For a view of these components in circuit, you may examine the DIY500 mkII schematic. For a verbal description of component functions and default values, see the DIY500 mkII Component Explanations page.
Please note that the second column from the left, titled "DIY500v1-4 PCB" lists equivalent component designations for the now discontinued original DIY500 PCB. Legacy DIY500 owners can use this to translate their old designs to the updated DIY500 mkII structure.
Key:
A = Amplifier, e.g. A1
C = Capacitor, e.g. C14
CONN = Connector, e.g. CONN1
D = Diode,e.g. D3
R = Resistor, e.g. R7
RV = Variable Resistor, as in a potentiometer
SW = Switch, e.g. SW2
T = Transformer
| DIY500 mkII PCB (2008 - present) Component Designation | DIY500v1-4 PCB (discontinued 2007) Component Designation | Purpose | Package | Default Value |
| present component designation equivalent to | former component designation | component function | physical component type, at present | default value, if any |
| +48VDC phantom power supply polarity protection | DO-41 rectifier diode | 1N4003 | ||
| -16VDC power supply polarity protection | DO-41 rectifier diode | 1N4003 | ||
| +16VDC power supply polarity protection | DO-41 rectifier diode | 1N4003 | ||
| phantom power "ON" indicator | standard 3mm PCB mounting LED | red | ||
| phantom power supply decoupling | 0.25W %1 metal film resistor | 100 Ω | ||
| 1/2 of phantom power application, current-limiting | 0.25W %1 metal film resistor | 6k8 Ω | ||
| 1/2 of phantom power application, current-limiting | 0.25W %1 metal film resistor | 6k8 Ω | ||
| 1/2 of series portion of attenuation "PAD" function | 0.25W %1 metal film resistor | 680 Ω | ||
| 1/2 of series portion of attenuation "PAD" function | 0.25W %1 metal film resistor | 680 Ω | ||
| shunt portion of attenuation "PAD" function | 0.25W %1 metal film resistor | 150 Ω | ||
| 1/2 of input transformer zobel network/termination, when necessary | 0.25W %1 metal film resistor | |||
| input transformer loading/termination, when necessary | 0.25W %1 metal film resistor | |||
| for DC coupling of the input signal | 0.25W %1 metal film resistor | 0 (zero) Ω, short-circuit | ||
| series resistor for input isolation | 0.25W %1 metal film resistor | 0 (zero) Ω, short-circuit | ||
| discharges C4, lowers input impedance, and biases A1, when necessary | 0.25W %1 metal film resistor | 1M Ω | ||
| series portion of A1 feedback network - determines minimum gain and biases A1 | 0.25W %1 metal film resistor | 10k Ω | ||
| shunt portion of A1 feedback network - determines maximum gain | 0.25W %1 metal film resistor | 100 Ω | ||
| series resistor for output load isolation | 0.25W %1 metal film resistor | 51 Ω | ||
| specialized Output Load Isolator (inductive resistor) in place of R14, sometimes recommended but never required | axial | Jensen JT-OLI-3 or John Hardy Co. Output Isolator | ||
| for DC coupling of the output signal | 0.25W %1 metal film resistor | 0 (zero) Ω, short-circuit | ||
| discharges C9, when necessary | 0.25W %1 metal film resistor | 100k Ω | ||
| +16VDC power supply decoupling, current-limiting | 0.25W %1 metal film resistor | 22 Ω | ||
| -16VDC power supply decoupling, current-limiting | 0.25W %1 metal film resistor | 22 Ω | ||
| passes output signal in the absence of T2 (unbalanced output) | 0.25W %1 metal film resistor | 0 (zero) Ω, short-circuit | ||
| grounds lo side of output (XLR pin 3) in the absence of T2 (unbalanced output) | 0.25W %1 metal film resistor | equal to R14 | ||
| connects the lo side of output to R20 in the absense of T2, or to secondary finish when T2 has only two windings | 0.25W %1 metal film resistor | 0 (zero) Ω, short-circuit | ||
| 1/2 of output transformer zobel network/termination, when necessary | 0.25W %1 metal film resistor | |||
