| elizard |
well ..
i got my transformer today
now .. before i start complainin
i used a transformer with a single secondary and got the gc to work
onto my story
hook it up like i thought i should ..
seems to work .. no smoke yet
hooked up the gainclones to the PS .. a cap gets hot .. some smoke and a small poof - i turn it off
nothing exploded .. i think 2 wires touched .. *whew*
checked the voltages put out by the power supply .. both are positive
not good!
try 2 .. 3 .. 4 .. 5 different ways to hook it up and check the bridge
ok .. i got a +23 and a -23, but on what seemed to be the wrong terminals, and get +23 and +23 or -23 and -23
tried one combo which seemed to work .. but i got +23V on the speaker outs
ouch .. no speaker connected to it thankfully!!!
the other GC gave +5V .. odd
switch bridge around .. get +23 on one, -23 on another .. good so far!
hook up the gainclone .. no smoke right away
so i turn around to grab the multimeter .. something buzzed
i turn around to turn it off right away, but just as i reach for the switch a poof, and some smoke ..
and one of my GC's is swimming in oily liquid from the capacitor that blew
so .. i curse a little and give it up for the day
i also wish i had just bought a stereo .. but once i'm rested again, i'll change my mind and troubleshoot this :) |
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| tiroth |
| Your ground is floating all over the place. That's why you can't use a single secondary. |
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| Bricolo |
how did you build a GC with a single secondary trafo?
floating ground? (bad, bad, bad!)
single wave rectifier?
other? |
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| elizard |
i guess i didn't make myself clear, again ..
i USED to use a trafo with a single secondary, and it worked perfect :) (for testing purposes of course!)
today i got my toroid .. 2x22V secondaries ..
that's what i used when i blew it |
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| Bricolo |
I also blew up a cap one time
on the negative supply, make sure that the cap's - is connected to V- and not to ground |
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| elizard |
i'm leaving it until later today, or tomorrow
the cap stinks when it blows up .. the stuff that comes out of it
or smell unpleasant actually .. and strange, yet familiar for some reason |
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| karma |
lets just hope your LM3875T LM3875TF. LM3875 LM1875 one
of em:rolleyes: is not fried;)
yes cap's do stink i blew allot up as a teen:devilr:
wow big storm coming:censored: |
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| elizard |
| i think one MIGHT be fried .. but no confirmation as of yet, i just woke up from my nap :) |
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| elizard |
well ..
i fixed the voltages
now i get + on the right side, and - on the right side .. (it was good the first time!!!)
plug in the gc .. 2.5V on the speaker terminals
change the plug for the PS .. .25mV .. not TOO bad
plug in a ****-speaker .. nothing but a soft hum when there's input, and no hum when there's no input
check .. everything seems to be right
this might be the GC i saw smoke come out of earlier (not the cap related one)
now i gotta eat.. i'm starving
had next to nothing the whole day ..
then i'll replace the cap in the other GC and see if it works .. keep ya up to date |
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| elizard |
well .. now i know somethings wrong :)
i replaced the cap in the 2nd gc ..
power up ..
fire!
as i blow out the fire and shut the power off .. scared the **** out of me since there's so much flammable stuff around
pin #1 was burned off completely .. and now is detached from the op-amp
the op-amp is black .. so i'm going to assume its fried :)
so .. which means i need 2 new lm3875's ..
damn :(
maybe i'll order tomorrow .. maybe .. |
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| elizard |
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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| chris ma |
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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| karma |
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:rolleyes:
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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| Nuuk |
| 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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| cm961 |
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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| mothman |
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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| Gerontius |
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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| mikelm |
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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| elizard |
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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| Nuuk |
| quote: | | the caps look ok too |
Did you read what I said :att'n: 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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| elizard |
| how do i measure em??? |
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| Matttcattt |
| good advice from everyone else. keep at it is my advice. when i first made my gainclone, i tried being to smart and changing the circuit, and surpise surpise, it didnt work :) but i followed the circuit diagram (peter daniel) and it worked first time. |
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| nobody special |
| quote: | Originally posted by elizard
how do i measure em??? |
Put an ohm meter on them (+ to + and - to - of course) and watch the meter. As the cap charges, the resistance should climb- quick at first, and then slow down and almost settle. If you get constant high ohms, or really low ohms, it is probably dead. Unless they are BG or something, I would go ahead and replace them if for nothing more than the peace of mind. Hang in there. You'll get it!
Steve |
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| elizard |
do i need any sort of a load?
or can i just hook them up to the outputs of the bridges w/o anything on the end? |
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| nobody special |
you need to unhook one of the bridge leads, or you will be measuring through two diode junctions. You don't want a load connected when you do this. Make sure it is powered down!
Steve |
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| Rarkov |
| quote: | Originally posted by Gerontius
I had the power transformer in it's own case connected by an umbilical and a Neutrik connector.
...
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.
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That is EXACTLY the reason we have standard connectors so things like this never happen! Plz be careful - it will kill - or at least give you a bad hair day! |
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| Gerontius |
| quote: | Originally posted by Rarkov
That is EXACTLY the reason we have standard connectors ... |
This idea was crystalized in my mind in that moment I plugged it in. I realized the guy that invented the concept of uniquely shaped connectors was a genius. I'd of invented them at that moment if they weren't already.
:o |
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| moe29 |
i don't know if it's just me, but a Gain Clone seems like a tough
first project. Point to point wiring in small places... it sounds like
(smells like?) he probably had a short somewhere, polarity
reversed, etc... easy to do in in such cramped quarters.
my first DIY attempt was so laughable i won't even mention it
here! You're in good company elizard!!
good luck elizard, keep at it. |
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| Nuuk |
| quote: | | i don't know if it's just me, but a Gain Clone seems like a tough |
I disagree. If you have ever tried to troubleshoot a fault on a discrete amp, you'll know that the GC is comparatively easy! With so few parts, you could substitute all of them (if necessary) in an hour or two at the most.
I think it is because the Gainclone looks so easy, that some people 'throw' it together and then get problems. I do agree that point-to-point wiring in such a confined space does require extra skill. Maybe first-time builders would do better to start with a purchased PCB (the GC equivalent of buying a kit amp).
Also, because the GC looks so easy and attracts many newbies to the DIY hi-fi club, perhaps those of us with more experience should try and anticipate some of the problems/mistakes they may encounter. When I have time, I will try and include a few more of the 'basics' on my Gainclone page. |
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| davesaudio |
Blowing stuff up is a good kind of fault to troubleshoot- just follow
your nose.
I built a preamp early on and the two channels didn't sound the same :dead:
it's still sitting on the shelf 25yrs later.... |
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| mikelm |
I hope your not getting too fed up with advice, I just thought of something else that I always try and do even with the seemingly easiest of cct's and that is to draw a diagram.
Then when I have sorted that out I draw a picture of the layout, so when it comes to the actual action making the thing it is much more straight forward because most of the thinking & planning is already done.
good luck
mike |
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| elizard |
no, keep the advice coming :)
i've desoldered everything
next up, i'm gonna take apart the PS and re-do it ..
then after that, i'll wait for the lm3875's, and re-do the GC's, color code everything, and double check it
then wait till the next day to check again and power up :) |
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| Nuuk |
Good man elizard - may the force be with you.
You will be glad to know that you have inspired a new section for beginners on my Gainclone page |
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