Power supply

PCB reference RU80068.2

Estimated building time: 2 hours

To complete this step the PCB with reference RU80068.2 is required.

Elektor Vocoder

Sort all required components as indicated in the BOM:

Bend the diodes so that they fit neatly right away:

Solder the 8 diodes, note the direction of the white line (component) and tabbed indication (silkscreen). Do not reverse the polarity of these components:

Put the 21 pin connector to the board, do not exert any excessive force. Solder only pin 1 and pin 21 and check for a right angle. Correct if necessary and solder all remaining pins:

Place the 100 nF film capacitors and start soldering only 1 of both legs. This allows lining up the components. Correct if necessary and solder all remaining legs:

Bend the power regulators so that they fit neatly right away:

Fasten the PCB, heat sinks and regulators together with nuts & bolts and do not forget to apply some washers. Thermal paste is not necessary due to the limited dissipation in the regulators. Allign the heat sinks before tightening  the nuts & bolts.

Check twice the right regulator is on the right place:
            IC19 = 7815
            IC20 = 7905
            IC21 = 7805
            IC22 = 7915

On the prototyping boards the -15V DC & -5V DC indication on the solder side is exchanged, so do not use this indication as reference. Only rely on the above regulator list and the below pictures to put the components in place:

Apply some Loctite on the bolts to fix the power supply cover plate. The hex bushing is no longer accessible after soldering the transformer, so do not skip this step. Superglue can do the job as well, but loosening in any case becomes very difficult:

Fasten the 4 screws and bushings:

Solder the tranformer on the PCB, be carefull while bending the pins as they will break down if you are too rough. Apply pretty much solder wire and let it flow through the plated hole as this wil fix the transformer also on the component side of the PCB:

Select the mains voltage of your country by bridging the jumpers on the right position. For 110V AC both 2 bridges should be applied, for 240V AC only one brigde should be closed. Check twice before you proceed:

Insert the AC terminal block and make a solid solder connection. Depending on the choosen model it may happen that the connector legs are square, in that case use a plier to squeeze the pins a little. Do not exert any excessive force while inserting the AC terminal block to avoid damaging the plated holes:

Put the fuseholder and fuse in place. Do not forget to cover the fuseholder, otherwise mains voltage can be touched:

Bend the electrolytic capacitors (e-caps) and put them in the right position. Do not reverse the polarity of these components:

Thoroughly clean the PCB using flux cleaner and check for bad soldering or tin bulbs. Try not to touch the transformer as the white imprint will disappear as can seen on the below picture:

Elektor Vocoder

Place the power supply cover over the AC current parts and screw the lid in place.

Elektor Vocoder

Well done

Congratulations, you have finished the power supply section, click here to navigate back to the building guide.


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