Radio Shack CCR-81 Reference Handbook

Bent Pins
On socketed parts, it is easy to replace devices
for troubleshooting. But, be careful that you do
not cause more problems by getting in a hurry.
On RAMs, it's extremely easy to bend an IC pin
between the socket and the part. Suspect a bent
pin if the part is hard to insert: and, upon more
pressure, it suddenly snaps in. Make it part of
your isolation routine to peek under the CPU
chip and look for folded-under leads. The
decoupling capacitors near the RAM may pre-
vent you from looking at these sockets.
However,
you can usually inspect the RAM leads
from the top of the Board. You can also check
that the RAMs are level and of uniform height.
Maybe a
RAM has been loosened and only one
side is attached. A quick push on the loose part
may be all that's necessary to fix a malfunction-
ing unit.
DIP Shunts
It's been said before, but it needs to be said
again.
Be careful when programming DIP shunts.
If
undue stress is applied to a DIP shunt while
programming,
the plastic may crack. The crack
usually develops in the center of the part in line
with the shorting bar's narrowest point. The bars
may separate enough to cause an open. When
you program a DIP shunt, first install the part in
the socket. Use a scribe to break the bars you
need to open. Use only enough pressure to break
the bars (don't try to drive the scribe through
the Board). Be careful when you break bars near
pins 1 and 8 as this
is the weakest part of the
shunt.
If you suspect a cracked shunt. check resistance
of the unbroken bars. Do not press hard with
the meter probes. You might temporarily close a
cracked bar and it'll read 01<. If you find a
defective bar, replace
the shunt. Solder a broken
shunt only if a replacement is not available.
81

Radio Shack CCR-81 Specifications

General

Brand	Radio Shack
Model	CCR-81
Category	Desktop
Language	English