[jan-jaap]

Panasonic FR series are a good choice for switching power supplies, they have low ESR and are designed for it. Make sure to get 105c versions if you can.

[ghost180sx]

How did this repair go? Any update?

It very interesting!

[dexter1]

Finally i have some time tell you about the current status of the Crimson PSU repair. I haven't been active over here for the past two months because of my new role as home teacher/cleaning dude/DIY Contractor, but i have researched all of this and purchased all replacement caps, IC's and soldering consumables to assist me in the repair. 

Before i show you my restored boards, let me tell you that up till now this has been the most challenging repair i've ever done. Every single capacitor has been replaced with the exact same specs and there are 34 of them. I worked on it for dozens of hours in the course of weeks, and i don't know if i am done yet, since i haven't tried out the PSU yet. I'm kinda sick of it for now...

Anyway, the restored 5V board looks like this:



Black caps are all Panasonic FR series, recommended by Jan-Jaap. They cost about 40 eurocent, not the cheapest.
The red ones are Wurth Electronic, manufactured in a chinese factory. It's a relatively new brand and obtainable through regular channels from RS Online. I chose those because of the smaller lead pitch and the availability of unusual capacitance/voltage.

The thermal compound on the heatsinks also need to be replaced and one component needed glue to attach to a plastic bracket. I used polymax, since it is heat resistant and strong:



I am not going to show you the bottom side, since it still looks horrible.

The 12V board rework was optional, but i'm glad i did because all three Nichicon's started to leak. Not as bad as the 5V board, but it required some scrubbing.



My advice to all of you is that if you want to restore a PSU you need to replace every single electrolytic capacitor you can find, except maybe the big filter caps on the "Hot" side. To check those, i measured the DC voltage on the base connector rail of the mains and it was 317 V, a bit high but i may get away with that.

The black base daughter board only had two caps:



The base connector board has 13 caps. All of the 35V 47uF caps were bulging from the underside so they needed to be replaced.



A shot of the capacitor victims:


Something i should have done is to replace all IC's and all Germanium glass diodes (the small orange ones), at least the ones in the zones where corrosion had occurred. This is due to the capacitor liquid shorting pins on the IC's. The liquid can also enter the glass diode and destroy it. I got these tips from watching youtube videos, like Mr Carlson's lab and Adrian's digital basement.
To replace IC's you need to have a desoldering gun. It's not absolutely required, since you can get away by using a solder sucker, but there are so many pins to desolder that such a gun pays itself back time-wise.

I'm going to assemble it today and test it outside of the Crimson for now. I don't know if the 12V and 5V board are "on" as soon as i flip the switch on the mains: i guess this is dependent on the inhibitor signal being present or not. I have to research that a bit.

As soon as it is starting to oscillate again i might have to ask Jan-Jaap for help, since he had the same oscillating behavior in the past, which i experienced myself a couple of months ago, which prompted the repair.

To be continued again. Let's hope it produces some decent voltages...

[ghost180sx]

Good luck! It looks as though you have done a very professional job considering it's your first time doing such a crazy repair.

The things we do for the computers we love!

[GanjaTron]

Hi Dexter,

too bad I only saw this now having finally found this forum. Wow, that's a heck of a job. Been there, done that; I also had to rework the Power Ones in my Power Series and Crimson.

However, I just replaced all caps on the backplane (leaking all over the place) and the 12V module. In the Crimson, one of the latter had actually "burned" a hole in the PCB, which some knucklehead bridged with a piece of wire. I replaced it with a wider trace fashioned from sheet metal scavenged from an old Philips VCR's shielding! Another (or same?) knucklehead even bridged the blown fuse on the 5V module!
 
Alas, I was too lazy to rework all those caps on the 5V module. They looked/measured ok and have given me no probs, but I acknowledge they're a timebomb I'll have to revisit sometime down the road... 

So yeah, the Power Ones are serviceable thanks to their modular construction, but they are daunting and command some respect. You have to be very careful with those 300V on the backplane, which kick in as soon as the PSU is plugged in (but still inhibited). I put together a test rig of 5W load resistors on the outputs plus some wires to short the inhibit signal. I ran the whole thing off a combo isolation transformer / variac for safety.

Stupidly, I did actually manage to short the Power One while probing with what I thought was my bench meter after the fan stopped working... only to realise the probes were infact attached to my bench PSU instead... via long cables that disappeared under the bench! I'd previously used the bench supply to test the fan, which turned out to have a totally corroded connector that needed replacement. Anyway, I was rewarded with Hollywood FX, two molten probe tips, a charred backplane connector, and a smoking PSU... guess which one.
Well, congrats to Power One for building one solid PSU! I cleaned up the connector, powered back up, and it was good to go again. It took me a lot longer to fix the bench PSU, tho; cheap Voltcraft junk from Conrad with barely legible schematics...

Each Power One repair took me several months, which was compounded by the fact that I'm now away for work most of the year.

Good luck and keep us posted!

--GT