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Old 31st December 2013, 04:50 PM   #11
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Just the board, not parts. Dale (ibuildstuff4u) built his with the same exact parts though, and they work, so they are correct components.

Quote:
Originally Posted by mrWagner View Post
Speaker cables can be quite long in a room, so doesn't matter how long it is in the amp.
If the 2 sides are identical, then check the connections, maybe bad soldering somewhere. Everything is from chipamp.com? Board, parts?
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Old 31st December 2013, 05:37 PM   #12
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No we built the power supply our self, but my amp has the same design and it works fine. My nephew soldered up the boards, but I gave them a good look and they seem fine. I guess we will have to go over them again and re check.

The boards are from chip amp and the parts are from mouser, but I have the same set up and again it is working just fine. I ran mine for 6 hours yesterday and it ran good. I even put a 29v + 29V transformer in mine for a while and it did very well and only got warm when pushed really hard. I could up the heat sink size and leave the larger transformer in, but I didn't see much gain so I put my 18v + 18V back in.

This is the power supply circuit we used but shortened it up and only have two caps per channel instead of four.

Dale P.
Attached Files
File Type: pdf Nmos350-500powersupplyschematic.pdf (30.2 KB, 35 views)
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Old 31st December 2013, 10:51 PM   #13
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This afternoon I want to test a few more things on the amp, but immediately found a new/different problem. Before I went to pull the boards, I did one last check of the voltages. With both boards connected, I was getting about +22v or +23v on the positive side (I'm going off of memory). I was getting about -9v on the negative side. Curious, I disconnected the boards, and tested the voltage coming off the supply- and now I'm getting no voltage. I could follow the voltage all the way up to the bridge rectifiers, then lost it, so I figured they must be bad. I pulled them both off, and sure enough, the were both bad (I got no continuity across any of the pins, either direction). What would cause them to stop working? Especially both of them? I just want to see if I can find the reason before I go throwing new ones at it. They were rated for 400v, 4a, so it definitely was not too much power.

Also, I FINALLY took some pictures. But for whatever reason, it won't let me post them. I'll send them to my uncle tonight, and see if he has better luck.
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Old 1st January 2014, 12:18 AM   #14
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To post pictures you have to use the advanced reply button, or just mail them to me.

Dale P.
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Old 1st January 2014, 03:12 AM   #15
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I'll mail them. I know how to, it would load them then say I had a "missing security token" or something like that.

Quote:
Originally Posted by ibuildstuff4u View Post
To post pictures you have to use the advanced reply button, or just mail them to me.

Dale P.
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Old 1st January 2014, 04:03 AM   #16
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Quote:
They were rated for 400v, 4a, so it definitely was not too much power.
I respectfully disagree, 4 amp rectifiers are undersized here, you really sould be using at least 10 amp rated or higher. Your amp chips my be bad now also.

Mike
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Old 1st January 2014, 05:20 AM   #17
nezbleu is offline nezbleu  Canada
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Build a bulb tester before you plug anything in again, and then use it. It will tell you when you have a problem and prevent you damaging any more components.
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Old 1st January 2014, 05:49 AM   #18
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Quote:
Originally Posted by Michael Bean View Post
I respectfully disagree, 4 amp rectifiers are undersized here, you really sould be using at least 10 amp rated or higher. Your amp chips my be bad now also.

Mike
Alright, when I replace them I'll go 10 amp. Do you mind explaining your reasoning? I'm sure there is way more to it than I am thinking, I had figured as long as it was above the rating of my transformer I was fine.
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Old 1st January 2014, 08:29 AM   #19
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Discharged capacitors are a dead short at initial power up, heavy current surges caused by large caps require diodes with a higher surge rating than smaller diode can handle.

Mike
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Old 6th January 2014, 04:13 PM   #20
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So I think I found a new transformer. It is a dual 24v, 160VA.

Here is the link:

miscellaneous.html

I know the voltage is a little high, and the amperage is a little low, but really the $22 is all I'm willing to spend, and it's the best I can find at that price. Also, there are other items I want from apexjr anyways, so shipping cost isn't an issue.

So, would this be "good enough" for now? Keep in mind what it currently has is a tiny 22v, 25VA.
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