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Old 10th November 2004, 05:44 PM   #1
adalin is offline adalin  Sweden
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Default Heathkit A7 ?

Hi

I bought my self a Heathkit A7 amplifier but the mains transformer was busted.....

I have searched the net trying to fint a schematic but I cant seem to find it.

Is there someone out there who got a A7 or maybe a schematic???

It would be nice to repair it and use it to something
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Old 10th November 2004, 11:38 PM   #2
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How could a solid lump like a mains power transformer get busted and the rest of the amplifier, like the comparatively flimsy chassis not be a total write off?????

You are speaking to a technical audience. You have to use descriptive technical terms to communicate unambiguously.

Do you mean that someone let the smoke out of the power transformer?
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Old 11th November 2004, 01:06 AM   #3
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It's all too easy to let the smoke out of the transformers on the A7 - there's no line fuse... and a BUNCH of leaky caps.

Yes, I have one - it showed up after I sold my first one, KNOWING that I would never be able to make a pair... anyway there's a schematic on my web page for the A7-E, and I have a schematic for the C version (no phono preamp) and maybe one other verson too. Sooo, what tubes are innit?

A7E
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Old 12th November 2004, 10:43 AM   #4
adalin is offline adalin  Sweden
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Hi

Yes the tecnical term would be "fried"......

I have the A7E version so thats the right schematic.

Is this a good amplifier or a crappy type?

Is it worth to repair it and try to find another or is it best to salvage the outputtransformer and save it for future use?
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Old 14th November 2004, 05:05 PM   #5
adalin is offline adalin  Sweden
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Well it worked...

I replaced the transformer with one from my scrap pile and the amp played beautiful music...

the only problem I got now is that the transformer only gives out 375v instead of the 390v in the schematic. But I dont think it matters to much.

I was thinking about replacing all the caps but what about the eletrolytic in the powersuply? Its a special 4 in one cap with 40,30,10 uf 450v and 20 uF 25v.

The replacementcaps will not look as big as this one anyway

Now I just need another one...
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