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Old 16th July 2011, 02:47 AM   #1
JZatopa is offline JZatopa  United States
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Default A Cautionary Tale

So today I found the time to finally finish up my F5 amp. I have been using it with a bench power supply and loving it but I wanted to have the amp complete. I bought my parts from DIYaudio and techDIY with the exception of the PS board. For that I bought from gigaworks on ebay. The main reason I went with it was the fact that everything was included. I have to say the build quality was subpar. Well I got everything together and started listening to the amp. The first thing I notice is that there is much less bass. The bench PS I have is very robust, the gigawork just seemed to be lacking. Well I let it run in a few hours and although everything sounded ok it just didn't sound as nice as my bench PS. So here is where things get a bit scary. I left the room with music playing to do some paperwork. Everything was fine until my girl friend said it sounded like the cat was doing something he shouldn't be in the basement. That moment I smelled burnt circutboard and rushed down. The PS board was on fire!!! I unpluged everything and blew the fire out. It seems that the traces heated up and shorted, the fuse I had did not blow for what ever reason. Everything is ok and only the PS is damaged but let my experience remind you guys that you should always be careful and don't use cheap Chinese parts no matter what your reason.
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Old 16th July 2011, 03:59 AM   #2
limono is offline limono  United States
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"traces heated up an shorted". I had similar experience with my analog tube board cought on fire just because there was a micro short between the traces on DIY audio board bought in some group buy. Thats the hores of DIY audio.
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Old 16th July 2011, 08:03 AM   #3
NYCOne is offline NYCOne  United States
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Quote:
Originally Posted by DJNUBZ View Post
So today I found the time to finally finish up my F5 amp. I have been using it with a bench power supply and loving it but I wanted to have the amp complete. I bought my parts from DIYaudio and techDIY with the exception of the PS board. For that I bought from gigaworks on ebay. The main reason I went with it was the fact that everything was included. I have to say the build quality was subpar. Well I got everything together and started listening to the amp. The first thing I notice is that there is much less bass. The bench PS I have is very robust, the gigawork just seemed to be lacking. Well I let it run in a few hours and although everything sounded ok it just didn't sound as nice as my bench PS. So here is where things get a bit scary. I left the room with music playing to do some paperwork. Everything was fine until my girl friend said it sounded like the cat was doing something he shouldn't be in the basement. That moment I smelled burnt circutboard and rushed down. The PS board was on fire!!! I unpluged everything and blew the fire out. It seems that the traces heated up and shorted, the fuse I had did not blow for what ever reason. Everything is ok and only the PS is damaged but let my experience remind you guys that you should always be careful and don't use cheap Chinese parts no matter what your reason.
I've had great luck with Chinese parts. I buy with the same care I use for any purchase. Though I considered it, I specifically didn't buy the PS you mentioned because I didn't know the parts. I did buy Chinese PCBs for my first two PS (when I was just starting DIY, now I etch my own) and I bought my parts from well known US suppliers. Those PS are still running.

I've gotten good and bad from every major market, the Chinese market is no different. If you're unsure of a part, ask in the forum, you'll do well.
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Old 16th July 2011, 05:08 PM   #4
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I'm running the same Gigaworks power supply board--but I increased the cross-section of the +/-/ground rails on the power supply PCB by soldering a bare 16-gauge solid copper "buss" onto the high-current traces, with a continuous solder bead. No problems noted. (Just something to consider, if the power traces look a little wimpy.)

You can get almost the same results just by running a heavy solder bead (without the added copper wire) along each high-current trace

I also swapped out the Gigaworks 10,000 mfd caps with 18,000 mfd ones, purchased from Apex.
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Old 17th July 2011, 12:11 PM   #5
ramallo is offline ramallo  Europe
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Curious, I was running my F5 with a similar board (From tubeshunter) more than a year and worked perfect (16 hours at day "on"), the traces are ok (Thick cooper). Now I'm using a identical board with a thicker cooper and gold plated from Jims Audio (More than enough for this current), but with Mundorf and MUR rectifiers and is great.

I don't heard a significative differences between my actual Mundorf board against the cheap 10000uF Rubycons, but I felt a big differente with the MUR instead the square rectifiers.

Maybe a defective serial of boards with a thin cooper.
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Old 18th July 2011, 06:06 AM   #6
JZatopa is offline JZatopa  United States
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Well now I need to build a new PS. I am debating trying a jims audio board (which looks much better designed then the gigaworks) or using what I have laying around and wiring point to point. I think part of the problem with the gigaworks was that the V+/- + ground traces were too close together. I was careful not to bridge anything but as the amp heated up anything could of happened.

Any input on using 2 X 63V 22000uf + 2 X 40V 68000UF caps to make a power supply. They just barely fit in the chassis but I would only need some resistors or if I could fit them 2 chokes and I would have a power supply (I think, LOL). I am still very new to amps and although I think I get parts if it I still have doubts.

Last edited by JZatopa; 18th July 2011 at 06:19 AM.
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Old 18th July 2011, 10:36 AM   #7
ramallo is offline ramallo  Europe
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The Jims boards have a very thick cooper tracks (The board is heavy). The outs are as close as Gigaworks, but IMHO is more than enough

This is a board that I use in a F5 (before Mundorf)
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Old 18th July 2011, 10:43 AM   #8
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Peter Daniels power supply boards are very good quality, not expensive and are well tried and tested. He is a member here too...
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Old 18th July 2011, 02:16 PM   #9
Itsmee is offline Itsmee  England
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Some people may not know where to look for Peter's PSU boards, here's a link.

Universal Power Supply PCB
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Old 18th July 2011, 06:04 PM   #10
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Quote:
Originally Posted by DJNUBZ View Post
It seems that the traces heated up and shorted.
DJNUBZ...... I'm trying to better understand the "failure mode" of your power supply. You say the traces heated up and shorted. I can understand the traces (perhaps) getting warm with a very high current load (typically more than the F5 would require), but can you explain the "shorted" comment? All the PCBs I've seen for these amp's power supplies (Jim's Audio, Peter Daniels, Gigaworks, etc) seem to have about the same "buss spacing", so I don't understand why you saw shorted traces....where, in particular? Was the PCB substraight (the fiberglass itself) on fire?

Just curious..... trying to better understand how your power supply failed.
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