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Pawn shops, if you are lucky.

Last time I went to a pawn shop, my wife almost divorced me...

Wait you mean PAWN shop....? Sorrrryyyy.

:-)


Jong

Last year I got a Phillips PM3267 100MHz scope
(with probe) like new for $10!

Oh I hate you....

And now I hate my 15 Mhz scope (that I bought for $15).

====

And by the way...? what city is this, that people trash such nice toys ?? Any gold bars for $10?


Jong

Yardsales. It is going to be tough to find one quite that cheap that isn't very old and with problems.

Maybe a single trace 5MHz. Or you might get lucky.

Are you anywhere Tacoma, WA? I have a couple of analog 'scopes I'll be putting on Craigslist soon. Dual trace, I'll have to go look up the specs but they are both at least 20MHz.

Steve Greenfield AE7HD

where can I get a scope for $10?

In some kind of junk/surplus sale.

Even on ebay you can find one, just don't expect it to work.

Ah... but all due respect to the great ST, I bought an o-scope on eBay for $15 (or was that $25) and it works.? It is just 15 Mhz, but for my hobby / learning experimentation, it is still great.? It has mode for Color TV color burst mode - so it was designed for real life / real lab use (problem solving & fixing old color TV).

To top it off, it is so simple, I figured out how to "calibrate it" on my own.? Believe me, I'm no genius (why is that not so difficult to swallow?).? One STRONG WARNING - don't open up a CRT type of device unless...? there's a LOT OF HV wiring in there.

====

Since then the price of old o-scopes have gone up.? But if you take your time and don't get emotional, you can still find cheap deals online.? I took months searching and hunting online.


Jong

At 10:53 25 01 11, Herbert wrote:

where can I get a scope for $10?

eBay, if you are lucky.
Estate sales, if you are lucky.
Pawn shops, if you are lucky.

Fortuitous things do happen, just not for me.

Reese

At 09:21 25 01 11, vaclav_sal wrote:

To Reese and others who were after the capacitors (me included).
Please keep the subject handy. There must be something wrong with design or manufacturing them if so many of them fail.

Sure. Though, I think it's just low quality manufacture and expected
failure rates.

PS Last question - did your failure occured while monitor was running or you noticed (!) it when you turned it on next time?

I've usually left the monitor on, relying on the OS to blank the screen
after about 20 minutes of inactivity. On the belief that constantly on
causes less electronic stress than endless on/off cycles. We can debate
the wisdom of that practice in another thread.

So it worked fine one night, didn't work the next morning. Power "on"
LED on the monitor was flickering, pressing the o-n/o-f-f controller
on the monitor had no effect. Physically cutting/restoring power by
removing/replacing the power cable had no discernable effect either.
Power LED on the brick was not lighted. There was no hint of escaped
smoke in the aroma of the air.

It may be that I fried the monitor when I connected a non-switching
wall wart type power supply, but the monitor was suspect and about
5 years old anyway.

Brick specs:
input 100-240 volts AC, 1.6 amps (max), 50/60 Hz
output 12 volts DC, 4 amps
switching power supply

Wall wart specs:
input ~110 volts in, blah blah
output 12 volts DC, 3.5 amps.
non-switching power supply

I measured the wall wart output voltage at about 16 volts, actual.
Maybe that is what let smoke out of the monitor. Or maybe there was
something else going on. Dunno.

Reese

On Tue, 25 Jan 2011 11:15:50 -0500, you wrote:

Yard sales and flea markets.

I bought an EICO 430 5MHz recurrent trace scope for $10.
A few years later, I got a Heathkit 4205 5MHz dual trace triggered scope
for $8.
Last year I got a Phillips PM3267 100MHz scope (with probe) like new for
$10!

So, just spend every weekend for the next few years hitting every flea
market and yard sale you can, and you might get lucky, too. Or, if you
need one in this lifetime, expect to pay a bit more.

Kerry

Depending on where you are located Google for "hamfest" (ham radio swapfest).
Over the years I've picked up all kinds of interesting stuff.

