Download
Share
Print this page
  1. Manuals
  2. Brands
  3. Oakley Sound Manuals
  4. Power Supply
  5. PSU
  6. Builder's manual

Oakley Sound PSU Builder's Manual

Pcb issue 4
Hide thumbs

Advertisement

Quick Links

Download this manual
Oakley Sound Systems
Power Supply Unit (PSU)
PCB Issue 4
Project Builder's Guide
V4.4
Tony Allgood
Oakley Sound Systems
CARLISLE
United Kingdom
1

Advertisement

loading
Need help?

Need help?

Do you have a question about the PSU and is the answer not in the manual?

Questions and answers

Related Manuals for Oakley Sound PSU

Summary of Contents for Oakley Sound PSU

  • Page 1 Oakley Sound Systems Power Supply Unit (PSU) PCB Issue 4 Project Builder's Guide V4.4 Tony Allgood Oakley Sound Systems CARLISLE United Kingdom...
  • Page 2 This document hopefully contains everything you need to know to build and install the Oakley power supply unit. The PSU 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.

  • Page 3: Safety Warning

    Safety Warning The PSU 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 PSU circuit board. This metal panel should have adequate airflow around it. An example of such a panel is the 3U wide master panel which also contains a handy multiple and power switch.
  • Page 5 1A output one than this will be able to drive up to 250mA per rail. The Oakley PSU 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 Dizzy board to each output block. Multiple Dizzy boards should never be connected in daisy chain fashion. That is, each Dizzy board should always go back to the PSU separately and with the shortest and thickness wire you can use.
  • Page 7 15V or 18V AC output wallwart of linelump you can source. The current capability of the mains adapter will be the chief limiting factor in determining the maximum current draw of your PSU. For a variety of reasons I recommend the Yamaha PA- 20 and PA-30 supplies.
  • 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 The input and switch wiring to suit a PA-20 power supply.
  • Page 9 Which Power Devices? The two recommanded power transistors are chunky devices in a TO-247 package. These are the TIP35C for the NPN, and the TIP145 or TIP147 for the Darlington PNP. The TO-247 version of the TIP147. Note that the mounting hole is insulated from the metal parts of the case.

  • Page 10: Circuit Description

    It is possible to run the Oakley PSU module on a single phase. This means that the unit could be connected to a single output AC adapter, ie. one with just two leads to pins 1 and 2.
  • Page 11 (pin 1). Decrease the voltage at its base with respect to its emitter (pin 3) and the transistor will increase its effective resistance and the output voltage of the PSU will drop. The base voltage is controlled by the internal electronics of the LM723, but this in turn responds to the feedback from the output of the power supply.
  • Page 12 PA-20 can supply 0.94A of alternating current into a simple resistive load from each of its two outputs. But by the time the output of the PSU has been rectified and smoothed the DC current taken should not exceed 0.52A on a continuous basis.
  • Page 13 increased heat dissipation but a good heatsink will keep the temperature down to a safe level. If you can't comfortably touch a power device for more than ten seconds it is too hot. The 3U wide 5U high panel design has only been tested to work with a maximum of 0.52A per rail when driven from a PA-20 or PA-30.
  • Page 14 D1, D7, D2 and D6 protect the +15V and -15V output rails from a variety of naughties. On power down any excess current left in the modular will be shunted to the smoothing caps and not damage the now unpowered power supply components. Also, they also prevent the negative rail from going positive should the negative rail die for some reason.

  • Page 15: 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 16 Capacitors 22pF low-K ceramic 2.5mm 330p low-K ceramic 2.5mm 100nF axial multilayer ceramic C1, C2, C9 10uF, 35V electrolytic C3, C6, C10, C11 22uF, 35V electrolytic 470uF, 35V electrolytic 1800uF, 35V electrolytic C7, C8, C13, C14 Note: C7, C8, C13 and C14 are 105 degree Celsius radial types and have standard wire ended leads.
  • Page 17 There are three LEDs that can be fitted to the board to indicate power status. All three can be fitted to any panel you are using if you wish. I typically fit the green and orange ones to the board and have only a red LED fitted to the panel to indicate that the AC input is active. The colours of the LEDs are not important and these are just suggestions.
  • Page 18 Mounting hardware for Master Panel M3 10mm countersunk screws 4 off Panel front side M3 6mm pan head screws 4 off PCB top side M3 20mm countersunk screws 2 off For power devices M3 hex threaded 10mm spacers 4 off M3 star washers 10 off M3 washers...
  • Page 19 Attaching the Power Devices The PSU board fitted to a 4U 19” rack panel. Note the blue TO-247 insulator pads underneath the two chunky power devices. This section assumes you have purchased the 3U Schaeffer or FPE master panel or have a suitably drilled 5U high 19”...
  • Page 20 screw (countersunk for the master panel design) into the hole from the front, and fit a washer, star washer and nut onto the screw but keep it loose. Do the same for the TIP145. Now if you have done all this correctly, you should find that the when the power supply PCB is aligned once more, you can coax the power devices’...
  • Page 21 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. AC2 and 0V2 are left unused.
  • Page 22 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 23 Each case has its own PSU and each one is powered by a Yamaha PA-20. It is useful in this situation to ensure that both PSUs are grounded together. In other words, the two 0V lines from each power supply are electrically connected together.
  • Page 24 4mm banana sockets and plugs. The dedicated 0V screw terminal on the PSU board has been connected first to a bonding point which grounds the panel. The bonding point then connects to a 4mm banana socket on the left. Thus both the metal panel and the banana socket have a good connection to the PSU's 0V.
  • Page 25 An M4 ring terminal crimped to 24/0.2 insulated wire. This sort of connector is suitable for both the panel ground bonding point and attaching to the dedicated 0V screw terminal on the PSU board. 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.
  • Page 26 signal ground and clean ground. They'd all be connected to 0V somewhere in the system but the term ground was in common usage. Ground, when used in this way, is then a local common reference connection tied to the 0V of the unit's power supply.
  • Page 27 Using an Internal Mains transformer A 50VA toroidal transformer powering an Oakley PSU 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. The AC power indicator has not been fitted in this particular build.
  • Page 28 The mains transformer's secondaries should be rated: 18-0, 18-0 (twin secondaries) or 18-0-18 (centre tapped) 80VA This will give you a power supply that should be theoretically capable of just over 1A each rail assuming your heatsink and smoothing capacitors are up to the job. In this case you should make both R2 and R3 0R56 2W resistors.
  • Page 29 Connect the dedicated 0V screw terminal on the PSU board back to the panel's earth bonding point using at least 24/0.2 wire. It may be useful to make a two bonding points on the panel. One solely for the mains earth which can be located near the mains IEC inlet socket.
  • Page 30 Mains wiring diagram. For experienced builders only!
  • Page 31 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. MOTM modules can be modified to allow full Oakley compatibility although this should be done as you are building the module.
  • Page 32 Now with insulated wire connect this wire frame back to the dedicated 0V screw terminal on the PSU board. Now connect all the signal lugs, marked as T on the body of the socket, on the first four of the right hand column of sockets.

  • Page 33: Testing And Calibration

    Testing and Calibration Note all testing must be done with the heatsink or panel attached to the power devices. After wiring the unit according to the instructions given in the Users Manual 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 34: Final Comments

    Final Comments I hope that the Oakley PSU 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.