tech: monitor blasting
Joey Oravec
have been exaggeration) tool for doing monitor neck blasting.
I'm of course familiar with the randyfromm.com article where you basically
use a charged cap to blow the neck clean. This person told me that there's
regulation involved and didn't seem to be familiar with the randyfromm.com
article.
So does anybody know about packaged tools for doing that which I've never
heard of in my limited arcade game experience? It makes sense that some
regulation might help, but do tools exist that really increase your odds
of getting good results when blasting a monitor?
--
O..O GT/CS/S d+ H+ s !g !p1+ !au a-- w++ v--- C+++ USL++ P+ L++
(----) 3- E---- N++ K+ W-- M-- V-- -po+ Y t++ 5+ jx R
( >__< ) G? tv b++ D++ B- e*(k-12) u- h! f* r+ n-- y?
^^ ~~ ^^ Web - http://www.science.wayne.edu/~joey/index.html
Bob Roberts
>
> Somebody told me today that there is an expensive (the $2000 figure might
> have been exaggeration) tool for doing monitor neck blasting.
>
> I'm of course familiar with the randyfromm.com article where you basically
> use a charged cap to blow the neck clean. This person told me that there's
> regulation involved and didn't seem to be familiar with the randyfromm.com
> article.
>
> So does anybody know about packaged tools for doing that which I've never
> heard of in my limited arcade game experience? It makes sense that some
> regulation might help, but do tools exist that really increase your odds
> of getting good results when blasting a monitor?
>
If you are asking if there are restorers/rejuvinators for CRTs,
the answer is yes, and they do run from 1k$ to 3k$, although, I have
seen some imports as low as $800 & I think B & K makes an el cheapo,
as well.
--
Big Bear <bob...@bellsouth.net> Thanks The Real Bob Roberts™
Gamester
Bob Roberts <bob...@bellsouth.net> wrote in article
<35F238...@bellsouth.net>...
And maybe to follow up with a little more info.
A REJUVINATOR does not REPAIR your tube.
What it does is BURN the debrie off the grids inside the tube.
In time (about 6 months m/l), the SAME debrie will reform causing the same
problems again.
You might successfully rejuvinate a tube 2 or 3 times, but each time it
weakins the grids and each time the time it lasts gets shorter.
I have picked up old tube rejuvinators for less than $100 used, but the
chances of having the right socket for monitor tubes is slim.
Most of these were used in TV shops. None of the tvs use the sockets that
monitors use.
I have asked about ordering the right socket and have gotten $100+ replies.
So if ya happen to see one at a flea market or yard sale, don't get excited
till you know the right sockets are there.
Gamester
A218
repair/refurbishing field, and they work the nuts on most 'weak' CRTs.
The BK 470/467 series is an excellent choice - I bought mine in '92 for < $750
The sockets are about $30 - 40 each, and many monitors DO use standard based TV
CRTs - esp the G07's
Dont be scared off by rumors and unfounded info from others - a rejuvenator is
an excellent way to prolong the life of a game (or TV) as long as you
understand that it is not a cure for life. Some problems in a CRT however (esp
heater/cathode shorts) do not respond well to the rejuvenation process,
although some restorers will fix a small percentage of them.
MCM is a good source for B&K - also Signal Electronics 1-800-842-8240
If shopping for a new one, ask for other distributors and shop hard -there isnt
a lot of TV repair equipment selling right now and prices are dropping off.
Art
Joey Oravec
: And maybe to follow up with a little more info.
: A REJUVINATOR does not REPAIR your tube.
: What it does is BURN the debrie off the grids inside the tube.
: In time (about 6 months m/l), the SAME debrie will reform causing the same
: problems again.
: You might successfully rejuvinate a tube 2 or 3 times, but each time it
: weakins the grids and each time the time it lasts gets shorter.
I must have missed the "right way" in Randy's article before, because I
only remembered what he said about using a clip lead with the voltage pin
to blow away shorts.
I get the feeling that one of these rejuvinators has a whole lot more
control built in and probably gives you a lot better results. I'm going to
watch out for one of those which would definately give better results than
an alligator clip across the neck as the poor man's way.
