What kills a 1Spot? (UN-buried from another thread)

[R.G.]

Not to hijack the thread, or anything, but: what kills a 1-Spot?
I've been happily running my PB off mine for a couple of years (including a couple of testimonials around here) with no problems (well, ok, a Line6 Chorus didn't like it, but that box was noisy with any power supply). A month or so ago I had to pack up my pedalboard for a while. When I plugged it back in, no power from the 1-Spot, nada. No external sign of damage, and no intermittence when I wiggle the cord (not that I'd expect that with the nice, heavy lamp cord it comes with). I'm sure it's not under warranty anymore, but I'm reluctant to pry it apart, and even if I did, I don't know that I'd have enough information to troubleshoot it.

There's an important phrase there that indicates you're a smart guy -
"but I'm reluctant to pry it apart, and even if I did, I don't know that I'd have enough information to troubleshoot it."
The insides of that thing are an off-line switching power supply, meaning that the first thing that happens inside is that the AC power line is rectified to between 160 and 350Vdc, and this is NOT isolated from the AC power line by the nature of the beast. About half of the business-card-size power supply is hot to the AC power line, and the arrangement of traces on the PCB is critical to the safe isolation of the secondary from that AC power line. Unless you are a working professional with experience on off-line switching power supplies and access to equipment to do the work, it is actively dangerous to ever take that thing apart and put it back together. The safety agencies which certified its safe design would not have certified if the case were not glued together or otherwise protected against users getting inside. That wasn't for convenience.

I designed off-line switching power supplies for years, but I still get really, really sober before messing with one of these things. Seriously, one careless moment and you could die. Even the filter caps inside can retain charge *after* it's unplugged from the wall. Not always, but sometimes. And it's not just this power supply - all small switching power supplies have these "features". It's hard to get that much power (AC line) so close to safety-rated DC power and send it off into the world for unknown users to play with.

I'm sure it's not under warranty anymore,

Yeah, the warranty is a year on those. Sorry. Fortunately, a new one is only about $20-$25. And since we do actively follow the field reports, you may catch updates that have been made.

When I plugged it back in, no power from the 1-Spot, nada. No external sign of damage, and no intermittence when I wiggle the cord (not that I'd expect that with the nice, heavy lamp cord it comes with).

Here's my super-secret list of symptoms about 1Spots:
1- Random intermittent operation:
  > broken/breaking wire from body to plug
  > broken/breaking plug
======================Dang, hit the alt+something key and it posted prematurely =================
  >bad internal contact from the wall plug prongs
2 - Regular "Ticking" operation
  > happens when the unit detects an overload; if you connect a 4.7R resistor across the output of a good one, it should start to "tick".
    this is what it does when it powers up, checks to see if the output is coming up to voltage properly, not too much or too little, and is
    demanding less than the rated current. If the output is not coming up to speed somehow, it will shut down so as to not burn out either
    the load or itself, and then try again.
3 - nothing at all, no ticking, no output
======================Dang, I did it again. need more coffee - or less.=======================
    > Either there's a broken conductor inside the unit, or a part is broken so that the circuit smarts never even lets it try to come up.

I've never found one in all the defect/warranty returns that we get that wasn't one of the three. However, it takes some skilled debugging time to figure out what is actually broken. Could be a cracked trace, could be a tin whisker (thank you, RoHS!), could be an early failure on an electro cap. Could be an early failure on any of the turn-on/switching stuff. Could even be that mechanical stresses (including thermal heating/cooling) has caused a good-but-marginal lead-free solder joint (thank you , RoHS!) to finally crack.

But in all cases, you are quite literally taking your life in your own hands if you open it up and try to tinker with it.

I do know how to fix them, have the experience, and could set up a workstation to do that. But it is simply not cost effective to do so. To long-time readers: go ahead and laugh as I lapse into MBA-speak; I know the language, I just don't like it.

The actual value of a 1Spot starts at, say, $25 and goes up for the first few hours (which weeds out any early life failures - I personally would prefer the new-and-tested one to a new-out-of-box one). After that it declines very slowly until warranty ends, at which time, the dollars-value does drop (would you pay more for a unit in warranty, or out of warranty?). But it's not zero value then, as you know. In many cases, these things go on, just like the value of anything which goes out of warranty. The warranty on a 59 Les Paul is long expired, for instance. 

