SLIM-CB-NV rev C
Control Board

Updated 11-11-08.  Add link for LPT Parallel Printer Port Test in Liberty Basic: testlptport.bas
Updated 1-20-09.  Change page to reflect that Control Board is modified to Revision C.  The schematic is now rev C, the parts list is rev C, and the PWB is rev B.

SLIM-CB-NV,  Control Board, size-C
    The Control Board is the Interface between the Computer and other SLIMs.  It consists of 4 sections,  Latch, Power Conditioner, Voltage Converter, and Noise Filter.
Use your mouse's "right click" and "Save Link" to download:
a.  SKSLIM-CB-NV rev C, Schematic of SLIM Control Board, in ExpressPCB software.
b.  PWB-CB-NV rev B, Base artwork for PWB, in ExpressPCB software.  Use this drawing to order the pwb from Express, or to locate the parts on the SLIM Control Board.
c.  PLSLIM-CB-NV rev C , Parts List for SLIM Control Board, in .txt format.  Open with Exel or Lotus, etc.

Revision A changed nomenclature on the schematic, only.
Revision B is a significant modification to the Voltage Converter section. This changed the PWB artwork.  However, the original pwb assembly can be modified for the new changes.
 Revision C is a change to sheet 1, only.  It consists of adding resistors, R13 through R24, and capacitors, C29 through C40.  The resistor/capacitor combination creates a low pass filter to improve the noise immunity of the computer's LPT signal lines.  This RC modification can be performed on the previous versions of the Control Board, if required.  This modification should be performed if the Control Board has symptoms of inconsistant commanding from the home computer.

Pictures of Schematic, SK-CB-NV rev C, 4 sheets:
Latch Section, sheet 1 of 4.  Click on drawings to enlarge for viewing.
skslim_cb_nv1.gif
    The Latch Section consists of 4 ea, TTL/CMOS input compatable Buffer Latches with CMOS outputs.  The inputs are from the Computer's Standard LPT printer port, carried on a DB-25 female connector.  The outputs of the latchs are accessable on 4 ea, 9-pin connector headers.  Note: Connector headers are not mandatory.  Direct wiring to the other modules is optional.  A fifth connector (P5) is a direct connection for four LPT signals that are "read" by the Computer.  Two of these are used by the SLIM AtoD Converter.  The other two status lines, PE and SELECT are not used by the MSA or VNA, but may be in the future.
    Revision B calls out a change to add 2.2 K ohm pull up resistors to these 4 status lines.  Some home computers do not have internal pull-up resistors and if so, these resistors are necessary.  Only WAIT and ACK lines may need these resistors.  Previous versions of the Control Board may need this revision if connected to one of these home computers.  Here is a test to see if the pull-up resistors are required.  Re-boot the home computer.  Use a voltmeter to measure from computer ground to LPT port, pins 10, 11, 12, and 13.  If any of these pins are showing greater than +2.0 volts, the pull-ups are not required.
    All 4 of the latch I.C.'s are fed by the Parallel Data from the Computer.  The Data will be passed to the latch's output when it's enable line is commanded high.  If enable is kept high, the output data will follow the input data.  When the enable is brought low, the data will be retained as a latch.
    The SLIM Control Board is a generic module that will be integrated into a higher assembly.  Therefore, the signal names in the schematic are generic (changed 10-13-07).  For example, the data signal that exits the computer is called D0.  It is buffered by the four latches, U1-U4.  The name changes at the output of each latch, for example, P1D0.  This is Data Bit 0 on connector P1 (U1 output).
    Once the Control Board is integrated into a higher assembly, the signals are assigned more meaningful names.

Power Conditioner Section, sheet 2 of 4
slim/skslim_cb_nv2.gif
    The Power Conditioner receives a nominal +12 volts to +13.6 volts and outputs +10 volts to multiple, 2-pin power connectors that connect to the other SLIMs.  The maximum total output current allowed is 1 amp.  D1 is used as a reverse protection diode.  If the power input is shorted during operation, D2 should protect U5 from destruction.  FB1 and FB2 do very little for EMI.  They are there to act as fuses in case of reversed polarity input.  U5 is mounted on the PWB from the bottom, with it's heat sink tab bolted to the case that is housing the Control Board.  Revision B changes the input voltage range to +12v to +15v.  However, higher input voltage is allowed, up to 20 volts, if the original DC to DC integrated circuit is maintained.  See sheet 4.
    Revision B has an added connector, P25, that can supply raw input voltage to the Voltage Converter, shown on sheet 4.  This option increases the 20 volt output voltage to about 26 volts.  This is optional, and the previous SLIM Control Board is not required to be modified for this.
    Revision B also calls out 10 uF/35v non-polarized, ceramic capacitors as alternates for the electrolytic capacitors.  These capacitors are optional with the builder.  Recommended for new builds.

