Equipment going stand-by rather than off when power switch is flipped. - Page 1
Forum section: electronics / testgear

author: tkamiya
author_rank: Super Contributor
timestamp: October 13, 2019, 02:16:01 am
content: I have various equipment, mostly HP and Fluke that keeps few things warm at all times. When I turn switches OFF, it goes to stand-by mode. Typically, signal generators, frequency counters, and some power supplies(?) work this way. I can understand the need to keep OCXO and XO running so they are instantly available.But in home lab environment, it sucks down power (which I have to pay for), gets the room warm, generate noise (sound from fan), and it is not that desirable. I have all frequency dependent equipment hooked up to a common lab reference, which is always on.In this setup, would it hurt anything to physically remove the power and turn everything off? And when I turn them on, because of the external reference, be available and accurate immediately? I ask this because I don't know external reference is used as standard, or it actually steers internal oscillators. In later case, it might take a while to stabilize.

author: 0culus
author_rank: Super Contributor
timestamp: October 13, 2019, 02:18:11 am
content: Personally, I just leave it all on power UNLESS I'm going to be gone for any extended period. Electricity is pretty cheap where I live though. Probably would be singing a different tune if it wasn't. Plus, the extra warmth is great in the winter!Why not experiment and see how your equipment behaves? Can't imagine it would do much harm.

author: jadew
author_rank: Frequent Contributor
timestamp: October 13, 2019, 02:26:12 am
content: It wouldn't hurt, I do it all the time.Like you, I also use an external reference for everything. Those pieces of gear that don't use the reference directly, will usually heat up in about 5 minutes and become reasonably stable (depends what you're measuring I guess). I think that's a small price to pay for having a silent lab.

author: tkamiya
author_rank: Super Contributor
timestamp: October 13, 2019, 02:37:08 am
content: Well.... my problems are two fold.Electricity is NOT cheap in Florida, USA, although not as expensive as say, in Japan.Another thing is, I live in Florida. It gets pretty warm and A/C is necessity. All these stuff running makes my lab at least 3 to 4 degrees (centigrade) warmer than rest of the house.I should experiment. Yes. But this can't be an uncommon problem in US. So I was looking for stories from experience.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: October 13, 2019, 02:49:38 am
content: I don't think there is a simple, general answer to your question.All of my TE gear that uses external frequency reference uses it directly, so accuracy is fine immediately on turn on.Most of my voltmeters and power supplies and the like aren't run off of external reference, so if turned off they need a while to stabilize. Up to about four hours for the ones I have looked at. But those I have looked at I am chasing ppm stability. They are fine for most uses almost immediately.You could also throw the reliability impact of turn off cycles into your decision matrix. Most things last longer when continuously powered.In general though, my experience is that powering off doesn't do any significant harm to any instrument I have owned or used for most general purpose lab applications.

author: james_s
author_rank: Super Contributor
timestamp: October 13, 2019, 03:30:46 am
content: I have my whole bench on a big power strip with a switch on it, I always turn off the power whenever I'm finished working. Makes sure I never leave soldering equipment on and it prevents anything else from drawing power or being a potential fire risk. I would never want to leave my gear powered up when I'm not using it, CRTs have limited life and even older LCDs with CCFL backlights eventually make the light spreader behind the panel go yellow and brittle from the UV.

author: tkamiya
author_rank: Super Contributor
timestamp: October 13, 2019, 04:32:32 am
content: I guess I'll just have to try this. My electric bill used to be 100 around 100 dollars. Since I set up my lab, it has never been around 100 dollars. My A/C is basically running at all times and I'm paying 170 dollars on average. I suppose, on a typical week, I can turn off EVERYTHING in lab and take a record of my electric meter, and turn normal stuff on and take a measurement.I'll accept it as necessary expense if I did NOT have an external reference but I do. I spent considerable effort to make sure it's always available and stable. It'll be silly if I kept internal oscillator alive at all times and pay for it, and it never gets used.

author: don.r
author_rank: Frequent Contributor
timestamp: October 13, 2019, 04:42:34 am
content: I turn everything off except for my GPSDO which is maybe 10 watts mostly going to the TCXO. The only issue is equipment with an internal voltage ref may need time to heat up to stabilize. So my precision PSUs or DMM needs a few minutes of uptime before using.

author: james_s
author_rank: Super Contributor
timestamp: October 13, 2019, 05:14:59 am
content: I don't have an external reference and I still see no reason to leave gear drawing that kind of power all the time. There are a few things like the GPDSO mentioned above that I would make an exception for but otherwise I just don't see there being much gain from it. I rarely do anything requiring extreme precision.

author: nctnico
author_rank: Super Contributor
timestamp: October 13, 2019, 01:23:24 pm
content: Quote from: tkamiya on October 13, 2019, 02:37:08 amI usually unplug equipment which doesn't have a real power switch. In some occasions I have added a physical power switch in case I use a piece of equipment often. In standby you can often hear the PSU make a whining noise and that irritates me.

