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MP566 Tube microphone preamplifier / Re: No Mic Input And Saturation on DI
« on: February 25, 2021, 06:31:09 PM »
The No Mic issue may come from a damaged 2N7000 (Q1). This component is sensitive to static electricity and is better handled without your shoes on (body grounded).
You can check this by creating a short between the 2 extreme pins of this component. It should activate the mic relay.
Do you have a gain variation between the mid and high gain?
Check the DC voltage on TP4. it should be close to 0.
You can check this by creating a short between the 2 extreme pins of this component. It should activate the mic relay.
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I have a click between the Low and the Mid but nothing for the HighThis is normal, the high gain is directly controlled by the switch, without a relay.
Do you have a gain variation between the mid and high gain?
Check the DC voltage on TP4. it should be close to 0.