Voltage Converter Section, sheet 3 of 4
slim/skslim_cb_nv3.gif
    Revision B: The Voltage Converter section contains one voltage converter.  The previous revision had two.  However, one converter will supply enough voltage and current for the MSA and Tracking Generator, combined.
    The Voltage Converter section is completely surrounded by a ground trace and a fence and lid could be installed to prevent the section from transmitting noise.  However, extensive testing did not prove that this section radiated any noise.  DC connections are provided on the bottom of the board, using 3-pin connectors.  If this section is not needed or if any of the outputs is not needed, the components do not need to be installed.  The SLIM MSA / Tracking Generator does not require -10 volts.  C18 and C19 can be deleted.
    Revision B allows 5 options for the Voltage Converter section.
1. Option 1, using the LMC7660, with 10 v input.  Nominal output voltage of +19 volts.
    The converter receives +10 volts from the Power Conditioner and converts it to +19 volts and -10 volts.  It can supply up to 20 ma for each.  The MSA/TG requires a total of 7 ma at +19 volts.  -10 volts is not used, and components C18 and C19 may be omitted.  The output will contain a small ripple voltage with a frequency at which the LMC7660 is operating, approximately 8.5 KHz.
2. Option 2, using the TC7662, with 10 v input.  Nominal output voltage of +19 volts.  With U7 pin 1 connected to Vcc, the ripple frequency is approximately 30 kHz.  This has not been tested but should result in much lower ripple.  At this frequency it is possible that this section could begin to radiate and require fencing.
3. Option 3, using the TC7662, with 10 v input.  Nominal output voltage of +19 volts.  With U7 pin 1 disconnected from Vcc (trace cut), the ripple frequency is approximately 10 kHz.  This has not been tested, but should give the same results as Option 1.
4. Option 4, using the TC7662, with 13.6 v input.  Nominal output voltage of +26 volts.  With U7 pin 1 connected to Vcc, the ripple frequency is approximately 30 kHz.  This has not been tested but should result in low ripple.  At this frequency it is possible that this section could begin to radiate and require fencing.
5. Option 5, using the TC7662, with 13.6 v input.  Nominal output voltage of +26 volts.  With U7 pin 1 disconnected from Vcc (trace cut), the ripple frequency is approximately 10 kHz.  This has not been tested.
    I have tested the MSA system using Option 1, only.  Options 2 - 4 can be experimented with.  With an output voltage of at least 21 volts, the MSA will have an extended operating frequency range to about 1200 MHz.
    The previous SLIM Control Board, Revision 0, must be modified.  Using the above schematic as a guide, the following components must be incorporated.  R6, C23, R7, C24, R8, C25.  The second voltage converter can be removed to allow space for these added components.  Or this modification can be added, external to the Voltage Converter Section.  This is a necessary modification to decrease noise on both the 10 volt input line and the 20 volt output line.

Noise Filter Section, sheet 4 of 4
slim/skslim_cb_nv4.gif
    The Noise Filter, (N) contains a Murata Ceramic Filter, having a center frequency of 10.7 MHz and a bandwidth of 150 KHz.  Included, are impedance converter networks for 50 ohm to 330 ohm.  Loss is approximately -4.5 dB.  This section is completely surrounded by a fence and lid to isolate the section from external noise.  RF connections are provided on the bottom of the board.  If this filter is not wanted, the section does not need to be populated with components.  If so, the shield is not required.
    This section could be removed from the Control Board by cutting it away with a fine tooth saw.  If left in position, only the two outside fence shields are soldered on both sides of the board.  The two "inside" fences are soldered on the top side, only.
    This section is not used or required for the MSA, Tracking Generator addition, or the VNA extension and is not populated with components.

PWB-CB-NV rev B, Artwork and Component Locations for SLIM Control Board
slim/pwb_cb_nv.gif
    The Control board is intended to be mounted in a position so that the LPT connector extends to the outside of the enclosure.  Holes are drilled in the enclosure to accomodated the DB-25 size "D" connector and two mounting screws.