• Hello MLAers! We've re-enabled auto-approval for accounts. If you are still waiting on account approval, please check this thread for more information.

In search of list of capcaitors for Delta SMP-220DB PSU (Apple P/N 614-0012)

Oh boy! Mine was also filthy, but nothing compared to this.
I used some strong general purpose cleaner / degreaser and lots scrubbing with toothbrush, and rinsing with water jets.

Wish you good luck. I think zener diodes do have markings on them, so it should not be too hard to replace them. Of course this kind of restoration is a total time waster, but in the end you perhaps get awarded or you do everything right, then it just blows up again. Before turning it on, check every single diode and transistor for shorts. First try to get +5V_TKL and VCC (15.5V) up and running, then proceed on the main board. And don't change the capacitors before you get it running! I have 2 exact same supplies, and I checked every single capacitor with ESR meter on both, and found just 1 that was bit on a tired side, but still in spec (22uF 50V / C511).
 
mitchW said:
Oh boy! Mine was also filthy, but nothing compared to this.
I used some strong general purpose cleaner / degreaser and lots scrubbing with toothbrush, and rinsing with water jets.

Wish you good luck. I think zener diodes do have markings on them, so it should not be too hard to replace them. Of course this kind of restoration is a total time waster, but in the end you perhaps get awarded or you do everything right, then it just blows up again. Before turning it on, check every single diode and transistor for shorts. First try to get +5V_TKL and VCC (15.5V) up and running, then proceed on the main board. And don't change the capacitors before you get it running! I have 2 exact same supplies, and I checked every single capacitor with ESR meter on both, and found just 1 that was bit on a tired side, but still in spec (22uF 50V / C511).
Click to expand...
Thanks Mitch - good tips 👍
I’ll probably have to intelligently guess the values of some of the Zeners as the blown glass takes the markings with them. But will have to find other shorts first.
I only have enough Power Supply knowledge to be dangerous so will be taking my sweet time and with an extra dose of paranoia.
 
Are you getting +5VSB?
If not, this is the first thing to get sorted then.

Those units don't get bad caps as such, my two PSUs both still run perfectly with all original caps.
Sadly not much is known about common failure points on those. One of mine had blown standby power circuit and also a blown main switching transistor. Some passives also got fried, but not much else really.
 
mitchW said:
Are you getting +5VSB?
If not, this is the first thing to get sorted then.

Those units don't get bad caps as such, my two PSUs both still run perfectly with all original caps.
Sadly not much is known about common failure points on those. One of mine had blown standby power circuit and also a blown main switching transistor. Some passives also got fried, but not much else really.
Click to expand...
I'm not sure - i haven't run those tests yet - I'm more of a logic board repair guy so my expertise is poor on psus. I'll hit it w the meter later.
 
I'm a relative novice but I've managed to get mine to the point where I have +5VSB out and PFW activity when powering on but my +5V, +12V, and -12V are still all zip.
To get to that stage I had to replace a lot of the zener diodes, some diodes, caps, and some resistors which had all degraded in some way or another - most problems being on the board with the big 820uF caps.
So... my 5 cents is to visually inspect all those glass zeners and diodes for damage. And also inspect for general corrosive damage - I live in an island nation so corrison is just par for the course.
Next session is to focus on the DC-267 controller board and get some readings from the 339 and UC3843 chips. I've checked the diodes and transitors but they all seem fine.
I'm trying to be super careful not to kill myself on the high voltage so taking things nice and easy.
If I find the fault (maybe one of those chips), I'll post back here.
1765409789679.png
 
If you have +5VSB and nothing happens when you connect it to the PS_ON pin, then it could be the LM339 chip - it was dead on my PSU.
Also worth checking all diodes and transistors for shorts.

YMMV
 
I think I’ve honed in on the UC3843.
I’ve removed it from the PCB and my understanding is that I should get 5V on pin 8 (VRef) if I supply 15.5V on pin 7 (Vcc) (Gnd to 5). But my little chip measures 0V on pin 8.
I’ll have to send for a replacement chip all the way from Yankee Doodle land ☹️
 
You must log in or register to reply here.
Back
Top