M1 Active Alesis speaker schematic & advice please

[zen]

Hi all , working on my next project .

Rebuilt PSU

Repaired damaged print track , including through hole connections & cleaned off corrosive glue .

Ran up the PSU via my variac , gradually increasing AC supply , but discovered Q1 ( IRF 840 ) , becoming quite hot , therefore reluctant to increase supply to full .

Also replaced PWM chip UC3842 .

Anyone had this scenario ?

[Khron]

Re: M1 Active Alesis speaker schematic & advice please

Why not post this in the main thread about this? The one that's stickied at the top here?

[zen]

Re: M1 Active Alesis speaker schematic & advice please

Thanks , can do but was hoping to keep it as a separate issue , rather than mixing with other problems on the M1'S

[zen]

Re: M1 Active Alesis speaker schematic & advice please

Replaced Q3 ( 2N5551 ) & Q4 ( 2N5401 )

Both measured good on a cold test , therefore failing under load . Located on gate drive circuitry for Q1 , which is now running cool .

Speaker working & on test .