Mackie M1400 poweramp problem

T

Tim

Guest
In article <e1c9e6e0-ff27-4723-8918-91eb929d51d6
@c65g2000hsa.googlegroups.com>, hrhofmann@att.net says...
On Jun 3, 12:15 pm, bz <bz+...@ch100-5.chem.lsu.edu> wrote:
Tim <t...@tim.tim> wrote innews:MPG.22af3e66c44ceb15989707@news.aliant.net:





In article <Xns9AB18DEB06E2DWQAHBGMXSZHVspamm...@130.39.198.139>,
bz+...@ch100-5.chem.lsu.edu says...
Tim <t...@tim.tim> wrote in
news:MPG.22adfa799165188989706@news.aliant.net:

OK, this is a problem with a 19" Citizen TV. It is just over a year
old.

If the set is put on a stand that has a metal object (like a
Satellite Receiver on a shelf) mounted within 8 inches below the set,
the pic has a very noticeable purity problem all the way across the
bottom and about 1/2 way up each side. If I raise the set up, the
purity problem will diminish, but even up at 8" away from the console
stand, it still has slight purity issues.

Raising the set up on boxes is problematic, as the space is very
limited. I would like to shield whatever it is. I am not sure if it
is a reflection from the set or radiated magnetic fields from the
equipment below.

The console is in a travel trailer, so I cannot move everything away
from the tv, as most of the electronics are in this one console, with
the TV on top of it.

Any helpful suggestions are appreciated.

I assume that this is a CRT tv, not a LCD or plasma tv.

Sounds like the 'metal object' contains a strong magnet or has been
magnetized.
I have some magnets that will effect a CRT from over 2 feet away.

A transformer can also radiate a[n AC] magnetic field  that disrupts
nearby devices.

If you can find the source of the magnetic field and move THAT away
from the TV, it should fix the problem.

It is possible that putting the set in place and then 'degaussing'
everything in the vicinity will 'fix' the problem.

Does your Satellite receiver have a built in hard drive for recording
programs? It is possible that the drive is 'leaking' a strong magnetic
field [but most hard drives confine the field very well]

Yes the TV is CRT, and no, the receiver does not have a HD in it, nor
does it have a large transformer. The purity problem is static, that is
it does not change colour, so I don't think it's a transformer, as that
would cause a rainbow effect.

Maybe I'll try rearranging the "stack" of components to see if one of
the other devices cause less magnetic radiation, or reflection if that's
the case.

It would be nice if this set had a manual degaussing option, but alas it
doesn't. I don't even hear the coils buzz when the set comes on, but
there are no other purity issues, so they must be functional. I'll take
my tape eraser down with me, and try that to see if the problem returns
after zapping the screen.

Lacking an eraser, if you can hang a magnet on a string so that you can
spin it, you can sometime degauss with that.

I had a nice heavy magnet from an old radar magnetron that had a hole in
just the right spot.
I had a loop of copper wire threaded through the hole and hung the
contraption from a piece of string.
I would wind it up good and let it spin, slowly moving it away from the
monitor.
Did a good job of degaussing.

Sometimes, for a joke, I would spin it on the other side of a wall, near
someones monitor.
They would come running out of their office "something strange is happening
to my monitor. The picture is wobbling all over the place and changing
colors!"   :)

--
bz      73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

bz+...@ch100-5.chem.lsu.edu   remove ch100-5 to avoid spam trap- Hide quoted text -

- Show quoted text -

The OP did not say if the stand was metal or not. If it is metal, that
may be adding to the problem. The spinning magnet to degauss is an
old trick that works well as long as it is spinning rapidly compared
to how fast you are moving awa from the set.

The stand is wooden. The shelf is merely a 3/4" press board with
arborite on the top. The lower shelf has 3 devices stacked up on it,
with the satellite receiver on the top of the pile, and about 1" away
from the bottom of the shelf the tv sets on. The whole thing is only
about 21" wide and about 3 feet tall.

- Tim -
 
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James Sweet Inscribed thus:

Baron wrote:
msg Inscribed thus:

James Sweet wrote:

msg wrote:

This Saturday I replaced seven popped Nichicon electrolytics
in my iMac G5; it took me nearly five hours of intense battling
with too-tight hole sizes and high-thermal conductivity planes
but the job got done and the fix worked. Has anyone worked
on this planar and can comment? What wattage and tip sizes
worked for you? I used a 65 watt iron and ground the tip into
various chisels and angled points, used excess solder and flux
and tried an amount of preheating but it really was a _bitch_
to do. I kinda doubt the board was made for repairing.

