My poor take on a series server psu

[JoeBailey]

By not floating the DC on the units properly and not connecting the earth you have allowed the case of the second unit to become live all the time. It's not a case of when it becomes live in a fault it is already live to start with.

Floating the dc side is relatively painless I did both of mine in 30 mins with a Dremel but by not doing it in the first place I had to replace a lot of cable in the house due to overloading the earth cable in the ring circuit. Cramming the better part of 120a down it didn't do it much good.

[Heliben]

im looking at the inside of one at the moment and nothing is really jumping out at me as to what i should be removing....

[Heliben]

the insides

[JoeBailey]

Test from the dc negative output to the mounting holes on the pcb with an ohm meter. Some of them will read 0 ohms or very low some will me a lot higher the high ones are decoupled using capacitors and can be left the others need to be isolated. I used a Dremel to buzz through the tracks on the pcb and then retested to ensure there was no DC negative to earth connection.

[Heliben]

righty, i will give that a try....i am reading your post from a while back joe, it is proving quite helpful

[Heliben]

no luck so far, gotta say im not over sure what im supposed to be cutting still, and dont seem to be able to find any pics of what it should look like

[xygax]

if you get really stuck bring it to Bristol. its a ten min job...

[Heliben]

after a quick call to steve i know understand what it is that im removing and have successfully done so shame i buggered up my second psu last night whiles blindly attempting to do it ( hit a resistor). ty for all the help guys. will update when i get another psu delivered and it all up and running

[nobbycopter]

I was going to do the conversion, but as I know b***er all about electrickery (apart from you can't see it and it hurts when you get it wrong...) I decided to err on the safe side and purchased one from Coolice...job done

[MarkG_R1]

Quick Hijack then i'll butt out Thought it may be useful to others seeing this thread, Is it necessary to float both server unit's dc grounds? if so why? Thanks

[xygax]

Quick Hijack then i'll butt out Thought it may be useful to others seeing this thread, Is it necessary to float both server unit's dc grounds? if so why? Thanks

No. you need to float only one. Reason. If you have two grounds on the output system in different locations then something is shorted (in our case the PSU nearest the negative) all computer systems come with the case (ground) connected to the logic return voltage (0v) so when we stack them to give 24v the second ground appears at +12v. and hence it needs to be disconnected. Removing both grounds isn't necessary and you do end up removing one level of protection. (if you have a primary to secondary short in either unit) then the fault current has nowhere to go and that can in theory place a potential equivalent to the fault application voltage between the case and the DC. (the DC could become live) that's why the secondary is connected solidly to earth. .........

[JoeBailey]

Done some front panel work on mine.

ImageUploadedByTapatalk1377202530.074115.jpg

I think I may need to recover it but it looks ok as is.

[JoeBailey]

After one mammoth soldering session it's all on and working ok (I think)

ImageUploadedByTapatalk1377292436.204137.jpg

Huge amount of soldering done

ImageUploadedByTapatalk1377292460.036896.jpg

And powered up.
Gotta cut a bit more Ali to finnish my case and then it's test time. I know the psu's work fine I've been using them for 12 months without issue but they needed boxing up and tidying up.

[Heliben]

That looks pretty awesome Joe