- Shortest period to switch off electronic equipent for before switching on - 21 Updates
- Astron Power Supply Repair - 2 Updates
- EPROMs nearing end of life? - 2 Updates
| Stephen <stephen_hope@xyzworld.com>: Apr 11 07:51PM +0100 >>consistent. >Exactly so. This is common with flash-based systems. The power >system has to guarantee at least the current block has been written. Well - not really. What can you do with an app that is running and doesnt keep files in a "safe" state? Even some working apps dont leave files in a consistent state while idle (although agreed that is bad design). Less said about malware busy scribbling all over your drive to maximise the chance of coming back to life after a reboot the better... The point is that an operating system cannot make assumptions about what programs are trying to do and having "well formed" behaviour - they need to try to be robust no matter what is mucking around, while a disk is full and a drive is trying to remap to sort out bad sectors. >but they were there, so the were tested. >It's a really good idea to test your system backups from time to time, >too. You may find the restore doesn't work. :-( But the only true test of a restore is to actually wipe and restore on the same hardware build - when it is too late to find out it didnt get recorded correctly if you only have 1 machine (or 2 with different builds)...... >>Moral of the story: always try any new hardware during the warranty period! And keep the old one as a fallback.... >Anything that's important has to be tested. Stephen Hope stephen_hope@xyzworld.com Replace xyz with ntl to reply |
| Stephen <stephen_hope@xyzworld.com>: Apr 11 07:52PM +0100 On Sun, 9 Apr 2017 15:34:01 +0100, MJC <gravity@mjcoon.plus.com> wrote: >Conversely the possibly apocryphal story I heard had the generator >tested regularly. When eventually needed it ran for a few minutes and >then ran out of fuel. The protocol didn't include top-ups! We had one where someone spoofed the guage and drained the tank. >Mike. Stephen Hope stephen_hope@xyzworld.com Replace xyz with ntl to reply |
| David Woolley <david@ex.djwhome.demon.invalid>: Apr 09 09:35AM +0100 On 08/04/17 17:15, MJC wrote: > My Humax (old 9200T) will record even when in standby That's why I said you must make sure there are no recordings scheduled! |
| Look165 <look165@numericable.fr>: Apr 09 02:17PM +0200 Generally, the off/on if too short implies caps (generally somme 100µF) not to discharge totally and if on again during this state, the result is unpredictable. Thje more the device uses power, the less this time is needed. Today, it seems that 10-15 s are enough. For a modem (ADSL or cable) it's OK. For a LCD or plasma TV too. To be secure, count on 20s. pamela a écrit : |
| "Brian Gaff" <briang1@blueyonder.co.uk>: Apr 09 09:55AM +0100 In my view all devices should have a little pin hole switch that does this for you. It really depends on the device I think. Things like my Smart talk freeview box almost instantaneous resets are OK if done via the little plug from the psu on the back, but if you do it from the mains it needs a little longer as I suspect the wall wart has some capacitors in it. Phones are awhole other ball of nuts. Some seem to remember crashes indefinitely. there is one which is not out of production where the software crashes and stops the voice from working at all, even if you take the battery out. Sadly as nobody has the gear to reblow the software any more its a brick. Brian -- ----- - This newsgroup posting comes to you directly from... The Sofa of Brian Gaff... briang1@blueyonder.co.uk Blind user, so no pictures please! "pamela" <invalid@nospam.com> wrote in message news:XnsA7516B728743CD4AM2@81.171.92.183... |
| krw@notreal.com: Apr 09 07:14PM -0400 On Sun, 9 Apr 2017 19:55:27 +0100, "Benderthe.evilrobot" >> Only if it's designed by a moron. >There's not exactly a shortage of those - but it does tend to be more older >designs. IC designers tend to do a better job protecting against weird power cycles and a lot more system designers have been burned and learned. >It does sometimes happen - pretending it doesn't won't save you. Of course. There are morons designing stuff all the time. Worse, there are companies that don't care that they're making crap. |
