I don't know how it happened, but these Hafler amps are starting to follow
me around. This one was given to me by a friend, with the warning that the
right channel doesn't work properly. Well I've bloodied my hands on one, so
why not try to fix another one?

The problem this time is something very different. The right channel DOES work,
but the sound is much lower-level, and distorted. When I put a scope on the
output, I find that I get flawless signal reproduction at the output, as long
as I do NOT have a load on the thing! When I put a speaker across the outputs,
the level drops by a factor of three, and the waveform gets messed up badly.

Any ideas folks? All of the things I've checked on my own DH-200 over the last
while have turned up nothing.

Thanks,
Colin

With a conventional amp, this might indicate an open base-emitter junction.
The Hafler of course uses mosfets, but could be a similar type problem, like
an open junction on a driver transistor. I do think I'd look first for
something "open" and not shorted or leaky, though of course I could be
wrong.....

My .02 worth.

Mark Z.

--
Please reply only to Group. I regret this is necessary. Viruses and spam
have rendered my regular e-mail address useless.


"Colin Bigam" wrote in message
om...
I don't know how it happened, but these Hafler amps are starting to follow
me around. This one was given to me by a friend, with the warning that the
right channel doesn't work properly. Well I've bloodied my hands on one,
so
why not try to fix another one?

The problem this time is something very different. The right channel DOES
work,
but the sound is much lower-level, and distorted. When I put a scope on
the
output, I find that I get flawless signal reproduction at the output, as
long
as I do NOT have a load on the thing! When I put a speaker across the
outputs,
the level drops by a factor of three, and the waveform gets messed up
badly.

Any ideas folks? All of the things I've checked on my own DH-200 over the
last
while have turned up nothing.

Thanks,
Colin

With a conventional amp, this might indicate an open base-emitter junction.
The Hafler of course uses mosfets, but could be a similar type problem, like
an open junction on a driver transistor. I do think I'd look first for
something "open" and not shorted or leaky, though of course I could be
wrong.....

My .02 worth.

Mark Z.

--
Please reply only to Group. I regret this is necessary. Viruses and spam
have rendered my regular e-mail address useless.


"Colin Bigam" wrote in message
om...
I don't know how it happened, but these Hafler amps are starting to follow
me around. This one was given to me by a friend, with the warning that the
right channel doesn't work properly. Well I've bloodied my hands on one,
so
why not try to fix another one?

The problem this time is something very different. The right channel DOES
work,
but the sound is much lower-level, and distorted. When I put a scope on
the
output, I find that I get flawless signal reproduction at the output, as
long
as I do NOT have a load on the thing! When I put a speaker across the
outputs,
the level drops by a factor of three, and the waveform gets messed up
badly.

Any ideas folks? All of the things I've checked on my own DH-200 over the
last
while have turned up nothing.

Thanks,
Colin

With a conventional amp, this might indicate an open base-emitter junction.
The Hafler of course uses mosfets, but could be a similar type problem, like
an open junction on a driver transistor. I do think I'd look first for
something "open" and not shorted or leaky, though of course I could be
wrong.....

My .02 worth.

Mark Z.

--
Please reply only to Group. I regret this is necessary. Viruses and spam
have rendered my regular e-mail address useless.


"Colin Bigam" wrote in message
om...
I don't know how it happened, but these Hafler amps are starting to follow
me around. This one was given to me by a friend, with the warning that the
right channel doesn't work properly. Well I've bloodied my hands on one,
so
why not try to fix another one?

The problem this time is something very different. The right channel DOES
work,
but the sound is much lower-level, and distorted. When I put a scope on
the
output, I find that I get flawless signal reproduction at the output, as
long
as I do NOT have a load on the thing! When I put a speaker across the
outputs,
the level drops by a factor of three, and the waveform gets messed up
badly.

Any ideas folks? All of the things I've checked on my own DH-200 over the
last
while have turned up nothing.

Thanks,
Colin

With a conventional amp, this might indicate an open base-emitter junction.
The Hafler of course uses mosfets, but could be a similar type problem, like
an open junction on a driver transistor. I do think I'd look first for
something "open" and not shorted or leaky, though of course I could be
wrong.....

My .02 worth.

Mark Z.

--
Please reply only to Group. I regret this is necessary. Viruses and spam
have rendered my regular e-mail address useless.


"Colin Bigam" wrote in message
om...
I don't know how it happened, but these Hafler amps are starting to follow
me around. This one was given to me by a friend, with the warning that the
right channel doesn't work properly. Well I've bloodied my hands on one,
so
why not try to fix another one?

