Seedysea
Well-known member
I have been building a green pre as my first foray into serious diy. I am learning a lot as I go, a very steep learning curve it is too.
I have a problem with phantom on the psu, which is one of PeterC?s boards. I get +15.3V and ?15.1V at the outputs, so that part of the circuit seems ok, but nothing out of phantom. That?s 0 V
I read as many threads as I could find and Peter had suggested to someone else to take out the voltage doubler and tripler caps and diodes and reinsert one at a time to check these. I did this and, although I don?t understand how a diode and a cap can double voltage, I know that this part of the circuit works, which was kind of cool to learn. I get 25.5V, 51V and 76.5V at each stage, so I can see that it works perfectly.
These figures are higher than those Peter kindly supplied on the documentation. Is it possible that the regulator (LM317) is not able to cope with this? I checked the voltage on the AC side of the first diode, (straight out of the transformer), and get 17.8V AC. The transformer is a 15-0-15 30VA that I want to use to power four preamps.
Can anyone help educate me here? What further tests can I make?
BTW, my first pre seems ok, although I haven?t put the ic?s in yet. I measured the voltages as per Peter?s chart and they seem good considering my voltage input to the board. I want to get the psu going before I move on.
I have a problem with phantom on the psu, which is one of PeterC?s boards. I get +15.3V and ?15.1V at the outputs, so that part of the circuit seems ok, but nothing out of phantom. That?s 0 V
I read as many threads as I could find and Peter had suggested to someone else to take out the voltage doubler and tripler caps and diodes and reinsert one at a time to check these. I did this and, although I don?t understand how a diode and a cap can double voltage, I know that this part of the circuit works, which was kind of cool to learn. I get 25.5V, 51V and 76.5V at each stage, so I can see that it works perfectly.
These figures are higher than those Peter kindly supplied on the documentation. Is it possible that the regulator (LM317) is not able to cope with this? I checked the voltage on the AC side of the first diode, (straight out of the transformer), and get 17.8V AC. The transformer is a 15-0-15 30VA that I want to use to power four preamps.
Can anyone help educate me here? What further tests can I make?
BTW, my first pre seems ok, although I haven?t put the ic?s in yet. I measured the voltages as per Peter?s chart and they seem good considering my voltage input to the board. I want to get the psu going before I move on.