Fucked my amp. Help?



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Fucked my amp. Help?

Postby spacelordmother » Sat Apr 22, 2017 5:13 pm

Well, not my main amp, but...

My main amp is way too loud for our house. I have an old small solid state practice amp that sounds like shit through the stock speaker, but really good through the 2 12s in the big amp so I decided to mod it into a 10w head. Everything worked great until I got it all closed up and powered it on -- then it was just a loud hum and it started to smell hot. Turned it off and opened it back up, but didn't see anything obviously damaged. Last I tested it was before I soldered the output leads to the speaker jack and I noticed I accidentally used a shorting jack so my assumption is that blew it. Fuse looks and tests ok, so what else could/should I be looking at? Blown mosfet? I do also see one of the large caps near the transformer with a slight bulge -- could a short do that?

In the end the project isn't really worth spending that much time on, but I figure it's good experience. Thanks, duders.
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Re: Fucked my amp. Help?

Postby spacelordmother » Sat Apr 22, 2017 9:21 pm

Both capacitors at the power supply tested fine -- multimeter read 1, touching the leads gave me a raising voltage and then back to 1. (internet says this means good)

Turns out it's not a mosfet -- it's a linear IC. http://pdf.datasheetcatalog.com/datasheet_pdf/contek-microelectronics/TDA2030A.pdf
How do I test this? Measure the pins against the spec in the datasheet?

I'm also not sure that I shorted the output -- 1. Looking at how I had the jack wired makes me think it wouldn't have shorted, and 2.when I tested it I had headphones in and that cuts the speaker out.

Hrmmmmm grrrrrrrrrrr.

I think the amp is an earlier version of this schematic: http://music-electronics-forum.com/attachments/42626d1488705354-kga10c.pdf

Bad board pics:

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