Bang & Olufsen Beogram CD 5500 Service Manual page 28

Bang & Olufsen
Kontrol af laserforsyning
Laseren, laserforsyningen i 301C6101 og monitordio-
den danner et tilbagekoblings system. En fejl i laser-
forsyningen kan medfore at laseren adelegges.
Hvis dette er tilfeeldet, og laseren (= komplet RAFOC
enhed) udskiftes, vil den nye laser ogs4 edelegges.
Da det er umuligt at kontrollere og reparere et tilba-
gekoblingssystem hvor en af komponenterne mangler,
kan nedenstaende kredsleb bruges til at kontrollere
laserforsyningen.
Den gronne LED udgor laseren. Spzendingen over
18 ohms modstanden udgor monitor tilbagekoblings
spzendingen. 33 ohms modstanden og omskifteren gor
det muligt at andre stromforbruget fra laserfor-
syningen.
GREEN ¥t
uD
Gren LED f.eks. CQY 94 bestillings. nr. 8330054.
Fleks printet tages ud af P31. pa servo PCB'en.
Ovenstdende kredslob loddes p& P31 pa servo PCB'en.
SI (ben 20 pa 301C6101) kortsluttes til stel.
Nar SI (Start initialization) er low, kan laserforsynin-
gen tandes i service position 1. Sat apparatet i servi-
ceposition 1. (Kortslut service stikket pa PCB5 samti-
dig med at netstikket szttes i).
Tryk derefter OPEN og PLAY samtidigt.
LO spendingen pa 30P31 ben 9 males.
S1 afbrudt: LO fra 1,8 V iil 2,3 V
LM fra 170 mV til 220 mV
Den granne lysdiode lyser svagt.
Si kortsluttet: LO fra 1,8 V til 2,3 V
LM fra 170 mV til 220 mV
Den gronne lysdiode lyser svagt.
Nar $1 skiftes fra kortsluttet til afbrudt vil LED'en
lyse kraftigere i et kort ojeblik. Tilbagekoblings-
systemet bevirker at der gar samme stram i LED
hvadenten S1 er kortsluttet eller afbrudt.
5-11
Check of laser supply
The laser and the laser supply in 301C6101 plus the
monitor diode form a feedback system. A defect in
the laser supply may result in the destruction of the ,
laser. *
If, in that case, the laser (= complete RAFOC unit
pos. no. 9607) is replaced, the new laser will also
become defective.
However, it is impossible to check and repair a feed-
back system if a link is missing. For this reason the
laser supply can be checked with the circuit below.
The green LED replaces the laser, the voltage across
the 18-Ohm resistor is fed back as monitor voltage,
the 33-Ohm resistor and the switch serve to draw
more current from the laser supply.
To LO 30P31-9
i Connected dir-
To Um 30P3+8 Ot hp the
servo PCB30 P31
To 4 30P31-10
LED green e.g. CQY 94 part no, 8330054.
Take the flex PCB out of P31 on the servo PCB.
Connect above mentioned circuit to P31 on the servo
Connect SI (pin 20 of 30JC6101) to ground.
With SI (start initialization) low, the laser supply can
be switched on. Put the player in service position 1.
(Short circuit the service plug on PCB5 and plug into
mains supply at the same time).
Then press OPEN and PLAY simultaneously,
Measure the voltage LO at 30P31 pin 9.
S1 open: LO from 18 V ti! 2.3 V
LM from 170 mV to 220 mV
The green LED emits little light.
S1 closed: LO from 18 V to 2.3 V
LM from 170 mV to 220 V
The green LED emits little light.
During the change over from SI closed to $1 open,
the LED will emit more light for a short moment.
The control sees to it that the same amount of cur-
rent flows through the LED when $1 is open and
when $1 is closed.