Anybody got any experience of an Audio Telex Communications of Sydney P.A.
amp model AMIS 250 ? I am particularly looking for a copy of the schematics,
but any help with it from anyone who knows the model, would be appreciated.
So far I have only been able to find a user manual.

As it came to me, the main bridge reccy had one limb s/c, and the wires to
it looked as though they had got pretty distressed from heat in the past.
With the reccy replaced, it seemed to come up ok, but had no output. Signal
is getting up to the front pcb from the rear one, and the signal presence
detector for channels 1 and 2 is working, as the channels 3,4,5,6 mute relay
triggers when signal is applied to Ch1 or 2. You can also see the signal at
the detector opamp. But that's it. There doesn't seem to be any further
preamp activity at all. There is an 'insert' jack on the rear panel, and
this should carry preamp output, which it then links back to power amp
input. There is no preamp out signal at this jack. Nor anything at the 'tape
out' RCAs on the rear panel.

One further thing. Sometimes when you switch it on, the output stage very
quickly runs very hot, and the bridge gets very hot, which I guess is the
problem which led to the demise of the original, and made the wiring look as
though it has got hot, so when this problem occurs, there's some serious
current going through the output devices for some reason. When it's doing
this, there are no signs of any instability - in fact still no output of any
description. I would add that this is a crap lead-free product, and every
joint on the output board of course *looks* bad. I have not been able to
provoke the heating up problem when it is running cool, by any kind of
disturbance, but with lead-free, in my experience, that doesn't necessarily
mean that the problem is *not* a bad joint, and that is still my gut feeling
about it ...

So, anyone got any hints, tips or insights (or schematics :-) !!) for
this model, please ?

Arfa

Arfa Daily wrote:
Anybody got any experience of an Audio Telex Communications of Sydney P.A.
amp model AMIS 250 ? I am particularly looking for a copy of the schematics,
but any help with it from anyone who knows the model, would be appreciated.
So far I have only been able to find a user manual.

I can't help you, I'm afraid. I've never serviced PA equipment.
You might have better odds asking in aus.electronics, which is a pretty
lively group. I've added them to the newsgroups line.

As it came to me, the main bridge reccy had one limb s/c, and the wires to
it looked as though they had got pretty distressed from heat in the past.
With the reccy replaced, it seemed to come up ok, but had no output. Signal
is getting up to the front pcb from the rear one, and the signal presence
detector for channels 1 and 2 is working, as the channels 3,4,5,6 mute relay
triggers when signal is applied to Ch1 or 2. You can also see the signal at
the detector opamp. But that's it. There doesn't seem to be any further
preamp activity at all. There is an 'insert' jack on the rear panel, and
this should carry preamp output, which it then links back to power amp
input. There is no preamp out signal at this jack. Nor anything at the 'tape
out' RCAs on the rear panel.

One further thing. Sometimes when you switch it on, the output stage very
quickly runs very hot, and the bridge gets very hot, which I guess is the
problem which led to the demise of the original, and made the wiring look as
though it has got hot, so when this problem occurs, there's some serious
current going through the output devices for some reason.

Supersonic oscillation maybe? Have you tried hanging a scope on the
preamp output?

When it's doing
this, there are no signs of any instability - in fact still no output of any
description. I would add that this is a crap lead-free product, and every
joint on the output board of course *looks* bad.

Ew.

I have not been able to
provoke the heating up problem when it is running cool, by any kind of
disturbance, but with lead-free, in my experience, that doesn't necessarily
mean that the problem is *not* a bad joint, and that is still my gut feeling
about it ...

Fair enough, too.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

Arfa Daily wrote:

Anybody got any experience of an Audio Telex Communications of Sydney P.A.
amp model AMIS 250 ? I am particularly looking for a copy of the schematics,
but any help with it from anyone who knows the model, would be appreciated.
So far I have only been able to find a user manual.

As it came to me, the main bridge reccy had one limb s/c, and the wires to
it looked as though they had got pretty distressed from heat in the past.
With the reccy replaced, it seemed to come up ok, but had no output. Signal
is getting up to the front pcb from the rear one, and the signal presence
detector for channels 1 and 2 is working, as the channels 3,4,5,6 mute relay
triggers when signal is applied to Ch1 or 2. You can also see the signal at
the detector opamp. But that's it. There doesn't seem to be any further
preamp activity at all. There is an 'insert' jack on the rear panel, and
this should carry preamp output, which it then links back to power amp
input. There is no preamp out signal at this jack. Nor anything at the 'tape
out' RCAs on the rear panel.

One further thing. Sometimes when you switch it on, the output stage very
quickly runs very hot, and the bridge gets very hot, which I guess is the
problem which led to the demise of the original, and made the wiring look as
though it has got hot, so when this problem occurs, there's some serious
current going through the output devices for some reason.

Dodgy bias pot ?


When it's doing
this, there are no signs of any instability - in fact still no output of any
description. I would add that this is a crap lead-free product, and every
joint on the output board of course *looks* bad. I have not been able to
provoke the heating up problem when it is running cool, by any kind of
disturbance, but with lead-free, in my experience, that doesn't necessarily
mean that the problem is *not* a bad joint, and that is still my gut feeling
about it ...

