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Why do my power adapters keep failing?
Old 26th November 2009
  #1
Lives for gear
 
🎧 10 years
Why do my power adapters keep failing?

I have a few Alesis items in my rack and although not exactly high end they still have their uses. However, the AC power supplies keep failing on me, 4 in the last few months!

Being out of official Alesis power supplies I obtained yet another one which i plugged into one of my alesis units yesterday and all was well. Today I power up the studio and the unit fails to power up. I try the power supply on my other Alesis units that use the same type of power supply and nothing, yet another has failed on me!

The power supplys are not just failing on one piece of gear so I dont think the outboard gear etc is at fault and all the power supplies for my non Alesis gear in the studio are working fine.

Can anybody explain what is going on here?

I believe that the Alesis power supplies are AC. Could using such power adaptors on a power strip that also powers DC power supplies cause such problems? I cant see this being the case but its the only hunch that I have at the moment.

Any explanations/advice/solutions/suggestions would be GREATLY appreciated.

Many thanks in advance.
Old 26th November 2009
  #2
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2N1305's Avatar
 
🎧 10 years
wow, that is weird indeed...

I have three different hypothesis for you:

First one: Something is wrong with your your AC mains (as you say in England!) maybe the voltage is too high, and it's damaging the fragile transformers inside the power suppliesWhich probably has no Transient Voltage Suppressor, TVS).

Second one: Alesis has manufacturing issues with this power supply (unlikely but possible).

Third one: Your gear is damaged, it's drawing too much current for whatever reason.

I think hypothesis one is the most likely. you could also have some ground loop introducing a voltage differential somewhere in your studio wiring, adding to the voltage.

That's it for me!
2N
Old 26th November 2009 | Show parent
  #3
Registered User
 
Rick Sutton's Avatar
 
🎧 15 years
just a thought.....are the power supplies hot to the touch? Is there enough space between them so they can get air circulation. Early failure can be related to heat issues.
Also, are you positive these supplies are rated for the correct current for your specific Alesis units? You might have to go to a higher current supply.
Old 26th November 2009 | Show parent
  #4
Lives for gear
 
🎧 10 years
First of all, thank you for your responses to my problem, this is much appreciated...

Quote:
Originally Posted by Rick Sutton ➑️
just a thought.....are the power supplies hot to the touch? Is there enough space between them so they can get air circulation. Early failure can be related to heat issues.

The power supplies are not that hot; slightly warm but I’m pretty sure that this isn’t the problem. Plenty of air circulation too.
Quote:
Originally Posted by Rick Sutton ➑️
Also, are you positive these supplies are rated for the correct current for your specific Alesis units? You might have to go to a higher current supply.
Yes, the power supplies are the correct type for the units, the Alesis P3 which is used for most of their devices including he DM5, SR-16, Midiverbs etc.
Quote:
Originally Posted by 2N1305 ➑️
I have three different hypothesis for you:

First one: Something is wrong with your your AC mains (as you say in England! ) maybe the voltage is too high, and it's damaging the fragile transformers inside the power suppliesWhich probably has no Transient Voltage Suppressor, TVS).

Second one: Alesis has manufacturing issues with this power supply (unlikely but possible).

Third one: Your gear is damaged, it's drawing too much current for whatever reason.

I think hypothesis one is the most likely. you could also have some ground loop introducing a voltage differential somewhere in your studio wiring, adding to the voltage.

That's it for me!
2N
Your last suggestion has got me thinking. Around 6 months ago after reconfiguring my home studio and installing a few new bits of gear I did have an issue with a ground loop which drove me mad for a couple of weeks. After connecting a small wire between a couple of hum inducing culprits and the studio rack they were housed in I did managed to eliminate the hum but maybe I have an underlying issue that is now causing a more serious problem?

Anyone else feel that this could be the cause?

Would the Alesis AC power supplies be more prone to being affected/ damaged?

Any suggestions on how to resolve this problem?
Old 26th November 2009 | Show parent
  #5
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JohnRoberts's Avatar
 
🎧 10 years
Another vote for thermal.

The common failure mode for wall warts is an internal thermal fuse opening up.

Generally this is because of pulling more current than they are rated for, but ambient temperature can have a marginal effect.

JR
Old 26th November 2009 | Show parent
  #6
Registered User
 
Rick Sutton's Avatar
 
🎧 15 years
Quote:
Originally Posted by dialectic ➑️

Around 6 months ago after reconfiguring my home studio and installing a few new bits of gear I did have an issue with a ground loop which drove me mad for a couple of weeks. After connecting a small wire between a couple of hum inducing culprits and the studio rack they were housed in I did managed to eliminate the hum but maybe I have an underlying issue that is now causing a more serious problem?
That shouldn't have anything to do with the supplies failing.

