DEC DECtape 551 Manual page 57

S.
Inspe<:t
all
wiring and cables for cuts, breaks, fraying, deterioration, kinks,
,train, and mechanical security. Tape, solder, or replace any defective wIring.
6. Inspect the following for security: switches, controls, knobs, iacks, connectors,
transformers, fan, capac itors, lamp assembl ies, etc. Tighten or replace as required.
7. Inspect all racks of logic to assure that each module is securely seated in its
connector.
8.
Inspect power supply capacitors for leaks, bulges, or discoloration. Replace
any capacitors exhibiting these signs of malfunction.
Type 728 Power Supply Check
Check the output vol tage and ripple content of the 728 Power Supply and assure that it is with in
tolerance (see test data sheet for the particular supply). Use a multimeter to make the output
voltage measurements without disconnecting the load. Use the oscilloscope to measure the
peak-to-peak ripple content on the dc outputs of the supply. This supply is not adjustable, so
if
the output voltage or ripple content is not within the tolerance specified, the supply is con-
sidered defective and troubleshooting procedures shou Id be undertaken.
Check the
+
10-volt output between the black (-) and red
(+)
terminals to assure that it is between
9.5 and 11.0 volts with less than 800 millivolts ripple. Check the - 15-volt output to assure
that it is between 14.5 and 16.0 volts with less than 400 millivolts ripple.
Type 1501 Level Standardizer Check
The procedure for checking and adjusting the 50-ohm potentiometers
(l
B38) associated with the
Type 1501 Level Standardizer (1 B8) is as follows:
1. Make certain that all registers in the DECtape control are clear. The registers
are cleared each time the DECtape control is turned on.
2. Connect a jumper lead between ground and terminal 1C7H. This selects tape
transport \ by producing a ground level at lC6R.
6-3