| krw@notreal.com: Apr 09 08:34AM -0400 >licence to be paid to the inventors which is why a lot of PVRs use/read only >FAT/FAT32. If they are Linux-based they will be able to use filesystems >which are more robust (I'm not very clued up on Linux). That's an economics decision. There is nothing cast in jello that says they have to cheap out, or even use an existing FS. JFS techniques are well known. Even if they do want to use a vulnerable FS, a proper power system design can guarantee a safe shut down. >is not totally unexpected) is a bad design: you need some form of resilience >in terms of battery-backed supply until the file write is complete and >consistent. Exactly so. This is common with flash-based systems. The power system has to guarantee at least the current block has been written. >recording that was being made or the filesystem of the recording HDD (NTFS). >OK, Windows may do a chkdsk repair after the PC reboots, but it seems to >sort itself out. NTFS? >circuit rather than the battery itself. APC didn't want to know when we >asked what a repair might cost, so it went in the skip - a waste of money as >it was never even used. Always test your emergency system. When I was in IBM, they tested the emergency generators once a month. I have no idea why they had such in the building I was in (just offices and a few labs at that time) but they were there, so the were tested. It's a really good idea to test your system backups from time to time, too. You may find the restore doesn't work. :-( >Moral of the story: always try any new hardware during the warranty period! Anything that's important has to be tested. |
| David Woolley <david@ex.djwhome.demon.invalid>: Apr 08 12:03PM +0100 On 08/04/17 10:33, pamela wrote: > As a rule of thumb, what's the shortest period to switch off > electronic equipment for a reset before switching on? There are two issues here: 1) allowing long enough for a reset to be reliable; 2) ensuring it is safe to power down before doing so. On the second point, PVRs, in particular, do not seem to be designed to be really safe to power down at any time, as there is no way of putting them into a soft power down state. You have to make sure that there are no recordings scheduled and put them into standby. On my Humax, you then need to wait until the red light dims Otherwise, you will be relying on the consumer user defences built into the disk drives ensure that the current write completes and the heads park, and also to recover any logical damage to the filesystem. Even PC's are quite good at this these days, and should never be given a hard power down until a soft power down has completed, unless they have completely locked up and there is no reset button. On the first point, it depends on the design of the electronics as to how long it takes for all capacitors to discharge sufficiently to put them into a clearly off state. Remember that some devices will detect a warm start by reading RAM, and maximum retention times, without refreshes, are not characterised for dynamic RAM, only minimum ones. Also the time constants associated with some faults that require resets can be hours. Where a hard power cycle is needed, I would probably go for about 30 seconds for the first attempt, and then overnight, if the first attempt doesn't succeed. Of course, you should not need to reset the device this way at all, unless there is a fault, so it is probably something that you should not allow visitors to do at all. |
| alan_m <junk@admac.myzen.co.uk>: Apr 09 09:27AM +0100 On 08/04/2017 10:33, pamela wrote: > 20 seconds after the mains is disconnected. Also hard drives in > Playstations and PVRs will spin on. Telling impatient kids to go and > make a cup of coffee isn't going to work. Twenty years ago 5 seconds may have caused a problem due to the possibility of surges due to mains input filters. Often if the switch off is to cold boot crashed software then the internal PSU voltages have to decay. My rule of thumb is 30 seconds after any front panel LED has gone out. -- mailto: news {at} admac {dot] myzen {dot} co {dot} uk |
| "Brian Gaff" <briang1@blueyonder.co.uk>: Apr 09 10:01AM +0100 Not many people understand computer shut down via the button either If software has locked up or is doing odd things, then a short tap on the power button, ie NOT the reset is normally the way to get a good shutdown. If that fails, then hold in the power button, NOT the reset button as this normally protects the hard drive from corruption. all these folks wo either press reset or worse, just pull the plug out deserve the reinstall they evenntually end up having to do. Brian Of course if there is a power cut this can happen anyway, and I've often thought of putting in an uninteruptable supply to allow proper shut down. they are not that expensive these days, and laptops of course have one built in. Brian -- ----- - This newsgroup posting comes to you directly from... The Sofa of Brian Gaff... briang1@blueyonder.co.uk Blind user, so no pictures please! "Davey" <davey@example.invalid> wrote in message news:ocadad$j1m$4@n102.xanadu-bbs.net... |
