Re: problems with Vicor VI-200 dc-dc modules?

legg wrote:
On Sat, 06 Jan 2007 19:39:57 GMT, "Michael A. Terrell"
<mike.terrell@xxxxxxxxxxxxx> wrote:


Winfield Hill wrote:

Michael A. Terrell wrote on Jan 4 2007 in the
s.e.d. thread, "job thing, maybe"


We had already taken a quality hit from a high failure rate on Vicor
dual output supplies built with their VI-260-IY modules for dual 5 VDC
50 W outputs and VI-261-IY modules for dual 12 VDC 50 W outputs.
$20,000 radios still in warranty, and just out of warranty were having
lots of problems, all wich were traced back to their crappy modules
and whole power supplies.
<http://www.vicorpower.com/documents/datasheets/ds_vi-200.pdf>

Vicor's rev 1.7 datasheet says, "Vicor's broad series of zero-
current-switching component-level DC-DC converters, with
over 12 million units shipped..."

Vicor generally has a good reputation. So I have to ask, I notice
your modules were 300V-input (i.e. offline), 5V and 12V output,
with their lowest power rating, 50 watts. The other modules in
the VI-200 series are rated at 75, 100, 150 and 200 watts. Is it
possible the problem wasn't actually the modules, but something
else, like improper DC-input conditioning, or lack of proper
heat-sink cooling? Or perhaps your power circuit allowed the
12V supply to pull the 5V module output above +5 under certain
circumstances, such as at power-up or power-down. Just asking.



They were part of Vicor built power supplies. The ac line was doubled
to get the 300 volts inside the supply. The case was cast aluminum,
with fins. Vicor said our product's case had plenty of air flow, yet
they couldn't tell us why they were failing. I may still have a
complete, scrap supply for the model numbers, but all I could find the
other day was a bad module. Either one of the two module's output would
die, or the regulation would go to crap and have a lot of noise on the
output. The only load that came close to 50 watts was the +5 volts, and
I think it was only 7 amps or 35 watts. We tried for six months to find
a solution before we removed them from the qualified vendor list. They
may have been cause by the defective electrolytic problem, but the
modules are cast in epoxy so we couldn't take a look, in house. We had
too many angry customers to wait any longer. We paid for a bunch of new
supplies that were out of warranty to keep them happy, but the problem
kept growing.

The replacement power supplies had a built in fan, and were through
hole PCB construction. We tested over 20 different OEMs before we
decided on the new supplier. This was some time late in 2000, or early
2001. The replacement supply also ended up being a good choice for a
newer DSP based receiver design. I might have a datasheet on the
replacement power supply in my files. Changing the power supply vendor
meant a change in the bare aluminum chassis, a new wiring harness, and
designing a field conversion kit for high security locations that did
some self service in house. I don't know what conclusion Vicor finally
came to as the cause of the failures, because the company didn't want to
switch back to the old design and take a chance.


Vicor spent a lot of money on advertising and litigation, but I've yet
to hear anything positive about their products from end-users - and
have done good business revisioning them out of other people's
products.

There's reason why they shouldn't be able to come up with superior
products, given the decades they've had to get it right.

I'd stay clear of anything producing output voltages above 5V that
they make, no matter what power level, and wouldn't use any module
that wasn't second-sourced. It's not worth the risk, and it's not
necessary.

RL

I gutted a couple of their modules once. They had some beautiful magnetics with integrated shields (formed from thic Cu). They did things like run the switches from the +ve rather than -Ve DC bus, so the drains dont bounce up and down. Some very nice tricks to reduce EMI.

Of course the converters themselves sucked; a close read of the datasheet shows they achieved high power levels by requiring ludicrous heatsinks. We had nothing but trouble with the ones we used (hence I got to gut some).

Cheers
Terry
.

Relevant Pages

  • Re: problems with Vicor VI-200 dc-dc modules?
    ... dual output supplies built with their VI-260-IY modules for dual 5 VDC ... with their lowest power rating, ... They were part of Vicor built power supplies. ...
    (sci.electronics.design)
  • Re: problems with Vicor VI-200 dc-dc modules?
    ... dual output supplies built with their VI-260-IY modules for dual 5 VDC ... with their lowest power rating, ... They were part of Vicor built power supplies. ...
    (sci.electronics.design)
  • Re: OT: Powersupply For P5W DH
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    (alt.comp.periphs.mainboard.asus)
  • Re: problems with Vicor VI-200 dc-dc modules?
    ... dual output supplies built with their VI-260-IY modules for dual 5 VDC ... with their lowest power rating, ... They were part of Vicor built power supplies. ...
    (sci.electronics.design)
  • Re: OT: Powersupply For P5W DH
    ... Would you recommend than looking for supplies that can pull more amps on the ... I am going to see if I can dig up any info on that power supply. ... output rail. ... The triples and quads also look to be usable solutions. ...
    (alt.comp.periphs.mainboard.asus)