MagicianLord77
Enthusiast
Hi there, I am trying to make the PSU of Korean House of the Dead 1 "upright" cabinet work, it almost works, model 400-5306CE-01, exactly like the one from this image:
I'm testing the power supply individually before trying it in the cabinet for first time, with a dummy load in the +5v side.
At first it didn't turn on, five minutes later of it being connected it still didn't. Upon probing some of its components, trying to measure voltages, I found it had turned on by itself, its red led indicator was on and it was giving 5. and 12v fine on the output!
Turned it off, turned it on again and nothing again, poked around with just the red lead of the multimeter the legs of some diodes/resistors, and it turned on again!. Poking around the primary or the other side around the IC had the same effect, so can't figure out poking what does it tick, since poking nearly anything makes it start up.
Then did the same test but using freeze spray around the main IC (KA7500B), that made it turn on too!
Then the day after, sometimes it turned on by itself (maybe because temperature was less warm?), but sometimes didn't, and spraying around the IC did the trick.
So I decided to replace the KA7500B with the one from another unit that is in much worse condition, took it out, installed socket and tested, same issue.
Measured all nearby diodes, resistors, Q1, Q2 transistors, capacitors, all good (in circuit).
Here's a picture of it (before installing the socket).
I wonder what would diagnosis be to research more about it, startup circuit failure? Here are some measurements and their location:
I would really like to use this PSU, and not have to hack a different one in, since it "almost" works.
Appreciate any hint about this issue, my SMPS knowledge is not the best, just getting started
Thanks!
I'm testing the power supply individually before trying it in the cabinet for first time, with a dummy load in the +5v side.
At first it didn't turn on, five minutes later of it being connected it still didn't. Upon probing some of its components, trying to measure voltages, I found it had turned on by itself, its red led indicator was on and it was giving 5. and 12v fine on the output!
Turned it off, turned it on again and nothing again, poked around with just the red lead of the multimeter the legs of some diodes/resistors, and it turned on again!. Poking around the primary or the other side around the IC had the same effect, so can't figure out poking what does it tick, since poking nearly anything makes it start up.
Then did the same test but using freeze spray around the main IC (KA7500B), that made it turn on too!
Then the day after, sometimes it turned on by itself (maybe because temperature was less warm?), but sometimes didn't, and spraying around the IC did the trick.
So I decided to replace the KA7500B with the one from another unit that is in much worse condition, took it out, installed socket and tested, same issue.
Measured all nearby diodes, resistors, Q1, Q2 transistors, capacitors, all good (in circuit).
Here's a picture of it (before installing the socket).
I wonder what would diagnosis be to research more about it, startup circuit failure? Here are some measurements and their location:
I would really like to use this PSU, and not have to hack a different one in, since it "almost" works.
Appreciate any hint about this issue, my SMPS knowledge is not the best, just getting started
Thanks!