Excessive Pressure Fluctuations - Graco A Series Instructions-Parts List Manual

(Continued)
TYPE
OF
PROBLEM
WHAT TO
CHECK
If check Is OK, go to next check
NO
OUTPUT
I
4. Check to see if intake valve bail
and
Piston 4,
Motor runs but pump does
not stroke
EXCESSIVE PRESSURE
FLUCTUATIONS
Spray pattern variations.
MOTOR IS HOT
e
RUNS INTERMITTENTLY
307-793.
ball are seating property.
See
manuai
, Check for leaking around throat packing nut
which may indicate worn or damaged pack-
!ngs.See manual
307-793.
,
Check &lacement pump connecting rod
pin. See page
2 8 .
, Check connecting rod assembly for damage.
See page
28.
,
Be
sure crank in drive housing rotates; plug
Turn off and unplug sprayer. See page
2 9 .
in sprayer and turn on momentarily to check.
.
Be
sure both 0 1 and 62 leads from bridge
(3081
to circuit board
( 2 3 )
are fi r ml y
connected. See pege
2 5 .
procedure on page
27.
.
Check bourdon tube flag and detector posi-
tion. Turn pressure setting to maximum; flag
slot of circuit board.
should not drag or bind in optical detector
.
Check stall pressure. Refer to Calibration
,-CIRCUIT BOARD
OPTICAL
DETECTOR
I I "
FLAa
VIEW OF
OPTICAL DETECTOR AND FLAG
..
Check circuit board
( 2 3 )
by substituting with
a good board. See page
25.
f
.
Check
LOW OUTPUT section on page 16.
.
Check to see if sprayer has been operating a
high pressure with small tips, which c a u w
low motor RPM and results in excessive hea
build up.
!.
Check
to see if
ambient temperature where
sprayer is located is more than W F (32OC)
or if sprayer is located in direct sun.
I. Check to see if sprayer has been left in a
stalled condition (sprayer
turned
on,
pressurized, but not operating) for long
periods of time.
W e n
replacing the
bare pressure
control
box
* m ,
remove the circult b o a r d ,
brldge.
circuit board, and electrical-hardware and reinstall in the new bare box.
,
Remove
intake
v a b
end dean. Check ba\b
and seats for nlcks; replace if necessaty. Sea
manual
307-793.
,
Replace packings. See manual
307-793.
Also
check piston valve nest for hardened paint
01
nicksandreplaceifnacessary.
Replace pin if missing. Be
sure reteiner
spring is fully
in
groove
all
around connect-
ing rod.
See
2 8 .
,
Replace connecting rod assembly. See page
2 8 .
,
Check drive housing assembly for damage
and replace
if necessary. See
page
2 9 .
,
Rewnnect securely. See page
24
and
25.
,
Calibrate pressure control. See page
27.
,
Carehlly bend flag into alignment with
detector slot to
see
if that corrects problem.
If not, replace bare pressure control
assembly (301)'. Calibrate pressure control
after reassemblv.
.
Replace circuit board. See page
26.
.
Decrease pressure m ' n g or increesa tip
size.
:.
Move sprayer
to shaded, cooler area if
possible.
I . Tum
off
sprayer whenever you stop spraying
for
a
while end relieve fluid pressure.
Troublashooting continued on nexf page