# Warning to All Axe effects Ultra owners.



## Church-Audio (Sep 27, 2014)

I have an Axe effects ultra in my repair shop this is the second time I have seen this failure its do to screws not being lock tighted on the fan housing that cools the processor. These screws become loose and fall out shorting out the power supply or worse the main board if you have one of these great processors open it up and check the screws that hold the fan to the lid. Make sure they are t secured with lock tight or some thread locker product you have to be careful not to over tighten these screws or the fan will get warped. But you should check if you own one. Lots of guys use this processor in a rack where it bounces around and these screws can become loose and do damage. This is a great product I just wanted to share my findings with the members so that they can avoid having to bring it to a shop like mine for a costly repair. The other thing I recommend with this processor is the internal 2 amp fuse on the psu board should be changed from 2 amp to 500mA. The reason being the processor only draws 100mA AC when its working so this fuse will be more than enough to protect it and blow quickly in the event of a failure the 2 amp fuse allows way to much damage to happen to the PSU board. 
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## Adcandour (Apr 21, 2013)

Thanks. I'll track down the guy I sold mine to and let him know. It'd be a shame for it to go over something easily preventable.


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## Church-Audio (Sep 27, 2014)

Yep and they are great processors. It was a very simple mistake and I am not sure they are all affected.. But every one I fix has loose bolts on the fan.


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## Guest (Oct 21, 2014)

Amprepair said:


> The other thing I recommend with this processor is the internal 2 amp fuse on the psu board should be changed from 2 amp to 500mA. The reason being the processor only draws 100mA AC when its working so this fuse will be more than enough to protect it and blow quickly in the event of a failure the 2 amp fuse allows way to much damage to happen to the PSU board.


This is not recommended. Digital power distribution networks are not analog amplifier circuits. There are far more parallel systems on this board than just the TigerSHARC (which itself is running at 5.5V so can draw 500 mA when it's running hot). The Xilinx FPGA draws another 300 mA and even more during power-on. The DACs, when all are running, even more. 500 mA is far too low. Leave it a 2A, it's a well designed power network built by an engineer who knows what he's doing.


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## Church-Audio (Sep 27, 2014)

iaresee said:


> This is not recommended. Digital power distribution networks are not analog amplifier circuits. There are far more parallel systems on this board than just the TigerSHARC (which itself is running at 5.5V so can draw 500 mA when it's running hot). The Xilinx FPGA draws another 300 mA and even more during power-on. The DACs, when all are running, even more. 500 mA is far too low. Leave it a 2A, it's a well designed power network built by an engineer who knows what he's doing.


I too too know what I am doing the whole supply draws less than 150 Ma from ac input where this fuse is located. It will not harm anything to put in a 500ma fuse in this psu. And will prevent catastrophic failure of the auto transformer on the switching supply. Also I am talking about the AC side of the supply not the DC side.... The AC side only draws 150mA at the most. That's the part of the supply that is failing. If we were talking on the screen side that would be a different story.. I would agree that 500Ma is not enough  I also work on digital electronics, consoles and processing.


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## davetcan (Feb 27, 2006)

Methinks Mr Iaresee actually woks for Fractal, but I'm sure he'll respond.



Amprepair said:


> I too too know what I am doing the whole supply draws less than 150 Ma from ac input where this fuse is located. It will not harm anything to put in a 500ma fuse in this psu. And will prevent catastrophic failure of the auto transformer on the switching supply. Also I am tAsking about the AC side of the supply not the DC side.... The AC side only draws 150mA at the most. That's the part of the supply that is failing. If we were talking on the screen side that would be a different story.. I would agree that 500Ma is not enough  I also work on digital electronics, consoles and processing.


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## Guest (Oct 21, 2014)

davetcan said:


> Methinks Mr Iaresee actually woks for Fractal, but I'm sure he'll respond.


I don't work for Fractal, but I've been a beta tester and friend of Cliff's for many years now. Normally that's disclosed in a signature on any forum I post in but signatures are only for supporting members here.