The problem this time is something very different. The right channel DOES
work,
but the sound is much lower-level, and distorted. When I put a scope on
the
output, I find that I get flawless signal reproduction at the output, as
long
as I do NOT have a load on the thing! When I put a speaker across the
outputs,
the level drops by a factor of three, and the waveform gets messed up
badly.

Any ideas folks? All of the things I've checked on my own DH-200 over the
last
while have turned up nothing.

Thanks,
Colin

Colin Bigam wrote:
I don't know how it happened, but these Hafler amps are starting to follow
me around. This one was given to me by a friend, with the warning that the
right channel doesn't work properly. Well I've bloodied my hands on one, so
why not try to fix another one?

The problem this time is something very different. The right channel DOES work,
but the sound is much lower-level, and distorted. When I put a scope on the
output, I find that I get flawless signal reproduction at the output, as long
as I do NOT have a load on the thing! When I put a speaker across the outputs,
the level drops by a factor of three, and the waveform gets messed up badly.

Any ideas folks? All of the things I've checked on my own DH-200 over the last
while have turned up nothing.

Thanks,
Colin

Since you have a scope and one good - one bad channel, the obvious thing
to do is put a sine wave as input to both channels, use 8 ohm resistors
as loads on both channels, and work from the front end to output
comparing the good/bad channels. When you find a difference in wave form
or voltage, you have found the problem part.

Colin Bigam wrote:
I don't know how it happened, but these Hafler amps are starting to follow
me around. This one was given to me by a friend, with the warning that the
right channel doesn't work properly. Well I've bloodied my hands on one, so
why not try to fix another one?

The problem this time is something very different. The right channel DOES work,
but the sound is much lower-level, and distorted. When I put a scope on the
output, I find that I get flawless signal reproduction at the output, as long
as I do NOT have a load on the thing! When I put a speaker across the outputs,
the level drops by a factor of three, and the waveform gets messed up badly.

Any ideas folks? All of the things I've checked on my own DH-200 over the last
while have turned up nothing.

Thanks,
Colin

Since you have a scope and one good - one bad channel, the obvious thing
to do is put a sine wave as input to both channels, use 8 ohm resistors
as loads on both channels, and work from the front end to output
comparing the good/bad channels. When you find a difference in wave form
or voltage, you have found the problem part.

Colin Bigam wrote:
I don't know how it happened, but these Hafler amps are starting to follow
me around. This one was given to me by a friend, with the warning that the
right channel doesn't work properly. Well I've bloodied my hands on one, so
why not try to fix another one?

The problem this time is something very different. The right channel DOES work,
but the sound is much lower-level, and distorted. When I put a scope on the
output, I find that I get flawless signal reproduction at the output, as long
as I do NOT have a load on the thing! When I put a speaker across the outputs,
the level drops by a factor of three, and the waveform gets messed up badly.

Any ideas folks? All of the things I've checked on my own DH-200 over the last
while have turned up nothing.

Thanks,
Colin

Since you have a scope and one good - one bad channel, the obvious thing
to do is put a sine wave as input to both channels, use 8 ohm resistors
as loads on both channels, and work from the front end to output
comparing the good/bad channels. When you find a difference in wave form
or voltage, you have found the problem part.

Colin Bigam wrote:
I don't know how it happened, but these Hafler amps are starting to follow
me around. This one was given to me by a friend, with the warning that the
right channel doesn't work properly. Well I've bloodied my hands on one, so
why not try to fix another one?

The problem this time is something very different. The right channel DOES work,
but the sound is much lower-level, and distorted. When I put a scope on the
output, I find that I get flawless signal reproduction at the output, as long
as I do NOT have a load on the thing! When I put a speaker across the outputs,
the level drops by a factor of three, and the waveform gets messed up badly.

Any ideas folks? All of the things I've checked on my own DH-200 over the last
while have turned up nothing.

Thanks,
Colin

Since you have a scope and one good - one bad channel, the obvious thing
to do is put a sine wave as input to both channels, use 8 ohm resistors
as loads on both channels, and work from the front end to output
comparing the good/bad channels. When you find a difference in wave form
or voltage, you have found the problem part.

In article ,
(Colin Bigam) wrote:

I don't know how it happened, but these Hafler amps are starting to follow
me around. This one was given to me by a friend, with the warning that the
right channel doesn't work properly. Well I've bloodied my hands on one, so
why not try to fix another one?

The problem this time is something very different. The right channel DOES
work,
but the sound is much lower-level, and distorted. When I put a scope on the
output, I find that I get flawless signal reproduction at the output, as long
as I do NOT have a load on the thing! When I put a speaker across the
outputs,
the level drops by a factor of three, and the waveform gets messed up badly.

