29


External Speed Controller
Notes
The speed controller PCB can be left inside the plinth, in which case a cutout in the plinth layers is required, along with holes drilled in the top plate for the rotary switch shaft and the trim pots. Another possibility is to move the speed controller into an external case, either integrated with a power supply, or separate.  This section covers building a standalone unit.
As all PT1 turntables are at least twenty-five years old, it is worth considering replacing the electrolytic capacitors on the PCB; there are three in the circuit, so the cost and effort is minimal - use good-quality replacements of the same rating; they are common and easy to find.
This guide covers building a case with specific parts I have used, it must be adapted if other parts are used.

Building an external controller divides into these parts, which are documented over the following pages
Cutting and assembling the front panel, its switches and its PCB
Cutting and assembling the rear panel and its connectors
Removing the rotary switch and trim pots from the speed controller PCB
Building the Veroboard chassis and mounting the the speed controller PCB
Assembling the speed controller in its case and building the power lead
Components
Case and fittings
Black aluminium heat-sink case, 16510360mm – RS part – the case must be at least this size to comfortable accommodate the speed controller PCB and its ancillary components.
8 25mm M3 allen head stainless steel bolts
Replacement front panel 10360mm in laser etched and cut black 3mm acrylic – not essential, but looks nicer.
4 self-adhesive small rubber feet
1x Neutrik mono panel mount 3.5mm jack.
1x Neutrik 7 pin DIN socket
(Optional) IP67 black latching switch with LED indicator
100165mm Veroboard
Front Panel PCB

2 2 way terminal blocks
4 PC brass standoffs
4 PC M3 screws
4 5/32" nuts

7 Pin DIN power lead
1m+ of 8 core wire
1m+ nylon cable sheath
2   Neutrik 7 pin DIN plugs
Heatshrink or nylon mesh cover for power leads

Construction
Do not try unless you are competent and confident; this is just a guide, and assumes you know what you are doing.

Cut Veroboard to length of case; screw on front endplate with the M3 allen head bolts, and slide the Veroboard into the bottom slot of the case to check.