Augustica.com

This thread is for various questions as they come up while I put together my Frigate.

First up: Am I going to regret having put thermal paste between IC1 and its heat sink?

No, you do not need to.

OK, but will it hurt anything if I did? Or should I try to remove it?

No, it will not hurt anything. It is OK if you did, but it was not necessary.

OK, I'll leave it off the other two. That stuff is really messy even if you're careful.

Next question: Part of testing the power supply as you put it together is measuring the AC ripple component of the DC output. Can you do this if you don't have an oscilloscope?

I think you can do this with a true RMS multimeter if it has a "relative" feature. First, measure the DC to be sure it's at the right voltage. Then, use the relative button to zero the display. Then, switch the meter to read AC. You may need to adjust the range to get down to millivolts. At least, when I did this, I got the values predicted in the instructions.

Another question I think I've answered myself:

The parts list provided shows Vishay resistors but my kit included Dale resistors. This is not a problem but it took me an hour or so of painstakingly checking every resistor repeatedly looking for the 118 ohm ones. Eventually I realized that the Dale must not be available at exactly that value, and decided the 110 ohm resistors were the ones.

Some questions Augustica was kind enough to answer via email:

Can you stack the amplifier board atop the power supply?

Yes, but be careful of cooling. There will be no problem with magnetic flux. But this is a class A amplifier which means both boards will be generating significant heat. The heat sinks are handling 1.2 amps and need proper ventilation to function properly. And the 6H30PI tubes will get "very hot".

The Vishay resitors were not available for 118 Ohm and they were replaced by Dale at 110 Ohm.

You can measure the AC component by any means that you feel comfortable with - oscilloscope and multimeter - as long as you determine that the MOSFET (IC1) and LD1084 (IC2) perform their functions of reducing the AC component in the DC voltage they regulate.

Now working on the filament supply. All components for left channel soldered in except the heat sink for IC2.

With 12V AC applied at K3, the instructions say I should read 17V dc at K4. I am getting 7.12V dc with an AC component of around 1.5 to 2 mV.

What should I be looking at to determine and fix the problem? 7V actually seems like the right value to me but I have zero experience.

The manual says you should have 17VDC "after rectification" that is on the lids of the rectifying bridge D8-D11. On the K4 you should have about 7VDC which will drop to 6.3 - 6.5 VDC when you connect the headphone amplifier to the power supply. Your measurements are correct and show that everything works as it should.