People in this area have been pulling a scam lately. Computer monitors get
the same problems obviously. They've been buying up older monitors in bulk
and trying to rejuvinate the tubes. Burn the stuff off and you get a
beautiful picture, if it breaks you just throw it out. But they must be
really, really crappy because one of these ones still sell pretty high
priced and last only 3 months before failure.
Randy Fromm
Also - How CRTs Fail
By Randy Fromm
I got the call again today.
It comes about once a week now. It
goes something like this:
"I can't adjust the color
on this monitor. It looks real dim. If I try
to turn up the pots on the
neck board, the picture just smears
to the right. If I try to
turn up the brightness on the remote
adjustments board, the
picture smears to the right. If I try to
turn up the contrast, the
picture smears to the right. I have the
screen pot turned up as
high as it can go without seeing
raster and vertical retrace
lines washing over the whole
screen."
Then, as if a sudden
revelation has come over the caller, he
perks up and queries "Hey!
Could it be a bad picture tube?"
The answer, of course, is "Yes." To verify, I ask the age of the CRT.
After three or more years in operation,
many CRTs begin to fail. With so many CRTs in the world today, the
ability to test and repair (yes, repair!)
CRTs can be pretty darned handy. Testing and repairing CRTs will save
you time and money.
But how can you fix a bad picture tube and what the heck fails,
anyway? Those are good questions! As video
games get converted and reconverted, the monitors can easily log tens
of thousands of hours of operation. As
a result, picture tube or CRT (cathode ray tube) failure has become
increasingly more common.
Anyway, the answer to the question is yes. Sometimes Kinda Sorta.
Maybe. But before we get into repairing
picture tubes, let's take a look at some different types of picture
tube failures. More specifically, we're going to
look at the electron gun assembly that's located in the neck of the
picture tube.
Each of the three electron guns in
the electron gun assembly uses a
heated cathode as a source of
electrons. The heater is the element that
you see glowing when you look at
the neck of a picture tube. The heater
must fit closely inside the metal
cathode but it must not touch it. If the
heater shorts to the cathode, the
gun will be stuck "ON" and the screen
will appear a super bright color
(red, green or blue depending on which
of the three guns is affected) with
vertical retrace lines visible
throughout the screen. Vertical
retrace lines appear as diagonal lines
that run from lower left to upper
right across the screen.
If you believe you might have a
heater-to-cathode short, try unsoldering
and removing the associated video output transistor from the neck
board of the monitor. Fire up the monitor
with the transistor removed. If you still have a brightly colored
screen with vertical retrace lines, there's a good
chance the CRT has a heater-to-cathode short.
You should be able to verify this with an ohmmeter. With the neck
board removed From the CRT, you should
have an infinite resistance between heater and cathode of the picture
tube .
Although there are many different types of CRTs, you will often find
the red cathode at pin 8, the green cathode
at pin 6 and the blue cathode at pin 11. Pins 9 and 10 are for the
heater.
It is also possible that one of the cathodes might become shorted to
the control grid. This can cause a similar
symptom as a heater-to-cathode short. If the cathode is shorted to the
control grid, you should be able to verify it
with your meter. The control grid will often be found at pin 5.
If the cathode has become damaged due to a buildup of oxides and other
crude, you will experience a loss of
one color (partial or total.) Try grounding the collector of the
associated video output transistor. If the color
comes on clear and bright (a brightly colored screen with vertical
retrace lines) the CRT is okay. If the color
does not come on or it is not as bright as the other two colors, the
picture tube is bad.
Another type of electron gun failure is a short between the control
grid and the screen grid. This will cause an
extremely dark picture (even with the screen control at maximum) or no
picture at all.
Measure the voltage at the screen grid (often pin 7) of the CRT. You
should be able to run it through a range of
250 to 750 volts DC using the screen potentiometer. If the voltage is
not high enough, pull the neck board off the
CRT and measure the voltage at the CRT socket again. If the voltage is
now normal, you probably have a short
between the control grid and the screen grid. Use your ohmmeter to
verify.
