superdelicious
New Member
Greetings!
Long time lurker, first time poster. Do let me know if this is the wrong thread to post this.
After 10 years of wonderful use, both units are now in amplifier heaven. I'm fairly competent with repair and soldering but in no way an engineer so I'm hoping anyone with expertise can chime in.
I tried emailing Monkey Banana for a schematic and they couldn't be assed to help me out. oh well.
Each speaker has 3 circuit boards:
1 - The Amp/Rectification board
2 - The Preamp board - help needed here
3 - Input board
Context
The transformer splits the secondary ±16v and ±10v to the amp board which has the rectifier and big caps and they seem to measure fine. But I dont really understand the PreAmp circuit. So the main winding is being fed to what looks like a mini PSU section?? Its also the section that seemed damaged... the x2 caps were dead (Open), 400v 2.2µF caps -dead and the SJE13003 (MJE13003 Clone? ) seemingly just blew up in one of em and crumbled in the other unit.
Replaced the x2 and caps, but still waiting on the 13003's .
BUT my question is, what is the purpose of this section?
- I assumed the 7812/7912 regulators were powering both the amp and preamp boards.
- Is this bit for adjusting 220v -->120v mains? Im confused because the transformer seems to already have the wires for 120v use, so i thought the mains voltage selector switch simple changes between the two..
Apologies if this all sounds convoluted. Any advice or correction on my assumptions is welcome.
Thank you all.
Long time lurker, first time poster. Do let me know if this is the wrong thread to post this.
After 10 years of wonderful use, both units are now in amplifier heaven. I'm fairly competent with repair and soldering but in no way an engineer so I'm hoping anyone with expertise can chime in.
I tried emailing Monkey Banana for a schematic and they couldn't be assed to help me out. oh well.
Each speaker has 3 circuit boards:
1 - The Amp/Rectification board
2 - The Preamp board - help needed here
3 - Input board
Context
The transformer splits the secondary ±16v and ±10v to the amp board which has the rectifier and big caps and they seem to measure fine. But I dont really understand the PreAmp circuit. So the main winding is being fed to what looks like a mini PSU section?? Its also the section that seemed damaged... the x2 caps were dead (Open), 400v 2.2µF caps -dead and the SJE13003 (MJE13003 Clone? ) seemingly just blew up in one of em and crumbled in the other unit.
Replaced the x2 and caps, but still waiting on the 13003's .
BUT my question is, what is the purpose of this section?
- I assumed the 7812/7912 regulators were powering both the amp and preamp boards.
- Is this bit for adjusting 220v -->120v mains? Im confused because the transformer seems to already have the wires for 120v use, so i thought the mains voltage selector switch simple changes between the two..
Apologies if this all sounds convoluted. Any advice or correction on my assumptions is welcome.
Thank you all.