Keith Bowers WB4LSJ- Thomasville, NC

At 02:12 25 01 11, Stefan Trethan wrote:

If the backlight inverter looks like it would function individually keep it,
they often go bad and are easy to replace as a module.

What you don't want is an inverter with many control wires, but one with
just 2 or 3 leads is ideal to keep.

Cool, thank you for the pointer. I'll have to disassemble the screen
a bit further to access the backlight. There's a gang of about a dozen
wires that go to the monitor in one wiring bundle, 4 others with only
2 wires each (2 top, 2 bottom, 4 leads and 8 individual wires) - so
those are probably the power leads to the backlight. The larger bundle
with a dozen wires is probably the data cable.

Reese

Try to search for an old Heathkit or Eico scope that was built up from a kit.
You might find someone who has one in garage, attic, or basement that they
would love to get rid of. They might even have the original assembly manual,
which would make rehabilitation easier. Also, there are places where one
can purchase assembly manuals for Heathkit and Eico kit products.

Roland F. Harriston, P.D.




Stefan Trethan wrote:

Yard sales and flea markets.

I bought an EICO 430 5MHz recurrent trace scope for $10.
A few years later, I got a Heathkit 4205 5MHz dual trace triggered scope for $8.
Last year I got a Phillips PM3267 100MHz scope (with probe) like new for $10!

So, just spend every weekend for the next few years hitting every flea market and yard sale you can, and you might get lucky, too. Or, if you need one in this lifetime, expect to pay a bit more.

Kerry


Herbert wrote:

--
Internal Virus Database is out-of-date.
Checked by AVG Anti-Virus.
Version: 7.0.289 / Virus Database: 267.11.13 - Release Date: 10/6/05

In some kind of junk/surplus sale.
Even on ebay you can find one, just don't expect it to work.
It would be much easier to fix than to make one from a monitor.

ST

where can I get a scope for $10?

To Reese and others who were after the capacitors (me included).
Please keep the subject handy. There must be something wrong with design or manufacturing them if so many of them fail.
Vaclav

PS Last question - did your failure occured while monitor was running or you noticed (!) it when you turned it on next time?

The digest is compiled as messages are posted.

Software posts such as those about electronics simulation software or PCB/Schematic software are on topic. Posts about general computer topics are off-topic. There are plenty of groups for that, and it can easily take over a group.

The four people who responded to your post are now on moderated status. They've all been here long enough to know better, two even said so but posted anyway.

Steve Greenfield AE7HD
Your grumpy neighborhood moderator

If the backlight inverter looks like it would function individually keep it,
they often go bad and are easy to replace as a module.

What you don't want is an inverter with many control wires, but one with
just 2 or 3 leads is ideal to keep.

ST

All,

I am throwing in the towel on the LCD monitor itself. Please
cease and desist all discussions of the LCD Monitor circuit
board under this thread. Or elsewhere.

I have purchased a replacement LCD monitor and will be shitcanning
the old LCD monitor at the recycle place. I'd like to keep it on
hand for spare parts but "on hand" is a space with limited room.
So, it must go.

Meanwhile, the brick is still on my desk and it's malfunction,
still a curiosity. It's also potentially useful for other
projects if it can be made to work again. And unlike the
monitor, it doesn't have quite so many SMT components. So.

I'll bring the brick up again when some time has passed
(read, when I get the caps replaced). Or not, if like too
many other projects, this one gets pushed aside. It's not
my fault, the 73 Camino needs quarter panel replacements...

Reese

Thanks Rob, now I know I am not that senile .
I'll look for it again there.
Actually I was looking for the article because they did have some comments on why they did it.
I was thinking to use their footprint to eliminate the header socket for my Nixie tube adapter.
( One less part to work with)
But I am wondering if it is a bad idea because the Nixie is pretty light and I would not want the adapter header to be pushed out of the circuit board. ( Or use rubber band to hold the tube adapter it – kluge!)
I guess 5 mills offset should be OK on all of the holes.
Vaclav

The only relation this display should have with a scope is with the type of scope mounted firmly atop a high powered rifle.