| MJC <gravity@mjcoon.plus.com>: Apr 09 03:34PM +0100 In article <V-KdnUieLtZb3HfFnZ2dnUU78c_NnZ2d@brightview.co.uk>, me@privacy.net says... > The office building where I worked had huge diesel-powered generator to cope > out that it had been specced back in the days when there wasn't a PC on > every single person's desk, and it was woefully underpowered for the modern > demands that were placed on it. Conversely the possibly apocryphal story I heard had the generator tested regularly. When eventually needed it ran for a few minutes and then ran out of fuel. The protocol didn't include top-ups! Mike. |
| "Benderthe.evilrobot" <Benderthe.evilrobot@virginmedia.com>: Apr 09 07:55PM +0100 <krw@notreal.com> wrote in message news:sg5jeclipaol2ejgd0tuivrostvvad23bt@4ax.com... >>time for no protection - but it just stresses the components a little more >>than usual. Most user manuals seem more or less unanimous for about 30s. > Only if it's designed by a moron. There's not exactly a shortage of those - but it does tend to be more older designs. It does sometimes happen - pretending it doesn't won't save you. --- This email has been checked for viruses by AVG. http://www.avg.com |
| David Woolley <david@ex.djwhome.demon.invalid>: Apr 09 02:22PM +0100 On 09/04/17 10:01, Brian Gaff wrote: > If that > fails, then hold in the power button, NOT the reset button as this normally > protects the hard drive from corruption. As I understand it, a long press is handled by the hardware and forces a dirty shutdown. If it were handled by the firmware, it could be difficult to shut down a battery powered device which had locked up. RESET should be more gentle than a long press. Typically, power supplies will not have decayed before any sector write in progress has completed and disks should park. However, you are basically relying on fault recovery mechanisms to protect the physical media, and the low level formatting. Journalling file systems may protect the basic file structure, but data buffered in user space, and write back caches (OS and device) will not get written and very few application designers will have designed them to be completely safe against partially written files. Consumer devices have to be tolerant of such abuses, but whenever you start relying on fault recovery mechanisms, for normal operation, you are on dangerous ground. |
| Davey <davey@example.invalid>: Apr 08 12:11PM +0100 On Sat, 8 Apr 2017 12:03:14 +0100 > Of course, you should not need to reset the device this way at all, > unless there is a fault, A few days ago, for the first time that I have ever seen, my Humax refused to respond when I tried to turn it on. Neither the remote control nor the big button would make it work. I turned it off with the switch on the back panel, waited some time, probably less than 30 seconds, and then turned it on again. Since then, it's worked fine. The log showed nothing of any use, so I have no idea what the problem was. The unit is now about 4 years old, and was a refurbished unit when I got it, so I have had my money's worth if it failed at any time. -- Davey. |
| "NY" <me@privacy.net>: Apr 09 12:21PM +0100 <krw@notreal.com> wrote in message news:sg5jeclipaol2ejgd0tuivrostvvad23bt@4ax.com... >>Anything with a hard drive can trash a file if you power down in the >>middle >>of a write operation. I suppose anything with disk-like storage (including flash drives) can be trashed if the power goes off during a write, though the time during which the files is in an inconsistent state between data sectors and sector map may be less with solid state than a mechanical rotating disk. > Nonsense. There are many ways to design a device that will survive a > power failure during disk write. A bit of reserve power is probably > the best solution but a JFS works, too. It depends what filesystem they use. NTFS is pretty robust but it requires a licence to be paid to the inventors which is why a lot of PVRs use/read only FAT/FAT32. If they are Linux-based they will be able to