i have the krell kma 100 mono block amps.
bought them new.
had them adjusted maybe 5 / 6 times since then ,by krell.
the other day i noticed one of the boards inside was leaning.
so i bent it up to match the other 3 boards.
now one amp runs hot.
each amp has 2 small flat screw driver/blue box pots inside.
with a dab of glue holding them at their adjusted point.
can i turn these to reduce the amplifier heat possibly ?
i wrote krell 3 weeks ago, and have yet to get a reply.
i don't know how to post a picture or i could show better.
any help will do.
p.s.
i leaned the board back down to where it was,
but amp still gets hot.
bought them new.
had them adjusted maybe 5 / 6 times since then ,by krell.
the other day i noticed one of the boards inside was leaning.
so i bent it up to match the other 3 boards.
now one amp runs hot.
each amp has 2 small flat screw driver/blue box pots inside.
with a dab of glue holding them at their adjusted point.
can i turn these to reduce the amplifier heat possibly ?
i wrote krell 3 weeks ago, and have yet to get a reply.
i don't know how to post a picture or i could show better.
any help will do.
p.s.
i leaned the board back down to where it was,
but amp still gets hot.
this is confusing for me.
make sense to others ?
http://audioworld.com/sw/Forum1/HTML/004170.html
i will get out my multi meter now.
make sense to others ?
http://audioworld.com/sw/Forum1/HTML/004170.html
i will get out my multi meter now.
would turning a pot counter clockwise be a reduction in bias ?
or it doesn't always work this way ?
sorry i don't know how to build amplifiers,
i do " really" like audio.
just don't know how to build the gear.
or it doesn't always work this way ?
sorry i don't know how to build amplifiers,
i do " really" like audio.
just don't know how to build the gear.
You turn the pot in whichever way the designer intended. Most
will help you out by increasing the bias with clockwise movement.
Biasing an amp isn't all that tough, but it does require very
careful procedure, as it's easy to accidentally over-bias and
have the amp blow up. Of primary importance is to monitor
the current draw at all times and watch it for drift over a good
period of time, like an hour. Most circuits drift upward with
temperature, so watch out for that.
If you don't know the desired bias setting, I recommend that
you go for a specific heat sink temperature of 45 to 50 deg
C. This is a typical figure, and is a temperature range that you
can easily judge by tough. The 10 second rule: If you can
put your hand on the sink for 10 seconds, then the temperature
is 45 to 50 deg. C.
😎
will help you out by increasing the bias with clockwise movement.
Biasing an amp isn't all that tough, but it does require very
careful procedure, as it's easy to accidentally over-bias and
have the amp blow up. Of primary importance is to monitor
the current draw at all times and watch it for drift over a good
period of time, like an hour. Most circuits drift upward with
temperature, so watch out for that.
If you don't know the desired bias setting, I recommend that
you go for a specific heat sink temperature of 45 to 50 deg
C. This is a typical figure, and is a temperature range that you
can easily judge by tough. The 10 second rule: If you can
put your hand on the sink for 10 seconds, then the temperature
is 45 to 50 deg. C.
😎
i found out 1 pot is a dc offset and the other is the bias
but do not know which is which or the millivolt value or temp to set the amp at.
i am thinking that the board i "leaned" is the one with the pot that requires turning.(since i had no trouble prior)
but if i turn the pot counter clockwise/left.
will this reduce temp. and if so, how much of a turn accomplishes
the temp reduction.?
a hair of a turn or 1/4 turn ?
thank you so much for the help.
but do not know which is which or the millivolt value or temp to set the amp at.
i am thinking that the board i "leaned" is the one with the pot that requires turning.(since i had no trouble prior)
but if i turn the pot counter clockwise/left.
will this reduce temp. and if so, how much of a turn accomplishes
the temp reduction.?
a hair of a turn or 1/4 turn ?
thank you so much for the help.
Don't do anything without measuring the current draw. You
will have to use a multimeter at least. If you want, find the
DC voltage across the power Emitter resistors of the output
devices on the working channel as your guide. Again, watch
the current, as this is where people usually smoke their
amps if they're not careful.
will have to use a multimeter at least. If you want, find the
DC voltage across the power Emitter resistors of the output
devices on the working channel as your guide. Again, watch
the current, as this is where people usually smoke their
amps if they're not careful.
Hi,
when you said leaning and then bent it up. Did you mean you physically moved the PCB to a new position?
Could this have broken a solder joint and/or copper track somewhere?
when you said leaning and then bent it up. Did you mean you physically moved the PCB to a new position?
Could this have broken a solder joint and/or copper track somewhere?
what would happen if i turned
dc offset counterclockwise a small amount
without any multi meter connected ?
dc offset counterclockwise a small amount
without any multi meter connected ?
Wow, I'm brand new at this stuff, but I know enough to know that even small adjustments on a pot can make big differences in voltage.
When I read your question its like hearing someone say " I locked my keys in my Bentley. How much pressure can i put on the window with a pry bar before it breaks?"
Brother, At least spend a few bucks on a multimeter so someone can walk you through this. There is a really good chance that if it worked properly before and after you moved the PCB it stopped working properly that either something came loose or something got connected.
If you are running a Krell, chances are you are using nice speakers as well. It's not just your amp at stake here.
Measure twice, cut once.
Blessings, Terry
When I read your question its like hearing someone say " I locked my keys in my Bentley. How much pressure can i put on the window with a pry bar before it breaks?"
Brother, At least spend a few bucks on a multimeter so someone can walk you through this. There is a really good chance that if it worked properly before and after you moved the PCB it stopped working properly that either something came loose or something got connected.
If you are running a Krell, chances are you are using nice speakers as well. It's not just your amp at stake here.
Measure twice, cut once.
Blessings, Terry
zuki,
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