Phototechnik Durst EST 500 Setup guide

DurstEST500
" RgpnnNsmuczoivs
PI-IC'POIECI-IIIK

DurstEST500 Repairlnslructions EST500- I
'I. INTRODUCTION
TheEST500isanelectronic
vollageslabillserfunc-
lioningaccording
to the phase angle
control
prlnciple.
Duetolhe owel€ctrical
loss,theadjustment
resp.
control
iseffectedonthe
primary
winding-The
EST500suppliesthe
voltageforoperatingtheCLS
500
colourhead
andtheVLS500lightsource.
s/lo 1e.li monitorslhe triggeringof both
thyrisiors
and
prevents,
incasesofmisfiring,
thereactionolthe
luseon accountof theD.C.voltageshare
in the
4. DETAILED
DESCRIPTION
(see
enclosedcircuitdiagram)
Thephase angTe
controlledvoltage
is rectitiedby
diode
D16,thenevenedout
viacondensatorC11and
siabilisedby D 13.li amountsto 15
v andseruesas
supply
voliageJortheelectronics.
Thisvoltage
isalso
theaciual
voltagebeing
picked
off
viaD15.
(see
os-
cillogram1a).
(D
15andD
T2
are
locatedunderneath
lC1andare
flttedwitha heatconducting
pasie
to compensate
for
temperature
variationsoflC1).
2. TECHNICALDATA
Inputvoltage
range
Powerconsumption
Outputvoliage
180-240V/{90-130V)
50
- 60cycles
3OOVA
24v
275v4
3. GENERAL
DESCRIPTIONOF OPERATION
TheloadcircuitconsistsofthyrlslorsTh1andTh2as
wellastransJormerTr1,which
feedslhecolourhead's
lamp.Theactual
voltageis measuredat lhyristor
Th1andreachesdifferentialamplifier
lc1cld.ltlunc-
tionsas
R.M.S.converlerandsuppliesadirect
voltage
tobecomparedwiththereterence
voltage-
produced
by
D10,D11
and
adjusledbyP1
- incomparaior
lC1alb.
Theconlrolvoltageat the outputof comparatorlC
1alb is direcllyproporlional io the brightnessof the
colourhead'slampand
is passed on to thepulse
The
pulse
generalorproduces
the
ignilion
pulses
in
proporlion
tothemagniludeof
ihelC1a./bcomparalols
outpurvoh8ge.These,gritio'r
purses
are
requi'ed
forswitchingtheiwothyrislors
ThI and Th2.The
pulse
generaiof
issynchronisedwiththeIneirequencyby
opticalcouplerOK1.Thecircuiiboardfeaiuresalso
a protective circuit,consistingof componentsT 5/C acl0al
varue
(D15/D 16)
RMsvalue
(lC
ld/11)
*r I i
r--- + Ill
I
II
[*;;t
I *,".,1]]]

DurstEST500
synchionsation
(OK
1)
RepaiaInstruclions EST 500- 2
ThisvoliagereachesthebaseoJlC1candconirols
transisiorlC1dvlaemilterresistorR28.Thebiasvoltage
torlC1cldisJurthermorestabilisedviaD14.Theiran-
sistorslC1c/diunclionasdifferenialamplifiers
and
make
uptheR.M.S,valueofthe
phase
angleconlrolled
voltage.ThisvoltageappearsatPin11oflC1d
(see
oscillogram1b)
and s screened
via
condensatorC 10
andifansferredio Pin2 of lCla. AlsolClalb isa
dfterentlalamplifier.Al Pin4 oi lC 1/bthereis the
referencevoltage,
stabilisedby D 10,D 1T,evened
ouibyC12and
picked
oii
al
thebrushofP1.Thisvolt-
age
amolnts10approximately14
V.
AtP
n 1ol lC
1a
thereappearsthedlfferenialvoltagebelweenaclual
and reierencevohagewhlch is then lransfefiedvia
transistorT 3lo ihe
pu
se
generation.
CondensalorC 4 functionswiihPUT
(Th
3)forihe
generat
onofthetrigger
pulses.
Thecurrentsopplied
byiransisiorT 3 chargescondensatorC4.Assoon
asihecondensatorvoltagereachesthevalue
oJ
the
gate
voltage
of PUT
(Th
3) approximaiely6 V - ihe laiier
cutslhrough
(see
osc
llogram2b).The
pulsegeneraied
byPUT
(Th
3) is amplilledviatranslsiorT 4 and
transferred
tothe
gales
ofthyristorsTh1andTh2(see
oscillogram3a/b).
TheopticalcouplerOK1,whlchisdirecilyconnected
io themalnsvoliagev
a diodes
D
3- D 6,hasthelask
ofcompleielydischargingcondensatorC
4 during
eachzero
phasepassage
oftheslnewave.The
pholo-
lransstorntheoptca couplerocks
brieflyduring
the zero passage
phase,
transistorT1 becomesthere-
lorecondLrct
ve
and
dischargescondensaiorC4(see
oscillograms2 a/b).
Thecircultboardfeaturesa proleciive circuii,
loo.
11makes
sureihalfuseSi
1doesn'iburnlhrough
if
eiiheroneolihetwolhyrislors
(Th
1and
Th2)should
m
slire
ithis
wouldbeihecaseonaccountofa D.C-
voltageshareappearingsuddenly
in theprimary
windingof
Tr1).
The
phase
anglecontrolledvoliageispicked
oflvia
resistorsR 34and Fl35andlransferredto the baseol
iransjsiorT5 (see oscillogram
4a).At thesameiime
theoutpLrt
pulse
of
PUT
(Th
3)isatthecollecloror
transistorT5.Theseiwo
pulses
bringabout
thecharging
ofcondensatorC
5 (see oscillogram4 b).
mainsvollage
(R34/R35)
prolection circull (C5/F 10)
Condensator
C5dischargescontinuosly
vialransislor
T 2,butil isalwayschargedagain
allereachignjlion.
lf either oneof thetwolhyrisiorsshouldn
t ignte,
condensatorC5 iscompletely
discharged,lransislor
T2locksand
transistoflC1ebecomesthus
conductive,
slmulatingtoohighanactual
voliageaiihebase
oflC
1a.Theoutpulvoliagefallsthereloreoff
unlilitreaches
anrnnocuos
value.
5. ADJUSTMENTOF
THEOUTPUTVOLTAGE
The23,5V output
voltageof the EST500maybe
adjustedbyturnlng
potentiometer
P1.
Noie:
- Themeasur€menimusibetakenoffthelampsockel,
- Thestabllisefsoutpul
mustbeloaded.
Sirce I isa phase anqecontrollFd
alerraL'19-cLr-
rent
voltage,
a trueR.M.S.metermustbe!sed.
Welurthermore
suggesito usea 2,3Ohm(250
W)
wireresislancein
place
of
lhelampwhenmakingthe
a)tr
sser
pulse
(Rl
rB2)
b)lrigger
pulse(R6/Th
3)