** I have a Tannoy TS10 in for repair.

The PSU switching FET (IRF740) is shorted so I expect the drive IC ( UC3842)
is also dead. There appears to be NO source resistor with the FET for
current sensing.

The PSU produces a *single* DC rail for the bridge mode amplifier of about
140 volts - there is a 1000uF, 160V electro. I guess the speaker outputs
rest at 0 volts and the DC rail electronically splits into +/- 70 volts.

Question is, how in hell are only four *puny* TO220 mosfets supposed to form
a bridged output stage and drive a 4 ohm woofer from such a supply voltage ?

Looks to me like a real piece of Chinese ****.



.... Phil