New Sept 2020: CLICK HERE for detailed information on active circuitry on Thunder models
courtesy of Forum member Purge (David Blair)
Active circuit Version 1
Volume, tone, active gain, 3 mini switches for coil tap, phase and active on/off:
Notes
- Based on the wiring in a January 1983 Thunder IIA
- It should be suitable for any Thunder active guitar with controls for volume, tone and active gain and 3 mini switches for coil tap, phase reverse, and active on/off
- The coil tap and phase mini switches are DPDT
- The active bypass switch is a 4 pole changeover switch
- The volume pot is 500K log
- The gain pot is 250K log and the active tone pot is a 500K linear pot with a centre detent
- Resistor R1 is 1 meg, capacitor C1 is 0.022 microfarad mylar
1 – the white wire from the neck pickup connects directly to the red wire on the shielded cable to the pickup switch. The join is wrapped in insulated sleeving
2 – there is a pcb on the back of the phase switch which provides the interconnections between the terminals. If the switch needs replaced the pcb is not needed and can be replaced by 2 link wires as shown
3 – this is a bare wire which connects to single terminals on the coil tap and phase switches and also is soldered to the bodies of all three mini switches
4 – this battery earth connects to the switch terminal on the (3 terminal) jack socket – the circuit is completed when a jack is inserted, connecting this terminal to earth.
5 – One end of R1 and C1 connects to the switch terminal, the other end of both components is soldered to the switch body
click to enlarge
Fault Finding / Trouble Shooting Information for this Circuit
Active circuit Version 2
Volume, passive tone, active tone, 3 mini switches for coil tap, phase and active on/off:
Notes
- This diagram is based on the wiring in a mid-1983 Thunder II-A
- The wiring in a 1984 Thunder I-A is identical
- The 3 mini switches are all DPDT
- The volume and tone pots are 500K log
- The active tone pot is a 500K linear pot with a centre detent
- The tone cap C1 is a 0.022 microfarad mylar capacitor
All the passive components on the PCB are easily available, should any need replaced. The only active component is the IC, an LA6358 dual op-amp. These may be difficult to obtain, and can be directly replaced if needed by an LM358.
1 – the white wire from the neck pickup connects directly to the red wire on the shielded cable to the pickup switch. The join is wrapped in insulated sleeving
2 – there is a pcb on the back of the phase switch which provides the interconnections between the terminals. If the switch needs replaced the pcb is not needed and can be replaced by 2 link wires as shown
3 – this is a bare wire which connects to single terminals on the coil tap and phase switches and also is soldered to the bodies of all three mini switches
4 – this battery earth connects to the switch terminal on the (3 terminal) jack socket – the circuit is completed when a jack is inserted, connecting this terminal to ground.
click to enlarge
Active circuit Version 3
Volume, passive tone, active tone, pull switches for coil tap and phase, mini switch for active on/off:
Notes
- This diagram is based on the wiring in a 1985
- The PCB layout and components are identical to those in Version 2 of the active circuit (above)
- Pull switches for coil tap and phase reverse
- Mini toggle switch for active on/off
- The active on/off mini switch is DPDT
- The volume and tone pots are 500K log
- DPDT pull switches
- The active tone pot is a 500K linear pot with a centre detent
- The tone cap C1 is a 0.022 microfarad mylar capacitor
- All the passive components on the PCB are easily available, should any need replaced
- The only active component is the IC, an LA6358 dual op-amp. These may be difficult to obtain, and can be directly replaced if needed by an LM358.
1 – the white wire from the neck pickup connects directly to the red wire on the shielded cable to the pickup switch. The join is wrapped in insulated sleeving
2 – the ground wire/screen on the cables from the pickup switch and both pickups are all soldered to the body of the active EQ pot
3 – this battery earth connects to the switch terminal on the (3 terminal) jack socket – the circuit is completed when a jack is inserted, connecting this terminal to ground
click to enlarge
