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Calling any of the Australian lads on here ...

A

Arfa Daily

Jan 1, 1970
0
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
 
B

Bob Larter

Jan 1, 1970
0
Arfa said:
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.
 
E

Eeyore

Jan 1, 1970
0
Arfa said:
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
 
R

Ross Herbert

Jan 1, 1970
0
On Thu, 07 May 2009 13:59:29 +0100, Eeyore

:
:
: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


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/inner.asp?pageID=7&main=0
 
A

Arfa Daily

Jan 1, 1970
0
Ross Herbert said:
On Thu, 07 May 2009 13:59:29 +0100, Eeyore

:
:
: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


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/inner.asp?pageID=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
 
D

Don Richmond

Jan 1, 1970
0
Arfa Daily said:
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 Info...50/AMIS250/Service Docs/AMIS250 Manual-ex.pdf

It may be what you need.

Regards,

Don

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

Franc Zabkar

Jan 1, 1970
0
A

Arfa Daily

Jan 1, 1970
0
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 Info...50/AMIS250/Service Docs/AMIS250 Manual-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
 
A

Arfa Daily

Jan 1, 1970
0
Franc Zabkar said:
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" filetype:pdf

... gets two hits.

- Franc Zabkar

Hi Franc. These are the references that I keep coming back to. Regarding the
first result that Google throws back, see my reply to Don in this thread.
The second result is from the same site, but is actually for the AMIS120.
This version actually has a much more complex preamp / mixer, but it is 8
channel rather than 6, and still doesn't even resemble what's in the one on
my bench. Thanks for your efforts anyway.

Arfa
 
F

Franc Zabkar

Jan 1, 1970
0
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.

Are we looking at the same diagrams? The mixer board on page 11 of the
manual has a lot more than three ICs. For example, IC7 is a 28-pin PIC
uP. The layout on page 14 has at least 7 ICs.
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

According to this URL ...

http://www.australianmonitor.us/index.php?action=products&area=am

.... the "P" version is a power amp while the plain version is a
mixer/amp.

==================================================================
Mixer/Amps: Integration

AMIS250
250 Watt Rackmount Mixer Amplifier (2RU) • 70 volt, 4 ohm, balanced
XLR & record outputs • 6 x dual balanced mic/line inputs • Phantom
power on all mics with defeat switch • Multi-level VOX muting from
channels 1 & 2 • Overall bass, treble & master controls • Fan cooled
for added reliability

==================================================================
Amplifiers: Power Amplifiers

AMIS250P
250 Watt Rackmount Amplifier (2RU) • 70 volt, 4 ohm • Balanced line
level input • Current limiting
==================================================================

- Franc Zabkar
 
A

Arfa Daily

Jan 1, 1970
0
Are we looking at the same diagrams? The mixer board on page 11 of the
manual has a lot more than three ICs. For example, IC7 is a 28-pin PIC
uP. The layout on page 14 has at least 7 ICs.

Hmmmm. You might be right there Franc. I have downloaded so many different
versions and schematic sets, that I seem to have missed looking closely
enough at a couple of the pages. I will have to get the amp back on the
bench again tomorrow, and compare the schematic and layout I have just
found, to what is actually in there. In the meantime, could I trouble you to
post the URL of the manual you are looking at, just to make sure that we are
both looking at the same one.

Thanks
Arfa
 
A

Arfa Daily

Jan 1, 1970
0
Franc Zabkar said:

Ah yes, OK. We are in fact looking at the same one. Unfortunately, what is
shown in there on pages 11 and 14, is still nothing like what is actually in
the unit itself. For instance, IC7 on that diagram, is a PIC. On the 'real
thing', IC7 is an 8 pin SIL opamp. And many other differences. I am
beginning to think that I am not going to get the correct diagram for this.
I think as a next move, I will take the board out, and see if I can follow
the tracking from where I know that there is signal present, to see if I can
arrive at the first opamp, and figure what is going on. Beyond that, I'm not
going to waste a lot more time on it. As I'm sure you know yourself, there
comes a point when you have to make a decision based on commercial logic,
rather than a desire to be satisfied by fixing everything that gets thrown
under your gaze ... :-\

