Smoke Emitting Amplifier--Not Good--Need Help - diyAudio
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Old 20th April 2009, 09:07 PM   #1
Getsum is offline Getsum  United States
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Question Smoke Emitting Amplifier--Not Good--Need Help

Hello all, thanks for the great site to come to..it appears as though I'm in need of someone's expert help.

I have a pair of Sony TA-N80ES amplifiers that I have owned since they were new. I have hooked these up at least 8 times in the past (moved around a lot in the military). I was hooking up them this last week after we moved into our house and managed to blow capacitors in both of them...not sure what I did but it happened just the same. I pulled them apart, found the blown caps on the main board and de-soldered the bad caps. I then downloaded the specific amp repair manual, ordered the replacements direct from Sony, received them, then re-soldered them in (positive and negative sides in correct position and a good job on the solder joint). I powered the amp back on and it blew again withing 10 seconds. It appears as though something else was damaged causing the capacitors to blow.

The caps that blew are C404 on one amp and C453 on the other.

Does anyone have any idea why they blew to begin with?

Next question is what can I do from here. I live in an area short on electronic repair shops and sending them o the Sony repair depot in Texas is out of the question due to he heavy weight of these amps.

Thanks again for the great site, I hope to hear back from anyone who has advice. Lee
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Old 20th April 2009, 09:39 PM   #2
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I know its obvious but have you got them in the right way round?

Secondly, did you alter the voltage selector on your travels in any way? Capacitors generally fail (ie blow) either due to a too high voltage on them or they're in the wrong way round.
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Old 20th April 2009, 09:43 PM   #3
jaycee is offline jaycee  United Kingdom
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Check the bridge rectifier (or diodes which make one) arent shot. If there's a short in one diode, AC could be getting to the cap and killing it.
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Old 21st April 2009, 12:39 AM   #4
Eva is offline Eva  Spain
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Wrong mains voltage?
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Old 21st April 2009, 12:45 AM   #5
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Isn't Japan the same as here and the US? 120V?
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Old 21st April 2009, 01:58 AM   #6
llwhtt is offline llwhtt  United States
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Japan is on a 100V grid, 50Hz or 60Hz depending on what part of Japan you are. The exception will be military bases which are 120V. So with 100V being the lowest around the world a wrong setting would have to 120V or greater, probably not the problem. Where are these capacitors in the circuit?

Wish I was there,
Craig
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Old 21st April 2009, 01:59 PM   #7
Getsum is offline Getsum  United States
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Question Great Replies

First off, thanks for the interest and replies; I am impressed!

The mains selector is set to 120V on both amps, I double checked this setting on all 12 component pieces because I lived in England prior to moving back to the states...I had to use transformers there to step down the power. I also used these amps in Japan (stationed there for 15 years) with zero problems...funny thing is that this is actually the first time these amps have had 60hz 120 V coursing through them...think that is an issue? I don't think so but I'm trying to stay objective here.

Craig: Wish you were here too...probably locate and fix the problem from the sounds of it... The caps are located on the main board A, beneath the main row of large caps, left & right edge (there are two caps sitting vertical on either edge, on one amp the left top one blew, on the other the right bottom one blew). I tried to e-mail you the repair guide for your viewing pleasure but since I'm a newbie on the site I can't. If there is some way to contact me via e-mail I can/will send it.

kevvywevvywoo: You mention having them the "right way round" not too sure what you're referring to unless you're talking about the polarity of the cap...If so, then yes I referenced the schematic on the repair manual and insured (twice) that I had the positive lead on top and the negative lead down. This is also easy to check because both sides/sets of caps are set up the same so they're easy to double check as the negative side is clearly marked on the capacitor. The solder joint is not bleeding over and looks quite good (I say this humbly of course ).

Jaycee: As much as I like to think I'm well rounded...you're talking above my head. How can I find where the bridge rectifier is/what it is? I have checked every circuit board in the amp and see no other damage, blown caps, burned circuits/diodes/resisters...there are some areas covered though that I can't access unless I do a full disassembly and I'm not quite at that stage...yet.

Again, I thank all who have replied and hope we can get to the bottom of the mystery. I currently have a workaround with my JBL L-7s running on the Yamaha AX1's internal amp and they just don't sound as good as when they're bi-amped with the Sonys.
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Old 21st April 2009, 02:45 PM   #8
llwhtt is offline llwhtt  United States
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I thought you were in Misawa, that's where I wished I was.

Craig
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Old 22nd April 2009, 02:53 AM   #9
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OK the bridge rectifier in the amp will either be four individual diodes that are rather large or a square or rectangular block.

The rectifier converts the AC form the transformer into pulsating DC, which is then fed into the capacitors to be smoothed out (filtered).

Tn the circuit it sits in between the transformer and the main capacitors.

Send me a pic of the inside of the amp, and the caps and we can go from there. I need to know where in the circuit these are. If they are the main filters, then a shorted rectifier is all but certain.

Don't worry... rectifiers are cheap. A cap in parallel will block AC by shorting it so the rest of the amp might very well be OK provided the caps didn't fail open circuit. (if they did, you'd probably notice widespread and quite catastrophic destruction...burned traces, more blown caps, transistors cracked in two, etc.)
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Old 23rd April 2009, 01:48 PM   #10
Getsum is offline Getsum  United States
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hardwareguy: I would love to send the pics but my account is under moderation because I haven't made enough posts and I am unable to see your e-mail address. Can you please shoot me a mail to my address so I can reply with the pics? Thanks for the reply and your effort in trying to help me getting this repaired. Lee
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