How to test a Bi-Directional Triode Thyristor

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SUMMARY

The discussion focuses on testing a Bi-Directional Triode Thyristor (commonly known as a Triac) in a Carver model M-1.0t stereo amplifier. Participants suggest various testing methods, including measuring gate voltage across R409 and using a light bulb in series for out-of-circuit tests. The importance of the Triac in regulating power supply and its potential failure due to asymmetric firing is emphasized. Participants also discuss the complexities of the circuit design and the necessity of understanding the role of the Triac and associated components like opto-isolators.

PREREQUISITES
  • Understanding of Bi-Directional Triode Thyristors (Triacs)
  • Familiarity with amplifier circuit schematics
  • Knowledge of voltage measurement techniques using a Digital Multimeter (DMM)
  • Basic principles of AC power control and regulation
NEXT STEPS
  • Research testing methods for Triacs, including in-circuit and out-of-circuit techniques
  • Learn about the operation of opto-isolators in power control circuits
  • Study the principles of asymmetric firing in Triacs and its effects on circuit performance
  • Explore troubleshooting techniques for audio amplifier power supply issues
USEFUL FOR

Electronics technicians, audio amplifier repair specialists, and hobbyists interested in troubleshooting and understanding power control circuits in audio equipment.

  • #151
Referring to posts #146 (by Jim) & #147 (by Tom) above, the speaker current feedback seems to be explained here:

Particularly in the graphs at the bottom of post #5.
Small Amp Project (Tube/power stage info needed)
 
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  • #152
Good eye Tom !

I hadn't caught that in the Carver,
i only assumed they used current just to invoke a power limit.

But it's right there on the block diagrams , page 8 of service manual.
And specification page says
Damping Factor Greater than 9 - Tube Characteristics

Thanks !