Arfa
 
D

Don Richmond

Jan 1, 1970
0
Arfa Daily said:
Ah yes, OK. We are in fact looking at the same one. Unfortunately, what is
shown in there on pages 11 and 14, is still nothing like what is actually in
the unit itself. For instance, IC7 on that diagram, is a PIC. On the 'real
thing', IC7 is an 8 pin SIL opamp. And many other differences. I am
beginning to think that I am not going to get the correct diagram for this.
I think as a next move, I will take the board out, and see if I can follow
the tracking from where I know that there is signal present, to see if I can
arrive at the first opamp, and figure what is going on. Beyond that, I'm not
going to waste a lot more time on it. As I'm sure you know yourself, there
comes a point when you have to make a decision based on commercial logic,
rather than a desire to be satisfied by fixing everything that gets thrown
under your gaze ... :-\

Arfa
I did some more searching a couple of nights ago and found these links that
might be useful, perhaps not so much for this thread.
http://pdf.textfiles.com/manuals/STARINMANUALS/Australian Monitor/
This one has a number of product schematics for a range of companies.

It seems that AM is still a busy brand....
http://www.australianmonitor.us/
http://www.australianmonitor.com.au/_uploads/products/511328_AMIS250_manual.pdf
http://www.audiotelex.com.au/_uploads/products/2381832_AMIS250_-_Spec_Sheet.pdf

I also found these two comments in an old repair forum:
"On the Australian Monitor site are a number of schematics, but not the
KA-1500 - I emailed them and told them that I am a repairer and got the
service manual in pdf form immediately - thanks AM."

"Unlike the other guy in this thread i haven´t had the luck of recieving a
schematic for the AM1200 even though i´ve written Australian Monitor a mail
for it."

Maybe a message to their tech support about variants of the model may elicit
a useful response?

Don
 
A

Arfa Daily

Jan 1, 1970
0
Don Richmond said:
I did some more searching a couple of nights ago and found these links
that
might be useful, perhaps not so much for this thread.
http://pdf.textfiles.com/manuals/STARINMANUALS/Australian Monitor/
This one has a number of product schematics for a range of companies.

It seems that AM is still a busy brand....
http://www.australianmonitor.us/
http://www.australianmonitor.com.au/_uploads/products/511328_AMIS250_manual.pdf
http://www.audiotelex.com.au/_uploads/products/2381832_AMIS250_-_Spec_Sheet.pdf

I also found these two comments in an old repair forum:
"On the Australian Monitor site are a number of schematics, but not the
KA-1500 - I emailed them and told them that I am a repairer and got the
service manual in pdf form immediately - thanks AM."

"Unlike the other guy in this thread i haven´t had the luck of recieving a
schematic for the AM1200 even though i´ve written Australian Monitor a
mail
for it."

Maybe a message to their tech support about variants of the model may
elicit
a useful response?

Don

Worth a try perhaps. I'll see if I can get a number off the board, and see
if they are able (willing?) to supply the appropriate schematic. Thanks all
for the efforts anyway.

Arfa
 
A

Arfa Daily

Jan 1, 1970
0
Worth a try perhaps. I'll see if I can get a number off the board, and see
if they are able (willing?) to supply the appropriate schematic. Thanks
all for the efforts anyway.

Arfa

Ha ! A result ! I flashed the service manager an e-mail, and back came
three zip archives containing everything they have. I have now found the
correct schematic for the mixer board (I think ... ) Unfortunately, there
doesn't seem to be a layout diagram anywhere for this particular board, but
I guess you can't have it all ways, and at least I have a schematic now. So
if anyone else ever needs these diagrams, I have them d;~}

Arfa
 
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