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Old 9th September 2012, 05:18 PM   #1361
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Default What Is The diyAudio Forums purpose

Quote:
Originally Posted by qusp View Post
yes sadly he did and its mentioned under his username if someone took the trouble to look.

I agree it really would be better if you started a new thread rather than filling this one with the unending stream of 'problems' posted here over the last 2 years.

work out what the inrush current will be based on your power supply transformer, inductors, resistors and caps, then size your fuse accordingly.
This forms existance is for the exchange of information between people with common interests. If this forum did not exist I would not have been able to make the class of amplifier that I have done, yes I have made the current work I am doing on the Aleph J-X public in this Forum, mostly the choice of components because the working of the amplifiers circuits are explained in detail in Nelson Pass's Projects, and other assembly papers created by hobiest like Grey and others, you know all of this, so why would you say I should not be communicating in this Forum, when I am currently its largest contributer of comunication directly related to the building of two Aleph J-X mono amps.

Getting back to the fuse problem, is it posible that my amps are drawing over 30amps when started with a 750VA transformer, or is it actually 18volts X 41.67amps equals 750VA, could I be getting a surge of 41.67amps ?

Thank You For Your Help

Ian
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Old 9th September 2012, 07:33 PM   #1362
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first off. disconect the amp board from the PSU. and check that there is no shorts in the PSU.
then try to power up only the PSU. if it still blows then there is a foult in your PSU or wiring.
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Old 10th September 2012, 02:37 AM   #1363
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SCAIFF001:

You're welcome in the forum. We just don't want you diluting *this* thread with information that *isn't relevant to the Aleph J-X*. Nobody else here needs to read about sizing PSU fuses because we all would have known well before we attempted this amp.

I just ask that you open a thread of your own. Also there is a seperate forum in fact for power supply issues.
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Old 10th September 2012, 08:20 AM   #1364
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these general psu queries have been covered many times, I would suggest even before starting a thread in the PSU forum that you use the search function to search for similar threads and solutions. the basic issues under discussion are not specific to this amp and too much space has been devoted to it in this thread.

I'm not telling you to **** off in general =) it just gets a little frustrating when I get continual email updates for off topic posts in the thread (just as this post is). your build appears to be pretty epic so I would like you to succeed and see build pics, but please keep the posts in here limited to AJ/AJX related inquiries.

I would recommend checking out Duncans PSUD psu calculator, modelling software and spice. I gather your PSU is total overkill as far as caps, provided you dont have a short, perhaps the inrush current is tripping your fuse and you should look into a soft start, otherwise you may need to size the fuse too large and it will not be useful under fault conditions. You could also place additional inline fuses in the DC lines, or on the secondary AC side. Adjust these secondary side fuses after you work out what the normal peak operating current of the amp is in your system.

I would also recommend you test out the PSU with the amp disconnected and if you have one, at least initially troubleshoot with a lower voltage, lower power transformer, a variac would be ideal. build yourself a bulb tester too,

Last edited by qusp; 10th September 2012 at 08:26 AM.
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Old 10th September 2012, 02:11 PM   #1365
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Default start up current

Quote:
Originally Posted by qusp View Post
these general psu queries have been covered many times, I would suggest even before starting a thread in the PSU forum that you use the search function to search for similar threads and solutions. the basic issues under discussion are not specific to this amp and too much space has been devoted to it in this thread.

I'm not telling you to **** off in general =) it just gets a little frustrating when I get continual email updates for off topic posts in the thread (just as this post is). your build appears to be pretty epic so I would like you to succeed and see build pics, but please keep the posts in here limited to AJ/AJX related inquiries.

I would recommend checking out Duncans PSUD psu calculator, modelling software and spice. I gather your PSU is total overkill as far as caps, provided you dont have a short, perhaps the inrush current is tripping your fuse and you should look into a soft start, otherwise you may need to size the fuse too large and it will not be useful under fault conditions. You could also place additional inline fuses in the DC lines, or on the secondary AC side. Adjust these secondary side fuses after you work out what the normal peak operating current of the amp is in your system.

