"John Smith"
"Phil Allison"

** 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 ?

This page says it uses something called BASH, which I'd never heard of.
http://www.samash.com/p/Tannoy_TS10%...ofer_-49998207

After much googling I found this:
http://www.thompdale.com/bash_amplifier/bash_amp.htm

Which suggests it does something similar to the Yamaha XM6150 I currently
have waiting for parts.


** Thanks for going to all that trouble.

There is indeed a switching regulator on the main DC output and the scheme
is similar to the Klipsch one.



..... Phil