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Servicing Ampeg V2. |
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The amplifier came to the workshop with the following error message! When it has played five minutes It becomes unstable and fluctuating in strength. In addition, both lights defective. I found quickly a schematic. |
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The amplifier came on the workbench. |
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There were home bought a new set of JJ 7027A paired outlet from Germany and a set of new glim lamps from the US. |
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The amplifier was opened and troubleshooting could begin. The problem focused quickly around a series resistance of 180 K ohms at "Standby" glim lamp. the original resistance ½ watt on the PCB had burned It was replaced by a 1/4 watt which was also burned. Bias voltage should, according to the diagram be at -65 volts. There were inserted an adjustable resistance in BIAS circuit. It was adjusted to -45 volts. With the correct voltage amplifier played fine. |
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A small video with sound check. |
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