I would also recommend you test out the PSU with the amp disconnected and if you have one, at least initially troubleshoot with a lower voltage, lower power transformer, a variac would be ideal. build yourself a bulb tester too,
Hi,

Thank you for the communication, I need it even though we are all aware of what you have said, it migt seem to uncomplicated for some people, but being a professional scientist I am all to aware that the uncomplicated looking problems are easy to fix when looking at them from outside, scientists are capable of making the stupidest errors in calculations and unable to see the errors no matter how many times they have reviewed them, that is why we have research teams, without this forum I stand alone and unable to pass through the small details while thinking of the whole picture.

I have made an error when communicating my power supply components, I have a 600VA transformer not a 750VA, I have been useing a Nelson Pass A75 Part2 project schematic for a model of my power supply and it has a 750VA transformer, so a 30amp slow blow fuse should be logical, because 18volts by 33.33amps equals 600VA, the manufacure states that the lagest current it will output is 31.6amps(see attachment "Antek AN-6218" parallel coils test specifications for this current of 31.6amps at 17.9volts). This current of 31.6amps is not what I have been naturally calculating with, but insted I have been useing 8.3amps at 18volts as also stated by the manufacturer at the following site:
Antek - AN-6218

Sorry for talking so much about an easy calculation that should have been performed early in the project, and everything I talk about here is the Aleph J-X amplifier I am constructing, I have way over $2,000.00 invested so far in my components for two mono amps.
Attached Files
File Type: pdf Antek 18volt 600VA transformer spec sheet AN-6218.pdf (40.3 KB, 11 views)
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Old 10th September 2012, 02:19 PM   #1366
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What is your mains breaker value? If your calculations are correct, which they aren't, would you not expect to trip the mains breaker first?

What do transformers do?
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Old 10th September 2012, 03:06 PM   #1367
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Quote:
Originally Posted by luvdunhill View Post
What is your mains breaker value? If your calculations are correct, which they aren't, would you not expect to trip the mains breaker first?

What do transformers do?
haha wow good catch, I didnt even register that, my brain assumed that he, like Antek was talking about secondary current rating. but honestly I didnt read it that closely, I was just trying to avoid this convo in here.

scaff, as i'm sure you are aware, the large current is on the secondary side, high voltage, lower current on the primary side, lower voltage, higher current on the secondary. 115vac at 30A is 3.45kVA (disregarding copper losses etc), what good is your fuse? the TX will be a molten puddle of copper and lead before it trips from over-current. the fact you are still popping it means short circuit, theres no way the fuse isnt big enough and no amount of inrush current is going to pop that sucker either =)

but, just to check that we arent talking about such a simple mistake, i'm baffled, are you actually blowing a fuse of that rating? where is it? on the rail or on the IEC? I would have thought the amp would vaporize before that happened, no magic blue smoke?

sorry I really dont have time for this though, i'm going to have to just leave you with it, good luck. after blowing that much on the amp and no small amount of it on the PSU, I would definitely try and get a variac, or start with a low voltage transformer and make up a bulb tester

Last edited by qusp; 10th September 2012 at 03:32 PM.
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Old 10th September 2012, 03:14 PM   #1368
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the fuses he is talking about is at the sec after the rectifiers.
but 30Amps is way to high. each sec is rated at 16A at 18V.
and it is better to put fuses after the cap bank and use fast type fuses. and ofcourse slowblow on the mains.
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Old 11th September 2012, 09:57 AM   #1369
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Default Picture of my 1of2 mono amp, not working yet

Hi,

I understand that peple want to see what my amps look like, I am having trouble making a photo that I can load into this forum, I have Photoshop but have not been able to make a smaller data size image without loss of to much detail or size, I am open to any ideas of how to create a better image for you.

Ian
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File Type: bmp scatterbrain001_alephjx-bmp-00-01.bmp (93.8 KB, 84 views)
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Old 11th September 2012, 05:00 PM   #1370
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Default better pickture 1of2 mono Aleph J-X, not working yet

Hi everyone,

This is a clearer photo of my amp, I will try to creat many better photos, my amps have alot of AC processing before it gets to the transformer: 2 AC lines DC filter, soft start, thermal shutdown, 4 AC fan controlers, I ahve bypassed all of the AC line circuits untill I can get the amp working without them.

Thank You

Ian
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