Any ideas folks? All of the things I've checked on my own DH-200 over the
last
while have turned up nothing.

That would be the symptom if the inline protection fuse was blown.

Isaac

In article ,
(Colin Bigam) wrote:

I don't know how it happened, but these Hafler amps are starting to follow
me around. This one was given to me by a friend, with the warning that the
right channel doesn't work properly. Well I've bloodied my hands on one, so
why not try to fix another one?

The problem this time is something very different. The right channel DOES
work,
but the sound is much lower-level, and distorted. When I put a scope on the
output, I find that I get flawless signal reproduction at the output, as long
as I do NOT have a load on the thing! When I put a speaker across the
outputs,
the level drops by a factor of three, and the waveform gets messed up badly.

Any ideas folks? All of the things I've checked on my own DH-200 over the
last
while have turned up nothing.

That would be the symptom if the inline protection fuse was blown.

Isaac

In article ,
(Colin Bigam) wrote:

I don't know how it happened, but these Hafler amps are starting to follow
me around. This one was given to me by a friend, with the warning that the
right channel doesn't work properly. Well I've bloodied my hands on one, so
why not try to fix another one?

The problem this time is something very different. The right channel DOES
work,
but the sound is much lower-level, and distorted. When I put a scope on the
output, I find that I get flawless signal reproduction at the output, as long
as I do NOT have a load on the thing! When I put a speaker across the
outputs,
the level drops by a factor of three, and the waveform gets messed up badly.

Any ideas folks? All of the things I've checked on my own DH-200 over the
last
while have turned up nothing.

That would be the symptom if the inline protection fuse was blown.

Isaac

In article ,
(Colin Bigam) wrote:

I don't know how it happened, but these Hafler amps are starting to follow
me around. This one was given to me by a friend, with the warning that the
right channel doesn't work properly. Well I've bloodied my hands on one, so
why not try to fix another one?

The problem this time is something very different. The right channel DOES
work,
but the sound is much lower-level, and distorted. When I put a scope on the
output, I find that I get flawless signal reproduction at the output, as long
as I do NOT have a load on the thing! When I put a speaker across the
outputs,
the level drops by a factor of three, and the waveform gets messed up badly.

Any ideas folks? All of the things I've checked on my own DH-200 over the
last
while have turned up nothing.

That would be the symptom if the inline protection fuse was blown.

Isaac

work from the front end to output
comparing the good/bad channels. When you find a difference in wave form
or voltage, you have found the problem part.

This is often more difficult than one might think. In an amp utilizing
feedback, the error appears everywhere after the differential pair.


Mark Z.

--
Please reply only to Group. I regret this is necessary. Viruses and spam
have rendered my regular e-mail address useless.


"Robert Gault" wrote in message
...
Colin Bigam wrote:
I don't know how it happened, but these Hafler amps are starting to
follow
me around. This one was given to me by a friend, with the warning that
the
right channel doesn't work properly. Well I've bloodied my hands on one,
so
why not try to fix another one?

The problem this time is something very different. The right channel
DOES work,
but the sound is much lower-level, and distorted. When I put a scope on
the
output, I find that I get flawless signal reproduction at the output, as
long
as I do NOT have a load on the thing! When I put a speaker across the
outputs,
the level drops by a factor of three, and the waveform gets messed up
badly.

Any ideas folks? All of the things I've checked on my own DH-200 over
the last
while have turned up nothing.

Thanks,
Colin

Since you have a scope and one good - one bad channel, the obvious thing
to do is put a sine wave as input to both channels, use 8 ohm resistors
as loads on both channels, and work from the front end to output
comparing the good/bad channels. When you find a difference in wave form
or voltage, you have found the problem part.

work from the front end to output
comparing the good/bad channels. When you find a difference in wave form
or voltage, you have found the problem part.

This is often more difficult than one might think. In an amp utilizing
feedback, the error appears everywhere after the differential pair.


Mark Z.

--
Please reply only to Group. I regret this is necessary. Viruses and spam
have rendered my regular e-mail address useless.


"Robert Gault" wrote in message
...
Colin Bigam wrote:
I don't know how it happened, but these Hafler amps are starting to
follow
me around. This one was given to me by a friend, with the warning that
the
right channel doesn't work properly. Well I've bloodied my hands on one,
so
why not try to fix another one?

The problem this time is something very different. The right channel
DOES work,
but the sound is much lower-level, and distorted. When I put a scope on
the
output, I find that I get flawless signal reproduction at the output, as
long
as I do NOT have a load on the thing! When I put a speaker across the
outputs,
the level drops by a factor of three, and the waveform gets messed up
badly.