use filesystems which are more robust (I'm not very clued up on Linux). But I'd say that a design which trashes the file that is being written to or the whole filesystem when the power goes off (eg due to a power-cut, which is not totally unexpected) is a bad design: you need some form of resilience in terms of battery-backed supply until the file write is complete and consistent. I use my Windows 7 PC as a PVR (either Windows Media Centre or NextPVR) and I've occasionally had power cuts during recording. I've never yet lost the recording that was being made or the filesystem of the recording HDD (NTFS). OK, Windows may do a chkdsk repair after the PC reboots, but it seems to sort itself out. A UPS would be useful for graceful shutting down during power cuts, but it might be more trouble that it's worth. At present my BIOS is set to reboot the PC automatically after the power is restored. If the UPS keeps the power up and initiates a graceful shutdown, the PC may not boot back up once the power comes back. My wife bought a 3kVA UPS with her big Dell PC about 10 years ago. We didn't get round to setting up the UPS for a couple of years. By the time we did (and after the warranty had expired, inevitably) we found that it had virtually no battery capacity: the battery monitoring software (monitored by USB connection) showed the battery accepting charge and gradually charging up and eventually showing as fully charged, but as soon as the mains was removed, the battery discharged within about 10 seconds with a nominal 40 W lightbulb as the load. Utterly useless, and it wasn't even worth buying a replacement battery for it because the fault may have been in the charging circuit rather than the battery itself. APC didn't want to know when we asked what a repair might cost, so it went in the skip - a waste of money as it was never even used. Moral of the story: always try any new hardware during the warranty period! |
| Vir Campestris <vir.campestris@invalid.invalid>: Apr 09 06:09PM +0100 On 09/04/2017 15:34, MJC wrote: > Conversely the possibly apocryphal story I heard had the generator > tested regularly. When eventually needed it ran for a few minutes and > then ran out of fuel. The protocol didn't include top-ups! The one I know of is where the fuel pump was on the non-maintained mains. All the tests were fine. But when the power went off for real so did the fuel pump... BTW I use 30 seconds too. 30 odd years of computers here, quite often dealing directly with the HW designers so I could write the tests. Andy --- This email has been checked for viruses by AVG. http://www.avg.com |
| Rheilly Phoull <rheilly@bigslong.com>: Apr 08 06:04PM +0800 On 8/04/2017 5:33 PM, pamela wrote: > 20 seconds after the mains is disconnected. Also hard drives in > Playstations and PVRs will spin on. Telling impatient kids to go and > make a cup of coffee isn't going to work. You might want to regulate your relatives when they are in YOUR HOME. As you say some things need a few seconds to reset. |
| "Benderthe.evilrobot" <Benderthe.evilrobot@virginmedia.com>: Apr 08 08:17PM +0100 "pamela" <invalid@nospam.com> wrote in message news:XnsA7516B728743CD4AM2@81.171.92.183... > 20 seconds after the mains is disconnected. Also hard drives in > Playstations and PVRs will spin on. Telling impatient kids to go and > make a cup of coffee isn't going to work. You can't just lump everything into the same bracket - a lot of people just turn the TV off "cold turkey", its a lot better than leaving it unattended on standby. Anything with a hard drive can trash a file if you power down in the middle of a write operation. Some designs of SMPSU can go bang if you switch back on before the reservoir caps discharge and those with inrush surge limiting have a thermal recovery time for no protection - but it just stresses the components a little more than usual. Most user manuals seem more or less unanimous for about 30s. --- This email has been checked for viruses by AVG. http://www.avg.com |
| MJC <gravity@mjcoon.plus.com>: Apr 08 05:15PM +0100 In article <ocafrr$ehp$1@dont-email.me>, david@ex.djwhome.demon.invalid says... > On the second point, PVRs, in particular, do not seem to be designed to > them into a soft power down state. You have to make sure that there are > no recordings scheduled and put them into standby. On my Humax, you > then need to wait until the red light dims My Humax (old 9200T) will record even when in standby. On the other hand, it sometimes gets stuck and has to be powered down to reset it. And I give it several seconds, but not as many as 30! Mike. |
