Electronics > Repair

Prisma elevator door controller, damaged psu, need identify components

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DavidAlfa:
Weird circuitry around Q32.
Normally Vcc is directy feed from HV (Yeah, 300V++) through a 200K-1M resistor.
This greatly limits the current, so the Vcc capacitor charges slowly.
When reachingthe threshold voltage the PWM IC will turn on, pulsing the driving transistor, and start feeding itself though the auxiliary winding.

Grandchuck:
Did U10 pop part of its top off?

PiotrMisiuna:
U10 did popped a piece of i
t.
More corrections. it gets better once the shorts get removed. BC807 was also shorted

timeandfrequency:
Hello PiotrMisiuna,


--- Quote from: PiotrMisiuna on December 04, 2024, 10:04:35 pm ---More corrections. it gets better once the shorts get removed. BC807 was also shorted

--- End quote ---
Nice holes in U10 & Q32 : 'magic smoke' generators :P
Your latest schematic starts to match with the UC3842 reference design (figure 8-2)
Opto on the right of your schematic is for the SMPS feedback : you should also find a TL431 in that area.
Opto on the left of your schematic is probably for checking the mains presence or grabbing 50/60 Hz synchronization ticks : is it connected to the Fujitsu µC located on the far right side of the PCB ?

PiotrMisiuna:
Yes, the opto on the left goes to the large Fujitsu. Above it there is a motorola Eprom. There is also a MAX 232 next to the DE9 port. There is really not that much stuff on this board, and the service guys ask  long waiting time and a small  fortune for the replacement.

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