woods@robohack.uucp (Greg A. Woods) (06/27/91)
I just went through an episode that gave me a good scare.
I came home this evening to find my DM/135e with its power light out
and tons of messages spewing out on the console about a bad block 0 on
that device. Oh-oh! I tried an emergency power down, but it
"failed", so I logged in and tried 'telinit 0' which eventually worked.
When I tried to power back up, only the DCM/4e came on, and not even
the TM/60S! After much goofing around and searching through the
maintenance manual, I finally looked at the SCSI Operations Manual.
A very short paragraph suggested shutting everything off *and*
disconnecting all of the power cables, and starting up from scratch.
It almost worked, but I was getting funny clicks from my new line
conditioner (TrippLite LS-600 b). I also noticed noise on my AM radio
when I removed the power cords from units that were supposedly off.
Ah yes! That wee paragraph said problems might occur if either
someone accidentally powered off a module, *or* if there were
un-expected power transients.
So, I removed the "line conditioner" from the power bar and went
through the disconnect procedure again before everything was stable.
I think I'll leave the line conditioner for some other application,
after I check it's output under load with a scope! Meanwhile, I think
that I'll let those "intelligent" SCSI module power supplies fend for
themselves.
--
Greg A. Woods
woods@{robohack,gate,eci386,tmsoft,ontmoh}.UUCP
+1 416 443-1734 [h] +1 416 595-5425 [w] VE3-TCP Toronto, Ontario; CANADAjrallen@devildog.att.com (Jon Allen) (06/28/91)
In article <1991Jun27.021618.664@robohack.UUCP> woods@robohack.uucp (Greg A. Woods) writes: > >I just went through an episode that gave me a good scare. > >I came home this evening to find my DM/135e with its power light out This happens very often at work. Our building has several power hits per week and quite often all the SCSI drive power lights will be out. The first time this happened really scared me too. I had about 10 SCSI items out (135s, 300s, TS60s, TS120s). After messing around with the power switch, I uncabled everything to swap out the controller. Lo and behold, it all came back up when re-cabled. Since then I have learned that unplugging the power to the drives for about 30seconds seems to cure the problem. This same thing happens if the drive overheats when the AC fails (this happens 2-3 times a year - nice building eh?). I sure would like to see a schematic of the power supplies. I can't imagine how line problems and overheating trigger the drive to shut off and a 20 second unplug (not just a switch off) resets the power supply. -Jon -- jon_r_allen@att.com Piscataway, NJ USA
wgs@cuuxb.ATT.COM (~XT6562000~Bill Simeon~C82~rfe~xxxx~) (06/28/91)
In article <1991Jun27.021618.664@robohack.UUCP> woods@robohack.uucp (Greg A. Woods) writes: > >I just went through an episode that gave me a good scare. > >I came home this evening to find my DM/135e with its power light out >and tons of messages spewing out on the console about a bad block 0 on >that device. Oh-oh! I tried an emergency power down, but it >"failed", so I logged in and tried 'telinit 0' which eventually worked. > >When I tried to power back up, only the DCM/4e came on, and not even >the TM/60S! After much goofing around and searching through the >maintenance manual, I finally looked at the SCSI Operations Manual. >A very short paragraph suggested shutting everything off *and* >disconnecting all of the power cables, and starting up from scratch. (Stuff deleted) Here is an excerpt from a product flash that was issued back in 1988. It still applies! The power supplies used in high-end 3B2 Computers (3B2/500,600,700) and all 3B2/SCSI peripherals (excluding 9-tracks) sense the AC power line voltage and automatically configure for either 110vac or 220vac operation. Unfortunately, a noisy 110vac power line can, and has, cause the power supply to attempt to reconfigure itself to 220vac operation. When this occurs, the power supply is unable to sustain the correct output levels, and it shuts down. Once powered down in the manner described above, the supply must be manually reset to its 110vac configuration before it will again operate properly. This is because once configured for 220vac operation, the power supply is not allowed to automatically change to a lower voltage. Manual reset of a power supply is accomplished by a physical disconnect from the AC power line for a minimum of two minutes ( five minutes is recommended ). Physical disconnect is absolutely required; the on/off switch on the power supply will not effect a physical disconnect as the sensing circuits are wired in front of the switch. Troubles diagnosed to this condition are likely to occur again (the power supplies themselves are in spec). A permanent solution is however available at this time through Tier 4 support in Lisle. A call to Tier 4 support on 1-800-222-9333 will result in either a mail out of a power supply hardwired for 110vac operation or instructions for local modifications where repair facilities are available. Please take immediate steps to distribute this information to all DSO personnel involved in servicing the 3B2 product line. Questions may be referred to me at (201) 898-6832 [RNX 964]. Thanks. -- * Men Make Plans - And GOD Laughs * * W.G. (Bill) Simeon | d1wxs@nyfast.ATT.COM * * AT&T Remote Systems Engineer | attmail!wsimeon * * New York City, NY | *