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- Joined
- Feb 9, 2013
- Messages
- 424
Welcome to EP Muhamad,
Please describe more about the problem.
Please describe more about the problem.
73's de Edd
- Aug 21, 2015
- 3,622
- Joined
- Aug 21, 2015
- Messages
- 3,622
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Sir muhamad. . . . . . .
Of your very first consideration, would be a voltage check of the marked in two YELLOW test blocks areas of their voltages, to see if the power amps + and- 21 volts of each of the power amps are balancing out to ~ 0 VDC by proper biasing of the individual power amps transistors.
If that voltage is proper, then the next consideration would be if the power output stages are pulling excess current, which would be shown at the GREEN test block area which is fed from the two Q129-Q130 sampling transistors.
If it takes SOME time to fail to O/L, that could be due to the heat sink gradually heating up and shifting its thermistor samplers TH101-102.
They would activate Q 291-291 by the voltage shift at the GREEN test blocks area.
POWER AMP Schema:
73's de Edd
.
Sir muhamad. . . . . . .
Of your very first consideration, would be a voltage check of the marked in two YELLOW test blocks areas of their voltages, to see if the power amps + and- 21 volts of each of the power amps are balancing out to ~ 0 VDC by proper biasing of the individual power amps transistors.
If that voltage is proper, then the next consideration would be if the power output stages are pulling excess current, which would be shown at the GREEN test block area which is fed from the two Q129-Q130 sampling transistors.
If it takes SOME time to fail to O/L, that could be due to the heat sink gradually heating up and shifting its thermistor samplers TH101-102.
They would activate Q 291-291 by the voltage shift at the GREEN test blocks area.
POWER AMP Schema:
73's de Edd
.
