Maybe an insulation issue? Does it work if you will lift the PCB off the chassis? Don't worry about developing heat without sinks when unloaded.
yes that did it. It now measures perfect when everything is detached from the chassis. Now I have to find the cause. Q2 has a isolation pad. the rectifying diodes did not get and isolation pas as a I assumed that these do not need isolation
thx
The diodes tabs in your picture do look encapsulated in plastic. Maybe a screw bites through the plastic to a diode tab?
Or a solder joint stresses when the build gets fastened down? Rework the bridge diodes and Q2 joints when assembled to the chassis so they may reposition pins a little in the pads holes.
To self relieve possible mechanical tensions. It's usually recommended in power amps and PSU builds to last solder chassis or sink loaded parts pins. After fixed in place for that reason.
To self relieve possible mechanical tensions. It's usually recommended in power amps and PSU builds to last solder chassis or sink loaded parts pins. After fixed in place for that reason.
That last thing is exactly what I did. First populated the pcb, then mounted all chassis mounted parts. Fixed the pcb's on the standoffs and as a last step I soldered the rectifier diodes and Q2 to avoid solder joint stresses when tensioning the screws for the chassis mounted parts.
I used a plastic shoulder washer on Q2 and mounted everything again on the chassis, checking voltages after every connection. Now all is fine. I think it was the srew for Q2 just touching the edge of the metal.
I am using it now on the RME ADI2. There is a clear difference. Tighter bass, more details and above all more rest. Let's see what it does in a few days.
In this version I used 2 Mundorf 10000uf/40V caps which i already had. I also have 6 pieces of Vishay/BC-components 15000uf/40V leftovers from a project.
Could i use these to build the next PSU? That will be a 19V version for a Intel NUC as Roon end point
I am using it now on the RME ADI2. There is a clear difference. Tighter bass, more details and above all more rest. Let's see what it does in a few days.
In this version I used 2 Mundorf 10000uf/40V caps which i already had. I also have 6 pieces of Vishay/BC-components 15000uf/40V leftovers from a project.
Could i use these to build the next PSU? That will be a 19V version for a Intel NUC as Roon end point
You can surely use the 15mF BC reservoirs for the NUC. It should utilize them during CPU bursts even.
Congratulations for finishing the first one for the RME DAC. Very nice to know it gives you audibly better results already.
Congratulations for finishing the first one for the RME DAC. Very nice to know it gives you audibly better results already.
I have done a prototype board and fired it up. Seems to work but with less voltage reduction. I have used some leds i have at home and they seems not to work out any good. Any suggestions for replacements? As you can see i need common single leds. I tried to measure them for voltage drop at 5mA but did not come out good in reality.
Attachments
I bought some Cisco Meraki ms220 8 port switches very cheap. I want to experiment with a LPSU upgrade and maybe later a OCXO clock. I will loose the original SMPS, also the one for the POE. I only need max .5A for the switch and 1 A for the clock. Would the L-adapter be a good choice or rather go to UltraBIB’s?
Regards,
Harold
Regards,
Harold
Transformer
I will be building a PSU for RPI4 plus Allo boss dac and I am only able to source a toroidal transformer 50VA 2 x 9V and just wanted to check if this would be OK.
I will be building a PSU for RPI4 plus Allo boss dac and I am only able to source a toroidal transformer 50VA 2 x 9V and just wanted to check if this would be OK.
You should add together the peak DC current consumption of that system's components first, and compare the transformer's current spec for both secondaries wired in parallel. Making sure it's sufficient. Keep in mind that due to full bridge rectification, the DC current spec is about 60% of the transformer's secondary side AC current spec.
A 50VA 9V toroidal example you can find full specs for, is Antek AS-0509. Other good makes should be of comparable spec.
Computers run on low average consumption compared to their peak spec when not pushed in peripheral configuration and heavy tasks. It's mainly about booting correctly in audio use. It's that phase when they pull most.
In such mini computer + dac systems 50VA is usually sufficient but always check the parameters of your own configuration and possible modes of use.
Computers run on low average consumption compared to their peak spec when not pushed in peripheral configuration and heavy tasks. It's mainly about booting correctly in audio use. It's that phase when they pull most.
In such mini computer + dac systems 50VA is usually sufficient but always check the parameters of your own configuration and possible modes of use.
You are welcome. Think mostly about average consumption. Transformers can cover strong peaks with some voltage sag. We don't want them to become hot by a high average is the main concern.
Hello!
I load on board 12V, 2A by electronic loader. Transformer 200Va. Power consumtion is 50W, so on transistors: 50 - 12*2 = 26W.
Is it ok for L-Adapter? It is extreamly high. What will be when wanted to have 4-6A load?
I load on board 12V, 2A by electronic loader. Transformer 200Va. Power consumtion is 50W, so on transistors: 50 - 12*2 = 26W.
Is it ok for L-Adapter? It is extreamly high. What will be when wanted to have 4-6A load?
L-Adapter can handle up to 100W output if with very good external sinking. Q2 dissipation in Watts is the voltage across its collector to emitter (Vce) multiplied by the output current it passes. Vce can be easily probed between the pins of D11 protection diode that spans Q2. Multimeter's red probe to cathode pin, black probe to anode pin.