5. Assembly

5.1

5.1.1
The Assembly Drawing (No. 101930) is to be found on Page 39, and the Parts List (No. 101840) is on Page 40.

5.1.2
The components have been numbered on the Assembly Drawing (No. 101830, page 39 ), in ascending numerical order. Viewing the board in the orientation that it will have in the computer (i.e. 'landscape' not 'portrait' position), numbering begins at the top left hand corner and proceeds in horizontal lines. For example 'IC4' is the fourth IC along, 'IC6' is the sixth and so on.

5.1.5
The Parts List has the components listed in two ways. Firstly by the circuit reference number R1, R2, R3 etc., which gives the component value if the reference number is known, and secondly by the component value 22R, 220R, 1K etc., which gives the circuit reference numbers with that value.

5.1.6
This latter feature is quite helpful during assembly as for example, all seven 10K resistors can be collected together and installed at the same time, rather than in 7 individual operations. It is also helpful when collecting together or checking a 'kit' of parts.

5.1.7
There are numerous 'thro' wire links to be fitted, but these are not marked on the diagram because they are easier to see on the board itself. Short lengths of wire (e.g. resistor lead off-cuts) can be used, or purpose made 'thro' pins. Do not fit the numbered links T1 to T10 until you understand their purpose -they will not all be needed.

5.1.8
It is worth mentioning that it would cost more to have a 'thro' hole plated board than it would cost to pay someone (e.g. Greenbank Electronics) to solder in the 'thro' links for you. So if there is anyone who is willing to pay the extra to avoid soldering his own 'thro' links remember....... it can be arranged!

5.1.9
It is assumed that the user will have sufficient experience to be able to identify the various components and to install them properly with due regard to polarity where this matters. Please contact us if this assumption is incorrect in your particular case, as it is possible to make some very expensive mistakes.

5.2

We would imagine however that even the experienced user would appreciate a brief list of some of the main points where an individual decision must be taken, which will affect construction:

  1. Decide whether a card front or simple card handle is to be fitted and drill the board accordingly.
  2. If the polarising slot (position A37, B37 on the edge connector) is required this should be cut at an early stage of construction, if not already present.
  3. Protect the gold plating at all time, against damage due to finger marks, solder, and scratches.
  4. If it is wished to conform to the ISBUS allocations for NWAIT cut the copper track on the upper (component) side of the board between positions P20 and P21. Use an insulated wire jumper (J13) to connect 920 to P25 and so transfer the NWAIT line to edge connector A34.
  5. If IC11 is to be a 2708 instead of the (preferred) 2516, then -5V should be used on edge connector pins A38, A39. Alternatively, as the 'ISBUS' standard allocates -12V to A38, A39, then a modification is required if IC11 is a 2708: Cut the track on the under (non-component) side of the board between P14 and P15 and insert D1 (carefully, as the board designer has provided no space for this modification) on the component side between P14 and P15, cathode to P14.
  6. If IC11 is a type 2516 then C11, C12, and D1 need not be fitted, and it is important to isolate the +12V and -12V edge connector voltages (A35, 36 and A38, 39) from the rest of the board. A convenient method is to omit T9 and T10, the two through board links which carry +12V and -12V, but there is no substitute for a physically cut track to give the maximum confidence that the voltage rails have been properly isolated.
  7. If IC11 is a type 2516 then J9 and J10 both marked '6' should be fitted. It is essential to leave these out if IC11 is a type 2708.
  8. Note that J9 is positioned beneath IC10, and will require fitting before the IC, also some types of IC socket will be unsuitable.
  9. Note also that Kemitron, the board designers, have positioned C9 beneath IC10. If the capacitor is too large to fit as intended, it should be fitted on the underside of the board or omitted altogether, we have heard of no problems omitting it
  10. J11 and J12 can be left off NRFSH and RCLK are not required on the system bus. For 'ISBUS' compatibility J11 and J12 should be fitted.
  11. When inserting through links note that only one of T1-4 and one of T5-8 should be fitted, also note that only half the jumper links J1-8 are required. Consult the tables at the right hand side of the diagram on page 35 and the Section 4.3 for details.