FIXING BAD TUBES
Is it really possible to fix a bad CRT? I have had a fair bit of
success using some simple techniques. Shorted
electron guns are often caused by small flakes of cathode material
that have sloughed off and found their way
into the electron gun. This type of failure is common in games with
face-up mounted monitors (table games, gun
games that use mirrors. etc.) because any crud in the CRT will
naturally fall right into the electron gun. By turning
the picture tube face down and tapping lightly and repeatedly on the
neck with the plastic handle of a
screwdriver, the flakes can sometimes be dislodged.
Do not hit the convergence ring assembly and for goodness sake don't
hit the glass neck hard enough to break
it! Naturally if you manage to shake the shorting particle out of the
neck of the CRT, you do not want to use this
picture tube for a table game again, EVER!
There is another trick that you can use to save a shorted CRT.
Commercial CRT service equipment uses a
technique known as "rejuvenation" to remove shorts from electron guns.
The rejuvenating circuit uses a
capacitive discharge to blow away any little shorting particle. We'll
look at the CRT rejuvenator later but here's a
cheap and dirty way to repair some shorted CRTs using just a clip lead
or small piece of wire.
CAUTION: The procedures described herein involve potentially lethal
voltages and must be performed by
qualified personnel or at the very least by a mechanic with a decent
sense of self-preservation.
1. Remove the video output transistor associated with the bad color.
If in doubt, remove all three video output
transistors. I usually remove all three just to be sure.
2. Locate the screen voltage pin of the CRT socket (often pin 7 but
check schematic to be sure.) This pin is
often labeled "G2."
3. With the neck board installed on the CRT (without the video output
transistors installed) turn on the monitor
and adjust the screen potentiometer fully clockwise in order to obtain
maximum screen voltage.
4. Touch one end of a wire or clip lead to the screen voltage pin of
the CRT socket.
5. Momentarily touch the other end of the wire to the shorted cathode
pin (red, green or blue) of the picture tube.
With luck, you will see a small blue arc in the neck of the CRT as the
short is blown away.
6. Use your digital multimeter to verify that the short is gone. You
should now read an infinite resistance. If not,
repeat steps 1-6.
Cathode to grid shorts and grid to grid shorts can often be removed
with this technique. Heater to cathode
shorts are another story as the thin filament of the heater can blow
out before the short circuit does. I have had
about 25% success removing heater to cathode shorts this way.
THE RIGHT WAY TO TEST AND RESTORE CRTs
Now let's look at the "correct" way to test and restore CRTs using a
remarkable piece of test equipment, the
CR7000 "BeamRite" CRT Analyzer and Restorer. Before I begin to
describe what the BeamRite does and how
it works, let me say that I have repaired and restored dozens of bad
video game picture tubes using the
predecessor to the CR7000, the CR70. I have taken old CRTs that were
dim and virtually unusable and turned
them into beautiful, bright displays that look as good as the day they
were manufactured. In the process, I have
saved operators and Arcade School students hundreds of dollars in CRT
replacement costs. I saved $400 just
by restoring one high resolution CRT!
What is it?
First of all. Sencore's CR7000 BeamRite will test all types of picture
tubes. Individual tests are made for short
circuits in each of the three electron guns. Tests are made for
heater-to-cathode (H-K) shorts and
cathode-to-grid (G1) shorts as well. The electron guns are also tested
for proper cutoff (the level at which the
gun stops emitting electrons, producing black on the screen) and
"emission" (sufficient beam current to
produce a bright color on the screen).
Each of the tests closely duplicates the normal operation of the CRT
so you're testing it under typical operating
conditions. By the way, you do not need the entire monitor in order to
test the picture tube. The CR7000 will test
any CRT as a stand-alone unit. Naturally, you do not need to remove
the picture tube from the monitor to test it.
You simply remove the CRT socket (the neck board) from the monitor in
order to connect the picture tube to the
BeamRite. The CR7000 comes with adapter sockets for testing all types
of picture tubes. Notice I didn't say
"most picture tubes" or "all popular tubes." The BeamRite tests 'em
all!
