Power transformers play a critical role in electrical networks, making their uninterrupted functioning and durability paramount, especially in regions prone to seismic events like the Cianjur Earthquake in West Java, Indonesia in 2022. Ensuring transformers' resilience under various environmental conditions becomes imperative. This study explores innovative methodologies for transformer diagnostics, aiming to address gaps in existing practices. While conventional diagnostic techniques are widely used, this research uniquely integrates several methods to provide a comprehensive assessment. Notably, the Sweep Frequency Response Analysis (SFRA) emerges as a standout approach for detecting flaws or deformations in power transformers, offering insights beyond traditional diagnostic protocols. Our findings, juxtaposed against conventional tests such as turn ratio, insulation resistance, and breakdown voltage tests, reveal nuanced insights into transformer health. Contrary to conventional assessments indicating satisfactory performance, SFRA uncovers subtle yet significant flaws within the transformer, underscoring the novelty of our approach. Despite moderate degradation levels, our study underscores the critical need for advanced diagnostic strategies, shedding light on transformer resilience in seismic-prone regions. Such insights contribute to the evolving discourse on transformer diagnostics, guiding future maintenance practices for enhanced grid reliability.