I've shot a television before and the result was most satisfactory.

Yours in complete stress relief,

Daryl.

Joe in Texas:

CRT monitors are a horse of a different wagon compared to LCD animals.

The power supply is an integral part of the CRT monitor, not a little black box detatched from
the main circuitry.

I can understand replacing electro-caps on a CRT monitor....it makes sense.
It's either replace the caps or throw the whole thing away.

But where you have the power supply sitting outboard, then it makes sense to just
s--t can the power supply and spring a few bucks for a fresh, brand new "brick".

I think I have about five or six "bricks" of various output voltage and current capability
that I can use to experimentally replace a busted original equipment brick on any piece of equipment
that goes south as a result of power supply failure..

Roland F. Harriston, P.D.
****

For what it is worth,,,i have repaired around 3000 crt monitors,,,a couple dozen of these lcd,,power supplies,,,replace ALL Electrolytic (sp)Caps,,,remove any glu,,,it worked for me every time.
Joe Smith
405 West Point Loop
West Point
Texas
78963
I used to be the first hit on Google for monitor repair,,,had some really good years in AUSTIN,,Thanks to YOU!
pipester is right 100%

--- In Electronics_101@..., "Roland F. Harriston" <rolohar@...> wrote:

Replacing components on multi-layer motherboards can be daunting, and
the chances of
success are not very high IMHO.

I would not advise the average "Electronics 101" participant to attempt it.

Roland F. Harriston, P.D.



Peter Morris wrote:

The reason that you can often get away with using the wrong "brick" is
because most of the monitor's internal circuitry requires voltages other
that 12 (usually 5 and 3.3 among others). The monitor has DC-DC converters
inside which will maintain a constant output voltage over a wide range of
input voltages. When using DC-Dc converters, the higher the input voltage,
the less current will be drawn from the supply. I'd be careful going too
high though, as there will be some devices requiring 12V (audio op-amps
spring to mind). Also, there are probably some electrolytic capacitors
across the 12V rail rated at either 16V, 25V, or 35V. If 16V - 19V "brick"
will kill them. With 25V - 19V will be close, but probably ok. If the caps
are 35V rated, then 19V won't harm them.

When choosing a replacement PSU (brick), the voltage is usually the most
important point of specification. If the original was 12V 4A, then the
replacement should be 12V (or close, eg. 11-14ish) and at least 4A. If the
monitor requires 4 amps, a 2 amp PSU won't be able to cope. A 12V 10A PSU
will work fine. A 20V 4A supply is not recommended.

As for repairing the old "brick", in my experience, the most common
cause of
failure of switch-mode PSUs is electrolytic capacitors 'drying out'.
This is
often because the PSUs are built to a pathetic budget, meaning the
cheapest
parts are used, not the most appropriate. Switch-mode PSUs operate at high
frequencies (usually in the region of 100KHz). With current flowing in and
out of the bulk electrolytic capacitors at these rates, ESR of the
capacitors becomes crucial in order to keep ripple on the output (and
instability as a result) low. When capacitors with high ESR are used, the
result is that the capacitors heat up while in use. This often causes the
top of the can to bulge until the weak point in the middle breaks. At this
point, the electrolyte will evaporate. As this happens, the effective
capacitance of the capacitor reduces to almost nothing. The ripple of the
PSU will increase and eventually, the PSU will no longer even start.

In short, when I am presented with a faulty piece of equipment which I
suspect may be the SMPS, I immediately visually inspect the
electrolytic for
signs of bulging. If there are any with even the slightest of bulges, I
replace them without question. 9 times out of 10, this has worked.
Just last
week, I repaired a PC which would power on and then power down straight
away. I took the cover off and there were 7 caps on the MoBo with bulging
tops. I replaced them and the PC now works fine.

Hope this is insightful for some of you. Please tell me if you think I
missed the point, or have just wasted a lot of your time reading this.

Thanks

Pipester

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