Michael


The heatsinking effect of planes can be a real issue. I use a 140W
Weller soldering gun for motherboard capacitor replacement, it's
the only thing I've found that puts down enough heat to remove the
caps without ripping up traces.
Indeed. I neglected to mention that I cranked up the wattage with
a variac to about 90W but that is nowhere near what you use ;)

Michael

Hot air preheating works wonders. I use a hot air paint stripper gun
to preheat an area first before then desoldering the cap. Usually
they come out of the board quite cleanly but some manufacturers bend
the leads after insertion into the pcb, which can be a pain.



That's a great idea, I'll have to give it a try next time. Just have
to be careful not to overdo it and cause SMT parts to drop off the
board.
I have found that often SMT parts are glued down and are a right pig to
get off the board, particularly if its a part that you want to
salvage !

--
Best Reagrds:
Baron.
 
We have a customer who owns a series of 24 and 30 unit apartment
buildings. Presently on each floor as per local requirements there are
several self contained emergency lighting units. Some of these are
equipped with a small 6V battery and just two low voltage lamps that
aim in different directions down the hallway, while other larger units
having larger batteries sometimes might have as many as six 12volt
lamps wired remotely. These all are equipped with sealed lead acid
rechargeable batteries which need to be replaced every few years. Two
of his buildings are exceptions though and don’t have this type of
lighting. In these buildings, the hallway lighting circuit is wired
through an inverter system. This system, which was built by a company
in Massachusetts many years ago is installed in the boiler/electrical
room, and consists of two 12VDC to 120VAC 450W solid state inverters
operating in parallel and two group 24 size wet cell automotive
batteries. There is a built in charger and a huge contactor which
drops out upon loss of AC and applies 12VDC to the inverters. Loss of
AC will cause the load to toggle over to the inverter outputs and the
hallway lighting circuit remains powered. Maintenance on these two
buildings is minimal and his ultimate cost savings projection becomes
significant when multiplying installing this type of system into the
100’s of buildings which he presently owns. He has asked me to look
into finding this type of equipment for him to retrofit his other
buildings. The typical load is about 400W CFL and will probably never
exceed 550W. I don’t know how picky these particular 13W CFL units are
to anything other than sine wave AC. I know sine wave or even modified
sine wave will probably increase cost somewhat. Does anyone have any
ideas for inverter systems equipment they might be able to share with
me? Thanks, Lenny.
 
In article <d0401b14-67ae-409a-a50d-c5705fe65f27
@z24g2000prf.googlegroups.com>, philsvintageradios@yahoo.ca says...
On Jun 3, 7:02 pm, Tim <t...@tim.tim> wrote:
In article <e1c9e6e0-ff27-4723-8918-91eb929d51d6
@c65g2000hsa.googlegroups.com>, hrhofm...@att.net says...



On Jun 3, 12:15 pm, bz <bz+...@ch100-5.chem.lsu.edu> wrote:
Tim <t...@tim.tim> wrote innews:MPG.22af3e66c44ceb15989707@news.aliant.net:

In article <Xns9AB18DEB06E2DWQAHBGMXSZHVspamm...@130.39.198.139>,
bz+...@ch100-5.chem.lsu.edu says...
Tim <t...@tim.tim> wrote in
news:MPG.22adfa799165188989706@news.aliant.net:

OK, this is a problem with a 19" Citizen TV. It is just over a year
old.

If the set is put on a stand that has a metal object (like a
Satellite Receiver on a shelf) mounted within 8 inches below the set,
the pic has a very noticeable purity problem all the way across the
bottom and about 1/2 way up each side. If I raise the set up, the
purity problem will diminish, but even up at 8" away from the console
stand, it still has slight purity issues.

Raising the set up on boxes is problematic, as the space is very
limited. I would like to shield whatever it is. I am not sure if it
is a reflection from the set or radiated magnetic fields from the
equipment below.

The console is in a travel trailer, so I cannot move everything away
from the tv, as most of the electronics are in this one console, with
the TV on top of it.

