Hi to all, i've just finished my psu board for f5. I'm checking with my dmm the v+ and gnd and I have a value of 1kohm, sometimes the value starts at 0,6 and increases slowly. Now it's at 6kohm
Are your capacitors soldered already? You could be reading the internal resistance of the capacitor as it charges. You can check V- to GND and should show the same behavior.
I believe as of now there is no immediate plan to separate the diode section with the capacitor section.
I am selling a kit of parts for the Power Supply board, to make a PSU suitable for a Pass/Firstwatt amp.
Please take a look here for information -
http://www.diyaudio.com/forums/group-buys/241063-aleph-j-kit-parts-2.html#post3639220
Please take a look here for information -
http://www.diyaudio.com/forums/group-buys/241063-aleph-j-kit-parts-2.html#post3639220
R9,R10 are bleeder resistors used to empty the capacitors when power is removed. The value is is determined by the total capacitance, rail voltage and how fast you want to bleed off your caps balanced with the dissipation in the resistors. At <30V (Aleph-J) your bleeders can be a lot lower value than at 65V (Honey Badger)
R12-C17 and R11-C18 form output snubbers. These are optional, values specific to your particular setup. Pass doesn't think them necessary.
R20 and R21 are current limiting resistors for the LEDs that indicate the rails are working properly. You can omit if you would like, or use one as the front panel power indicator.
R12-C17 and R11-C18 form output snubbers. These are optional, values specific to your particular setup. Pass doesn't think them necessary.
R20 and R21 are current limiting resistors for the LEDs that indicate the rails are working properly. You can omit if you would like, or use one as the front panel power indicator.
I would also recommend that you read the build guide I prepared for the earlier version of the PSU. Lot's of stuff I think you would need. If you can't find it, shoot me an email and I'll send it to you.
The board is meant to be used not just for NP's amps but for other amps too. If you are dead set on following Pass's recommendations then just substitute his values and use those in the V3 boards.
Thanks Bob and Jojo.
I've already assembled the psu according to your guide and bom. So I can maintain the board populated according to jojo guide and wire it to the trafo and inlet according to NP design: 0.0033 capacitor and CL-60 to limit ripple and inrush. Is it right? What about the voltage of the little cap?
I've already assembled the psu according to your guide and bom. So I can maintain the board populated according to jojo guide and wire it to the trafo and inlet according to NP design: 0.0033 capacitor and CL-60 to limit ripple and inrush. Is it right? What about the voltage of the little cap?
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The voltage of that .0033 uf cap should exceed your mains voltage since it is connected across the mains.
MOST IMPORTANTLY IT SHOULD BE A "Y" RATED CAPACITOR. THIS IS A SAFETY ISSUE!
Y rated capacitors fail open, where other caps may fail in a short. The purpose of that cap is to suppress spike caused by switching the amp off.
The CL60 limits inrush, has nothing to do with ripple. When cold it has a high resistance that goes to a low value as it heats up and therefore becomes almost invisible once the amp has reached its steady state current.
MOST IMPORTANTLY IT SHOULD BE A "Y" RATED CAPACITOR. THIS IS A SAFETY ISSUE!
Y rated capacitors fail open, where other caps may fail in a short. The purpose of that cap is to suppress spike caused by switching the amp off.
The CL60 limits inrush, has nothing to do with ripple. When cold it has a high resistance that goes to a low value as it heats up and therefore becomes almost invisible once the amp has reached its steady state current.
An X-Class or a Y-Class capacitor is a MUST for that little cap. The special attention given to the Y-Class is because it is meant to be installed line-to-ground whereas the X-Class is more of a line-to-line type.
If the X-Class fails to a short in a line-to-line, your fuse blows whilst if a Y-Class cap fails into a short in a line-to-ground application your amp becomes an electrical hazard.
When the DC rails sag in the PSU unevenly, the dual bridges help keep the AC in the transformer from making mechanical hum and buzz.
You can of course use only one bridge. I've built an F5 that way and it works fine.