Another test checks the
"tracking" of the three color guns. In
order to produce a picture
that is properly color balanced, all
three electron guns have to be
alike. The emission levels of all
three guns are compared by the
CR7000. which measures the
ratio between the strongest
and weakest gun. If the difference is
more than 55 per cent. the gun
will show as "bad." Don't worry!
Bad guns can be restored by
the BeamRite as we'll see later.
The CR7000 BeamRite even has a
"life test." The life test will tell
you how much usable life you
call expect from your picture tube.
REMOVING SHORTS
Heater-to-cathode shorts are
caused by contact between the
CRT heater and the cathode. The CR7000 is not designed to correct this
fault as the surge current provided by
the BeamRite will often blow out the filament completely.
Control grid (G1)shorts are often caused by flakes of material that
have become lodged between the cathode
and the control grid. A G1 short can cause loss of control of the CRT
beam, resulting in a bright screen with
visible retrace lines.
G1 shorts also result in CRTs that cannot be controlled by the
brightness control or the incoming video or
blanking signals. The CR7000 "REMOVE G1 SHORT" function will vaporize
most shorting particles, resulting in
normal CRT operation.
CUTOFF RELATED FAILURES In order to understand the cutoff test, let's
take a closer look at the way the
cathode works. The cathode is the source of the electron beam. It is
coated with a material (such as barium or
thorium) which gives off large numbers of electrons when it is heated
by a filament. Believe it or not. there is a
finite amount of this electron emitting material and it gets used up
or "stripped" after years of extended use.
Once the barium is used up, the picture tube cannot be completely
restored.
The hot cathode emits electrons which form a cloud around the cathode
until they're attracted toward the front of
the screen by a positive voltage on the screen grid of the electron
gun assembly. Between the cathode and the
screen grid lies the control grid. In most video game monitors, the
control grid is grounded, giving the control
grid a negative bias with respect to the cathode. The video signal
modulates (changes) the voltage of the
cathode. It is the voltage difference between the cathode and the
control grid that controIs the beam current and
the brightness of the color.
The entire
surface of the cathode is not always
used to supply
the electrons that make up the
electron beam.
When the electron gun is only
partially turned
on, just the center part of the
cathode is used.
This means that the emitting
material at the
center of the cathode is used up
faster than the
material at the edges. The outer
areas only
supply electrons during peak
brightness
periods. When the center part
becomes worn,
the CRT screen still lights
brightly during
peak brightness but the beam
cuts off too
soon because the brightness drops
and the worn-out
center of the cathode is the only
part being used.
This results in a picture that`s a
combination of
over-driven, smearing color and
black, with no
intermediate shades of color.
Many technicians
call this a "gassy" tube.
Actually, the
tube is exhibiting poor gamma; the
ability to
correctly reproduce shades of gray or
color.
The CR7000 tests for proper cutoff. The cutoff test, combined with the
emission test that follows, indicate the
next steps to be taken in the restoration process.
EMISSION TEST
The emission test indicates if the edges of the cathode are poisoned.
Poisoning occurs when positive ions
coat the emitting material on the cathode. The ions are a result of a
minute amount of air that's left inside the
CRT during manufacturing. These ions react with the hot cathode
surface over a period of time and reduce (in
some cases completely shut off) the number of electrons emitted by the
CRT. Cathode poisoning is similar to
rust on a piece of steel.
If the tube fails both the emission test and the cutoff test, the
entire surface is poisoned or stripped of emitting
material. An emission life test reduces the filament voltage to detect
cathodes that are overly temperature
dependent, indicating short life expectancy.
CRT REJUVENATION AND RESTORATION
The CR7000 uses a number of different methods to fix picture tubes.
The method used varies from tube to tube,
depending on the nature of the CRT failure. The BeamRite uses a
"progressive restoration" technique that
allows you to carry out CRT restoration one step at a time, using just
the right combination of voltage, current
and heater voltage to get the job done while avoiding the tendency to
"overdo it" that many technicians have
when restoring a CRT. The process of restoring a CRT is often referred
to as "shooting the tube."