Ordinary technician bench time is in the range of $50 an hour, and the good ones are more. The insides of a 1Spot are a mixture of through-hole and surface mount stuff (to be able to cram it all in there). With experience and skill, I'd have a hard time keeping every 1Spot fix under 20 minutes. Some of them would be easy, but others would require firing them up in a safe, isolated setup and dinking around with meter and scope to isolate it. If I did this, I'd set myself a timer of about 15 minutes and start it when I first picked up the corpse to be revived. If I fixed the unit, including re-gluing, before the timer went off, I'd feel good. If the timer went off, I'd pitch the unit into the trash can. It's easy to make a $20 unit into a $50 unit you can only sell for $10 if you're not careful.

When we get a 1Spot back, it gets plugged and sorted into the symptoms above. Only if it happens to do something NOT one of the three symptoms above do I even break it open. I really want to know if our manufacturing is turning out problems that slip past final test but fail in the field. The new-symptoms test is a sensitive indicator of that. Beyond that, the number of ones in each bucket tells us what the failure rate is like, and lets us be sure that we're not going into declining quality. We periodically check out the percentages of problems and do the math to watch whether there is a subtle problem creeping in. If I ever happen to get to where I have little to do for a while, I'll crack open a few dead ones at random to see if I still like what manufacturing is turning out, or if there is a problem I haven't suspected before.

There is the occasional novel one. I had one that did whine a while back. It was notable because it was very much the exception; in fact the first in a very long time out of many thousands of units. I got this one because the author noted the problem on a forum, and I traded him a new one to get that one with the defect captured so I could debug it and make sure it was not a systemic design or manufacturing problem. Fortunately, I found it was a random failure in a ceramic cap.

This is a very long, rambling way of saying - Ben, I recommend you not waste the time to open that thing up if you intend to try to fix it and re-use it. There are real safety exposures to doing that, not only in the debugging phase but also in the future use of the unit. I wish it was one of the novel failures where I could offer you a replacement outside warranty so I could get the info on novel failures, but that's not something I can do for all failures - nothing lasts forever, and eventually 100% of all electronic equipment will fail.

When I read your note, the little view-screen in the back of my head keyed up the most likely parts to have failed. I'm not telling you those because even telling you the possibilities would encourage you to do something I think is dangerous for you. I want you to stay around and keep making music.

As a last note, PM me.

[Paul Marossy]

This is a very long, rambling way of saying - Ben, I recommend you not waste the time to open that thing up if you intend to try to fix it and re-use it. There are real safety exposures to doing that, not only in the debugging phase but also in the future use of the unit. I wish it was one of the novel failures where I could offer you a replacement outside warranty so I could get the info on novel failures, but that's not something I can do for all failures - nothing lasts forever, and eventually 100% of all electronic equipment will fail.

A smart DIYer will know when to stop. Some things are not worth the time and effort to fix them. It's not worth spending an hour carefully trying to cut the thing open and then exposing yourself to dangerous voltages.

To me, this similar to trying to fix a $5 wall wart. Just go to a thrift store, you can usually find some old wall wart for $1, change the connector and you're good to go. My pedalboard doesn't care what kind of crappy wall wart it is being supplied with, it has a well filtered voltage regulator in it.

So the question is, is your life worth more than $25? 

I am curious, though... Why is there such a high voltage in it? I don't really know much about these switching type power supplies. 

[Morocotopo]

R.G., very interesting thread, from the point of view of the economics involved in manufacturing and repairing stuff.

My ´59 Les Paul is out of warranty? Oh well, I´ll throw it away together with my 1st generation microwave oven.

[Paul Marossy]

R.G., very interesting thread, from the point of view of the economics involved in manufacturing and repairing stuff.

I agree. But it is also this attitude which contributes to land fills being filled with people's junk that was "not cost effective" to repair. 

[jkokura]

R.G., very interesting thread, from the point of view of the economics involved in manufacturing and repairing stuff.

I agree. But it is also this attitude which contributes to land fills being filled with people's junk that was "not cost effective" to repair. 

True, so if you can fix it yourself you should. If you can't, you shouldn't, and should try to recycle it if you can. If you can't, then you have a problem.

In the case of a 1 spot, there aren't many who can fix them (RG being the obvious exception) so it's hard to say that it's worth opening up and not just trying to get it recycled.

Jacob

[earthtonesaudio]

I am curious, though... Why is there such a high voltage in it? I don't really know much about these switching type power supplies. 

