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.
Fucked my amp. Help?
Moderator: Ghost Hip
- spacelordmother
- HERO

- Posts: 5719
- Joined: Sun May 16, 2010 4:45 pm
- Location: Rochester, NY
- Contact:
- spacelordmother
- HERO

- Posts: 5719
- Joined: Sun May 16, 2010 4:45 pm
- Location: Rochester, NY
- Contact:
Re: Fucked my amp. Help?
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/datashe ... A2030A.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/atta ... kga10c.pdf
Bad board pics:


Turns out it's not a mosfet -- it's a linear IC. http://pdf.datasheetcatalog.com/datashe ... A2030A.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/atta ... kga10c.pdf
Bad board pics:

