Flashgun - Polaroid 100 Series Repair Manual

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FIG. 2.14 ELECTRONIC TIMER SCHEMATIC
b;,jtl\:.'r~ 1l~$1_
Figure
~~
14 presents the electronic
timcr schematic.
Operation of the timer sfarts with the setting of
Ihe dial on Ihe camera back which is directly
n.:mn<:l.:lcd to the one megohm potentiometer
"hown
In
Ihe schcm.uic. (The potentiomeIer, in
[urn,
j"
connecled 10 the
g~
microfarad capacitor.)
Cb:II)~mg lhe dial Selling aiters the value [or rt!­
"1\l.tnn'j of tilt' pOlentl()meteL
For example. if
Ib\., til.11 wefe s.:!
to
15.
it
would take 15 seconds
lilT ",'lIrrdH
rJ~ing
Ihroug.h the potentiometer
to
dUf}!4" 111\'
tC tnlt:rof:uad capadtor.
11l~' tllm:l~
..:ydc i" imtl:.lh:d by the removal of tht;
'.-'\!,pwu
plo..:wrl!"
(Pulhng Ihe yellow tab, from the
,::,JmcrJ
Till'-
momentarily doses:J
two~pok.
OOf­
mall;.
()p~'n
"wlleh
JIllJ
completes
the timing
dr~
tun. TI1-.:
dosm~ or one role allows the capacitor
10 lull) tl!:-.dl~T}!e throtl~h the -;'7 ohm resistoL
IIbmIllJ.~
tll:J!
It
ha" no
resiuuaJ
voha~c from a pre­
VIOU~
fimmg cyck. The
dosin,g
of
the
~econd
puit' HIm' til.:
Ie·
trunslstocreslstor cin:uil on and
l!~hh Ilh:
bmr"
\\'hen the "wHeh
orens.
thl:! g2
mit:roIJr;u.l cap~..:ltor begins charg.ing again, While
lIlt'
Lap:J.:llor
l~ charging. tht: lamp remains iilumi­
nated, Once the capacitor has fuJly charged, a
difference in potentiai in the other
Ie
transistorl
resistor circuit excites the transducer which emits
a high frequency "beep", At the same time, the
lamp goes out. The high frequency "beep"
coupled with the extinguishing of the- lamp indj~
cales that the timing cycle has been completed,
FLASHGUN
This discussion concerns Hself only with the
Model 268 flashgun
used WIth
all cameras in
the
fOO, 200. and 300 lines, except for the Model
360. The e)ectronJc flash used with the Model
360 earner .. is covered in the- "Repair Manual for
the Polaroid Land Camera Model 360" pubUshed
in September 1969.*
Early Model 268 nashguns were manufactured
with a 4.5 vdc battery while newer nash guns rely
on a 1.5 vdc cell for their power source. All 4.5
vd.c flashguns should be converted to 1.5 vdc
• lntegt31ed circuit
*
Available only to authorized repair stalions..
10