I believe that's part of the "universal input" that allows you to plug in anywhere in the world.  Basically if the line voltage is too low it turns on a doubler (or tripler, etc), so that the main circuit always starts from the same place.

[R.G.]

I am curious, though... Why is there such a high voltage in it? I don't really know much about these switching type power supplies. 

Modern electrical power technology has made great strides in letting you make what you need out of what you have, and doing it without wasting a lot off heat in the process.

Transformers are near-miraculous, in that they make any AC that's within their power handling bandwidth into higher or lower AC with near perfect efficiency. A well designed transformer that's neither too small to be efficient nor for so large a voltage that the electricity leaks out by capacitance and corona discharge will have an efficiency of 98-99%. 95% is for amateur designers to hit. You pay for this in size and weight. That "within their power handling bandwidth" is the catch. The lowest frequency you feed them interacts with the power requirements to set the size and weight. For 50/60 hz, you get the ordinary power transformers we have come to appreciate. Getting to much smaller, or lighter (as highly-technically-qualified ... legislators... have required by law) higher efficiency requires you to do something very different.

All switching power supplies that isolate the power source from the load power use a transformer¹. You can force the transformer to be smaller by operating it at a higher frequency. So modern switching power supply practice takes the 50/60Hz AC line, rectifies it to DC, and then chops it to high voltage, high frequency AC with semiconductors, and runs THAT through a smaller, lighter transformer. The smaller transformer works just as well because the high frequency AC is now inside it's much high frequency bandwidth. Then the high frequency, transformed AC is rectified to isolated DC and used. The first step is making DC to work with from the incoming AC power line.

For the USA, the incoming power line is 120vac (nominal); this full wave rectifies to the peak value, 170Vdc roughly. If you double it, you get twice that, 340Vdc. If you full wave rectify 240Vac, you get about 340Vdc. Most times, they don't double 240Vac. This is the raw DC that is then chopped to feed the transformer to make the lower voltage. I believe that all 1Spots now work from 100Vac up through 240Vac. They do this because the insides are flexible enough in operation to make the right stuff out of raw DC (made from the power line) from 140 to 340Vdc. The only change is the outer case and plug and some internal insulating details.

All this trouble with rectifying, chopping, regulating, etc. repays going to all the trouble by being very flexible. You get 9Vdc from essentially any wall-socket AC you stick in there, plus light weight, inexpensive, safe², and so on. But like all high tech stuff, the tech is somewhat involved. There is no alternative to having to understand it in order to mess with it both successfully and safely.

R.G., very interesting thread, from the point of view of the economics involved in manufacturing and repairing stuff.

Like I say, I don't always agree with MBA disease sufferers, but I do know the symptoms. 

I agree. But it is also this attitude which contributes to land fills being filled with people's junk that was "not cost effective" to repair. 

Paul, with respect, let's not get into those issues. We try really hard not to damage the earth and other people in what we do, either now or in the future.
....
I've written several pages about this issue and erased them. I'm biting my tongue hard enough to really hurt. I would appreciate it if we did not continue the thread along those lines; not because I want to duck the topic, but because it's just not good for this forum.

True, so if you can fix it yourself you should. If you can't, you shouldn't, and should try to recycle it if you can. If you can't, then you have a problem.

In the case of a 1 spot, there aren't many who can fix them (RG being the obvious exception) so it's hard to say that it's worth opening up and not just trying to get it recycled.

I'm a big believer in one of the principal precepts of medical ethics that all medical students are taught in medical school - first do no harm.  Don't kill yourself, because then you can't help others and at the same time don't harm the others; then don't harm theoretical others that may come to be.

Breaking open this thing and fixing at it without the prior skills is making it into a danger to yourself and others. We like you and your music and want both to continue.


1. There are ways to capacitively couple the power, but they're not as yet practical for a bunch of technical reasons, and may not do what you actually mean by "isolate".
2. If you don't actively defeat the safety stuff.

[Paul Marossy]

Paul, with respect, let's not get into those issues. We try really hard not to damage the earth and other people in what we do, either now or in the future.

Just making a point, not trying to be argumentative.

Anyway, thanks for explaining how these 1-spots work. That makes them much less mysterious now. 

[Morocotopo]

R.G., very interesting thread, from the point of view of the economics involved in manufacturing and repairing stuff.

I agree. But it is also this attitude which contributes to land fills being filled with people's junk that was "not cost effective" to repair. 

Welcome to capitalism dear DIYer!

OK, I´ll shut up now. Sorry, R.G., couldn´t help it.