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Amprepair said:


> I too too know what I am doing the whole supply draws less than 150 Ma from ac input where this fuse is located. It will not harm anything to put in a 500ma fuse in this psu. And will prevent catastrophic failure of the auto transformer on the switching supply. Also I am tAsking about the AC side of the supply not the DC side.... The AC side only draws 150mA at the most. That's the part of the supply that is failing. If we were talking on the screen side that would be a different story.. I would agree that 500Ma is not enough  I also work on digital electronics, consoles and processing.


I hope your advice is backed up with free parts and repairs for units that end up damaged when people follow it.


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## Church-Audio (Sep 27, 2014)

Reducing the fuse from 2A to 500mA if anything would save the power supply from damage not cause it. So no need for spare parts. I actually consult for many companies about design changes to existing products. Fractal makes a great product however they don't make the power supply it's an off the shelf part. And the 2 amp fuse for this exact application is a tad too high in my opinion. This is the 2nd power supply I have replaced and they both failed for the same reason. Bolts that hold the fan in we're not thread locked. And fell on the power supply causing it to short out since the ac side of the supply only draws 150 mA it's totally safe to use a half amp slow blow fuse as a replacement in hopes that the fuse will blow before the power supply gets damaged from a short circuit again. Not rocket science you seem to think just because I don't work for fractal I don't know what I am talking about I assure you I do. It should also be pointed out that the great guys at fractal provided me with a free power supply after I described how it failed. Great customer service I simply passed on my info to help others that may have this unit in a rack touring on the road like my customer did. Based on the fuse I recommended the amount of power consumption would be 60 watts before this fuse would fail. The axe effect ultra only draws 20 watts.. So a 500mA fuse will be sufficient a 2 amp fuse is overkill and the power supply will fail before this fuse blows.


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## Church-Audio (Sep 27, 2014)

Update. I was looking at the two dead power supplies I have on my bench guess what??? They are both rated for one amp max ! You can't protect a power supply that is rated for one amp maximum with a 2 amp fuse  if I owned one I would use one of two values 1 amp fast blow. Or 500mA slow blow and I would be more tempted to go the 500mA slow blow I feel fuses should always be under the maximum a switching power supply can put out. Again this is for the first series I don't know what power supply is is the new series. I talked to Charles over in service at they are going to look into it.


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## jb welder (Sep 14, 2010)

Too much turn on surge for a fast blow 1/2A ?


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## Church-Audio (Sep 27, 2014)

jb welder said:


> Too much turn on surge for a fast blow 1/2A ?


I dont know probably. The thing only draws 150mA from the wall but to be on the safe side and because its a universal power supply from 100v to 220 or 240v its better to have something that will hold up I figure 500mAT would be ok, one things for sure a 500 mA fuse slow or fast will blow if it gets anywhere near 1A of current draw and since this thing is only 20 Watts total thats not going to happen unless there is a short the 500 mA fuse slow or fast will save the Power supply from damage. But when you make power supplies for a living  As the company does that supplies the "supplies" to Fractal maybe its not in your best interest to lower the value  I think for Fracktal in the long run it would be. I can't think of one effects unit off the top of my head Lexicon, Eventide, Tc electronics. That uses a 2 amp fuse on the main AC input.


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## nonreverb (Sep 19, 2006)

Since this is an "off the shelf" supply, the question is what's it's max power capability? If it's considerably more than what Fracktal specs, it could be the reason why there's a 2A fuse in there as the power supply manufacturer specs the 2A fuse to meet it's max operating limit. 
If that were the case, than it would be incumbent upon Fracktal's designers to adjust the fuse rating.


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## Church-Audio (Sep 27, 2014)

Supply is rated at 1 amp on the input at max load 27 watts. The actual load is much less. I suspect the Auto transformer that converts the ac voltage is rated at much less than 2 amps So by the time the fuse blows the auto transformer gives up the ghost. Here are two of the supplies you can see the primary side Ac side is blown out. The circuit is like this AC input from source to Fuse to Auto transformer. Fuse holds Auto transformer does not so that tells me that the auto transformer is the weak link and the fuse must be lowered in value to protect it. And they are calling for a time delayed fuse at 2 amps !


