170

0007 13 Mar 68

Found that DP kept getting NON EX MEM
from Ampex Core 1.

B137 1/2 at J22 wouldn't produce output (GND)
at D.

I₂P₂ GO clamped load coard at H23 had
open diode in the forward drop string for pin H.

B204 at H22 wouldn't set by
grounding pin P.

Down at 2130 2 hrs + 30 min down.

SRR

Mar 13

Checked into QI failure and found a capacitor
shorted which caused the H.V. isolation transformer
to burn up. Replaced Transformer and capacitor.
Found probably cause of capacitor failure to be a
4 KV spike on HV input when HU was turned.
Tried various methods to remove spike with no luck.
Only reasonable solution seems to be to remove HV.
Reed relay and replace put a similarly controlled
relay on the primary of the H.V. supply to
produce a gradual HV buildup and turnoff.

Ted Panofsky

1800 13 Mar 68

Also last night installed a [?] to
AMPEX Boxes that makes a NULL
cycle happen as if complete and
turn on VA rather than hanging waiting
for WDA. This makes "hanging" bugs easier
to scope. CHanges is wire
from 2DG46 to 2DB15

SRR