CIRCUITRY   CHASSIS   WIRING AND PARTS   BUILDERS COMMENTS  

THE LONE WOLF 6L6SE

STEP BY STEP FREE HARP AMP PROJECT

CHASSIS

First determine where you want the components that will be mounted to your chassis to be located, some considerations are the size of the cutout on the cab for your controls, power transformer location, output transformer location, length and routing of input signal wires as well as the pt wires and heater wiring. The design shown takes all of these factors into consideration, the wiring is kept as short and direct as possible, the input signal wires are not routed along power wires and the transformers are mounted at 90deg angles and the pt is horizontally mounted and the ot is vertically mounted.

The controls are spaced for at least an 8 1/2" x 2" cab opening, if you are using a cab with a smaller opening you will have to make the needed changes to the control component spacing. When using faceplates, secure the faceplate to the chassis and drill pilot holes through both the faceplate and the chassis so that everything will line up properly.

Tools needed include a drill, a unibit and a jigsaw to cut out the hole for the power transformer.

I chose a turret setup for the circuit board as opposed to eyelets or point-to-point for ease of modifying and troubleshooting, although I do not do much modding anymore but I know that many others do and it is very easy to change parts and wireing on a turrent board. The other types mentioned and excellent board types and the chioce is really up to the builder, one method is not any more prone to noise than the other as long as your design is good, wires are run properly and transformers are orientated 180deg out of phase and are spaced far apart.

I made a staking tool by drilling a hole in a bolt to place the turret in and grinding a screw to a wide angle point. The turret is placed in the hole in the bolt and the pointed screw is inserted into a drill press and when pressed down onto the turret it will spread the turret skirt and secure it into the circuit board. Staking tools can be purchased from Mouser if you do not want to make your own and a hammer can be used to tap the screw and spread the turret skirt in leu of a drill press. It is recommended to tape an image of your layout onto the circuit board as a guide for drilling the holes.




Care should be taken installing the power transformer and the output transformer, they should be mounted as far apart as practical and they should be mounted 180deg out of phase, one horizontal and one verticle to minimize coupling between them. Chassis strength is another consideration when mounting transformers, I used plate washers on the output transformers to spread the stress on the aluminum chassis. The turret board is then mounted on 1/2" spacers.

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CIRCUITRY   CHASSIS   WIRING AND PARTS   BUILDERS COMMENTS  

For questions or comments, email me at randy@lonewolfblues.com