Read Checks - IBM 1620 Manual

1) Check transfer to MDR
2) If Op 37 check set of MBR from
zone translator
3) Check sync lamp timing and
duration (Note 2) (Page 3. 11)
4) Refer to Section IV (Core Storage)
(Page 4.2)
Scoping Procedures
Notes:
1. Read Photo Diode Adjustment Procedure
Read Checks
1621
MBR
Checks
READ
Checks
MBR and READ Checks
1) Check Photo Diode outputs
(Note 1)
2) Check Sync Lamp Timing and
Duration (Note 2) (Page 3. 11)
3) Check Voltage Taps on 1621
power transformer to insure
they conform to the tap settings
on the 1620 transformers (208V
or 230VAC)
4) Check Read Window to insure
that it is free of dust and that
the window mask is clear of
photo diode
I
ight path.
(False Read Check)
Check VRC Circuit)
G, and A4A05B, D, H, G on 02.83.50.1.
Before the following diode adjustments are made,
clean the read head area to remove a
II
dust from
the read window. Make certain that the +12 and
-12v power supplies are adjusted to the nominal
values given on the 1620 voltage specification
chart.
4) Select a diode that has an output that is
near to the average output of all diodes and
use it as a reference or base for Steps 5 and 6.
For example, see Figure 1.
Channel Scope Point Voltage Reading
1 A4A04 B -lO.Ov
1) Center diode potentiometers 1 through 8.
2) Set read lamp potentiometer for minimum
intensity.
3) Record diode output with no tape in machine.
Scope channels 1 through 8 at A4A04B, D, H.
3. 10
2 A4A04 D - 8.0v*
3
A4A04 H - 9.2v
4 A4A04 G - 6.4v
5 A4A05 B -11.3v
6 A4A05 D - 2.2v**
7 A4A05
H -
9.8v
8 A4A05 G -1O.4v
-67.3