Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.naic.edu/~tghosh/mk5-AO/AntecXRearXPanelXREPLACE.desc Дата изменения: Thu Aug 18 18:03:20 2005 Дата индексирования: Sun Apr 10 23:58:28 2016 Кодировка: Поисковые слова: arp 220

THIS IS A VERY IMPORTANT MESSAGE FOR ALL MARK 5 USERS -- PLEASE READ IT
CAREFULLY!!
(I apologize if you receive more than one copy of this note - Alan)
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This is a followup to yesterday's e-mail regarding potential problems with
some Mark 5 power supplies with using Maxtor or Seagate disks. The
original e-mail is copied below for your reference.
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We have just received further information from Conduant after they have
been doing some further testing. It now appears that Antec has shipped
several variants of the suspect Antec True550 power supply (*not* the Antec
True550 EPS12V, which does not exhibit a problem), including ones with
different specs for the 12V amperage. Not all of the the Antec True550
supplies seem to exhibit the problem, as explained below. If you have an
Antec True550 supply, you should compare it against the attached
photographs to determine whether it is one of the suspect ones.
Thanks, Alan
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>From: "Ken Owens"
>To: "Alan Whitney"
>Subject: Power supply pictures
>Date: Tue, 16 Aug 2005 16:06:13 -0600
>
>Alan,
>
>To the best of our knowledge, the power supply that we experienced a
>problem with has a unique look on the back is as shown in "Antec Rear
>Panel REPLACE.jpg". The difference is the newer power supplies have a
>"D" connector with a black plastic cover on it above the switch as
>shown in "Antec Rear Panel OK.jpg". Both the good 24A and 30A supply
>have this connector on the rear panel. Hopefully this will help in
>identifying the suspect power supplies.
>
>Regards...Ken
>
>Ken Owens 303-485-2721 x103
>ken@conduant.com www.conduant.com
>-
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Following is the original note distributed on 16 August 2005:
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THIS IS A VERY IMPORTANT MESSAGE FOR ALL MARK 5 USERS -- PLEASE READ IT
CAREFULLY!!
(I apologize if you receive more than one copy of this note - Alan)
-
Conduant Corporation has recently informed us that there may be problems
with marginal power supplies in some Mark 5A units when using disk modules
populated with Maxtor or Seagate disks. The particulars of the problem and
the suggested solution are as follows:
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1. Due to the unusually large number of problems with Hitachi 250GB disks,
Conduant is now shipping disk modules with 250GB Maxtor disks. They have
discovered, however, that the power draw of the Maxtor disks is
significantly greater than the Hitachi disks and have observed occasional
problems in some Mark 5A systems due to this extra power draw.
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2. The problem has been observed in the following circumstance: With one
Maxtor disk module inserted and powered up, insert another Maxtor module in
the other slot. The disks in a module are powered up in groups of
four. Maximum 12V power draw occurs when the second set of 4 disks in the
second module are powered up (with the other 12 disks already powered up
and spinning). The 12V can temporarily dip below spec and cause problems,
particularly if the first module is actively recording or playing at the time.
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3. The Mark 5A units that are affected were supplied with an Antec True550
supply; Conduant indicates that units prior to serial number Mark5-638 are
the most likely to be affected. More recently, Conduant has been using the
Antec True550 EPS12V supply (note the subtle difference in model number!)
or PC Power & Cooling Turbo-Cool 510XE, which have heftier 12V performance
and have proven to be OK. All Antec power supplies are clearly labeled on
the top of the supply, which is easily visible if you remove the top cover
of the Mark 5A; PC Power & Cooling label is on side of power supply under
the system disk. At this time we do not know about the suitability of
other power supplies that may be in use, such as the triple-redundant
supply in some of the early units built at Haystack; we plan to do some
testing as soon as we can get a couple of Maxtor-populated disk modules.
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4. If you need to replace your power supply, Conduant recommends the PC
Power & Cooling Turbo-Cool 510XE as a replacement. We at Haystack concur
with this recommendation as the quality and reputation of these supplies is
outstanding.
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5. The price of this supply is ~$200 from PC Power & Cooling. Your can
purchase these supplies independently if you wish, but Conduant is offering
them for a small markup at $250. In addition, Conduant will specially
prepare these units for installation in the Mark 5A. As you may be aware,
the connection of the power supply to the Mark 5A backplane is by screwdown
connectors because of the high power draw. This requires removing an
existing connector and stripping back the wires.
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6. Conduant is preparing an instruction sheet for replacing the power
supply, which I will distribute as soon as it is available. The
replacement job is straightforward and should take a competent technician
no more than an hour, but it is obviously critical that the job be done
correctly.
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7. USNO is taking delivery of 45 new modules populated with Maxtor disks,
many of which will be used in CONT05 observations, which are starting in
less than one month, so this problem is not just a theoretical one. It is
imperative that you be aware of this problem and take appropriate action as
soon as possible.
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8. Conduant will place a label on all Maxtor-populated modules purchased
from them warning of this potential problem. Please pay attention to this
warning!
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9. Conduant has also warned us that Seagate disks, which we know are being
used in some places, draw even more power than the Maxtor disks, so beware
of using modules populated with Seagate disks without a proper power
supply. In order of increasing 12V power requirements for 250GB disks are
WD, Hitachi, Maxtor, and Seagate.
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10. If you are not sure about your power supply or are unable to replace an
Antec True500, we suggest that power be applied to a second disk module
only when the first module is quiet (i.e. not recording or playing) and the
disk-activity lights are off. This will minimize the risk of problems.
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11. If you have any questions, please contact
. If you wish to purchase a power supply from
Conduant, please contact Tom Skrobacz at .
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Thanks and regards, Alan