Any helpful suggestions are appreciated.

I assume that this is a CRT tv, not a LCD or plasma tv.

Sounds like the 'metal object' contains a strong magnet or has been
magnetized.
I have some magnets that will effect a CRT from over 2 feet away..

A transformer can also radiate a[n AC] magnetic field  that disrupts
nearby devices.

If you can find the source of the magnetic field and move THAT away
from the TV, it should fix the problem.

It is possible that putting the set in place and then 'degaussing'
everything in the vicinity will 'fix' the problem.

Does your Satellite receiver have a built in hard drive for recording
programs? It is possible that the drive is 'leaking' a strong magnetic
field [but most hard drives confine the field very well]

Yes the TV is CRT, and no, the receiver does not have a HD in it, nor
does it have a large transformer. The purity problem is static, that is
it does not change colour, so I don't think it's a transformer, as that
would cause a rainbow effect.

Maybe I'll try rearranging the "stack" of components to see if one of
the other devices cause less magnetic radiation, or reflection if that's
the case.

It would be nice if this set had a manual degaussing option, but alas it
doesn't. I don't even hear the coils buzz when the set comes on, but
there are no other purity issues, so they must be functional. I'll take
my tape eraser down with me, and try that to see if the problem returns
after zapping the screen.

Lacking an eraser, if you can hang a magnet on a string so that you can
spin it, you can sometime degauss with that.

I had a nice heavy magnet from an old radar magnetron that had a hole in
just the right spot.
I had a loop of copper wire threaded through the hole and hung the
contraption from a piece of string.
I would wind it up good and let it spin, slowly moving it away from the
monitor.
Did a good job of degaussing.

Sometimes, for a joke, I would spin it on the other side of a wall, near
someones monitor.
They would come running out of their office "something strange is happening
to my monitor. The picture is wobbling all over the place and changing
colors!"   :)

--
bz      73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

bz+...@ch100-5.chem.lsu.edu   remove ch100-5 to avoid spam trap- Hide quoted text -

- Show quoted text -

The OP did not say if the stand was metal or not. If it is metal, that
may be adding to the problem.  The spinning magnet to degauss is an
old trick that works well as long as it is spinning rapidly compared
to how fast you are moving awa from the set.

The stand is wooden. The shelf is merely a 3/4" press board with
arborite on the top. The lower shelf has 3 devices stacked up on it,
with the satellite receiver on the top of the pile, and about 1" away
from the bottom of the shelf the tv sets on. The whole thing is only
about 21" wide and about 3 feet tall.

- Tim -- Hide quoted text -

- Show quoted text -


try putting a sheild between, see what you can find, a sheet of
alunimum might be enough. sheet of tin that is grounded might be even
better.
I have screwed up a couple of TV's by playing with magnets near them,
never had much success with degaussing them that way but I am sure it
is possible.

Phil
In the past I have tried using Aluminum to shield against RF, but
haven't had much success with that. I will try a grounded sheet though,
maybe that will work better. The worse case is that it makes the problem
even worse, but it will go away the next start up.

- Tim -
 
Mark D. Zacharias wrote:
"davidlaska" <Davidlaska@gmail.com> wrote in message
news:2bd0e1df-f6de-4f6a-aadf-9cae8e20dadd@b9g2000prh.googlegroups.com...
I have had it for decades but I do not want to give it up because it
works fine withstand the popping and hissing it does in all modes
except off. Is it over for it?


It's fixable - get it to a shop that knows these things. Likely it's only
doing it on one channel, and this in turn would most likely be a noisy
transistor - they had a few problems with those, like 2SC458 and 2SC1213 and
the like. Can also be caused by a bad coupling capacitor, or if it's making
the static on both channels, could be an arcing power switch - although this
would cause interference on nearby AM radios and cause the dial lights to
flash and dim.


Mark Z.

I had an intermittent problem exactly like this on an old Wards
receiver, problem turned out to be a bad mosfet transistor in the preamp
section. Since mine was intermittent I was able to track it down with
some freeze spray.
 
William Sommerwerck wrote:

"Eeyore" wrote

Do you know what I mean by the "output Zobel network"?

A Zobel network is used for impedance compensation -- usually to make a
circuit look more resistive.
Which it needs to be to counter the effect of the output inductor or you'll
wreck the phase stability of the amplifier.