I'm sure you've checked this, but these supplies are rated for UK use, right?
Old 26th November 2009 | Show parent
  #7
Lives for gear
 
🎧 10 years
Quote:
Originally Posted by JohnRoberts ➑️
Another vote for thermal.

The common failure mode for wall warts is an internal thermal fuse opening up.

Generally this is because of pulling more current than they are rated for, but ambient temperature can have a marginal effect.

JR
There is plenty of air circulation around the power supplies and they are the correct type for the units that they are being used for.

In addition to this, It appears that this issue is affecting a number of Alesis units.

It seems that if I were to purchased another power supply, nomatter what Alesis unit was being powered by it, in no time at all the power supply would fail.

I feel that it is something more sinister that just a thermal issue. I have used these units and power supplies for many years and have never encountered a problem such as this before. I have only had this problem in the last 6 months or so which I'm sure coincided with the ground loop problem I mentioned in my previous post. Could a ground loop be the cause of the problem?
Old 26th November 2009 | Show parent
  #8
Lives for gear
 
🎧 10 years
Quote:
Originally Posted by Rick Sutton ➑️
That shouldn't have anything to do with the supplies failing.
It does seem unlikely but I cant believe that a thermal issue is causing the power supplies to fail so quickly. The last one I used had the unit running for around 5 mins last night. Today when I powered up the unit it had no power running to it. I tried the power supply on other units that use the same type and its dead. Its really starting to do my head in!

Quote:
Originally Posted by Rick Sutton ➑️
I'm sure you've checked this, but these supplies are rated for UK use, right?
Yes, and have been happily using them for years with no problems.
Old 26th November 2009 | Show parent
  #9
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Rick Sutton's Avatar
 
🎧 15 years
Sorry, no more thoughts other than to go up to a higher current supply and see how that does.
Old 26th November 2009 | Show parent
  #10
Gear Nut
 
🎧 10 years
unfortunately there are many manufacturers that supply switchmode PSU's that are rated too close to the current draw of the unit that it is supposed to run. It all comes down to keeping costs down for them which in turn sucks for the end user.

Take Lacie hard drives for example.. their supplies fail all the time.. gets very boring..

I'm sure there are many people here who can vouch for that.
Old 26th November 2009 | Show parent
  #11
Lives for gear
 
🎧 10 years
Quote:
Originally Posted by Rick Sutton ➑️
Sorry, no more thoughts other than to go up to a higher current supply and see how that does.
Quote:
Originally Posted by diezel_addict ➑️
unfortunately there are many manufacturers that supply switchmode PSU's that are rated too close to the current draw of the unit that it is supposed to run. It all comes down to keeping costs down for them which in turn sucks for the end user.

Take Lacie hard drives for example.. their supplies fail all the time.. gets very boring..

I'm sure there are many people here who can vouch for that.
Thanks again for all your feedback so far, much appreciated guys.
I understand what you are saying regarding the units drawing too much current and needing to go up to a higher current supply etc but why hasnt this been an issue before in all the years i've owned these units and only now start causing power supplies to fail after only 5min use?
Old 27th November 2009 | Show parent
  #12
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2N1305's Avatar
 
🎧 10 years
All interesting comments. I had not thought of the thermal issue, I don't know why it slipped me by. Anyway, that obviously is not your problem, because you've said that they have lots of air around them.

SO I am still thinking about this ground loop-new wiring issue. There is a way to debug this logically.

Do you have a mulitimeter? Anything to measure AC voltage with?

If so measure thevoltage on the plug on which those supplies are connected to. yyou should see (just guessign here, I'm in North America 120V) around 210 to 230volts AC. roughly. That's from one prong to the other. HOWEVER, you must not get anything from GROUND prong (earth) to NEUTRAL, and must get no more than 220V from GROUND to LIVE. If you could provide us with a picture of that wire you added to cancel the noise, that would be another good thing for us trying to help you.

It might be that there is current flowing from the negative side of the bridge rectifier inside the device it's powering, to the transformer. I am not exactly sure of how to explain it, but I could if I'd be there with an oscilloscope. Hmm.
Yah, ze transformer, vell, ze AC current is making foltage dropp vetween DC ground und ze AC return line. Or somesing like zis.

Very Intriguing problem.
Old 27th November 2009 | Show parent
  #13
Lives for gear
 
🎧 10 years
I do have a multimeter here which I have just dug out but to be honest i have never used it before so please be patient with me and my noobness.

I have it set up for AC voltage (red probe into 'V', black probe into 'COM' and ACV is selected) but need a little more clarification on how to go about performing the necessary checks. Would you mind explaining this in a little more detail for me please.
Old 27th November 2009 | Show parent
  #14
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2N1305's Avatar
 
🎧 10 years
No problem.