After removing any shorts and testing each gun for cutoff and
emission, you're ready to try restoring any weak
guns. The CR7000 does this by boosting the CRT heater voltage. This
makes the cathode super hot. Then, a
40 to 100 milliamp current is passed through the cathode. The
combination of high temperature and high
cathode current removes the cathode poisoning, exposing fresh cathode
material.
Restoration
The CR7000 "BEAM-RITE" offers four automatic CRT "Restore" functions
to return near normal performance to
the CRT cathode. The four functions are progressive levels of current
and current durations including Low,
Normal, High, and Extended. Progressive restoration allows you to use
only what the gun needs to restore its
operation.
Re-activate 30 sec. (1 mA)
Low - 2 sec. (40 mA)
Normal - 2 cycles (80 mA)
High - 3 cycles (100 mA)
Extended - 15 sec. (100 mA)
Re-activate The CR7000 "Re-activate" function safely activates the
existing cathode emitting material with little
or no threat to the CRT gun. Re-activation also works well on some CRT
guns that have aged causing minor
cathode contamination or poisoning. You can use the Re-activate
function repeatedly with little threat of
damaging the CRT cathode.
The Low Restore function uses a brief two second current, limited to
40 mA, to heal the contaminated cathode
surface. The Low Restore function uses a much lower current and
shorter current duration than offered by any
other CRT tester On many weak cathodes, this is enough to be effective
while eliminating the cathode damage
that would result from other testers and higher levels of restore
currents.
The Normal Restore function offers additional restore current, limited
to 80 mA, and two automatic cycles
lasting three seconds each. The higher current and duration removes
the contamination more aggressively from
the cathode while permitting a three second pause between current
cycles. The High Restore functions boost
the filament voltage to superheat the cathode while increasing the
maximum current to 100 mA. The High
Restore function is effective in removing thicker cathode
contamination. For tougher cathode contamination, the
Extended Function draws continuous restore current up to 15 seconds.
This has worked like a charm every time I've used it.
If you cannot get any cathode current to flow due to complete
poisoning of the cathode, the CR7000 has a
"rejuvenate" function. The rejuvenate function is used when the CRT
cathode is so totally encrusted that no
restore current can be drawn by any of the other restore functions.
In the rejuvenate function. a charged capacitor is connected between
the cathode and the control grid (G1).
When the sudden positive voltage from the capacitor is applied to G1,
the electrons under the poison crust
break free, essentially cracking the layer of contamination. Once the
layer of contamination has been cracked,
the other restore functions can be used successfully.
Other CRT Gun Problems and Tests
G1 & H-K Short Tests When testing a color CRT gun, the G1 Short and
H-K Short tests are performed
simultaneously on the red, green, and blue electron guns. The
three-bar graph display indicates the resistance
of the respective guns simultaneously. You know at a glance if any of
the color guns has an inter-element short.
G1 Shorts Test These common shorts are automatically tested with the
CR7000 and the display shows which
elements have the short.
In the "Remove G1 Short" function, the cathode (K) and G2 grids are
connected together. The filament voltage
is removed to cool the cathode and prevent filament or cathode damage.
After a delay, pressing the "Press To
Restore" button discharges a 350 volt capacitor through the short path
between the G1 and the K/G2
connection.
Cutoff Test The CR7000 simulates cutoff bias conditions relating to
the manufacturer's specified range and
circuit bias conditions.
Lo Tracking The Lo Tracking test compares the level of` G2 voltage
needed by each gun to produce cutoff
current. It is automatically performed while testing cutoff of all
three guns of a color CRT. The "Good" GUN
TRACKING LED lights when all three guns are conducting within the
"Cutoff" area of the display and the G2
voltages are within a ratio of 1.25:1.
Emission Test First, the CR7000 measures "true beam" current or the
current passing from the cathode
through the opening in G1 and on to G2. This provides the best
representation of the actual CRT beam current
that strikes the phosphor screen. A second and exclusive feature of
the CR7000 is a "sliding" Good/Bad scale
for testing emission to manufacturer specifications.
The CR7000's Emission Life Test cools the cathodes slightly by
decreasing the filament voltage by 25%. A
cooled cathode produces less emission, but most good cathodes are
capable of producing more current than
is needed for full beam current (white picture level).