Graham
 
William Sommerwerck wrote:

An amp with such a network at its output might very well be unusually
load-sensitive.
Every amp has one prior tot he output inductor.

Graham
 
Meat Plow wrote:

Besides, I can buy a 2000 watt amp brand new also made in China for around
$300 US.
I wouldn't expect it to work for very long.

Graham
 
On Jun 1, 9:03 pm, gruv2...@gmail.com wrote:
Hello All,
My laptop no longer charges the battery. I need a motherboard
schematic or at least somebody that knows what 'normally' dies in that
circuit. There is a current sense resistor in the charge path, and
some FETs that i cannot find a datasheet for. There must be some
comparators somewhere in there controlling the FETs. Dose anybody know
about this circuit,or have a schematic??

Thanks!!!
-Stephen
Most likely failure: Broken solder joints on the DC input connector.
Fix: disassemble enough to reach the solder side, re-solder. It is
much easier to find instruction on disassembly than a schematic. If
you REALLY need a schematic, then the machine is not repairable.
 
JA wrote:

hi guys!
I need to have an obsolete 2708 eprom programmer-reader..
It's very difficult to find modern eprom programmers that do this!
I have buyed a willeim but it does everithing but 2708!!
Well if it's possible i would make one.
I'm very good skinned as electronic handy man , but i can't know how to make
it.
Can someone help me?
And if someone got an old eprom programmer let me know!


I think Needham's used to make a reasonably priced programmer. You can
probably find one on eBay if you watch for a while.



--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form che...@prodigy.net.
 
On Jun 4, 3:55 pm, philsvintageradios <philsvintagerad...@yahoo.ca>
wrote:
I am trying to couple my air conditioner to a blower. I want the
blower to start when the fan in the AC does. It is a 3 speed motor ,
has 5 wires, neuteral and black ( across the AC supply  with an
electrolytic cap between them)  then yel,orange red , these three
wires go to solenoids on the PC board.

I bought a 110V relay, thinking I could connect it between neutral and
one of the three wires from the relay.
It does work, but it takes about 3 seconds before the relay clicks on.
I don't care about the 3 seconds but I am not really understanding how
these three wires affect the motor's speed.

Between the black and white, with the capacitor between I measure
about 170 Volts, I guessed that perhaps the cap is smoothing the sine
wave of the AC current , or somehow playing games with my digital
meter.

I get something close to 110 at all three wires from the solenoids
irreguardless of which fan speed is used.  well that isn't exactly
true , I did notice the voltage very slowly dropping at some of these
points, but after 5 mins was still  pretty close to 110.  perhaps the
windings are not completely separated electrically and I am reading
voltage which is present because it is fed back through the windings
being interconnected?

I guess my main concern is that the windings of the relay aren't
connected in such a way that it is loading up the little PC board, and
I would like to understand better how the motor is being controlled by
these relays.
can anyone with a better understanding of motor control enlighten
me ?  I have a scope I could connect to better understand ( by seeing
the waveform) if that would help, I assume the phase or lag of the
power is being changed by the circutry or something but I don't really
understand it.

Phil
Your posting is confusing! You don't say which motor you are talking
about when you give colors and voltages, youdon't say what the votlage
is on the AC motor, and are youtrying to connect it to the AC blower
motor in the furnace or to the AC compressor mnotor. Try starting
over and maybe someone wioll eb able to understand you better. Sorry,
 
William Sommerwerck wrote:

Which it needs to be to counter the effect of the output inductor
or you'll wreck the phase stability of the amplifier.

It's the other way around, I believe. The inductor is there for a good
reason.
They both are.

I design power amps btw.

Graham
 
William Sommerwerck wrote:

William Sommerwerck wrote:

An amp with such a network at its output might
very well be unusually load-sensitive.

Every amp has one prior tot he output inductor.

I will ask JC about this.
Who is JC and why would his opinion change the facts ?

Grahama
 
Hi,
I'm using a 700W UPS (localy made) with a 120 Ampere battery to run
three ceiling fans (150W each), a tube (40W), and my laptop (70W?) and two
energy savers (18W each) to cover load shedding time which is mostly for one
hour several times a day. The problem is if all tree fans are running for
some time, they begin to slow down considerably. Is the battery responsible
for this or the UPS.
If I add another battery in parallel will this solve the problem. I intend
to add another fan to this. Also is there a way to test what is the actual
strength of the UPS? It is common here to sell UPS that are lower in power
than what is printed on them.