| output transformer loading/termination, when necessary | 0.25W %1 metal film resistor | 1k5 Ω | ||
| LED1 current-limiting | 0.25W %1 metal film resistor | 10k Ω | ||
| Hi-Z front panel instrument input ("DI") | 1/4" TRS, switching, rt. angle PCB | Neutrik NRJ6HF-1 | ||
| Lo-Z front panel mic input (instead of using the rear panel input) | XLR female, rt. angle PCB | Neutrik NC3FAH2-0 | ||
| short-circuit C4 for testing | 3-position 0.1" pin headers with 2-position shunt connector | |||
| short-circuit C9 for testing | 3-position 0.1" pin headers with 2-position shunt connector | |||
| connect/disconnect R23 | 3-position 0.1" pin headers with 2-position shunt connector | Pos 1 | ||
| connect/disconnect chassis and ground | 3-position 0.1" pin headers with 2-position shunt connector | Pos 1 | ||
| provides additional filtering of high-frequency noise, improves transient response | 5mm (LS) radial metalized polyester film capacitor | 0.1uF 50V or 100VDC | ||
| phantom power supply decoupling | 8mm (dia.) radial electrolytic capacitor | 47uF 63V | ||
| 1/2 of input transformer zobel network/termination, when necessary | 5mm (LS) radial film capacitor | |||
| for AC coupling of the input signal | 5mm (LS) radial film or 5mm (dia.) bipolar/non-polar radial electolytic capacitor | 4.7uF 16VDC | ||
| high frequency compensation, when necessary | axial C0G/NP0 ceramic or 5mm (LS) radial capacitor | 100pF 50V or 100VDC | ||
| for separating the AC and DC feedback of A1 | 12.5mm (dia.) radial bipolar/non-polar electrolytic capacitor | 1000uF 6.3VDC | ||
| provides an alternate low impedance path for higher frequencies, improving transient response - rarely recommended, and never required | 5mm (LS) radial film capacitor | |||
| phase correction portion of A1 feedback network | axial C0G/NP0 ceramic or 5mm (LS) radial capacitor | 100pF 50V or 100VDC | ||
| for AC coupling of the output signal | 12.5mm (dia.) radial bipolar/non-polar electrolytic capacitor | 470uF 16VDC | ||
| provides an alternate low impedance path for higher frequencies, improving transient response - rarely recommended, and never required | 5mm (LS) radial film capacitor | |||
| +16VDC power supply decoupling | 8mm (dia.) radial electrolytic capacitor | 100uF 25VDC | ||
| -16VDC power supply decoupling | 8mm (dia.) radial electrolytic capacitor | 100uF 25VDC | ||
| provides additional filtering of high-frequency noise, improves transient response | 5mm (LS) radial metalized polyester film capacitor | 0.1uF 50V or 100VDC | ||
| provides additional filtering of high-frequency noise, improves transient response | 5mm (LS) radial metalized polyester film capacitor | 0.1uF 50V or 100VDC | ||
| 1/2 of output transformer zobel network/termination, when necessary | 5mm (LS) radial film capacitor | |||
| provides adjustable gain and drives the output | discrete or hybrid operational amplifier, same format as an API™ 2520 | |||
| adjusts gain | Bourns 51 Series or Clarostat 308 Series, 1/8" shaft, PCB pins | 25k Ω reverse (CCW) audio taper | ||
| unbalances input (CMR) and alters signal level/impedance, when necessary | many, leaded or PCB pins | |||
| balances the output and alters signal level/impedance, when necessary | American EI625 or EI50, leaded, w/o channel frame | quad litz (quadfilar) 150 Ω per winding | ||
| engages +48VDC phantom power when depressed | schadow-style DPDT pushbuttom, gold contacts | C&K (ITT) F2UEE AU | ||
| engages the attenuation "PAD" when depressed | schadow-style DPDT pushbuttom, gold contacts | C&K (ITT) F2UEE AU | ||
| reverses the signal polarity (equivalent to 180° phase inversion) when depressed | schadow-style DPDT pushbuttom, gold contacts | C&K (ITT) F2UEE AU |