You have the correct setting, thank you for mentionning that, it's not obvious that everyone takes the time to mention the obvious (for a techie anyway!).

You also want to select a voltage range that is apropriate to what you will be measuring, like a scale of 300volts. Something higher than what you will be measuring.

So measure the voltage at a wall plug in your home. Another one that isn't in your studio. Do this by putting the red probe in (this is where I fall short, but have referenced the internet to help me, you most probably have a type G receptacle AC power plugs and sockets - Wikipedia, the free encyclopedia ) the left hole of the receptacle. Now put the black probe in the right hole. Check the meter, what does it indicate? Remember that. Now go measure the receptacles in your studio in the same manner.

After you do these measurements, measure the output of one of the good AC supplies. First, disconnect it from the device it is powering, and put the probes inside the holes of the plug. You should measure the voltage that is indicated on the power supply.

Man it takes time to write this on a freakin defective keyboard! (I have to rewrite every "o"!)

later,
2N

Last edited by 2N1305; 27th November 2009 at 03:01 AM.. Reason: phrasing
Old 27th November 2009 | Show parent
  #15
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🎧 10 years
Thanks for the info. Will perform checks later today and report back.
Old 27th November 2009 | Show parent
  #16
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🎧 10 years
Quote:
Originally Posted by 2N1305 ➑️

After you do these measurements, measure the output of one of the good AC supplies. First, disconnect it from the device it is powering, and put the probes inside the holes of the plug. You should measure the voltage that is indicated on the power supply.
Just to clarify, the power supplys have a 'barrel' type connector. Are both probes inserted into this barrel or does one get inserted and the other probe connect to the outside?
Old 27th November 2009 | Show parent
  #17
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brianroth's Avatar
 
🎧 15 years
Has ANYONE discovered that the crappy PSUs from China can barely exist past the 90 day warrenty period???

I ran into that with a DVD player. And other and Not the first time, either.

PSUs from China are JUNK! Be glad it lasted that long...and did not catch on fire.

Bri
Old 27th November 2009 | Show parent
  #18
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2N1305's Avatar
 
🎧 10 years
Quote:
Originally Posted by brianroth ➑️
Has ANYONE discovered that the crappy PSUs from China can barely exist past the 90 day warrenty period???

I ran into that with a DVD player. And other and Not the first time, either.

PSUs from China are JUNK! Be glad it lasted that long...and did not catch on fire.

Bri
Is it really that bad? I mean most of the made-in-wherever wallwarts I have are still good. Plus I find it hard to beileve that Alesis, a respected company would source inferior components.
Konka DVD players are not Alesis products, much less if those products are more than 10 years old, which I am guessing, they are.

But generally I agree with the opinion (it's almost a fact) that every electronic device made in "nameless" is garbage and doesn't last more than 2 years.

Companies should give the customer a choice : Do you want the crappy power supply or the Acopian/Condor/Lambda/what have you supply for x$ more?
Old 27th November 2009 | Show parent
  #19
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JohnRoberts's Avatar
 
🎧 10 years
I don't think it's as simple as all chinese transformers are crap...

In fact if they are UL approved, the components and factory are actually certified. While there may not be a UL peep in house 24x7, they have been visited and periodically inspected.

More likely a bad batch of thermal fuses that trip prematurely, or maybe some mid level production manager substituted a lesser part to keep his production line running.

When using contract manufacturing or sourcing components from halfway around the world, stuff happens, but the same stuff has happened before when manufacturing was done here..

JR
Old 27th November 2009 | Show parent
  #20
Gear Maniac
 
🎧 15 years
Remember that these supplies are just transformers in a box - so I would ensure that they are of the correct voltage for the mains side.

Examine a faulty one - (if you haven't yet thrown them away!). With your multimeter on the 'ohms' range measure the resistance on the primary (mains side). So across the Live and Neutral mains pins you should see several hundreds of ohms. But most likely it will be open circuit, as this is the usual failure mode, normally due to thermal fuse failure, or breakage of the fine primary winding wire where it is terminated on a tag for example.

The secondary side resistance will be very low (only a few ohms) - and is normally found to be fine.

Now consider making yourself a high quality supply - with a good transformer in a box!
Old 28th November 2009 | Show parent
  #21
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2N1305's Avatar
 
🎧 10 years
Quote:
Originally Posted by JohnRoberts ➑️
I don't think it's as simple as all chinese transformers are crap...
...
More likely a bad batch of thermal fuses that trip prematurely, or maybe some mid level production manager substituted a lesser part to keep his production line running.

