C
Cydrome Leader
Guest
One of my test power supplies in a rather large switching unit from Power
One in the SPM5 series. It's basically a mainframe of sorts with power
factor correction, timing and a fan on the backplane and 5 slots for
various factory installed output modules. Unit is rated 1500 watts. Date
code on the outside is 1990.
unit is pretty much this thing with the small slot having a different card
http://www.ebay.com/itm/Power-One-SPM5D2D2V6-Switching-DC-Power-Supply-Unit-Module-Industrial-24V-32A-/111844628139
Mine has two double wide 24 volts 32 amp modules in parallel and the fifth
slot filled with a 12 volt 20 amp module. Very handy thing to have around.
The fan started to go crazy as in slowing down and speeding up, stopping
and stuff like that, then I noticed the outputs all lost regulation, 12
volts output dropped to about 9 under load and other weird stuff.
About two dozen screws later, the thing opened up and I got the modules
out. Fuses seemed ok, and the DC bus had 320 volts on it (sales sheets say
300 volts, but whatever). There's some sort of SCR based active power
factor correction trapped under heatsinks, thermal grease and dust. At
this point the 24 volt cooling fan was still erratic then basically made
sad noises maybe twice a second as it tried to start but didn't have
enough voltage. It could not bootstrap or regulate and was
restarting. Amazingly the main board only has some 1980s type 8 pin SMPS
regulator, not a crazy module thats impossible to work with. Swapped that,
no dice. No burned parts, but lots of discolored under the solder mask
traces.
To complicate things the control board where the fan attaches was covered
in something greasy and apparently corrosive as seen from the blue colors
on some leads. Parts cleaner and a brush got that off, mostly.
Probing around didn't show much other than the 24 volts for the fan was
pulsating at under 2 volts. It also looked like each module slot has a
dedicated winding off the same ferrite transformer to supply isolated
power. Those were also way too low. Voltage to one 7805 regulator was
zero. It appears that each module gets 320 volts, something around 24
volts and a timing signal and from that they all do their own thing.
Finally found a shorted diode, but the markings were worn off from the
cleaning process and whatever. The other similar parts were MUR something
and from motorola. I just went ahead and stole one from a backplane slot
what would never have a module card edge attached. All the caps on these
outputs were rated the same 35V, so it seemed safe enough. I've also
noticed the American power supply companies like to keep the part type
count low so many parts appear to be grossly overrated, but it keeps
assembly simple. Turns out the diode was probably just a MUR115, 150V 1A
fast recovery rectifier, judging from the others.
Powered up the chassis and it worked fine. Closer inspection showed one
contact for a module slot was broken off from corrosion. Now I have to
transplant a heavily glued down card edge connector from the slot I
disabled to the slots that does get a card.
Lazy, but it should be OK in the end. Replacement power supplies of this
type range from about $150 to $2000 on ebay. Not sure who's paying list
prices from decades ago for this stuff.
One in the SPM5 series. It's basically a mainframe of sorts with power
factor correction, timing and a fan on the backplane and 5 slots for
various factory installed output modules. Unit is rated 1500 watts. Date
code on the outside is 1990.
unit is pretty much this thing with the small slot having a different card
http://www.ebay.com/itm/Power-One-SPM5D2D2V6-Switching-DC-Power-Supply-Unit-Module-Industrial-24V-32A-/111844628139
Mine has two double wide 24 volts 32 amp modules in parallel and the fifth
slot filled with a 12 volt 20 amp module. Very handy thing to have around.
The fan started to go crazy as in slowing down and speeding up, stopping
and stuff like that, then I noticed the outputs all lost regulation, 12
volts output dropped to about 9 under load and other weird stuff.
About two dozen screws later, the thing opened up and I got the modules
out. Fuses seemed ok, and the DC bus had 320 volts on it (sales sheets say
300 volts, but whatever). There's some sort of SCR based active power
factor correction trapped under heatsinks, thermal grease and dust. At
this point the 24 volt cooling fan was still erratic then basically made
sad noises maybe twice a second as it tried to start but didn't have
enough voltage. It could not bootstrap or regulate and was
restarting. Amazingly the main board only has some 1980s type 8 pin SMPS
regulator, not a crazy module thats impossible to work with. Swapped that,
no dice. No burned parts, but lots of discolored under the solder mask
traces.
To complicate things the control board where the fan attaches was covered
in something greasy and apparently corrosive as seen from the blue colors
on some leads. Parts cleaner and a brush got that off, mostly.
Probing around didn't show much other than the 24 volts for the fan was
pulsating at under 2 volts. It also looked like each module slot has a
dedicated winding off the same ferrite transformer to supply isolated
power. Those were also way too low. Voltage to one 7805 regulator was
zero. It appears that each module gets 320 volts, something around 24
volts and a timing signal and from that they all do their own thing.
Finally found a shorted diode, but the markings were worn off from the
cleaning process and whatever. The other similar parts were MUR something
and from motorola. I just went ahead and stole one from a backplane slot
what would never have a module card edge attached. All the caps on these
outputs were rated the same 35V, so it seemed safe enough. I've also
noticed the American power supply companies like to keep the part type
count low so many parts appear to be grossly overrated, but it keeps
assembly simple. Turns out the diode was probably just a MUR115, 150V 1A
fast recovery rectifier, judging from the others.
Powered up the chassis and it worked fine. Closer inspection showed one
contact for a module slot was broken off from corrosion. Now I have to
transplant a heavily glued down card edge connector from the slot I
disabled to the slots that does get a card.
Lazy, but it should be OK in the end. Replacement power supplies of this
type range from about $150 to $2000 on ebay. Not sure who's paying list
prices from decades ago for this stuff.