So, anyone got any hints, tips or insights (or schematics :-) !!) for
this model, please ?

Are we talking of the original Telex or another company ? Bosch picked up Telex
along with EV, Midas, KT and Dynacord and technically DDA although they've
dropped the brand.

Graham

On Thu, 07 May 2009 13:59:29 +0100, Eeyore
wrote:

:
:
:Arfa Daily wrote:
:
: Anybody got any experience of an Audio Telex Communications of Sydney P.A.
: amp model AMIS 250 ? I am particularly looking for a copy of the schematics,
: but any help with it from anyone who knows the model, would be appreciated.
: So far I have only been able to find a user manual.
:
: As it came to me, the main bridge reccy had one limb s/c, and the wires to
: it looked as though they had got pretty distressed from heat in the past.
: With the reccy replaced, it seemed to come up ok, but had no output. Signal
: is getting up to the front pcb from the rear one, and the signal presence
: detector for channels 1 and 2 is working, as the channels 3,4,5,6 mute relay
: triggers when signal is applied to Ch1 or 2. You can also see the signal at
: the detector opamp. But that's it. There doesn't seem to be any further
: preamp activity at all. There is an 'insert' jack on the rear panel, and
: this should carry preamp output, which it then links back to power amp
: input. There is no preamp out signal at this jack. Nor anything at the 'tape
: out' RCAs on the rear panel.
:
: One further thing. Sometimes when you switch it on, the output stage very
: quickly runs very hot, and the bridge gets very hot, which I guess is the
: problem which led to the demise of the original, and made the wiring look as
: though it has got hot, so when this problem occurs, there's some serious
: current going through the output devices for some reason.
:
odgy bias pot ?
:
:
: When it's doing
: this, there are no signs of any instability - in fact still no output of any
: description. I would add that this is a crap lead-free product, and every
: joint on the output board of course *looks* bad. I have not been able to
: provoke the heating up problem when it is running cool, by any kind of
: disturbance, but with lead-free, in my experience, that doesn't necessarily
: mean that the problem is *not* a bad joint, and that is still my gut feeling
: about it ...
:
: So, anyone got any hints, tips or insights (or schematics :-) !!) for
: this model, please ?
:
:Are we talking of the original Telex or another company ? Bosch picked up Telex
:along with EV, Midas, KT and Dynacord and technically DDA although they've
:dropped the brand.
:
:Graham


AIUI Audio Telex is purely and Australian company. I vaguely remember buying
something from them back in the late 80's. These days they are part of the Hills
group http://www.audiotelex.com.au/home/in...ageID=7&main=0

"Ross Herbert" wrote in message
...
On Thu, 07 May 2009 13:59:29 +0100, Eeyore
wrote:

:
:
:Arfa Daily wrote:
:
: Anybody got any experience of an Audio Telex Communications of Sydney
P.A.
: amp model AMIS 250 ? I am particularly looking for a copy of the
schematics,
: but any help with it from anyone who knows the model, would be
appreciated.
: So far I have only been able to find a user manual.
:
: As it came to me, the main bridge reccy had one limb s/c, and the wires
to
: it looked as though they had got pretty distressed from heat in the
past.
: With the reccy replaced, it seemed to come up ok, but had no output.
Signal
: is getting up to the front pcb from the rear one, and the signal
presence
: detector for channels 1 and 2 is working, as the channels 3,4,5,6 mute
relay
: triggers when signal is applied to Ch1 or 2. You can also see the
signal at
: the detector opamp. But that's it. There doesn't seem to be any further
: preamp activity at all. There is an 'insert' jack on the rear panel,
and
: this should carry preamp output, which it then links back to power amp
: input. There is no preamp out signal at this jack. Nor anything at the
'tape
: out' RCAs on the rear panel.
:
: One further thing. Sometimes when you switch it on, the output stage
very
: quickly runs very hot, and the bridge gets very hot, which I guess is
the
: problem which led to the demise of the original, and made the wiring
look as
: though it has got hot, so when this problem occurs, there's some
serious
: current going through the output devices for some reason.
:
odgy bias pot ?
:
:
: When it's doing
: this, there are no signs of any instability - in fact still no output
of any
: description. I would add that this is a crap lead-free product, and
every
: joint on the output board of course *looks* bad. I have not been able
to
: provoke the heating up problem when it is running cool, by any kind of
: disturbance, but with lead-free, in my experience, that doesn't
necessarily
: mean that the problem is *not* a bad joint, and that is still my gut
feeling
: about it ...
:
: So, anyone got any hints, tips or insights (or schematics :-) !!)
for
: this model, please ?
:
:Are we talking of the original Telex or another company ? Bosch picked up
Telex
:along with EV, Midas, KT and Dynacord and technically DDA although
they've
:dropped the brand.
:
:Graham


AIUI Audio Telex is purely and Australian company. I vaguely remember
buying
something from them back in the late 80's. These days they are part of the
Hills
group http://www.audiotelex.com.au/home/in...ageID=7&main=0

Yes, as far as I know they are an Oz company, and pretty well respected in
the field of 100v line PA equipment.

