On May 3, 2:32 pm, "Dave" wrote:
wrote in message
oups.com... On May 3, 10:38 am, "Dave" wrote:
Do you have a good transistor checker? (one that does good/bad and is
also capable of matching?)
Where are you (by region)?
Peter Wieck
Wyncote, PA
I've got a transistor checker on my multimeter, it shows an arbitrary hfe
which, for a given transistor, never matches what's in the data sheet. Of
course the gain in the datasheet is always at a particular voltage and
current and I'm not sure what voltages/currents are applied by the meter...
or whether the voltage or current is controlled at all. I'm guessing 9V at
whatever the multimeter battery can put out for current through an unknown
series resistor. If it's a truly fried transistor, no value is returned for
hfe. I've had as much luck testing transistors with an ohmmeter.
I've never really trusted it to be honest with you.
Are you thinking driver transistor? Maybe one early in the signal path
which could introduce DC voltage which carries right through and would
explain the elevated voltages I am seeing in the left channel?
I live in Penticton, British Columbia, Canada. It's about 250 miles inland
from Vancouver and about 40 miles from the Washington border. It's a town
of 30,000 and, as you may surmise, very little of my equipment and parts is
purchased locally.
Dave
Exactly on the driver transistor. And "by region" I was thinking if
you were relatively nearby I would send you my transistor checker to
help through this process. Canada may be squirrelly what with customs
and such, by the time it reached you, you would have found the
problem. Then you would have to send it back.
I have had very good luck "pairing" transistors when doing repairs/
upgrades for 70s vintage SS amps (Dynaco, Scott, AR, Fisher), that is
making sure the 'right-side' transistor is reasonably closely matched
to the same 'left-side' transistor. This little instrument really does
help.
http://cgi.ebay.com/Schlumberger-Hea...mZ170108095101
Not as fancy as their IT-30, but it does the trick
Peter Wieck
Wyncote, PA