Im having trouble figuring out what the problem is with this little board.
It is a board that shorts the outputs when off, of a valve preamp. Probably to protect against on/off transients.
16v AC comes from a secondary winding on the transformer. Its rectified, regulated to 12v and smoothed. That alone should do the job. But this board also has two transistors on it. I think the transistors provide a de-bounce protection for the relays, but aim not 100% on that.
This board has failed. I’ve confirmed that the rectifier is rectifying, the regulator is regulating, the capacitor is filtering. I’ve installed new transistors.
If i supply voltage to the relays directly from the output of the regulator, they click.
But otherwise, they do not. The circuit doesn’t work.
I need to understand what the transistors are there for. If not as a de-bounce function, then what?
My next step will be to replace the relays in case they are worn out.
It is a board that shorts the outputs when off, of a valve preamp. Probably to protect against on/off transients.
16v AC comes from a secondary winding on the transformer. Its rectified, regulated to 12v and smoothed. That alone should do the job. But this board also has two transistors on it. I think the transistors provide a de-bounce protection for the relays, but aim not 100% on that.
This board has failed. I’ve confirmed that the rectifier is rectifying, the regulator is regulating, the capacitor is filtering. I’ve installed new transistors.
If i supply voltage to the relays directly from the output of the regulator, they click.
But otherwise, they do not. The circuit doesn’t work.
I need to understand what the transistors are there for. If not as a de-bounce function, then what?
My next step will be to replace the relays in case they are worn out.