All of which still doesn't help me with my problem / need for schematics ,,,
:-\

Arfa

"Arfa Daily" wrote in message
...

"Ross Herbert" wrote in message
...
On Thu, 07 May 2009 13:59:29 +0100, Eeyore
wrote:

:
:
:Arfa Daily wrote:
:
: Anybody got any experience of an Audio Telex Communications of Sydney
P.A.
: amp model AMIS 250 ? I am particularly looking for a copy of the
schematics,
: but any help with it from anyone who knows the model, would be
appreciated.
: So far I have only been able to find a user manual.
:
: As it came to me, the main bridge reccy had one limb s/c, and the
wires
to
: it looked as though they had got pretty distressed from heat in the
past.
: With the reccy replaced, it seemed to come up ok, but had no output.
Signal
: is getting up to the front pcb from the rear one, and the signal
presence
: detector for channels 1 and 2 is working, as the channels 3,4,5,6
mute
relay
: triggers when signal is applied to Ch1 or 2. You can also see the
signal at
: the detector opamp. But that's it. There doesn't seem to be any
further
: preamp activity at all. There is an 'insert' jack on the rear panel,
and
: this should carry preamp output, which it then links back to power
amp
: input. There is no preamp out signal at this jack. Nor anything at
the
'tape
: out' RCAs on the rear panel.
:
: One further thing. Sometimes when you switch it on, the output stage
very
: quickly runs very hot, and the bridge gets very hot, which I guess is
the
: problem which led to the demise of the original, and made the wiring
look as
: though it has got hot, so when this problem occurs, there's some
serious
: current going through the output devices for some reason.
:
odgy bias pot ?
:
:
: When it's doing
: this, there are no signs of any instability - in fact still no output
of any
: description. I would add that this is a crap lead-free product, and
every
: joint on the output board of course *looks* bad. I have not been able
to
: provoke the heating up problem when it is running cool, by any kind
of
: disturbance, but with lead-free, in my experience, that doesn't
necessarily
: mean that the problem is *not* a bad joint, and that is still my gut
feeling
: about it ...
:
: So, anyone got any hints, tips or insights (or schematics :-) !!)
for
: this model, please ?
:
:Are we talking of the original Telex or another company ? Bosch picked
up
Telex
:along with EV, Midas, KT and Dynacord and technically DDA although
they've
:dropped the brand.
:
:Graham


AIUI Audio Telex is purely and Australian company. I vaguely remember
buying
something from them back in the late 80's. These days they are part of
the
Hills
group http://www.audiotelex.com.au/home/in...ageID=7&main=0

Yes, as far as I know they are an Oz company, and pretty well respected in
the field of 100v line PA equipment.

All of which still doesn't help me with my problem / need for schematics
,,,
:-\

Arfa


Some 7 or more? years ago Audio Telex took over the company, Australian
Monitor, that at that time made good PA amps etc. to extend their product
range.

I too found the user manual but then searched for
service manual Australian Monitor AMIS250 250w 100v Mixer Amp
and found this link....

http://www.starin.info/Product%20Inf...0Manual-ex.pdf

It may be what you need.

Regards,

Don

ps. I once worked in the same building as them in a former job.

On Mon, 11 May 2009 04:27:20 +1000, "Don Richmond"
put finger to keyboard and composed:

I too found the user manual but then searched for
service manual Australian Monitor AMIS250 250w 100v Mixer Amp
and found this link....

http://www.starin.info/Product%20Inf...0Manual-ex.pdf

FYI, I notice that transistors V19 - V24 on page 10 are drawn
incorrectly. Their emitters and collectors should be interchanged.

Here's a tip:

A Google search for ...

AMIS250 "service manual" filetypedf

.... gets two hits.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

Some 7 or more? years ago Audio Telex took over the company, Australian
Monitor, that at that time made good PA amps etc. to extend their product
range.

I too found the user manual but then searched for
service manual Australian Monitor AMIS250 250w 100v Mixer Amp
and found this link....

http://www.starin.info/Product%20Inf...0Manual-ex.pdf

It may be what you need.

Regards,

Don

ps. I once worked in the same building as them in a former job.



Hi Don, thanks for the pointer. However, there's something strange going on
here. Another guy contacted me off-group and had also found these
schematics. Thing is that although they claim to be for an AMIS250, they
don't match what is actually in the item. Let me just qualify that. The
input board is spot on. Everything matches - schematic, layout, component
numbering. The power amp is pretty damned close. Layout looks about right.
Schematic looks about right. Component numbering is out the window, though.

Now the front panel mixer / preamp board. This is nothing like what is in
the actual unit. The board fitted has all the same pots etc, but instead of
the three ICs shown on the schematics and layouts, this version has no less
than 12 ICs - two of those 8 pin in-line devices like NMJ1458, one 14 pin
DIL, and the rest are 8 pin DILs. The layout is nothing like the one in the
manual. In my trawling around the 'net for info, I have come across
references to a "P" version which seems to be simpler. Maybe the manuals
which seem to be available, cover this variant, rather than the one that's
on my bench ? :-\

Arfa