Dynaco ST-70 Diagnosis

Job ID: 40183657

Budget: $30 – $250 CAD

My Dynaco ST-70 tube amplifier is not producing sound. The power tubes light up, but the preamp tubes do not. I'm seeking an expert to diagnose the issue.

Requirements:
- Experience with tube amplifiers, particularly Dynaco models
- Ability to identify electrical issues without needing specialized tools
- Prior troubleshooting and repair experience in audio equipment

Please provide a clear diagnosis and potential repair options.