Any ideas folks? All of the things I've checked on my own DH-200 over
the last
while have turned up nothing.

Thanks,
Colin

Since you have a scope and one good - one bad channel, the obvious thing
to do is put a sine wave as input to both channels, use 8 ohm resistors
as loads on both channels, and work from the front end to output
comparing the good/bad channels. When you find a difference in wave form
or voltage, you have found the problem part.

work from the front end to output
comparing the good/bad channels. When you find a difference in wave form
or voltage, you have found the problem part.

This is often more difficult than one might think. In an amp utilizing
feedback, the error appears everywhere after the differential pair.


Mark Z.

--
Please reply only to Group. I regret this is necessary. Viruses and spam
have rendered my regular e-mail address useless.


"Robert Gault" wrote in message
...
Colin Bigam wrote:
I don't know how it happened, but these Hafler amps are starting to
follow
me around. This one was given to me by a friend, with the warning that
the
right channel doesn't work properly. Well I've bloodied my hands on one,
so
why not try to fix another one?

The problem this time is something very different. The right channel
DOES work,
but the sound is much lower-level, and distorted. When I put a scope on
the
output, I find that I get flawless signal reproduction at the output, as
long
as I do NOT have a load on the thing! When I put a speaker across the
outputs,
the level drops by a factor of three, and the waveform gets messed up
badly.

Any ideas folks? All of the things I've checked on my own DH-200 over
the last
while have turned up nothing.

Thanks,
Colin

Since you have a scope and one good - one bad channel, the obvious thing
to do is put a sine wave as input to both channels, use 8 ohm resistors
as loads on both channels, and work from the front end to output
comparing the good/bad channels. When you find a difference in wave form
or voltage, you have found the problem part.

work from the front end to output
comparing the good/bad channels. When you find a difference in wave form
or voltage, you have found the problem part.

This is often more difficult than one might think. In an amp utilizing
feedback, the error appears everywhere after the differential pair.


Mark Z.

--
Please reply only to Group. I regret this is necessary. Viruses and spam
have rendered my regular e-mail address useless.


"Robert Gault" wrote in message
...
Colin Bigam wrote:
I don't know how it happened, but these Hafler amps are starting to
follow
me around. This one was given to me by a friend, with the warning that
the
right channel doesn't work properly. Well I've bloodied my hands on one,
so
why not try to fix another one?

The problem this time is something very different. The right channel
DOES work,
but the sound is much lower-level, and distorted. When I put a scope on
the
output, I find that I get flawless signal reproduction at the output, as
long
as I do NOT have a load on the thing! When I put a speaker across the
outputs,
the level drops by a factor of three, and the waveform gets messed up
badly.

Any ideas folks? All of the things I've checked on my own DH-200 over
the last
while have turned up nothing.

Thanks,
Colin

Since you have a scope and one good - one bad channel, the obvious thing
to do is put a sine wave as input to both channels, use 8 ohm resistors
as loads on both channels, and work from the front end to output
comparing the good/bad channels. When you find a difference in wave form
or voltage, you have found the problem part.

"Mark D. Zacharias" wrote:

work from the front end to output
comparing the good/bad channels. When you find a difference in wave form
or voltage, you have found the problem part.

This is often more difficult than one might think. In an amp utilizing
feedback, the error appears everywhere after the differential pair.

Mark Z.

--
Please reply only to Group. I regret this is necessary. Viruses and spam
have rendered my regular e-mail address useless.

"Robert Gault" wrote in message
...
Colin Bigam wrote:
I don't know how it happened, but these Hafler amps are starting to
follow
me around. This one was given to me by a friend, with the warning that
the
right channel doesn't work properly. Well I've bloodied my hands on one,
so
why not try to fix another one?

The problem this time is something very different. The right channel
DOES work,
but the sound is much lower-level, and distorted. When I put a scope on
the
output, I find that I get flawless signal reproduction at the output, as
long
as I do NOT have a load on the thing! When I put a speaker across the
outputs,
the level drops by a factor of three, and the waveform gets messed up
badly.

Any ideas folks? All of the things I've checked on my own DH-200 over
the last
while have turned up nothing.

Thanks,
Colin

Since you have a scope and one good - one bad channel, the obvious thing
to do is put a sine wave as input to both channels, use 8 ohm resistors
as loads on both channels, and work from the front end to output
comparing the good/bad channels. When you find a difference in wave form
or voltage, you have found the problem

Well said, Mark. For a long time I was going bonkers comparing voltages between
good and bad channels. It all begins with the diff pair and when they are
correct a lot of the other voltages fall into place.

