Related Manuals for Oakley Sound PSU2
Summary of Contents for Oakley Sound PSU2
- Page 1 Oakley Sound Systems PSU2 PCB Issue 1 Project Builder's Guide V1.3 Tony Allgood Oakley Sound Systems CARLISLE United Kingdom...
- Page 2 Introduction This is the Project Builder's Guide for issue 1 of the power supply unit, PSU2, circuit board from Oakley Sound. This document hopefully contains everything you need to know to build and install the Oakley power supply unit. The PSU2 allows for various options in the installation. You can use the unit either in full wave rectification mode for connection to tapped linelumps or twin transformer secondaries, or in half wave rectification for single phase AC output wallwarts and linelumps.
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Page 3: Safety Warning
Safety Warning The PSU2 has been designed to work with isolated low voltage AC inputs. Connection to any other supply, such as an internally mounted mains transformer, is done at your own risk. Low voltage is classified as being less than 25V with respect to the ground potential. Voltages above this level can, and often are, lethal to living creatures. - Page 4 The Oakley Power Supply Board The issue 1 PSU2 board from Oakley Sound Systems. The power supply board will allow the conversion of a suitable low voltage alternating current (AC) to be rectified, smoothed and regulated for operation with the Oakley Modular. The module is designed to be fitted to a suitably large metal panel which functions as a heatsink for the regulator ICs.
- Page 5 1A output one than this will be able to drive up to 250mA per rail. The Oakley PSU2 can be used with full wave or half wave rectification. The former allows it to utilise split AC outputs. With full rectification and using a centre tapped power supply the amount of current taken from each 15V rail can be up to just over half the rated current output of the power supply.
- Page 6 PSU2 board. I recommend that the metal panel the PSU module is mounted onto be securely connected to 0V. This can be done either via the PSU2's 0VA or 0VB terminal, or using a suitable point on your distribution system.
- Page 7 If you wish you can ditch their connector and use your own. Oakley Sound sell a suitable three way connector to fit the Yamaha one perfectly. In the UK the line lump’s part number is V9812300 and the total cost is around £30 including...
- Page 8 You should again fit both fuses and both should be 2A anti-surge types. If you have successfully used the Oakley PSU with any other types of power pack please do let people know via the Oakley Sound forum at www.muffwiggler.com...
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Page 9: Parts List
Parts List For general information regarding where to get parts and suggested part numbers please see our useful Parts Guide at the project webpage or http://www.oakleysound.com/parts.pdf. The components are grouped into values, the order of the component names is of no particular consequence. - Page 10 National's devices have a thicker and more rigid heatsink tab. Do not fit solder these into the board just yet. They are only to be soldered once the board is fitted to the panel. See the section on mounting the PSU2 board later in this document. Discrete Semiconductors...
- Page 11 Suitable power inlet socket Keystone 8191 PCB terminal & screw +15V, 0VA, 0VB, -15V 4mm 'banana' socket Optional – fitted on panel. * 4mm ring terminals (crimp/solder) For connection to outputs 2-way 0.1” Molex KK header LED (optional) You will also need thick wire to connect between the power inlet, switch and any connected distribution boards.
- Page 12 The LM337, U2, fitted into a 5U 19” rack panel. Note the grey TO-220 insulator pad underneath the regulator IC. The PSU2 PCB needs to be fitted to your chosen panel. Use the PCB as a template for marking the panel and then drilling the four 3.5mm holes needed for the mounting pillars. The...
- Page 13 mounting hole for the two devices. Now remove the board and regulators. Carefully drill a 3.8 or 4mm hole in the panel for each of the regulators. Clear off any swarf and, twisting with your hand only, use an 8mm drill bit to lightly deburr the edges of the holes on both sides. There should be no bumps around the holes.
- Page 14 Snip off any excess lead lengths above the solder joints. Assuming you haven't wired up the PSU2 board to any earth bond or distribution system yet, it is worth checking the insulation under the two regulators is working correctly. Check with your continuity tester, or using the resistance setting on your multimeter, that there is a very high resistance between the tab of each regulator and the metal panel.
