This service is similar to the full component replacement option except the active circuitry is replaced with high performance drop in replacements designed in house. If you opt for this option, the three vertical plug in PCBs and the tape PCB will be replaced with new circuits that fit the existing wiring looms and edge connectors. The remaining sockets, switches, fuse, pots, wound components will be reused. If any fail our test, we will inform you before going ahead with any work. We suggest you only go for this option if your Quad 33 is in physically good condition. e.g., good paintwork, push button switches functioning correctly, edge contacts undamaged, case intact. If you are unsure we will check for free (you are of course responsible for the cost of delivery and return). What we do: After verifying that your 33 'parts to keep' are in good condition (we inform you if any are not); we strip all the existing components from the motherboard PCBs as these boards will be re-populated with new high quality components. For example, the resistors are 1% metal film types and the old capacitors are replaced with new foil caps. The totally redesigned circuits, (the three internal vertical plug in PCBs and the horizontal 'tape' PCB), are designed in house to fit the existing slots. These use high performance op-amps to enhance the sonic performance. They fit straight in to the existing slots. The legend light is replaced with an LED with the same warm lamp glow as the original. The push button switches are individually dismantled, contacts cleaned and reassembled. A similar dismantling action is carried out on the slider pot. If the switched volume control and tone pots are in good working order, we clean the wipers and tracks. Faulty controls are replaced. The edge connectors are also checked for integrity and cleaned. Everything is then assembled back in place and the system is then checked for correct operation. Finally a full listening test, PAT and bench soak test is carried out. Like our full-component-replacement option, this is a labour intensive operation and hence more expensive than our standard full service.