When using contract manufacturing or sourcing components from halfway around the world, stuff happens, but the same stuff has happened before when manufacturing was done here..

JR
I think all of that is quite true.
Old 28th November 2009 | Show parent
  #22
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🎧 10 years
Quote:
Originally Posted by 2N1305 ➑️
After you do these measurements, measure the output of one of the good AC supplies.
2N1305, I currently have no working Alesis AC power supplies as the one that failed the other night was my last one and consequently I cannot undertake the necessary checks that you recomend. I will get a replacement next week and then post back here if thats ok. Your advice on this matter is greatly appreciated.
Old 28th November 2009 | Show parent
  #23
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2N1305's Avatar
 
🎧 10 years
Sure, you're very welcome. Buy what voltage reading did you get on the wall socket?
Old 28th November 2009 | Show parent
  #24
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🎧 10 years
Quote:
Originally Posted by dialectic ➑️
2N1305, I currently have no working Alesis AC power supplies as the one that failed the other night was my last one and consequently I cannot undertake the necessary checks that you recomend. I will get a replacement next week and then post back here if thats ok. Your advice on this matter is greatly appreciated.
Did you measure the DC resistance on the bad unit as mixermend suggested??
Old 29th November 2009 | Show parent
  #25
Here for the gear
 
tuvokzeta9's Avatar
 
🎧 10 years
This sounds like a house Mains issue... even the worst Chinese wall-wart can take a little abuse. I'd grab a meter and check the outlet voltage... and for a few minutes... AND... check it at various times of day/night too. The reading at 1am will probably be different at 9am and 8pm... when all them TVs are sucking up the juice yo.

You'll figure it out. Good luck man!
Old 29th November 2009 | Show parent
  #26
Lives for gear
 
🎧 10 years
When it comes to using a multimeter, what is the minimum category (cat I, cat II etc) required for safely checking a UK mains outlet?
Old 30th November 2009 | Show parent
  #27
Lives for gear
 
🎧 10 years
Quote:
Originally Posted by 2N1305 ➑️
So measure the voltage at a wall plug in your home. Another one that isn't in your studio. Do this by putting the red probe in (this is where I fall short, but have referenced the internet to help me, you most probably have a type G receptacle AC power plugs and sockets - Wikipedia, the free encyclopedia ) the left hole of the receptacle. Now put the black probe in the right hole. Check the meter, what does it indicate? Remember that. Now go measure the receptacles in your studio in the same manner.
After doing some research online it seems that there are conflicting opinions on how safe it is to use a multimeter for testing mains outlets. Some sites advise to never use one for this purpose which is making me reluctant to carry out the necassary checks that have been advised.

So what is the general consensus regarding the saftey of this for UK mains?
Old 30th November 2009 | Show parent
  #28
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JohnRoberts's Avatar
 
🎧 10 years
If you are uncomfortable,, don't.

You could make a set of test leads from an old power cord that you could connect to the meter, and test without touching anything. 230V deserves respect. But don't leave the power cord laying around.

I am not really that suspicious of your mains power being the problem if multiple failures are isolated to this one lump PS. More likely a bad batch of PS from mfr., or unusual heavy current draw in unit.

JR
Old 30th November 2009 | Show parent
  #29
Lives for gear
 
🎧 10 years
Quote:
Originally Posted by JohnRoberts ➑️
I am not really that suspicious of your mains power being the problem if multiple failures are isolated to this one lump PS. More likely a bad batch of PS from mfr., or unusual heavy current draw in unit.
The power supplys that have failed over the last few months were not all of the same batch, not all of the same age and had been running fine for years with no problems.

Also, they arent just failing on one unit but 6 different pieces of gear.

Even if all 6 units had an unusual heavy current draw why would they have all been working fine for many years then cause 5 power supplys to fail withing a few months?
Old 30th November 2009 | Show parent
  #30
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JohnRoberts's Avatar
 
🎧 10 years
Ok.. How bright are you light bulbs?

UK changing from nominal 240V to nominal 230V should result in soft if anything mains for older gear, but newer (230v) gear connected to a mains supply that is still old school 240V will be slightly hot.

I don't know for a fact what your problem is. The manufacturer of the PS/product should be your best source of advice.

My query about your light bulbs is not completely in jest. I had a situation at my home several years back where my nominal 240V mains drop had crept up to 260-270V and was still rising, because my local power distribution station had a stuck boost winding switch. I called my power company, and they whacked it with a spanner, or whatever they do to get it unstuck. I don't expect this to be your problem either, but do recall after the 230v transition, there were reports of power stations dragging their feet, because lower mains voltage meant lower revenue.

I am just offering my opinions from a distance with incomplete information.

JR
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