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## Guest (Oct 25, 2014)

The label on the side of the transformer is for steady state operation. Inrush current is generally much higher than operating current for transformers. The data sheet for this power supply says it can handle 30A @ 120V AC in inrush current: http://www.phihongusa.com/assets/pdf/PSA25L.pdf -- the fuse has to be spec'ed to handle that across the range of operating voltages the switching supply works for.


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## Church-Audio (Sep 27, 2014)

The real issues are now being looked at by Fractal I had a good conversation with them on friday.
The bottom line is I have two power supplies from two different units that had shorted out power supplies that BOTH took out the same exact part the Auto transformer. So That tells me this power supply can 
A not survive a dead short on the output and B the fuse protecting it is rated for a higher current rating than the TRANSFORMER IS  Its really pretty basic electronics here.


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## nonreverb (Sep 19, 2006)

Wow, that's a substantial current spike!


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## Guest (Oct 25, 2014)

Amprepair said:


> But again the real issues are now being looked at by Fractal I had a good conversation with them on friday.


That's nice to hear.


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## Church-Audio (Sep 27, 2014)

Yep I am sure they will figure it out. It is not a huge deal. I just want to help.


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## Guest (Oct 25, 2014)

nonreverb said:


> Wow, that's a substantial current spike!


That's the upper bound it should be able to handle and only for a very, very short period of time. Doubtful it's anywhere near that for the AxeFx but I've seen digital circuits draw 6-8x on cold start from their switching supplies. Based on the spec sheet I'm guessing there's no inrush current limiter on that power supply -- usually there's a thermistor in parallel to the AC line to keep inrush current from spiking. Note: varistors don't offer current spike protection, only voltage spike protection.


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## Guitar101 (Jan 19, 2011)

iaresee said:


> That's the upper bound it should be able to handle and only for a very, very short period of time. Doubtful it's anywhere near that for the AxeFx but I've seen digital circuits draw 6-8x on cold start from their switching supplies. Based on the spec sheet *I'm guessing* there's no inrush current limiter on that power supply -- usually there's a thermistor in parallel to the AC line to keep inrush current from spiking. Note: varistors don't offer current spike protection, only voltage spike protection.


Hmmm, now there's a lot of words I've never heard before. What I'd like to see is "yes, that was on the earlier versions of the Axe FX but they've corrected that and everything is fine now on the newer versions".
I'll be waiting for a reply from the makers of the Axe FX for their input.


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## Guest (Oct 26, 2014)

Guitar101 said:


> Hmmm, now there's a lot of words I've never heard before. What I'd like to see is "yes, that was on the earlier versions of the Axe FX but they've corrected that and everything is fine now on the newer versions".
> I'll be waiting for a reply from the makers of the Axe FX for their input.


Note I was talking about the power supply, not the Ultra, in the above post. There is nothing wrong with existing Ultras in the field. The power supply doesn't need inrush suppression.


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## Church-Audio (Sep 27, 2014)

Here is the deal. Phihong is the leader in power supplies they make tones of them!!! This 2 amp fuse is for fire suppression not for protection of the circuit it's connected too. The circuit is protected by many different techniques and will withstand a short in the power supply. Unfortunately the little tiny auto transformer phihong is using will not. So lowering the fuse to 500mA will protect the little transformer still give fire protection. and save you a costly repair on the unit down the road again this is for axe effects ultra first generation with this power supply. So if you want to prevent damage to the power supply in the event of an external short but still want to be able to travel with it around the word replacing the fuse with a 500mA makes perfect sense. Fire prevention in all switching supplies is necessary because when they fail the switching power transformer often flames out. This is true of every single supply built into a computer they all have them. So bottom line the 2 amp fuse was never intended to protect the power supply it was intended to cut power off in case of a total melt down of the switching supply. To prevent the melt down put a 500mA fuse in the unit it will protect the power supply from from blowing up in some cases in others catistophic failure will happen with or with out that fuse.


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