Thanks
 
captainvideo462002@yahoo.com wrote:
We have a customer who owns a series of 24 and 30 unit apartment
buildings. Presently on each floor as per local requirements there are
several self contained emergency lighting units. Some of these are
equipped with a small 6V battery and just two low voltage lamps that
aim in different directions down the hallway, while other larger units
having larger batteries sometimes might have as many as six 12volt
lamps wired remotely. These all are equipped with sealed lead acid
rechargeable batteries which need to be replaced every few years. Two
of his buildings are exceptions though and don’t have this type of
lighting. In these buildings, the hallway lighting circuit is wired
through an inverter system. This system, which was built by a company
in Massachusetts many years ago is installed in the boiler/electrical
room, and consists of two 12VDC to 120VAC 450W solid state inverters
operating in parallel and two group 24 size wet cell automotive
batteries. There is a built in charger and a huge contactor which
drops out upon loss of AC and applies 12VDC to the inverters. Loss of
AC will cause the load to toggle over to the inverter outputs and the
hallway lighting circuit remains powered. Maintenance on these two
buildings is minimal and his ultimate cost savings projection becomes
significant when multiplying installing this type of system into the
100’s of buildings which he presently owns. He has asked me to look
into finding this type of equipment for him to retrofit his other
buildings. The typical load is about 400W CFL and will probably never
exceed 550W. I don’t know how picky these particular 13W CFL units are
to anything other than sine wave AC. I know sine wave or even modified
sine wave will probably increase cost somewhat. Does anyone have any
ideas for inverter systems equipment they might be able to share with
me? Thanks, Lenny.

CFL's _Shouldn't_ be picky about power. They are usually always
rectified to DC inside.Sine,Square,sawtooth even-it doesn't matter to
the rectifier.
 
On a sunny day (Thu, 5 Jun 2008 08:22:12 -0700 (PDT)) it happened
cs_posting@hotmail.com wrote in
<24cd2e3e-ecb4-4c9e-b4bc-29a3c689f921@w7g2000hsa.googlegroups.com>:

The 2708 requires two additional supply voltages, +12 and -5 in
addition to the +5 required by 2716 onwards. That's probably why most
programmers don't support it.

Should not be hard to make one though - I made a 2716 programmer in
high school, and you could probably do a 2708 if you got the extra
voltages. I used an 8255 I/O chip wired into an expansion memory
socket on my Z80 computer;
Hey, I used 2 Z80 PIOs ;-)
 
On Thu, 05 Jun 2008 01:40:38 GMT, "JA" <formula1vhs@ TOGLIMI
hotmail.com> wrote:

hi guys!
I need to have an obsolete 2708 eprom programmer-reader..
It's very difficult to find modern eprom programmers that do this!
I have buyed a willeim but it does everithing but 2708!!
Well if it's possible i would make one.
I'm very good skinned as electronic handy man , but i can't know how to make
it.
Can someone help me?
And if someone got an old eprom programmer let me know!
The 2708 is similar to larger, newer EPROMs except for the extra
supply voltages, for reading.

However, IIRC, it uses a different programming algorithm where you are
supposed to cycle through the entire memory a number of times.

This thing is pretty old, thirty-plus years.

Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
 
On a sunny day (Thu, 05 Jun 2008 19:00:46 GMT) it happened "JA" <formula1vhs@
TOGLIMI hotmail.com> wrote in <yJW1k.92841$FR.334083@twister1.libero.it>:

"DaveM" <masondg4499@comcast99.net> ha scritto nel messaggio
news:wtydnT2I1dOwztrVnZ2dnUVZ_sudnZ2d@comcast.com...

The Andromeda Research EPROM+ programmer can handle the 2708. Price is
reasonable at US $289 plus shipping.

Fantastic work! I have contacted them!
I think that i will buy this!
Would it not be a lot cheaper to make a little plug in board with for example a 2716?
These once existed with SRAM and battery too IIRC.
Depends on how many EPROMS of that pre-historic age you need to replace.
 

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