SL-1176-KIT

ASSEMBLING THE BOARDS

Take your time stuffing components into the boards. Follow the parts list and schematic for a description of where each part goes. Each of the boards has its own separate numbering system for designators. For instance, designator R-1 appears on each of the 6 PCBs. The same applies to capacitors, transistors, and headers, so always check the parts list. If you have a question or believe the documentation may be in error, PLEASE contact us either by e-mail or via the message board.

One of the biggest pitfalls in assembling the boards is getting the correct value resistors where they belong. Check the web site for the resistor color tables to make certain you have the correct value. Sometimes it is hard to decipher the color bands on a resistor or misread them. Double checking resistor values with an ohmmeter is a quick way to ensure the correct value is in the right place. Checking your work carefully at this stage will save hours of troubleshooting headaches on the back end. You'll learn this from experience. The web site contains photos of finished boards to use for visual reference.

WATCH THAT DECIMAL PLACE

Be extra careful with resistor values when stuffing the side-chain board. There are a lot of resistors that can easily be mixed up because their significant digits are all the same but the decimal multipliers are not. There are 475, 4K75, 47K5 and 475K values for the various ratio settings. See how they are all related by a factor of ten? Also note that as often as possible we use the European style of substituting the magnitude a K or an M in place of the decimal, which could easily get "lost" in the printing process. It's amazing how a spec a dirt might even be misread a s adecimal place if it lands in the right place.

SIDE-CHAIN CAPS

Also, capacitors C-6 and C-7 of the side-chain PCB have different footprints on the boards than the parts on the parts list. C-7 is a .01 cap that will need its leads bent out slightly to fit into the holes. Carefully bend each leg with your needle-nose pliers close to the base of the cap. Then move the pliers down a few millimeters and bend the leads back in a bit so they point perpendicular to the board. This is done to widen the base of the cap to fit in the holes. Be careful to not break the base of the cap by bending too hard or too much when making the first outward bends.

Conversely, C-6 will need to be bent in the opposite direction to shorten the base. Bend the leads inward close to the base and then slide down and bend them out again to make them perpendicular to the base.

See the images below for a visual reference.

Hopefully you have already marked and drilled mounting holes on the chassis bottom before the boards were stuffed as indicated earlier in the instructions. Now the boards can be mounted to the chassis via stand-offs with screws through the bottom of the chassis.

PCB INTERCONNECTION

The next step is to connect the boards. The most important thing to get right is the power distribution. Check the schematics and note that the header pin-outs at the power supply do not match the receiving power pin-outs at each board. Note that pin-1 and pin-2 on each input power header is ground. The power supply output headers have only pin-1 as ground. The extra ground on the receiving PCBs is there for a convenient ground tap when connecting switches, or extra boards. You probably wont use them all, but be aware of their existance and intended purpose.

Hooking the 10volt and/or +30volt rails to the one of the ground pins can damage the FETs and transistors on the boards as well as cause damage to the power supply.