Crown PSA-2 - Page 108

SA2PSA2Z100280
High Speed Fan Modification
10000-11994
(PSA-2X)
226-360
(PSA-2D¥})
11947-112787
(SA2)
Many customers have experienced a problem with the fan going inte high speed
operation at both low power levels and at turn on. <The Crown Engineering De-
partment has issued a modification raising the threshold where the fan comes
on. This modification changes the high speed fan threshold point from -3.23Vde
(122
degrees
F)
to
~3.36Vde
(144
degrees
F).
Because
of
the
Self
Analyzing
protection circult, this change will not cause undo stress on the output devices.
The modification procedures and parts are as follows:
QUANTITY CPN DESCRIPTION
1
C
5744-5
5.
7OK
te
ke
1%
1 € 4223-1 360K -n. dw 5% (R3)
MODIFICATION PROCEDURES:
}. Change R2 (on the main drive printed circuit board) from $.49K n4w resistor
to 5. 76K nw 18.
2. Change 83 (on the main drive printed circuit board) from the 220K bw 5%
resistor to the new 360K n.uw 5% resistor.
AY amplifiers with serial. numbers.in. the above mentioned ranges. that exhibit
this problem should have this modification. All amplifiers above these serial
numbers are being modified in production.
If you have any further questions, please feel free to call or write.
Dave R. Engstrom
Product Specialist
Jao