I acquired a Yamaha yg15 amp. The power transformer is toast. I'm looking for a schematic for it. I've been all over the internet without any luck. What I'm mainly looking for is the output voltage on the rectifier circuit. Thinking about battery operated.
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The MA-104 is the one I got. I just changed that input cap to a 2-way switch with the original .047 on one side and a .1 on the other side. The speaker was a large Subwoofer from a TV Surround Sound System. With the Gain turned down and the tone at 50%, you can get great acoustic guitar amp sound with your piezo CBG or plug in a Bass. Just dial up a little Gain for some fuzz effect.
You can get these chips new from Mouser.com and Smallbear.com if you need any for repair or building your own circuits.
I'm thinking about buying a circuit board with the chip in it and modify it to use in in the second housing. The repaired amp sound great. Thanks for the info.
hi Guys while the folks into amps are gathered here, here is a list of the amp manufacturers who's circuit diagrams I have, just in case any of you are interested at any time.
There must be 80 diagrams for different models pre 1975 for the following brands
Epiphone - Estey - Gibson - Harmony - Kay - Supro - Sears Silvertone - Wards Airline - Ampeg - Valco.
Glad you got it sorted Will.
Taff
This sucker rocks! One of my neighbors has a Cube and he did a side by side comparison by wringing them out with the same song/settings(as close as possible). You'd be hard pressed to distinguish between the two. What the hell for free I'll take it! Man! You've gots some oldies there, my brother back in the day had a "Monkey Wards" I don't know if my nephew still has it and the lap steel, I had forgotten all about it until I saw your list. Thanks for the walk down memory lane. I might be taking you up on that offer. Thanks!
Glad you got it working.
I also have a lot of tube amp schematics - Fender, Gibson, Marshall, Valco, Silvertone and Ampeg.
On a side note: First Act has a little 4watt and 10watt guitar amp that most folks pawn because they sound so bad. I found one on the curbside and it did sound bad. The source of the bad sound? Cheap small speaker. I added a Jenson Mod speaker and the Bassman mod(Higher value input cap) on a switch and that little amp Rocks.
Google "MA104 mod", you'll be pleasantly surprised if you try it. I snatch up every First Act MA104 I can get my hands on now, do the mod and shove the guts into Acid Cigar boxes
I'm looking into it. Thanks
When my amp went out, it also fried some output caps along with the overheated chip. So have a good look at all the components and check them with a voltmeter if you have one.
Damn good idea about the specs for the chip, didn't even think about that. Thanks all other components check out. If it had been the secondary side I would probably scraped the unit.
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