Author Topic: Prisma elevator door controller, damaged psu, need identify components[SOLVED]  (Read 3577 times)

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Offline PiotrMisiunaTopic starter

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Could not locate any photos of the PCB, attaching best I could make, maybe will help someone else.
There is several versions of the box but I don't believe they will differ much in layout, especially on the primary side of the psu.

 Killed by a drop of water, I did some reverse engineering, but with my low experience I don't believe I can make it without help.
Components on the schematic marked in red are the damaged ones.

Seams obvious that all the carnage was caused by arc under the C37.
I hope that blown components broke the circuit before melting the transformer, it does not appear to me melted.
Not sure how to determine the value of the Z7 zener diode...


list of components I wish to find markings for:
R114
Q32
Z7
R85
U10
« Last Edit: February 02, 2025, 09:44:22 pm by PiotrMisiuna »
 

Offline fzabkar

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Offline Harry_22

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Re: Prisma elevator door controller, damaged psu, need identify components
« Reply #2 on: December 03, 2024, 06:05:34 am »
Well, finally! One person who got together and redrew the circuit from the PCB.

 It will be a pleasure to help you!
 I'll take a look a little later.
 

Offline Harry_22

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Re: Prisma elevator door controller, damaged psu, need identify components
« Reply #3 on: December 03, 2024, 10:42:21 pm »
Hi!
Could you carefully clean R114 and try to read the color code.
Also make a good photo of Q32, U10 area.
 

Offline PiotrMisiunaTopic starter

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Re: Prisma elevator door controller, damaged psu, need identify components
« Reply #4 on: December 04, 2024, 04:20:35 am »
R114 has the bands visible on the other side but I think the paint pealed off due to temperature and what's left is just a discolored substrate.
 

Offline Harry_22

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Re: Prisma elevator door controller, damaged psu, need identify components
« Reply #5 on: December 04, 2024, 05:07:45 pm »
Check Z13, Z14 for short and open.
I don't like that the base Q32 is connected only Z14.

Please measure C56.
 

Offline fzabkar

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Re: Prisma elevator door controller, damaged psu, need identify components
« Reply #6 on: December 04, 2024, 05:23:51 pm »
Q32 doesn't make any sense to me, nor does the feedback circuit involving the optocoupler.
 

Offline PiotrMisiunaTopic starter

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Re: Prisma elevator door controller, damaged psu, need identify components
« Reply #7 on: December 04, 2024, 07:18:29 pm »
Z13 and Z14 open circuit, tested out of circuit.
R112 - 10K,
C56  - 2,4nF

did some edits following your order

third attachment is just a back lit photo of the pcb, maybe useful.
 

Offline PiotrMisiunaTopic starter

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Re: Prisma elevator door controller, damaged psu, need identify components
« Reply #8 on: December 04, 2024, 07:21:39 pm »
Did some corrections to the schematic.
As to the optocouppler, I believe it is just a voltage sense for a controller. Tracks disappear under the row of sockets and run deep into secondary side.
 

Offline fzabkar

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Re: Prisma elevator door controller, damaged psu, need identify components
« Reply #9 on: December 04, 2024, 08:21:06 pm »
The Vcc pin needs to charge up to 16V before the IC starts pulsing the MOSFET. I don't see any path for this charging current.

Z7 must be a Schottky diode.

Why is the base of BC807 grounded?
« Last Edit: December 04, 2024, 08:27:46 pm by fzabkar »
 

Online DavidAlfa

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Re: Prisma elevator door controller, damaged psu, need identify components
« Reply #10 on: December 04, 2024, 08:54:09 pm »
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.
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Online Grandchuck

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Re: Prisma elevator door controller, damaged psu, need identify components
« Reply #11 on: December 04, 2024, 09:01:23 pm »
Did U10 pop part of its top off?
 

Offline PiotrMisiunaTopic starter

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Re: Prisma elevator door controller, damaged psu, need identify components
« Reply #12 on: December 04, 2024, 10:04:35 pm »
U10 did popped a piece of i
t.
More corrections. it gets better once the shorts get removed. BC807 was also shorted
 

Offline timeandfrequency

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Re: Prisma elevator door controller, damaged psu, need identify components
« Reply #13 on: December 04, 2024, 10:22:06 pm »
Hello PiotrMisiuna,

More corrections. it gets better once the shorts get removed. BC807 was also shorted
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 ?
« Last Edit: December 04, 2024, 10:52:12 pm by timeandfrequency »
 
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Offline PiotrMisiunaTopic starter

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Re: Prisma elevator door controller, damaged psu, need identify components
« Reply #14 on: December 04, 2024, 11:00:02 pm »
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.
 

Offline Harry_22

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Re: Prisma elevator door controller, damaged psu, need identify components
« Reply #15 on: December 05, 2024, 03:14:09 pm »
The oscillator frequency according to ST datasheet is around 90kHz.

