Hi Guys
First off I have no background of electronics so please bear that
in mind with your answers . I have a sony amplifier TA-FB730R . This
amp has just ceased to work . No lights sounds nothing .
I have changed the fuse on the plug and had a quick look for any
obvious fuses inside , of which I can not see any . I have basic
knowledge of how to solder and the use of a multimeter .
Basically is there any easy checks I can do to see if this can be
revived , any websites that might give guidance or any other info
anyone can share with me .
Merry Xmas & A Happy New Year
Thanks In Advance
Regards Dave

wrote in message
...
Hi Guys
First off I have no background of electronics so please bear that
in mind with your answers . I have a sony amplifier TA-FB730R . This
amp has just ceased to work . No lights sounds nothing .
I have changed the fuse on the plug and had a quick look for any
obvious fuses inside , of which I can not see any . I have basic
knowledge of how to solder and the use of a multimeter .
Basically is there any easy checks I can do to see if this can be
revived , any websites that might give guidance or any other info
anyone can share with me .
Merry Xmas & A Happy New Year
Thanks In Advance
Regards Dave


First, use your multimeter to check that you have line voltage on the power
transformer's primary. You might have to do a little wiring tracing to identify
the primary terminals, but it shouldn't be too hard.
If no line voltage on the primary, look more closely for other fuses. Also,
check the power cord and power switch on the amp for continuity.
If you have line voltage on the primary, do you have any secondary voltages?
Check the other terminals for voltages.
If no secondary voltages, you probably have a blown power transformer. Check
the primary winding(s) for continuity. You should see ~100 ohms or more on the
primary.
These transformers can have a thermal fuse INSIDE the transformer. You'll have
to tear into the transformer for that... It will usually be on the outside of
the windings, but under the outer insulations.
If no thermal fuse inside, you have a bad transformer that will have to be
replaced with either an OEM replacement part (you'll probably have to order
through a Sony service shop) or a generic replacement (you'll need to know the
original transformer voltage and current ratings to identify a suitable
replacement... good luck on that one).
If secondary voltages appear to be there, the most likely problem is failure of
the output devices (BJT or FET transistors). You'll need to unsolder these from
the circuit in order to properly check them. The usual failure is one or more
shorted transistors. Resistance checks on these will show very close to zero
ohms on your multimeter (be sure to use the diode setting on your multimeter).
If you do have shorted output devices, be sure to check the transistors in the
circuitry immediately preceding the outputs. One or more of those will probably
be bad as well.

If none of these checks get you in the ballpark, you'll need to find a good
service shop. Good luck on the repair.

--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)

"In theory, there isn't any difference between theory and practice. In
practice, there is." - Yogi Berra