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Chip Amps Amplifiers based on integrated circuits

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Old 29th May 2003, 03:16 AM   #11
elizard is offline elizard  Canada
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well .. hmm ..
now i've a choice to make

to continue making the GC .. order the new parts, costing $40 after shipping&tax (if not more), or to sell everything, maybe get most of the money out of it, and then go out and buy a new amp until i can afford to try to build another one ..

i'm afraid i'm gonna blow the next set of components too .. and the ones after too!
and then end up with $500 worth of components that doesn't work

so far i've invested over $300 in parts alone, plus another probably $50-$100 in other materials/tools
and i've nothing .. NOTHING!!!

gotta sleep on this .. must sleep on it
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Old 29th May 2003, 04:00 AM   #12
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Default Ouch

Hello,

Please make sure you wear some form of protective gears, a pair of eye glasses should be the minimal when first power up.
I always wear the eye protector when power up first time after any mod completed even though I use a variac to power up slowly; I did not do this before, until I've read Peter Daniel's unfortunate experience.

Best Regards
Chris
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Old 29th May 2003, 07:09 AM   #13
karma is offline karma  Canada
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Unhappy foobar

sorry to here it didnt work out with you gc.after you get your amp try again down the road.


i would buy the parts but i have to much as it is

ya flying parts god could i tell some storys like geting a sharp
peace of ic case in my eye that was not fun for about a month
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Old 29th May 2003, 01:36 PM   #14
Nuuk is offline Nuuk  United Kingdom
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Quote:
now i've a choice to make
Well Elizard, if you want help making that choice I would say stick with it! Rome wasn't built in a day and the man who hasn't made mistakes, hasn't made anything!

I set fire to one of my Arcam A60 amps earlier this year and I know that sick feeling that you experienced. I just walked away from the amp for 24 hours then got stuck in to sorting the problem (rebuilding one whole channel). I was as nervouses as hell when I powered it up again but it worked and now it just seems like an unpleasent dream.

From what you have told us, I would suggest the following:

1 Get into the habit of measuring the power supply before it is connected to the circuit it is powering.

2 Standardize on the colours of your wiring. I use red for positive voltage, black for negative voltage and blue for ground connections (and yellow or green for earth).

3 Where ever you use polarised caps, double, triple and quadruple check that the polarity is correct. If you don't have a circuit diagram to go by, ask somebody BEFORE powering up.

4 After you see smoke, smell burning or hear 'funny' noises coming from a circuit, assume that a component may have been damaged, dump it and replace it with a 'good' one. It may seem costly but in the long-term it will save you money and worry. Resistors can be checked easily enough but caps not so.

5 If you are hard wiring make sure that bare wires/leadouts can't touch each other, remembering that they may move slightly. Sleeve anything that you can using sleeving removed from scrap wire.

6 ALWAYS check all parts of the circuit to make sure there are no short circuits where there shouldn't be. Then go over the circuit again after you have had a break for a cup of tea/coffee.

So, if you get your PSU sorted and it measures correctly, and you follow the above suggestions, there is almost nothing to go wrong. DIY hi-fi is like riding a bike in some ways - if you fall off you need to get back on ASAP!
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Old 29th May 2003, 03:55 PM   #15
cm961 is offline cm961  Canada
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The first amp I built blew up. It was one of Randy Sloan's. I believe the problem was that I didn't use caps rated at a high enough voltage. The schematics don't give a voltage rating for most of the caps, but now that I'm a little more experienced I can generally figure it out. I eventually got that amp working but never built a proper power supply or case for it. I started on another amp about 3 years ago and still haven't finished it. I have however repaired an amp or two and rebuilt an amp.

Your confidence can take a real hit when things blow up, but as long as nobody gets hurt you haven't lost anything but money and time... And thats what hobbies are all about in the first place.

So keep on building.
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Old 29th May 2003, 04:44 PM   #16
mothman is offline mothman  United States
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I gotta add my two cents as I 've experienced the same depths of frustration from fiz,pops,blow ups and melt downs.
I bagan trying to rebuild a broke but promising lm3886 based clone without a whole lot of basic electronics knowledge and I payed the price several times over.
I didn't give up but dug in and read,read,re-read alot of basic info and got help from many people on this site and others until I finally understood and not guess at how to wire the amp.
I've now got a terrific sounding amp that I built from scratch and I know every solder joint,wire and connection in it.
I can tell you that the catastrophic problems I experienced were caused by either connecting a cap backwards or connecting one of the bridges backwards.Always seemed to be a reverse polarity somewhere.
If you are using a split rail supply ckeck the wiring again and don't give up.
Believe me if I can get one of these up ad running anybody can!
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Old 29th May 2003, 05:14 PM   #17
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Dude. I feel your pain.

I had just built my first big DIY project around christmas. It was too big and complicated for my first project. In one box there was:

6-channels of LM3886,
a stereo linkwitz phoenix active crossover/eq (4 tiny quad OPA4134 SOIC opamps plus 1 SOIC OPA2134) per channel,
a phono Eq,
linkwitz transform for a sealed sub,
a +/-15V PS for the opamp circuits.
It had a remote volume/tone control module with 2 more SOIC quad opamps connected by a cable.

I had the power transformer in it's own case connected by an umbilical and a Neutrik connector.
All of the boards were my own design and custom etched and drilled by me. It took about 18-months to get to this stage.

When I went to fire it up for the second or third time, I mistakenly connected the mains neutrik connector into the amp/eq chassis where the umbilical from the transformer chassis should have gone. 230V AC where 35V DC should have gone. It made a terrible squelching noise, and the result was that almost every chip in the case was fried instantly. It didn't smell too good either.

I could have thrown the thing through a window for about 10 seconds. But then I got so frustrated that I went beyond anger into a strange feeling of calmness and acceptence (A new experience for me). Somehow I got the idea in my head that this was a good prototype and learning experience, and that's what allowed me to go back into it.

I didn't even go in the room for a week. The stuff just sat there stinking. After about a week I cleaned and tidied the workshop and started again. with new designs for the eq boards using DIL chips this time with sockets.

The result was much better than it would have been had I just used the "Mark I" system.

Just give it some time off first, and read up on circuits and basic electronics to make sure you know what every cap and resistor does in the PS and circuit (there aren't that many). Then with a tidy mind and workbench go back at it. You'll get it to work, I'm sure of it. It's such a rush to hear the amp you've made for the first time. You'll think it's worth the frustration.
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Old 29th May 2003, 10:44 PM   #18
mikelm is offline mikelm  England
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well said nick ( nuuk )

I often like to get a good nights sleep before switching on, especially if it's getting manic !!!

mike
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Old 29th May 2003, 11:22 PM   #19
elizard is offline elizard  Canada
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well i just desoldered parts from one GC (the one that didn't blow) and the resistors, at least, check out ok
the caps look ok too .. shouldn't be a problem

the second GC, the one that blew ..
both pins #1 and #7 were blown clean off .. and smells bad too!
gotta check out the parts from the rest should be fine though

hmm .. V+ and Vin+ blown off ..
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Old 30th May 2003, 08:45 AM   #20
Nuuk is offline Nuuk  United Kingdom
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Quote:
the caps look ok too
Did you read what I said At least measure them or play safe and replace them. The cost of two caps is a small price to pay for peace of mind!
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