Nicron #29 11 апреля 1997

Железо

Iron - the experience of sadistic repair the keyboard port.

                      Resuscitation, with ...


(C) WLODEK BLACK


           Transplant tissue in the body "GrandRomMax",
    or "experience" sadistic repair the keyboard port.

The other day I happened to solve the problem in the circuit 
input data from the keyboard in "GRM 2 +. As a result,

electrostatic discharge was broken one channel chip
K555AP5 (hereinafter AP5), through which you are entering the 
state row of keys corresponding to the bit 0 of data bus. This 
channel connected: input - output 17, output - pin 3 AP5. I've 
been ready to savagely tear of the board faulty chip, when

I fear: the data lines keyboard - 5 plus 1 more
line tape input; total 6, and channels in the AP5 - 8. Then
that at least one of the other sort of free
channels do not really used in the scheme of the computer was
clear at a glance: the 11-foot chip, I was reliably
soldered to the ground. I unplug it from the ground and started 
her wire from the old, faulty channel. The yield of the new 
channel - 9-th output circuits - and so was free. Since the old

Channel is down a precipice, not short-circuit, I
left a 17-second output is connected to the board - no big 
deal. And all computer working! So if a GRM-e flies keyboard

port, but only one channel, not necessarily to change the 
AP-shku - reserve for repairs is in the scheme itself. Maybe 
the two channels can be replaced by unused - GRM-circuit and I 
have not, I to act as the scientific method, using as a spear

Probes avometra TS4315 and digital probe PRTS-2.
Location "sore spot" shown in the pseudo-
Figure:



             Circular connectors LPT


                        November 17


              AP3 AP5


                        September 3

                                         processor

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