"Mark D. Zacharias" wrote:

work from the front end to output
comparing the good/bad channels. When you find a difference in wave form
or voltage, you have found the problem part.

This is often more difficult than one might think. In an amp utilizing
feedback, the error appears everywhere after the differential pair.

Mark Z.

--
Please reply only to Group. I regret this is necessary. Viruses and spam
have rendered my regular e-mail address useless.

"Robert Gault" wrote in message
...
Colin Bigam wrote:
I don't know how it happened, but these Hafler amps are starting to
follow
me around. This one was given to me by a friend, with the warning that
the
right channel doesn't work properly. Well I've bloodied my hands on one,
so
why not try to fix another one?

The problem this time is something very different. The right channel
DOES work,
but the sound is much lower-level, and distorted. When I put a scope on
the
output, I find that I get flawless signal reproduction at the output, as
long
as I do NOT have a load on the thing! When I put a speaker across the
outputs,
the level drops by a factor of three, and the waveform gets messed up
badly.

Any ideas folks? All of the things I've checked on my own DH-200 over
the last
while have turned up nothing.

Thanks,
Colin

Since you have a scope and one good - one bad channel, the obvious thing
to do is put a sine wave as input to both channels, use 8 ohm resistors
as loads on both channels, and work from the front end to output
comparing the good/bad channels. When you find a difference in wave form
or voltage, you have found the problem

Well said, Mark. For a long time I was going bonkers comparing voltages between
good and bad channels. It all begins with the diff pair and when they are
correct a lot of the other voltages fall into place.

"Mark D. Zacharias" wrote:

work from the front end to output
comparing the good/bad channels. When you find a difference in wave form
or voltage, you have found the problem part.

This is often more difficult than one might think. In an amp utilizing
feedback, the error appears everywhere after the differential pair.

Mark Z.

--
Please reply only to Group. I regret this is necessary. Viruses and spam
have rendered my regular e-mail address useless.

"Robert Gault" wrote in message
...
Colin Bigam wrote:
I don't know how it happened, but these Hafler amps are starting to
follow
me around. This one was given to me by a friend, with the warning that
the
right channel doesn't work properly. Well I've bloodied my hands on one,
so
why not try to fix another one?

The problem this time is something very different. The right channel
DOES work,
but the sound is much lower-level, and distorted. When I put a scope on
the
output, I find that I get flawless signal reproduction at the output, as
long
as I do NOT have a load on the thing! When I put a speaker across the
outputs,
the level drops by a factor of three, and the waveform gets messed up
badly.

Any ideas folks? All of the things I've checked on my own DH-200 over
the last
while have turned up nothing.

Thanks,
Colin

Since you have a scope and one good - one bad channel, the obvious thing
to do is put a sine wave as input to both channels, use 8 ohm resistors
as loads on both channels, and work from the front end to output
comparing the good/bad channels. When you find a difference in wave form
or voltage, you have found the problem

Well said, Mark. For a long time I was going bonkers comparing voltages between
good and bad channels. It all begins with the diff pair and when they are
correct a lot of the other voltages fall into place.

"Mark D. Zacharias" wrote:

work from the front end to output
comparing the good/bad channels. When you find a difference in wave form
or voltage, you have found the problem part.

This is often more difficult than one might think. In an amp utilizing
feedback, the error appears everywhere after the differential pair.

Mark Z.

--
Please reply only to Group. I regret this is necessary. Viruses and spam
have rendered my regular e-mail address useless.

"Robert Gault" wrote in message
...
Colin Bigam wrote:
I don't know how it happened, but these Hafler amps are starting to
follow
me around. This one was given to me by a friend, with the warning that
the
right channel doesn't work properly. Well I've bloodied my hands on one,
so
why not try to fix another one?

The problem this time is something very different. The right channel
DOES work,
but the sound is much lower-level, and distorted. When I put a scope on
the
output, I find that I get flawless signal reproduction at the output, as
long
as I do NOT have a load on the thing! When I put a speaker across the
outputs,
the level drops by a factor of three, and the waveform gets messed up
badly.

Any ideas folks? All of the things I've checked on my own DH-200 over
the last
while have turned up nothing.

Thanks,
Colin

Since you have a scope and one good - one bad channel, the obvious thing
to do is put a sine wave as input to both channels, use 8 ohm resistors
as loads on both channels, and work from the front end to output
comparing the good/bad channels. When you find a difference in wave form
or voltage, you have found the problem

Well said, Mark. For a long time I was going bonkers comparing voltages between
good and bad channels. It all begins with the diff pair and when they are
correct a lot of the other voltages fall into place.