Hi Tracking The CR7000's Hi Tracking test compares the peak emission
levels of each gun of the color CRT.
The Hi Tracking test automatically calculates the tracking ratio as it
simultaneously displays the emission
readings for all three guns. The "Good" GUN TRACKING LED lights when
all three guns have emission currents
resulting in a ratio within 1.55:1.
FREE VIDEO TAPE AND TECHNICAL NEWSLETTER A very informative videotape
on CRT failures is
available from Sencore. Ask for Tech Tape #861A. The tape is free.
Sencore's toil-free number is
(800)SENCORE. The address is 3200 Sencore Drive, Sioux Falls, SD
57107. They have a website at
http://www.sencore.com. Ask to be put on their mailing list and you'll
receive a free subscription to Sencore's
technical newsletter on troubleshooting monitors and VCRs. Please tell
them Randy Fromm at Play Meter
Magazine recommended you call.
On Sun, 06 Sep 1998 14:13:36 GMT, "Gamester" <game...@isoc.net>
wrote:
>And maybe to follow up with a little more info.
>A REJUVINATOR does not REPAIR your tube.
>What it does is BURN the debrie off the grids inside the tube.
>In time (about 6 months m/l), the SAME debrie will reform causing the same
>problems again.
>You might successfully rejuvinate a tube 2 or 3 times, but each time it
>weakins the grids and each time the time it lasts gets shorter.
>
Randy Fromm
looking here:
http://randyfromm.com/techdept/cr7000.htm
BTW, Gamester is totally incorrect. The rejuvinator doesn't blow stuff
off the grids but rather from the cathodes.
rf
Bob Roberts
> > If you are asking if there are restorers/rejuvinators for CRTs,
> > the answer is yes, and they do run from 1k$ to 3k$, although, I have
> > seen some imports as low as $800 & I think B & K makes an el cheapo,
> > as well.
> > --
> > Big Bear <bob...@bellsouth.net> Thanks The Real Bob Roberts™
> >
>
> And maybe to follow up with a little more info.
> A REJUVINATOR does not REPAIR your tube.
> What it does is BURN the debrie off the grids inside the tube.
> In time (about 6 months m/l), the SAME debrie will reform causing the same
> problems again.
> You might successfully rejuvinate a tube 2 or 3 times, but each time it
> weakins the grids and each time the time it lasts gets shorter.
6 months to a year is when you wait for a 10 percent deflection or less,
and it is simply too late & you will be seeing it again real soon.
> I have picked up old tube rejuvinators for less than $100 used, but the
> chances of having the right socket for monitor tubes is slim.
> Most of these were used in TV shops. None of the tvs use the sockets that
> monitors use.
> I have asked about ordering the right socket and have gotten $100+ replies.
> So if ya happen to see one at a flea market or yard sale, don't get excited
> till you know the right sockets are there.
>
> Gamester
Steven....you're in the electronics field...buy an adaptor socket???
That's why they sell sockets & wires & connectors........make them
yourself. I wouldn't put too much faith in a $100 anti-Q , though.
We use to work those things to death, handing out 1 year certificates
with each boot, and from some of the trade shows, I gathered it was
pretty prevalent across the states.
The hardest adaptor to dupe was the 510TFB22 used in the Matsushita
monitors....the rest are a cake walk.
Gamester
Randy Fromm <ra...@randyfromm.com> wrote in article
<35f2c99b.4474855@news>...
Then I'm not TOTALLY incorrect :-)
I admit not to be super tech, but the results can be the same.
Gamester
Bob Roberts
Art's on the money based on my 40 years of using them. I booted my
first tube when I was working for a TV company while still in school.
Been addicted ever since!
Some tubes last a long time. I shot a tube in a Bradford TV (Note:
Made by a fledgling company, for Grant's Dept Stores, called.....
Wells-Gardner....hmmmm) about ????1974??? and it is still ticking.
(Geeeez, my aunt is thrifty!)
The only problem victims were the WG 4600 in slant back & CT cabs.
