Maker Pro
Maker Pro

power supply troubleshooting

hello anyone reading this.
i recived a broken light projector im trying to fix.
i am trying to troubleshoot the power supply.
my multimeter says it gives 24v
when i connect any load to it, the onboard diode keeps turning on and off immidiatly and repeatadly.

any idea on how can i inspect what the problem might be or where can i find tutorials on how to diagnose this?
 

bertus

Moderator
Hello,

What are you using as load for the powersupply?
It sound as if the current limiter is kicking in.

Bertus
 
so the power supply has 2 positive and two negative outputs. both were originally used.
when i disconnect all of them. the diode is solid and running. if i connect any of the two (motors or led display) it starts turning on and off repeatadly (and rapidly, once-twice a scond)
p.s. thank you!
 
Sounds like a fault downstream of the power supply.
Look for any obvious signs of damage.
Do you have any testing experience?
 
i have very little testing experiance.
except for the black on one of the screws, i saw nothing out of the ordinary. i tested the resistance on the capcitors and they seem to give a wrong reading. if i understand correctly (and i am rather clueless) if i put the multimeter leads on the capacitor leads under the resistance definition, they should show me a number close to the number written on the capacitor (xxxx-uf). but im not sure if its that or perhapse the contacts of the capacitor got somewhat oxidized.

a. am i correct about the way testing for the capcitors?
b. will a capacitor problem make such a type of problem?
c. any advice?
 

Attachments

  • IMG_20211027_013222_1_50.jpg
    IMG_20211027_013222_1_50.jpg
    163.7 KB · Views: 5
Sir ben_nexus
In your photo submitted, your potential faulty Electrolytic caps units are typically going to be the two LARGE ones near the 4 screw terminals at the rear end.
The gold stripe down the side is marking the negative terminal /lead of each unit.(Suspected as 2200 ufd @ 35VDC by the two singly visible numbers on cap ends.)
If being MY my unit to test . . . . .I would connect up just enough of a load to get the unit turning on and off / pulsing, as it was.
Then get / find yourself another new or even . . .suspected / assumed as good . . .test capacitor . It can be even less than that units marked capacitance,( say 1000-470) or more, should you be having a problem of EVEN having an electrolytic capacitor on hand, or it could be be temporarily cannibalized from some available other electronics. Be SURE it has at least the same voltage rating as the installed big caps or even a bit more.
Then, if finding yourself having a short leaded test unit, tack on some temporary extender wires and OBSERVE THE marked / + and - WIRE POLARITIES and then touch the " new " capacitors leads across one of those mentioned big electrolytics to see if the power pulsing does not then completely stop, or at least, get slower. Try that on both caps, one at a time.
If no good results, move to the MUCH smaller orange cased unit at center chassis, it being of much less capacitance , and possibly marked as having a lower voltage rating. You then need to find another test cap at or close to its marked on cap and voltage specs .

If no luck, then the last test would be for the two LARGE E-caps that have yellow tape across their tops.
A potentially simpler test for them would be merely using a DVM in its DC volts function and set for a voltage range of being more than the voltage rating marked on THOSE E-caps and initially have no load on your output terminals and be reading the voltage across those E- caps and commit the voltage read to memory and then connect the load and see if the degree of voltage dropping mimics the power supply's pulsing output.
I really think that the earlier caps would be the problem . . . . time of use and their eventual deep capacitance decline, down to the depleted storage capacity state of their now telling you . . . . " I can't . . .KEEP UP . . . and take it ANYMORE ! ! ! ! " . . . .so they are now just working in " built up bursts" .
 
Last edited:
Top