Two chips are currently under consideration:
UC3842B max 100% Duty Cycle/ 90kHz drive operation frequency
UC3844B  max 50% Duty Cycle/ 45kHz drive operation frequency
 

Offline timeandfrequency

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Re: Prisma elevator door controller, damaged psu, need identify components
« Reply #16 on: December 05, 2024, 05:12:36 pm »
Z13 and Z14 open circuit, tested out of circuit.
Might be high voltage zeners (tens of volts), even if one junction drop should be found in one way : any marking on them ?
Package is known as 'melf' https://services.taiwansemi.com/storage/resources/datasheet/ZM4728A%20SERIES_E2301.pdf
and wattage seems to be 1W  https://www.mouser.fr/c/semiconductors/discrete-semiconductors/diodes-rectifiers/zener-diodes/?mounting%20style=SMD%2FSMT&package%20%2F%20case=MELF
Check if your parts size correspond to a 1 W zener in melf package.

The circuit around Q32, Z13 and Z14 needs more attention/refinement, because it goes beyond the application note.
On this page :
- Figure 5 gives interesting information about the required voltage to power the UC3842, but this will be useful later.
- Figure 6 explains how most SMPS controllers like the UC3842 are powered : startup power comes from the mains DC rail (about 324 VDC in Europe) via 'Rin'. Once running, an auxiliary winding 'Waux' provides power through D1.

Let's go back to your latest schematic.
The 'aux winding' is present and the main power for U10 comes from D12, and this seems OK.

R114 is probably 'Rin' and even if the paint is peeled off, the value you measured (100 k) is probably correct, because the UC3842 asks for at least 1 mA to wake up.
Additionnal information : at 100k, the current is around 3.1 to 3.2 mA, which is more than enough to wake up the PWM controller.
R114 seems to be a 2W resistor. However, it is wise to replace the part with a new one.

Two chips are currently under consideration :
UC3842B max 100% Duty Cycle/ 90kHz drive operation frequency
UC3844B  max 50% Duty Cycle/ 45kHz drive operation frequency
You are right, and to solve the riddle, the transformer ratio and primary inductance is probably required  :palm:

« Last Edit: December 06, 2024, 08:58:19 am by timeandfrequency »
 

Offline Harry_22

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Re: Prisma elevator door controller, damaged psu, need identify components
« Reply #17 on: December 05, 2024, 09:52:06 pm »
Please check the both zener connection.

PS
Seems they are the same 18-20V to get 17.3-19.3 start at Vcc.
« Last Edit: December 05, 2024, 10:01:13 pm by Harry_22 »
 

Offline PiotrMisiunaTopic starter

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Re: Prisma elevator door controller, damaged psu, need identify components
« Reply #18 on: December 05, 2024, 10:25:56 pm »
 :palm: yes, you are correct. I need to stop making this edits at 1:00am.

as to the transformer, it has a sticker, no meaningful results in the search engines thou.
markings at the top just refer to the type of the core.
 

Offline timeandfrequency

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Re: Prisma elevator door controller, damaged psu, need identify components
« Reply #19 on: December 05, 2024, 10:38:02 pm »
as to the transformer, it has a sticker, no meaningful results in the search engines thou.
Yes it is for sure a custom made part and we won't find any datasheet.
If we really need to know the transformers' ratio and primary inductance to validate the PWM controller reference, those intrinsic parameters have to be measured... :scared:
 

Offline Harry_22

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Re: Prisma elevator door controller, damaged psu, need identify components
« Reply #20 on: December 05, 2024, 10:45:09 pm »
Some more thoughts.

There is no point in installing Q32 just to start the controller.
Most likely something else is being powered there, take a look.
If transistor Q32 is shorted on all pins then it is most likely a MOSFET.

Resistor R114 is marked with the first brown stripe, please check it. I set it to 100k but when applying high tension it will not burn like that. Looks like he's about 10 kilos.
 

Offline Harry_22

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Re: Prisma elevator door controller, damaged psu, need identify components
« Reply #21 on: December 07, 2024, 06:44:44 pm »
I corrected the circuit digram.
Due wake up resistor is replaced here by stabilized power supply on Q32 the controller should be with lower start threshold i.e. UC3843 or UC3845.
Seems all the zener diodes Z1,Z4, Z7, Z13 and Z14 are the same.
« Last Edit: December 08, 2024, 01:09:14 pm by Harry_22 »
 
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Offline PiotrMisiunaTopic starter

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Re: Prisma elevator door controller, damaged psu, need identify components
« Reply #22 on: December 08, 2024, 09:48:46 am »
I'm ordering the parts. it will take a while, Cyprus shipping is like 3 times the usual. I'll share results as soon as possible.
 

Offline Harry_22

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Re: Prisma elevator door controller, damaged psu, need identify components
« Reply #23 on: December 08, 2024, 11:02:32 am »
Cyprus shipping is like 3 times the usual.
Yes, life is't easy for you :)
 

Offline Greybeard

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Re: Prisma elevator door controller, damaged psu, need identify components
« Reply #24 on: December 08, 2024, 01:13:46 pm »
Don't forget to replace the blue bulged electrolytic cap.
 


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