[Brymus]

Well that explains a power supply for a mutliplex router(was donated after someones work upgraded)with two transformers the first part has high voltage caps,then it ends up 5v at several amps at the output.
Since the second transformer is really small,I am gonna guess it is a similiar type design and leave it be.
I was gonna try and intercept the high voltage (poking around with leads) and use it to power a tube preamp.
Its a rather long narrow supply on a sub board,I cant remember the brand ,that is in an HPackard hub with 20 ethernet outputs.
Obviously they bought the supplies in bulk to save designing their own.

[R.G.]

I was gonna try and intercept the high voltage (poking around with leads) and use it to power a tube preamp.
Its a rather long narrow supply on a sub board,I cant remember the brand ,that is in an HPackard hub with 20 ethernet outputs.

Be very careful. Before you go in there tinkering, verify that the high voltage DC supply is NOT connected either directly or through one or two diodes to either side of the AC power line. That's the death trap.

[01370022]

Aaaahhhhhh

Now all that stuff that my professor was going on about switching PSUs make sense now. Between that explanation and me now understanding DC to AC converters I now understand how to design the little beggers. I'm just minus a couple of years practical experience working under a EE who knows what they're doing 

Yes, I did fall asleep when they were explaining how switching PSUs work 

[joegagan]

great thread. thanks so much for taking the time, rg.

[Cliff Schecht]

R.G., how much are you allowed to say about the design of the 1Spot? I'm in no way interested in copying the design, but I was curious (mostly) about what style of control you guys chose for the design (i.e. voltage vs. current mode) and what controller you guys use specifically. I could always just buy a 1Spot and pop it open if you aren't allowed to say anything..

Also, in case you didn't read in the other thread, I got that Visual Volume up and running. Thanks again for the awesome pot!

[Ben N]

Thanks, RG, and all) for the clear, erudite and helpful response. (I'll forgive you the lapses into MBA-speak.) I wasn't really considering DIYing this--I know from the get-go that there is too much stuff crammed into that little box for my half-century-old eyes to deal with, and you gave me plenty of extra reasons to stear clear--mostly just curious.

As a side note, I'm now living in a land of 230v, and I looked into getting one with the euro-style plug, just to avoid having to use one of those junky little plug adapters that always seem to lose their grip at precisely the wrong time. Unfortunately, that tiny change seems to tack about $20 onto the cost of the thing. However, my amps all require a stepdown transformer anyway, so I guess I can just plug a US-style 1 Spot into my US-style power strip. Is there any preference between running it off the 230v mains versus stepped down 115v (all at 50 hz, of course)?

[PRR]

> Why is there such a high voltage in it?

Shorter answer: because you only have 120V or 240V handy.

Obviously you got 120/240V inside the case. That gets peak-stored as 160VDC-320VDC.

There will be many parts working at this high voltage before a step-down. Maybe half the board. Lots of nasty-points.

That chit is fatal.



> if the line voltage is too low it turns on a doubler

No.

Yes, larger PC power supplies have a 120/240 switch on the back, doubles 120VAC, so it always starts from ~~320VDC.

And auto-switch supplies have been made, but the extra parts are problematic.

A switcher _can_ run from a wide range of input. You have to design for both extremes. Some parts may be double the value needed for a constant-input supply. The control circuit gives Cliff and R.G. headaches. But in small sizes, the over-engineering to eat 120VDC-360VDC and chop it to constant output is cheaper than changing input voltage schemes.

[R.G.]

As a side note, I'm now living in a land of 230v, and I looked into getting one with the euro-style plug, just to avoid having to use one of those junky little plug adapters that always seem to lose their grip at precisely the wrong time. Unfortunately, that tiny change seems to tack about $20 onto the cost of the thing. However, my amps all require a stepdown transformer anyway, so I guess I can just plug a US-style 1 Spot into my US-style power strip. Is there any preference between running it off the 230v mains versus stepped down 115v (all at 50 hz, of course)?

Look at your 1Spot, the fine print on the wall-prong side. Most new ones say "100-240VAC input, 50-60Hz" or the equivalent. If it's one of those, it will work fine from any voltage in the range, and there's really not much preference. The safety regs for countries often get into specifying pinouts, but the insides don't care as long as it's one of the recent ones. I can't remember off the top of my head how far back that goes, but it's printed on the ratings area under the prongs. Whatever prongs are on the case, it will take any voltage from 100 to 240 and work fine.