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the flower man · Posted: Wed Mar 05, 2008 19:32 Post subject: old jvc home amp no right channel

hi all, this is not a car sterio but my be you can help? i have a JVC A-S3 silver intergrated amp for home use. it is mybe as old as me (30) but the sound and power is far better than anything moden that i can afford. it has 4 channels on a swich dile on the front ( off,A,B,A+b ) in all these positions appart from off, i have no right channel Crying or Very sad

it was ok and then i started to have less volume out of that side and not having the time to take it appart(and to know what i am doing) it has been left. i have no sound out that side now. what do you think it is? should i give up with it and start saving or are they like old motors which can be fixed. please let me know, i will try anything to get it working again Very Happy

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dxmedia · Posted: Wed Mar 05, 2008 19:39 Post subject:

Sounds like the main power transistors have gone on the 1 channel. It's probably worth repairing, as you say, sounds far better than a modern amp. Have a look in the yellow pages for TV repairs, give em a call, it will probably cost around £40 to have fixed and a general service as well.
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the flower man · Posted: Wed Mar 05, 2008 20:38 Post subject:

are ok mate,and i couldnt do this my self no?

dxmedia · Posted: Wed Mar 05, 2008 20:59 Post subject:

You could

What are you like with lectrics?

The power transistors will be (on an amp of that age) be 2 round ish components screwed to a heatsink with 3ish legs , unuslly at the back of the amp. You'll either need a multimeter which is capable of testing transistors whilst they are connected to a board, or an occiloscope and know how to test... sorry dunno how to do this Laughing

Somewhere like rs components or maplins should be able to get replacement transitors...

then again it might always be something else.

Do you get both channels through the headphone socket? If so the pre-amp is still working fine.
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Chris B · Posted: Wed Mar 05, 2008 21:30 Post subject:

the flower man · Posted: Wed Mar 05, 2008 23:57 Post subject:

i know basics but am no expert but i would have a go at that Very Happy

how badly could i brake it?

dxmedia · Posted: Thu Mar 06, 2008 9:34 Post subject:

Worst you could do would be kill the other channel and go to the repair man with your tail between your legs, make sure you get the right part numbers though.

Oh another good trick, if any of the components are black and have smoke on the board around them, they usualy need replacing Wink

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For great insurance deals on 4x4s, imports and more, contact Adrian Flux :

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MartQ · Posted: Thu Mar 06, 2008 10:17 Post subject:

Audio power transistors of that age will probably have "2N3055" printed on the top

Have a look here:

http://uk.rs-online.com/web/search/searchBrowseAction.html?method=searchProducts&searchTerm=2n3055

Just a point to note, between the mating sufaces of the transistor and the heatsink, there will be a VERY thin clear plastic film the same shape as the transistor. Make sure you put it back when replacing the transistors, they sometimes stick to the old transistors and if it's omitted, you'll just blow the new transistors.

Good luck.
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wv6z · Posted: Fri Mar 07, 2008 6:53 Post subject: