Created it, 06/10/19
Update it, 06/10/20
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2.2. - ASSEMBLY OF THE DIGITAL DESK
Before beginning the assembly, it is necessary to prepare the series of connectors having a precise number of contacts by suitably splitting the two connectors with 32 contacts which you bought or which you have already.
For this purpose, it is enough to be useful of a knife sharpened well as a practitioner to the illustrated manner appears 9-a.
Take one of the two connectors and pose it on your work table ; introduce the blade of the knife into the notch of separation between twentieth and the twenty and unième contact, then by firmly holding the handle of the knife pressed on the table (you ensure that you are at the good place), exert a pressure on the blade so as to make a clear notch in the support isolating from the connector.
By this method and by taking guard each time to count the number of contacts envisaged well, carry out three other notches at the points indicated in the figure 9-b. You will obtain the first four connectors thus having respectively 20, 7, 3, 2 contacts. Put to them side carefully in order not to lose them.
At the end of this operation, nine connectors available like are represented on the photograph 9-d.
In the event of error of cut, it is always possible to supplement the missing contacts by taking the additional contacts necessary on a bar. At the time of wiring, it is necessary in this case to put coast at coast the suitable number of contacts to obtain a complete connector.
You can now begin work by carrying out on the printed circuit the installation of resistances of R0 to R7. Proceed in the following way :
Take resistance R0 of 220
W - 1 / 4 W
tolerance ± 5%
(red - red - chestnut - but) and after
having suitably bent connections, lay out it on the printed circuit, with the
site indicated figure 10.
To do a good work, have care to fold two connections to the correct distance and right angle so that the body of resistance is well centered compared to the holes envisaged on the printed circuit, as indicated figure 11-b. If the distance from folding of the terminals is insufficient (figure 11-a) or excessive (figure 11-c), resistance cannot come to rest against the plate.
In such cases, it is necessary to correct the folding of the terminals while proceeding delicately with a grip without exerting of constraint on the body of the component:
turn over the circuit by maintaining resistance quite plated against this one,
draw aside connections slightly so that it is maintained in place. Carry out the
welding of its connections and cut the ends which exceed.
follow the same procedure and weld on their respective site onto the printed
circuit, resistances R1, R2,
R3, R4, R5, R6, R7, very of 220 W
- 1 / 4 W tolerances ± 5
% (red - red - chestnut - but).
You now will carry out the assembly of the supports for integrated circuits :
take a professional support with 14 pins, ensure you first of all that all its
pins are perfectly right : if one of them is not it, rectify it with
precaution, using a brucelle grip. Introduce the support into the holes
envisaged on the printed circuit and located by symbol ICX
(figure 12-a) by positioning it so that pin 1 (recognizable by the reference
mark) coincides with the hole indicated by figure 1 on the printed circuit
(figure 12-b).
maintain the support with a finger, in contact with the printed circuit, then
turn over this one and ensure you that the 14 pins sufficiently exceed in order
to be able to weld them correctly (figure 13-a).
The figure 13-b indicates a borderline case where a pin was folded up under the support during its insertion on the circuit. This pitfall should be avoided, because the pin is likely to break by rectifying it. Weld then the support:
by you ensuring that all the pins sufficient arise the side of the tracks of
copper and continuously to maintain the support plated with the circuit, fix
with two light points of welding the pins 7 and 14, as indicated on figure 14 ;
from now on the support cannot fall any more.
now, pose the printed circuit on the work table and carry out with much care the
welding of all the other pins of the support and to finish, take again the two
weldings of the pins 7 and 14.
while following the same procedure as for the welding of support ICX, introduce
and weld the two other professional supports in their respective sites onto the
printed circuit, and located by DIS 0 and DIS 1.
always with the same technique, weld three standard supports IC1, IC2, IC3, as
indicated in figure 15.
now take the connector with 20 contacts and introduce it into the located holes
of D1 with L2 as represented figure 16-a. While plating well the connector
against the printed circuit, turn over this last and fix the first and twentieth
pin of the connector.
Turn over the circuit again and ensure you good positioning of the connector, as represented figure 16-c.
If one of its ends does not adhere well to the circuit, to see the figure 16-b, it is enough to heat the welding which prevents the pin from sufficiently penetrating, while exerting a light pressure with the finger to make it penetrate thoroughly.
After the correct installation of the connector, you can proceed to the welding of the remaining pins and remake lastly those of pins 1 and 20.
Consequently method, carry out the assembly of the following connectors, by deferring you on figure 17 :
take the connector with 18 contacts and introduce its pins into the holes going
of L1 with SW0 ; position it and weld it as you made for the precedent.
mount and weld two connectors with 2 contacts in the marked holes (+) and
(-).
mount and weld the two connectors with 3 contacts in the marked corresponding
holes “1 Hz - 10 Hz - 100 Hz” and “1 kHz - 10 kHz - 100 kHz”.
mount and weld the last connector with 2 contacts in marked holes COM1 and COM2.
mount and weld the two connectors with 7 contacts on each side of support ICX.
You must now prepare two pieces of flex-wire, one red and the other black, provided with a crocodile clip at the end. They will be temporarily used to feed the printed circuit with a pile of 4,5 V ; thereafter you will have the occasion to carry out the final stabilized power supply :
take the piece of flex-wire red of approximately 25 cm, strip and galvanize the
two ends out of 3 to 5 mm then weld one of them with a crocodile clip. To carry
out this operation easily, it is advisable to fix the grip on a piece of
paperboard so as to maintain it like illustrated in the figure 18-a.
thread the red cap insulating on the crocodile clip, as indicated in the figure
18-b.
take the piece of black flex-wire of approximately 25 cm, strip and galvanize
the two ends out of 3 to 5 mm, then weld one of them with the other crocodile
clip.
thread then the black cap insulating on the crocodile clip while proceeding like
previously.
weld the loose lead of the red flex-wire onto the copper tape marked +
B of the lower face of the printed circuit (side tracks of copper) as
represented in the figure 19-a.
Weld the loose lead of the black flex-wire onto the copper tape marked -
B of the lower face of the printed circuit (side tracks of copper)
also illustrated in the figure 19-a.
assemble side of the copper tracks the four hexagonal spacers in the four holes
located at the angles of the printed circuit. Block without forcing them with
the screws Æ 3 x 6 mm, as you can see it in detail
in the figure 19-b.
In general, in electronics one always proceeds to two types of checks : checks out-tension or known as cold and checks undervoltage in order to check the conformity of wiring initially then to carry out measurements with regard to the most important tensions or most characteristic.
We will now make a checking of the assembly on another page in order not to encumber this one.
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