TECH: dead Amplifone (missing 20KHz?)

Hi

A big thanks to those who've already offered advice on my HV board, my
diagnostics have got me this far:

I don't have a square wave at the base of the BU406D: I DO have a 20KHz
square wave when measured at the base of Q2 (MPS-U07) but at the collector
it's mangled: here's some ASCII art (it's not strictly accurate but
hopefully gives an idea):

--- --- --- --- --- ---
      \ / \ / \ / \ / \ /
       \/ \/ \/ \/ \/

I'm testing with the BU406D removed and the HVT in place (as in the FAQ).

I've replaced Q2, the voltage regs (and verified +- 24v correct) , C1, and
tested all of the resistors. But I still have the same problem so what am I
missing??

Cheers,

Karl.

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Received on Sat Nov 16 18:37:05 2002