[Info-vax] rx2620 power supplies / VRM voltage low

[abrsvc]

On Wednesday, February 10, 2016 at 10:11:40 PM UTC-5, George Cornelius wrote:
> In article <a9a05da3-87ee-44b0-9084-1109d542ea06 at googlegroups.com>,
>  Steven Schweda <sms.antinode at gmail.com> writes:
> > Has anyone considered the possibility that the VRMs "on
> > the motherboard" are bad, and not every main power supply in
> > the world?  I know nothing, but I can imagine a case where a
> > fresh power supply might be just barely able to overcome a
> > faulty VRM, but not for long.  Swapping main power supplies
> > may be much easier/cheaper than swapping VRMs, but how many
> > bad main power supplies do you think are out there?
> > 
> >    How much would a whole spare system cost?
> 
> OK, well, thanks to the group.
> 
> The answer to my question: this is anomalous.
> 
> If this person has been getting supplies from people who
> are not being up front with him, then that's the first
> problem.  The second is that he is asking people who are
> not equipped to solve his problem to do his troubleshooting.
> 
> Yes, I have component level repair experience, but that
> was a million years ago.  I don't think I have ever taken
> a soldering iron to a motherboard except once in the old
> days when a soldered-in rechargeable CMOS battery failed,
> I suppose a NiCad.  So I probably won't be trying my hand
> at such things today.
> 
> We do have a number of techs who could check the
> capacitors and attach meters to test points.  That
> will likely not happen either except maybe to convince
> the "approved" vendor who sent us the first failing
> replacement that he needs to be considered for removal
> from approved status.
> 
> By the way, it is apparently well known that there
> was an era not so long ago when there were large
> numbers of faulty electrolytics from China and
> Taiwan making their way into PC's and servers,
> ultimately resulting in recalls.  Certain
> manufacturers were affected more than others,
> HP being perhaps one of those less affected.
> I do have sitting in the hall an HP PC, one that
> was shipped as a console for a GS1280, I am told,
> that has video display issues along with bulging
> capacitors on the motherboard.
> 
> I am going to discount that, though, and just
> say that electrolytics are known to have finite
> lifetimes and there are people who will just
> turn around used parts with minimal effort
> invested; and those who don't understand that
> deserve what they get.
> 
> We are perfectly capable of buying a working
> system and moving everything over to it, but
> I wanted to make sure that there was not, say,
> a known issue with power supplies in certain
> classes of servers first.
> 
> So thank you all very much for your help.
> 
> George Cornelius

I can say that the 3 RX2620s I have don't show this problem and never have.  I will admit however, that I don't use them 24x7 either.  These machines usually run about 10hr per day with some extended runs now and again.  I do keep spare parts around just in case.  I have seen only 1 PS fail and that was after a power surge from a defective UPS setup.  Once I replaced the smoked parts, the unit worked fine.  I have not yet seen any issues with capacitors in these supplies.  And yes, I repair to the component level (even surface mount devices) when necessary.

Dan