Editing QIDI (section)

===Solid-state relay (SSR) failure===

The primary component identified as a point of failure was the Solid-State Relay (SSR), an electronic switch that controls power to the mains-powered chamber heater. The investigation concluded that the SSR was under-specified for the electrical load, particularly in regions with a 110V power grid. The higher current draw at 110V caused the SSR to operate near its maximum rating, leading to overheating and a high likelihood of failure.<ref name="RedditSSR_PSA">{{Cite web |author=r/QIDI |date=2024 |title=PSA: SSR Safety Issues With Qidi Tech PLUS 4 Printer: 'The way it's been handled so far can only be described as negligent... As of right now I cannot recommend this printer.' |url=https://www.reddit.com/r/QIDI/comments/1ghh06b/psa_ssr_safety_issues_with_qidi_tech_plus_4/ |access-date=5 Aug 2025 |website=[[Reddit]]}}</ref>

Crucially, a common failure mode for an SSR is to fail "closed," meaning it becomes permanently stuck in the "on" position. This allows unregulated power to flow to the heating element, causing a thermal runaway where the temperature rises uncontrollably until a component ignites.<ref name="MakerForums" />