast
  • E4 error triggered on subsequent runs (~1 min)
  • No recovery of heating

Interpretation (working)

  • This does not match normal thermal protection behaviour (fan increase + stabilisation)
  • Behaviour suggests a failure in the heating system or power delivery rather than a control adjustment

This is recorded as a working hypothesis, not a confirmed diagnosis.

App / Data Limitation

The Gene Café app did not save the roast log for the failed run.

This reinforces an important limitation:

The app records state (temperature, fan, time) but does not log machine errors or failure events.

In this case, the most important signals were:

  • Sound
  • Temperature behaviour
  • On-machine error code

These sit outside the JSON data model.

Support and Resolution Path

Both Gene Café and 88graines have been responsive and supportive.

  • Gene Café (David) responded quickly and requested video evidence
  • 88graines (Ola) confirmed support under warranty

A replacement part is being arranged through 88graines. They have offered:

  • Installation by themselves
  • Or allowing installation directly

The plan is to:

  • Install the part directly
  • Document the process
  • Record and share the full installation and outcome

Why This Matters

This sits slightly outside roasting, but it is part of the same system:

  • Roasting is not just profiles and outcomes
  • It is also machine behaviour, reliability, and failure modes

This event adds a new layer to the project:

Understanding not just how the machine behaves when it works — but what happens when it doesn’t.

Next Steps

  • Receive replacement part
  • Install and document
  • Validate behaviour post-repair
  • Resume roasting with the same baseline approach

A follow-up note and video will document:

  • The repair process
  • Any internal observations
  • Whether behaviour returns to expected patterns

Closing Thought

This is part of the process.

Not everything is controllable, and not everything is predictable. But each event — including failures — adds clarity to the system as a whole.

Nothing changes about the approach:

  • Observe
  • Record
  • Understand
  • Continue

One roast at a time.