We can start to assemble the front panel from the PCB that constitute the panel itself. The new idea in this case is to realize the panels (and its cutouts) with standard PCB panels, without copper traces. It is sufficient to specify with a simple line the profile of the panel and its cutouts and all the web PCB realization services are able to deliver a well finished ready to use panel. For this purpose the GERBER and DXF files are included in the Universal charger assembly file, downloadable from this website. The panel has the cutout for display (16x2), for keys, for the D type connctor (serial communication) and for the 4mm-type sockets for battery connection. The 4mm sockets used are quite large, but the milling is compatible with some other connetors type (FARNELL 871760 e 1176427) and/or found on some eletronic stores. The sockets spacing is 19mm, the standard measure if someone want to connect a shunt between the force and sense connection and use a single wire for battery. The 4 wire connection is preferable because intrisically more accurate eliminating the voltage drop on the cables at high charge or discharge currents. The photo shows the "naked" version of the panel: the user can personalize the aspect using an adhesive label.

This photo shows the panel internal face with the 4mm-type sockets in place. This type of sockets (this version) has a small contact for wire soldering (down oriented), the economical types allows the wire to be soldered directly on the connector body.

Now we start with the assembly of the PCB. This circuit is "U" shaped in order to be fastened to the front panel and to allow the connection of the battery connectors. The first thing to solder is the 16x2 display: the dimensions are 80x36mm and the type is compatible with the APEX rc162051 yfhlyb. Equivalent displays are availables from some other brands or unbranded: the mounted one, for example is marked "Wintek Corp." and WM-C1602M-7GLYc. The display is simply put on the PCB surface making the electronic contacts with 16 wires (or 2.54mm stripe): important to put the display close to the PCB in order to have the right height of the overall assembly (10mm). Then we sold the keys (FARNELL 9471650) with blue covers for "UP/DOWN" (FARNELL 9561528), with green cover for "OK" (FARNELL 9561501) and with red cover for "ABORT" (FARNELL 9561536). Obviously all the colors for keys are equivalent, the only constraint is to follow the panel colors.

Then we mount the 5W, 47 Ohm power resistor for display backlight. The optimal lighting is btained with a voltage of 4.2V on the display LEDs with a current of 150-160mA. Calculate the right resistor with your power supply, the 47 Ohm value is OK for the range 10-18V. Take care for the dissipated power supply on the resistor, soldering the resistor up the PCB with a distance of 0.8-1.2mm.

The other components on the PCB are the connectors: DEM9S (socket) for serial communication and flat cable for panel connection to the main PCB. The DEM9S connector is soldered on the PCB using the (straight) pins, then fastened using the two spacers. The height of this connector is compatible with the overall assembly height. This type of connector allows the usage of female/male serial cables with NO inversion on the 2-3 pins of the wiring. The flat connector is an IDC (insulation displacement connector) type, the type that can be mounted directly on the PCB (FARNELL 1298771): the standard male/female solution is not compatible with the overall assembly height. The economical way is to sold 20 separated wires between the two PCB with very care for wire ordering (pin 1 to pin 1...up to the number 20).

Image of the panel rear with the display milling showing that the display is fastened only using the 16 electrical contacts, different the 9 pin connector that is mechanically fixed using screws and nuts.

The front panel is fixed to the PCB using 4 M3 screws (with conical head - in order to minimize the impact on the front) and with 4 x 10mm-spacers. The optimal result is to make conicals also the holes on the front panel to receive the head of the screws.

The images on the right shows the spacers height of 10mm and the particular of the flat cable exit over the 4mm socket connector. The flat cable can be substituted with 20 separated wires soldered between the MAIN PCB and the PANEL PCB.