- Page 15 Linelumps and Wallwarts: Wiring Diagrams Input wiring will depend on the type of wallwart or linelump you will be using. Standard AC output wallwart Single phase, two wire, wallwarts or linelumps need to use half wave rectification so the Oakley PSU can generate both positive and negative supplies simultaneously. They only need the terminal's AC1 and 0V1 wired to the power socket.
- Page 16 Recommended Option: Centre tapped wallwarts and linelumps Centre tapped linelumps like the Yamaha PA-20 will have three wires coming from their connector. It will have two AC outputs and one 0V. Take one of the AC outputs to terminal AC1 and the other AC output to terminal AC2. It should not matter which AC output goes to AC1 or AC2.
- Page 17 Fitting a Grounding Point and Grounding the Panel Using double insulated wallwarts and linelumps mean that you do not have to have a mains safety earth fitted to your modular. However, if your modular is to talk to the rest of the studio you need to make sure that the modular's 0V is tied to earth somewhere in your system.
- Page 18 This can be done in a variety of ways but one useful and simple method involves having a 4mm banana socket mounted near each power supply. The banana socket is then connected to 0V, using either the 0VA or 0VB screw terminal on the PSU2 board. Use at least 24/0.2 wire to make this connection.
- Page 19 A 4mm banana socket is taken to panel bond point which then is connected to the PSU2's 0VB terminal. Personal Note... One has to a little careful when using the word 'ground'. I sometimes talk about local ground and 0V as being the same thing. This is technically incorrect but it is used a lot. I worked at Marconi in the 80s and Soundcraft in the early 90s, and ground and 0V were used interchangeably even by seasoned engineers.
- Page 20 Using an Internal Mains transformer A 50VA toroidal transformer powering an Oakley PSU2 designed to deliver up to 750mA per rail. Note the wire loops fitted to the pads where normally the terminal block for the standby switch goes. Be afraid, be very afraid...
- Page 21 Mounting your PSU2 on a 4U or 5U 19” panel as detailed earlier will be more than adequate for a 1A supply. However, it is up to you to verify that your chosen panel is up to the job of keeping the two power devices cool.
- Page 22 restricting the current to below 90% of maximum will keep the transformer somewhat cooler. Hence the factor of two mentioned above is probably more realistic. Using a factor of two the maximum current drawn from our 80VA transformer is now 1.11A from both rails. In the wiring diagram shown I have included a suggested wiring method for connecting up a mains transformer.
- Page 23 IEC inlet socket, and another, located next to the PSU2 board, for the PSU's 0VB and optional 4mm banana socket connections. The metal panel serves as a low resistance connection between the two bonding points –...
- Page 24 Mains wiring diagram. For experienced builders only!
- Page 25 The Oakley Power Bus An Oakley PSU2 module connected to a single Dizzy board. Note that in this build the local 0V bond to the panel and 4mm socket is made via the Dizzy's 'Earth' connection and not directly from the PSU2's 0VB terminal.
- Page 26 The second ground is on pin 3. This is also connected to the power supply’s 0V output. This ground is connected only to the metal lugs of the sockets on each module, and therefore the panel itself, and nothing else on the module. This way it is impossible for any signal return currents to travel down the inserted patch cords since the panel is isolated from the system ground except at one point, the PSU.
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Page 27: Testing And Calibration
Testing and Calibration After wiring the unit according to the instructions given in this document you should apply power to the unit. Check that no device is running hot. Any sign of smoke or strange smells turn off the power immediately and recheck the all the external wiring first, and then the components on the board. -
Page 28: Final Comments
Final Comments I hope that the Oakley PSU2 lives up to your expectations and provides you with a reliable source of power for your modular system. If you have any questions about the module, an excellent source of support is the Oakley Sound Forum at Muffwiggler.com.