| "Benderthe.evilrobot" <Benderthe.evilrobot@virginmedia.com>: Apr 09 07:51PM +0100 "David Woolley" <david@ex.djwhome.demon.invalid> wrote in message news:ocdcd6$mn5$1@dont-email.me... > dirty shutdown. If it were handled by the firmware, it could be difficult > to shut down a battery powered device which had locked up. RESET should be > more gentle than a long press. AIUI: A short press is one way of a normal shutdown - sometimes you have to press it a little longer................... --- This email has been checked for viruses by AVG. http://www.avg.com |
| Davey <davey@example.invalid>: Apr 08 11:16AM +0100 On Sat, 08 Apr 2017 10:33:44 +0100 > 20 seconds after the mains is disconnected. Also hard drives in > Playstations and PVRs will spin on. Telling impatient kids to go and > make a cup of coffee isn't going to work. My Humax HDR Fox T2 says to wait until you hear the HDD wind down before turning it on again. Otherwise, I generally try to wait for 30 secs. as a rule of thumb, although I'm not always that patient. Not that I have to reset stuff much anyway. If they're in your home, then visitors work to your rules! -- Davey. |
| Michael Black <et472@ncf.ca>: Apr 14 11:51PM -0400 |
| Fred McKenzie <fmmck@aol.com>: Apr 14 04:48PM -0400 In article <ac61acb6-9240-49c1-a7df-c0f815b748d7@googlegroups.com>, > > output > > transistors? Thanks > > Bob This is a little old, but Astron power supplies are still around. I have had a couple of the regulator IC's go bad, but never a pass transistor. I would first suspect a short external to the transistor! The original 2N3771 transistors may come out of the same batch, but probably are not matched. Each one has an emitter resistor to help equalize current. Therefore you should not have a problem with un-equal current due to replacement transistors. The current meter measures voltage drop across one of the 4 emitter resistors. It may need slight re-calibration, but you should have no trouble with a replacement 2N3771. Fred |
| Michael Black <et472@ncf.ca>: Apr 09 02:33PM -0400 |
| etpm@whidbey.com: Apr 09 11:15AM -0700 >These units have a mechanical power switch, so I suspect that sometime the corruption is from turning it off at the wrong time. They are Karaoke players and usually the USB and SD puts became deaf dumb and blind. I had a whole set of them with good data to copy from. >I am somewhat surprised you found a used board for that thing. But since you did you probably should copy the data to either the old EEPROM or a new, compatible one for backup. If it happens once, it can happen again. >I really hadn't heard of that brad of lathe, but if it has Timken bearing, hardened ways and all that it is probably worth keeping for life. That is if you have a use for it. I used to have two lathes but then realized they had been used maybe once in five years I sold them off. Plus I need the room. The lathe is a great machine and a real money maker. When it runs that is. 15 HP spindle. One type of job I do on it, 3 and 5 inch diameter sheaves made from 6061 aluminum, sends the spindle load meter to 120% for each of the roughing cuts. The chips coming off spray the door like a sandblaster. Man, I love hearing that. The Miyano rep told me that they hardly ever need mechanical servicing. The spindle cartridge is designed so that as it heats up it doesn't expand into the machining envelope so there is no dimensional change to parts in the Z axis. Right now I am running a part, also from 6061, that has almost all the material removed. I load 4 foot long 1.25" diameter stock in the spindle tube. 2 inches stick out from the collet. The part ends up being 1.65" long, .25" daimeter but for a .200 thick knurled disc near the middle. After the machining is done the piece is parted off and a parts catcher swings out, catches the part, and drops it in a tray outside of the machining envelope. Cycle time is 47 seconds. Another job I do is cutting an o-ring groove on the underside of 1/4-20 flat head 304 stainless screws. The groove is normal to the 82 degree included angle of the head. The groove edges have a .004" radius machined on them to avoid sharp edges. 7 second cycle time. I'm gonna have to get the EPROMS copied soon as possible. First though I need to get all the late jobs finished. Eric |
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