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Step 10Building an "Isolation Module"
I built it as a small self-contained module, mounted on a block of wood.
There are other ways, of course. All the components can be mounted directly on the cabinet itself. The cab plywood is rather thin for this amp, so best to use the wooden block for a base.
Make the module base
A scrap piece of poplar 1x2 was used, cut to a length that easily fit all the components.
Add a fuse holder
The fuse holder is a pretty standard type. It's mounted in a small piece of galvanized metal plate (originally a truss plate.) Metal plate is definitely the best choice for securing this kind of fuse holder device. Thin plywood wouldn't be secure.
A stepped drill bit was used to drill the hole for the fuse holder. Wood screws were used to attach the plate to the base.
Mount the transformer
This is straight-forward. The N68-X transformer is attached with a pair of wood screws.
Make internal connections
Wire the module using the schematic / wiring diagram on Step 7. You can find it below.
Some pointers:
-- The switch and fuse should be on the Hot "mains" wire.
-- When routing the switch wire, avoid the signal path where ever possible.
-- Connect the transformer primary wires as noted. This is US, 120V wiring. Euro wiring will be different (and is explained on Step 7.)
-- I used "wire nuts" to connect the wires, but soldering is more secure. Once I'm satisfied with the setup, I'll replace the nuts with solder, and cover with heat-shrink tubing.
Add some strain-relief for the cord
I used plastic wire channels to fix the cord in place. Electrical cords must have some strain-relief, or flexing will quickly lead to disconnections or shorts.
There are other ways, of course. All the components can be mounted directly on the cabinet itself. The cab plywood is rather thin for this amp, so best to use the wooden block for a base.
Make the module base
A scrap piece of poplar 1x2 was used, cut to a length that easily fit all the components.
Add a fuse holder
The fuse holder is a pretty standard type. It's mounted in a small piece of galvanized metal plate (originally a truss plate.) Metal plate is definitely the best choice for securing this kind of fuse holder device. Thin plywood wouldn't be secure.
A stepped drill bit was used to drill the hole for the fuse holder. Wood screws were used to attach the plate to the base.
Mount the transformer
This is straight-forward. The N68-X transformer is attached with a pair of wood screws.
Make internal connections
Wire the module using the schematic / wiring diagram on Step 7. You can find it below.
Some pointers:
-- The switch and fuse should be on the Hot "mains" wire.
-- When routing the switch wire, avoid the signal path where ever possible.
-- Connect the transformer primary wires as noted. This is US, 120V wiring. Euro wiring will be different (and is explained on Step 7.)
-- I used "wire nuts" to connect the wires, but soldering is more secure. Once I'm satisfied with the setup, I'll replace the nuts with solder, and cover with heat-shrink tubing.
Add some strain-relief for the cord
I used plastic wire channels to fix the cord in place. Electrical cords must have some strain-relief, or flexing will quickly lead to disconnections or shorts.
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I looked up the datasheet.
Yes, you've got the correct wiring for the N-68X @ 230V. For 230V operation, wire the N-68X primary coils in series (they are in parallel for 120V.)
230V mains-- Black and Black/Green.
Connect Yellow/Black and Red/Black together.
(I'll add this to the instructable...)
There's no real difference between the Hot and Neutral regarding transformer primary --the potential of each wire will be the same. The only thing effected is "Phase," and the reference to ground. But to keep things consistent, connect Black on the n-58x to Hot (Black in the USA mains).
Because of the ground reference, there is a difference regarding Hot and the switch and fuse. Place these on the Hot side of the primary. If the amp develops a short, this insures the fuse blows and separates Hot from the circuit...