1ampman 11/8/2017 5:18 PM
Need Help- Acoustic B300H schematic
OH Crap! From what I read here it's not repairable. So R46 glows red hot,melts the solder...Other wise it looks brand new.
The Dude 11/8/2017 5:35 PM
Can you upload some gutshots? My experience is that you won't get any help from Acoustic, but if we can see it, we might be able to help figure something out.
1ampman 11/8/2017 6:44 PM
Hey, It uses 2pair of 2SC5200 On each side of the wind tunnel...NO STK nonsense. The outputs say Toshiba ..Also the sticker say #2 after the serial number. I'll try downloading pics....I'm thinking it's a second version of this model.. Maybe some transistor tests are in order? All the parts are listed on the circuit board. This resister R46=100ohm flame proof or FP. Just need to see where it goes to? Thx for the reply....
1ampman 11/8/2017 7:37 PM
I tried downloading pics, but it says my files are too big? Even with a single pic...........
The Dude 11/8/2017 7:40 PM
Do you have any photo editing software? If not, there should be a lower resolution setting on your phone or camera to get the file sizes smaller.
Jazz P Bass 11/9/2017 12:01 AM
I don't know if this will help or not. [ATTACH]45605[/ATTACH]
1ampman 11/9/2017 8:55 AM
NICE! It appears the power amp section is the same, but double the outputs. I see the 100 ohm resistors feeding transistors. I'll start there.....
1ampman 11/9/2017 10:41 AM
The power amp comes out as module. Wind tunnel screwed to circuit board. Has that difficult lead-free solder. Pulled a couple transistors and found a shorted small signal transistor 2sc2240 shorted. I'll pull a few more to see what gives. Anybody know a replacement for that transistor. So there is a pair of 2sc5200 on one side of the wind tunnel and a pair of 2sc1943 on the other side. I need to find a replacement for further testing
1ampman 11/10/2017 10:08 AM
ordered a few 2sc2240 from bdent, so give me some time to get them. They claim to be Toshiba. I could have got a hundred off Ebay for the same price. I can't read the original due to over heating/cracking. The amp looks like new and the cooling fan doesn't have any dirt on it, so I'm guessing this amp didn't get used much before blowing out. These amps seem to be showing up a lot on Ebay for repair....due to crap parts....