Cheap Power Supplies

[ZL2BKC]

Some dumpster diving at the office uncovered some nice IBM server power supplies rated at 12V 55Amps

After some reseach I found there is quite a lot of information about how to power them up, and I have spend some time tracking the circuit diagram to increase the OVP (over voltage protection) to 15V and the output voltage to 13.8V (which is not as well documented out there on the net)

On the left is 13.8V at 55 Amps (From a IBM x3550 server).
Middle is 13.8V at 48A (From a IBM x335 server)
On the right is 12.5V @ 35A (from an IBM DS3400 SAN)

I have also figured out the power up signals for a Cisco 4500 switch power supply (110A) and several others.

At some stage I plan on writing up the modifications with some tips on how to reverse engineer almost any server supply. I actually have about 10 of each supply in the cupboard, but kicking myself after sending over 100 of the servers to a surplus depot before I rialised what was inside. It wasn't until late in the decomissioning phase of the project that I discovered they were actually quite useful.
Plus the copper heatsinks went towards my 23cm PA project.....

It should ne noted that they are built using *real* engineering principals designed to survive in a datacentre, so they have good EMI filtering on the input and output compared to the PS in a home PC, or most of the asian supplies. All of the supplies have lots of protection on board (voltage, current, short circuit etc).

Lots of AMPS for Free!

PS. They are also RF quiet accoring to my limited testing in my lab. I have given one unit to a "ham in the sticks" and awaiting for his feedback on how it compares his SLA battery.

73,
Wayne

[VK3DXE]

Some dumpster diving at the office uncovered some nice IBM server power supplies rated at 12V 55Amps

After some reseach I found there is quite a lot of information about how to power them up, and I have spend some time tracking the circuit diagram to increase the OVP (over voltage protection) to 15V and the output voltage to 13.8V (which is not as well documented out there on the net)

DSC_0247.JPG

On the left is 13.8V at 55 Amps (From a IBM x3550 server).
Middle is 13.8V at 48A (From a IBM x335 server)
On the right is 12.5V @ 35A (from an IBM DS3400 SAN)

I have also figured out the power up signals for a Cisco 4500 switch power supply (110A) and several others.

At some stage I plan on writing up the modifications with some tips on how to reverse engineer almost any server supply. I actually have about 10 of each supply in the cupboard, but kicking myself after sending over 100 of the servers to a surplus depot before I rialised what was inside. It wasn't until late in the decomissioning phase of the project that I discovered they were actually quite useful.
Plus the copper heatsinks went towards my 23cm PA project.....

It should ne noted that they are built using *real* engineering principals designed to survive in a datacentre, so they have good EMI filtering on the input and output compared to the PS in a home PC, or most of the asian supplies. All of the supplies have lots of protection on board (voltage, current, short circuit etc).

Lots of AMPS for Free!

PS. They are also RF quiet accoring to my limited testing in my lab. I have given one unit to a "ham in the sticks" and awaiting for his feedback on how it compares his SLA battery.

73,
Wayne

There are plenty of old 32-bit servers sitting in storage with 50 - 60A PSU's that are probably anybody's for the asking. I've got a couple at work that I plan to liberate from the recycler soon.

[VK5TM]

Sorry Terry, not sure what is the meaning of "suitable for amateur radio".

I'm talking about public sites like Craigslist etc.

For the non-technical ham, not much at all for sale (or being given away) without needing to modify/build something from it.
And most of the plug and go stuff that i have seen is CB . Can only recall seeing one ham rig on Gumtree in the last couple of years.

For the technical ham, of course, there will always be something that can be re-purposed one way or another.

[VK2AAH]

Hi Terry,

I've seen so many perfectly good supplies go for scrap. I know my employer sent a pallet load of Imark PS5020s to auction not long ago & I'm pretty sure they went for scrap value. Some may have worked, others may have had a blown bridge rectifier... either way, I think it is more a case of some believing that unless something has a high price it can't be any good. In many cases (like the server PSUs) it is a case of them reaching their use by date for critical applications but they still have many good years of life for powering a ham rig. The Imarks are a great bench supply (so long as it is a sturdy bench) and will last for many years... they retailed for $1500+ new... keep looking, lots of supplies out there.

Cheers

Richard
VK2AAH

[VK2TS]

Hi Terry,

I've seen so many perfectly good supplies go for scrap. I know my employer sent a pallet load of Imark PS5020s to auction not long ago & I'm pretty sure they went for scrap value. Some may have worked, others may have had a blown bridge rectifier... either way, I think it is more a case of some believing that unless something has a high price it can't be any good. In many cases (like the server PSUs) it is a case of them reaching their use by date for critical applications but they still have many good years of life for powering a ham rig. The Imarks are a great bench supply (so long as it is a sturdy bench) and will last for many years... they retailed for $1500+ new... keep looking, lots of supplies out there.