If you shoot them once, be prepared to shoot them quarterly till they
die, or put them out of their misery.
Bob Roberts
>
> Gamester (game...@isoc.net) wrote:
> : And maybe to follow up with a little more info.
> : A REJUVINATOR does not REPAIR your tube.
> : What it does is BURN the debrie off the grids inside the tube.
> : In time (about 6 months m/l), the SAME debrie will reform causing the same
> : problems again.
> : You might successfully rejuvinate a tube 2 or 3 times, but each time it
> : weakins the grids and each time the time it lasts gets shorter.
>
> only remembered what he said about using a clip lead with the voltage pin
> to blow away shorts.
>
> I get the feeling that one of these rejuvinators has a whole lot more
> control built in and probably gives you a lot better results. I'm going to
> watch out for one of those which would definately give better results than
> an alligator clip across the neck as the poor man's way.
>
> People in this area have been pulling a scam lately. Computer monitors get
> the same problems obviously. They've been buying up older monitors in bulk
> and trying to rejuvinate the tubes. Burn the stuff off and you get a
> beautiful picture, if it breaks you just throw it out. But they must be
> really, really crappy because one of these ones still sell pretty high
> priced and last only 3 months before failure.
>
I can't explain why, but for some reason they do not last on the
computer monitors & have a high failure rate on attempts. I have ceased
& desisted on any attempts at restoring these. It makes for very bad
customer relations!
The prices on these have fallen below the CRT value, anyway. When you
buy a whole new monitor for $100 to $150, why bother?
Bob Roberts
>
> Sencore Blows Away CRT Failures With CR7000
>
> Also - How CRTs Fail
>
> By Randy Fromm
And I am told my posts are long :()
Randy....this one should be in hard cover, or is it alreadyż
Bob Roberts
You can't blow the stuff off, either. You see the tube is under a
vacuum :)
Not a super tech??? You've been doing ok...keep it up...what's
a little difference like..cathode or grid..going to make! Who's
going to open it up and see which is which, anyway.
Hey....Randy, what's up with *totally*....California term? Everything's
like totally :) Here in Louisiana, it's like sub-totally :(
MLK
wrote:
>Some tubes last a long time. I shot a tube in a Bradford TV (Note:
>Made by a fledgling company, for Grant's Dept Stores, called.....
>Wells-Gardner....hmmmm) about ????1974??? and it is still ticking.
>(Geeeez, my aunt is thrifty!)
That's a neat story! WG also made TVs for JC Penny's and Montgomery
Wards as well. I was in Lewisberg, TN to give a class for a large
operator there. My motel TV failed one night so, since I had all my
tech stuff with me (including a suitcase full of spare parts) I took
off the back to see what I could do. Hogen's Heros was coming on and I
had just an hour to fix it.
Inside, it was what we all know as the K4600 chassis but with all the
"extra" parts that are missing off the RGB version we use in coin-op.
I was very suprised.
rf
Ron Michallick
Gamester wrote:
> Randy Fromm <ra...@randyfromm.com> wrote in article
> <35f2c99b.4474855@news>...
> > Well, THAT was a pretty crappy post I just made. Sorry about that. Try
> > looking here:
> >
> > http://randyfromm.com/techdept/cr7000.htm
> >
> > BTW, Gamester is totally incorrect. The rejuvinator doesn't blow stuff
> > off the grids but rather from the cathodes.
> >
> > rf
> >
> Then I'm not TOTALLY incorrect :-)
>
> I admit not to be super tech, but the results can be the same.
>
> Gamester
If you "blast" your tube, don't haul the game on it's back. Some
of that "stuff" is sure to clog your guns. :-)
I've had some good results back in my TV repair days.
It certainly beats throwing the tube away.
Ron Michallick
> > > BTW, Gamester is totally incorrect. The rejuvinator doesn't blow stuff
> > > off the grids but rather from the cathodes.
> > >
> > > rf
> > >
> > Then I'm not TOTALLY incorrect :-)
> >
> > I admit not to be super tech, but the results can be the same.
> >
> > Gamester
>
> vacuum :)
Stuff can't move through a vacuum? How do you explain the universe?