author: tkamiya
author_rank: Super Contributor
timestamp: October 13, 2019, 07:58:44 pm
content: I am now thinking of having a "master switch" per rack. That will turn everything off. Almost all equipment I use often are behind my desk. Use of stuff on my racks are usually planned ahead of time, so I can turn it on a day ahead.By the way, few people commented keeping equipment turned on at all times. That's not what I am talking about. I am talking about equipment that portion of it won't turn off even when switch is flipped to off.

author: Kosmic
author_rank: Super Contributor
timestamp: October 13, 2019, 10:07:57 pm
content: Quote from: james_s on October 13, 2019, 03:30:46 amI'm doing the same thing. Just switch off the power bar on the wall before leaving the room. Most of the equipment is completely off.Having most of your equipment disconnected would also limit damage in case of a power surge.

author: wn1fju
author_rank: Frequent Contributor
timestamp: October 13, 2019, 10:38:42 pm
content: A lot of my equipment is vintage and have line filters ahead of the power switches. These are problematic - Schaffner ones like to explode for instance. After having one pop one day on a piece that was off (while I was nearby), I wired in a master kill switch to the entire lab. I'm not sure it would have caused a fire, but ever since then, I flick the switch and kill all power to everything at the end of my session. I'll gladly suffer the equipment warm-up time in order not to burn my house down.

author: tkamiya
author_rank: Super Contributor
timestamp: October 13, 2019, 11:55:22 pm
content: Many large UPS have external KILL switch port. My 3KVA one has it. It disables all power to all ports at once. Unfortunately, the way my lab is wired, it'll only be useful on emergency situations. I think I'll do the per-rack power control.

author: SilverSolder
author_rank: Super Contributor
timestamp: October 15, 2019, 12:50:12 am
content: I always cut the power with a master switch before leaving the lab area.When you have dozens of ageing instruments under power (even if switched off on their front panels) the chances would just be too high that one day, something will go wrong when you're not there to deal with it...This does mean power has to be turned on many hours before use to stabilize the instruments. Not a big deal, since my brain usually also requires many hours to stabilize before doing anything worthwhile in any case, so it and the instruments are usually on song at about the same time!

author: ArthurDent
author_rank: Super Contributor
timestamp: October 15, 2019, 01:39:42 am
content: I've modified a number of pieces of equipment to allow turning them totally off from the front rather than reaching around back to either turn a switch off or unplug them. I had re-caped the power supply in my HP53132A counter when I bought it as several caps were marginal at best so this was important to me to help prolong the life of the power supply, and the display. I added a switch button right under the CH3 input and left the original on-standby switch to function as intended. The button I added connects to a steel rod that is bent to clear the CH3 board and activate a switch I got from some old defunct piece of HP equipment so it doesn't look that bad and it works great. here's a couple of photos.

author: james_s
author_rank: Super Contributor
timestamp: October 15, 2019, 01:57:40 am
content: Seems like a switched power strip is a lot less brutal than modifying equipment like that. I really don't like doing any sort of cutting/drilling.

author: ArthurDent
author_rank: Super Contributor
timestamp: October 15, 2019, 02:17:25 am
content: "Seems like a switched power strip is a lot less brutal than modifying equipment like that. I really don't like doing any sort of cutting/drilling."I'd rather have an on-off switch right on each unit so I can find it.YMMV

author: tkamiya
author_rank: Super Contributor
timestamp: October 15, 2019, 02:19:54 am
content: Well.... on that, each to their own. It's their equipment.Personally, I try to keep everything as original as possible. Funny enough, HP53132A is one of my main complaint. The fan is loud and it's always on. I have two of them. Yet, I have an external ref so there is no need to keep internal ref powered on at all.I kind of wish HP was considerate enough to keep us a choice.Someone mentioned safety factor. That's very true. I have stuff dating back to 60s. That's nearly (geez, I'm an antique) 60 years ago! Now that I'm pretty convinced having a master switch is a good idea. My timing equipment are much newer, and they are already on a separate rack.Thanks everyone for their input.

author: tkamiya
author_rank: Super Contributor
timestamp: October 15, 2019, 02:22:04 am
content: Arthur,What's on the wall on left to with N fitting on one side and SMAs on the other? (with some kind of paper stuck to it?)

author: ArthurDent
author_rank: Super Contributor
timestamp: October 15, 2019, 03:59:02 am
content: On both ends of the black cable with type N connectors are GPS distribution amps. The 8-way on the right is externally powered, the left has 2 outputs that feed power and 3 that isolate D.C.

author: SilverSolder
author_rank: Super Contributor
timestamp: October 15, 2019, 12:35:41 pm
content: Some equipment, e.g. the venerable HP 3325A signal generator, keeps power on its GPIB circuitry even when the unit is switched off - in order to play nice on the GPIB bus (present a to-spec impedance to the bus) even if switched off. This means that it actually does make sense to "feed it some juice" when off if you use the GPIB. If you have a well populated GPIB that includes several 3325A, this makes a difference to the bus speed, number of devices you can attach, etc.So it is very convenient to just have everything on a big power strip so everything works as intended as soon as power is applied, including the GPIB bus.