Cheers

Richard
VK2AAH

Hi Richard

I have a Imark PS5020 and I can confirm they are an excellent supply but damn heavy. Mine in located in a rack about my shack desk and it was a struggle to get it up into the rack. I discovered how reliable they are when a commerical customer had loaded 2 massive gel cells onto the battery charge circuit. The charge current was 19Amps. I told him he had to many batteries and too high in capcity connected. I convinced him and instructed my techs to reconfigure it all and connect the loads to the supply output (as he had everything connected to the back up batteries) removed some redundant gear, and removed one of the big Gell Cells so the current fell right back. The supply was that hot you could smell the enamel paint burning. It wasnt even in an air conditioned comms room either. I guessed if it could handle that for 6months at 19Amps then i needed one of these supplies. Got it for $300 on Ebay. Bar a transformer buzz which turned out to be a aluminium plate just touching another piece of metal inside (Pliers and some pressure fixed that) it is still in service. By the way for anyone with one I have the complete manual including circuits if ever required. The commercial customer copied it for me after I obtained my own.

Linear supplies may be heavy but they are robust, noise free and easily repairable. Switch modes????..... Nah too hard

Cheers

[VK5TM]

That's one of the things I miss living in the middle of nowhere, you don't get hear of these things until it's too late (excluding Ebay ).

At least when I was living in town, they were only a phone call and less than 15 min trip in most cases.

[VK4WDM]

I had been using an Avair 40A switch-mode for about two years. It worked very well and was completely RF quiet until a month ago when it started to put out a high level of hash on 30m and to a lesser extent on 40 and 80m plus all the spectrum between, so something must have gone wrong when it got older. Had a poke around inside but there was nothing obvious and ferrite beads did not cure the problem. I replaced it with a Power Tech linear and the noise has gone. During the investigation I also discovered another noise source - a "wall-wart" used for a powered USB hub. It became the victim of a hammer attack.

73

Wayne VK4WDM

[VK5ACY]

Your crook Switch Mode Power Supply will (most likely !) require the replacement of an electrolytic capacitor/s....as is the case with almost all SMPS faults.

It is very common practice to 'replace all the electrolytics' in such devices...but use quality, low 'Effective Series Resistance' capacitors with a '105C' temperature rating.

Here at my rural RF-noise-silent location ( ) I run around the house switching off all the (many just 'idling', waiting for a remote-control input to TV/Video/HiFi etc.) SMPSs,
so I can hear the many low-level signals which are otherwise masked by the buzzing/popping/farting of said supplies. This is especially the case when participating in the (Thursday evenings) 160 Metre Band AM net.

Yep....I am spoilt ! .

Bill VK5ACY
BOWHILL
South Australia
PF95sb

[ZL2BKC]

I had been using an Avair 40A switch-mode for about two years. It worked very well and was completely RF quiet until a month ago when it started to put out a high level of hash on 30m and to a lesser extent on 40 and 80m plus all the spectrum between, so something must have gone wrong when it got older. Had a poke around inside but there was nothing obvious and ferrite beads did not cure the problem. I replaced it with a Power Tech linear and the noise has gone. During the investigation I also discovered another noise source - a "wall-wart" used for a powered USB hub. It became the victim of a hammer attack.

73

Wayne VK4WDM

Wayne,
There is a small chance that the EMI filter capacitors have gone on the main input. Look for X1 and Y1 type capacitors (special mains rated capacitors) which may have failed due to mains voltage pikes etc.

If the main electros go then you will normally have higher ripple @50hZ or 100KHz (or whatever the switching frequency is) and not something specific at 7-10MHz where large eletrolytric caps have quite a high impedance.

73,
Wayne

[ZL2WHO]

This supply http://oh6ac.net/oh6ac-kerho/?page_id=281 is powering the 024 6m beacon. On key down its supplying about 16-18 amps at 46 volts.
Cant comment on the HF noise because up on a hill in the middle of nowhere i dont care to much.
The 24/7 pulsing for CW will be a good test. I like the shut down input, its configured so that if the hut inside temp reaches x deg then the PSU shuts off.
As you can see from the link the standard PSU is quite long and in its normal state its too long to fit into any big rack mount enclosure. This PSU comprises of two PCBs which are mounted end for end. I had to remove them from the standard enclosure and rewire them side by side. I did note that the switching devices heatsink runs quite hot so good air flow is required. I also have a HP 120 series 3Kw supply under the bench for when my LDMOS BLF578 arrives soon, but that's a whole new story

Mark.

[VK2TS]

Go Mark!

all the work put into the Beacons is appreciated, I always look that way because if the band is open i know your beacons will be the first to be heard. A Big Bad boy supply is of course needed for continuous operation. Head room is always an issue.

Cheers mate