Hi friends,
I have a power supply unit of a PA system. I am a total beginner on repairing stuff. This unit is belongs to my friend and he asked me to look at it if i can help. I accepted it because i thought that it might be a fuse problem and i could solve it with my slight superficial knowledge by replacing it with a new one
.
As you may see at the attached image, i tried to delineate the bridge rectifier and transformer section of the pcb where i would like to ask some questions
The fuse has a continuity until the 3rd pin of the rectifier and there is no continuity i could measure beyond that leg. However i do not have enough knowledge to assume, still i assumed that there is nothing to be afraid of to replace a new fuse
instead of the bad one and the fuse
blown again.
I am getting continuity faults with the multimeter testings for the half of the semiconducter parts.
DMM diode mode in circuit probing results for the Brigde rectifier's legs (As noted in the image):LEG DMM TERMINAL LEG DMM TERMINAL READING (V)
1 (+) 2 (-) 0.472
2 (-) 1 (+) 0.480
3 (-) 4 (+) 0.483
4 (-) 3 (+) 0.503
IN BOTH WAYS FOR AC LEGS (2-3) 0.950
There is a continuity between the 1th and the 4th ( - and the + ) legs of the bridge rectifier and there are no any other continuity for any other combinations.
DMM probing in circuit results for the transformer's legs (As noted in the image):In every possible combinations for the legs number 1,2,3,4,5,6,7 the resistance is 0 ohms. Every one of them has a dead short with each other.
In every possible combinations for the legs number 8,9,10,11 the resistance is 0 ohms. Every one of them has a dead short with each other.
There are no any continuity between the leg group (1,2,3,4,5,6,7) <--> (8,9,10,11).
Do any of these inspections i made in the circuit for these two components are sufficient to desolder these parts and make some further inspections on them or are these behaviours normal for in circuit testing?
I am in the dark and i need some expert suggestions what i can test, how i can test to resolve the problem.
Instruments i have is a MASTECH-MS8268 multimeter and i will borrow a MASTECH-MS5308 LCR-ESR meter in few days.
Thanks for reading!