| Electronics > Repair |
| Prisma elevator door controller, damaged psu, need identify components |
| << < (7/8) > >> |
| Harry_22:
--- Quote from: Poroit on December 09, 2024, 05:40:24 am ---G'day All, I am not sure if the attached is a help or a hinderance but it contains similar components to the damaged PSU. I have seen similar damaged components in these as well. I do not have a schematic. --- End quote --- Hi Poroit! Yes, yours PSU is mostly similar. PFC provides its own Vcc supply. That is why low power start-up UCx845 is used there. Also 50% duty cycle is usually used with the high power transformer. |
| timeandfrequency:
Hello Poroit, --- Quote from: Poroit on December 09, 2024, 05:40:24 am ---G'day All, I am not sure if the attached is a help or a hinderance but it contains similar components to the damaged PSU. I have seen similar damaged components in these as well. I do not have a schematic. --- End quote --- Can you confirm that the document you provided shows an elevator door controller from Prisma ? |
| timeandfrequency:
About Z14 (Vz = 11 V in the latest schematic) @PiotrMisiuna Any marking on the zeners ? Minimum PWM controller startup voltage depends on IC reference : UC3842 & UC3844 : 16 VDC : Z14 value is underrated, PWM controller will not start UC3843 & UC3845 : 8,4 VDC : Z14 value is OK Interesting sentence in chapter '7.3.5 Undervoltage Lockout' of the datasheet : During normal circuit operation, VCC is developed from auxiliary winding NA with DBIAS and CVCC. At start-up, however, CVCC must be charged to 16 V (*) through RSTART. With a start-up current of 1 mA, RSTART can be as large as 100 kΩ and still charge CVCC when VAC = 90 V RMS (low line). Power dissipation in RSTART is then be less than 350 mW even under high line (VAC= 130 V RMS) conditions. (*) Actual minimal startup voltage depends on IC model, see above. Reminder : as PiotrMisiuna is located in Europe, VAC = 240 V RMS @ 50Hz (hence DC rail voltage = 339 VDC) |
| Poroit:
G'day timeandfrequency, Unfortunately not. It is an SMPS from a 25 year old Air Data Test Set. |
| timeandfrequency:
--- Quote from: Poroit on December 10, 2024, 05:36:16 am ---Unfortunately not. It is an SMPS from a 25 year old Air Data Test Set. --- End quote --- Thanks Poroit for this information. These UCx84x switchers have numerous applications and were used in many different designs. This thread is about the repair of a 'Prisma elevator door controller'. Unfortunately, the board you showed can not really be used as reference to identify the fried parts we have on that elevator controller. |
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