hi


my monitor has pin cushion effect problem, and the picture edges are out of
the view. the monitor controls don't solve it as the (horizontal size)/
(pincushion\trapezoid) controls don't have effect anymore. this problem is
the same as this one posted here
http://www.electronicskb.com/Uwe/For...uashed-picture

but no body offers a solution. i already opened the monitor case, i found
four chips;

1. LSC506429P 2. TDA4858 3. ATMEL008 4.
KA3842B
JD157V2 67974 24C08
E009C
IJ35BCTBW0025 YTD0021

only two of these i could know what they do, no. 2 and 3.

the first one is motorola and is discontinued, i couldn't find it's datasheet
so to decide whether was it a culprit or not, i couldn't bring the datasheet
of the fourth chip either.

the image is normal except for this problem, and all the controls work fine
except for those i mentioned.

the caps seem to have leaked, but i'm not sure as the monitor was never
opened until the problem showed up which was last thursday. these caps look
as if they have black heavy dust stuck to thier metal top, and there is
plenty of it everywhere inside but only very few caps have it like this and
they happen to be arround the four ics i mentioned. but also that indicates
the leak is old, and the problem appeared three days earlier which adds to
the confusion. anyway the first thing to do morning is to get new
replacements, but i need also to know if someone else had this problem and if
it was/or not related to the capacitors? did he manage to solve it or not and
how?

thanx

"d6xkr" u45258@uwe wrote in message news:882f878cb28b5@uwe...
hi


my monitor has pin cushion effect problem, and the picture edges are out
of
the view. the monitor controls don't solve it as the (horizontal size)/
(pincushion\trapezoid) controls don't have effect anymore. this problem is
the same as this one posted here
http://www.electronicskb.com/Uwe/For...uashed-picture

but no body offers a solution. i already opened the monitor case, i found
four chips;

1. LSC506429P 2. TDA4858 3. ATMEL008 4.
KA3842B
JD157V2 67974 24C08
E009C
IJ35BCTBW0025 YTD0021

only two of these i could know what they do, no. 2 and 3.

the first one is motorola and is discontinued, i couldn't find it's
datasheet
so to decide whether was it a culprit or not, i couldn't bring the
datasheet
of the fourth chip either.

the image is normal except for this problem, and all the controls work
fine
except for those i mentioned.

the caps seem to have leaked, but i'm not sure as the monitor was never
opened until the problem showed up which was last thursday. these caps
look
as if they have black heavy dust stuck to thier metal top, and there is
plenty of it everywhere inside but only very few caps have it like this
and
they happen to be arround the four ics i mentioned. but also that
indicates
the leak is old, and the problem appeared three days earlier which adds to
the confusion. anyway the first thing to do morning is to get new
replacements, but i need also to know if someone else had this problem and
if
it was/or not related to the capacitors? did he manage to solve it or not
and
how?

thanx


Seems to me that the advice being given on that forum, whilst not
definitive, is never-the-less exactly right. I would suggest that the first
thing to do would be to check the pincushion amp, and its drive. Also, if
any caps *have* leaked (and you are not confusing the glue that's often
found around their bases, with leaked electrolyte), then they need to be
replaced. Just because they had enough go in them to just about do their job
three days ago, doesn't mean that one of them hasn't gasped its last today.

To use a car analogy, you can drive around today with half a millimetre of
lining material on your brake pads, that stop the car today, and squeal
metal on metal tomorrow ...

The 24C08 is an EEPROM, where all of the setup parameters are stored. It's
not at all unusual for these to get corrupted in TV sets, and to produce
symptoms like you describe, which are not correctable. However, it's often
necessary to pre-program a new blank one with a basic set of parameters,
before it will work.

Finally, a warning. If you are not used to working on monitors, take extreme
care, as they employ switchmode power supplies, which are (literally)
potentially lethal. Also the high voltage generation circuits for the CRT
can give you a nasty bite, as can the CRT itself, long after you have
switched off.

Arfa

Arfa Daily wrote:
hi

[quoted text clipped - 43 lines]

thanx

Seems to me that the advice being given on that forum, whilst not
definitive, is never-the-less exactly right. I would suggest that the first
thing to do would be to check the pincushion amp, and its drive. Also, if
any caps *have* leaked (and you are not confusing the glue that's often
found around their bases, with leaked electrolyte), then they need to be
replaced. Just because they had enough go in them to just about do their job
three days ago, doesn't mean that one of them hasn't gasped its last today.

To use a car analogy, you can drive around today with half a millimetre of
lining material on your brake pads, that stop the car today, and squeal
metal on metal tomorrow ...

The 24C08 is an EEPROM, where all of the setup parameters are stored. It's
not at all unusual for these to get corrupted in TV sets, and to produce
symptoms like you describe, which are not correctable. However, it's often
necessary to pre-program a new blank one with a basic set of parameters,
before it will work.

Finally, a warning. If you are not used to working on monitors, take extreme
care, as they employ switchmode power supplies, which are (literally)
potentially lethal. Also the high voltage generation circuits for the CRT
can give you a nasty bite, as can the CRT itself, long after you have
switched off.

Arfa



hi and thanx for your reply.....

i'm sorry my post didn't show the fourth chip which is;

4. KA3842B and also there was a fifth one......
E009C

i wrote it's data on the back of the paper containing all the data of the
chips i found, it's data are;

5. PM02AF
LM this one i couldn't get any datasheet about
358N

the fourth chip is smps controller, this makes me know only three out of five
chips and i don't know exactly which is the pincushion amp, or where is it's
drive. it's kind of making me handicaped not having the service manual for
this piece of hardware. also i don't have the proper test equips, only an avo
meter, the data sheets and my personal experience.

today i replace the caps that i suspected of having leaked, and the truth to
be said, the pincushion became less by 8mm which is small but positive result.
also i tried to replace the ATMEL 24C08 EEPROM with a new blank one, but i
got a white screen with horizontal bright lines across it, it looked like a
writing paper and i didn't see any thing but shadows of what really was to be
shown behind this new look so i turned back to the old one and every thing is
fine relatively.

the first chip i mentioned "no. 1" is a big ic and since the begining i
suspected it but i don't have it's data sheet as to decide whether or not to
replace it. also it's said to be discontinued which makes me unsure whether
will i find it on the market or not.

as a matter of fact the monitor is eight years old and all of it's capacitors
are probably if not surely much older, so it needs all of it's caps to be
replaced. but i need to have it working as not to be throwing mony away for
nothing.

you are right about being extra careful while working with this type of
hardware, but the smps isn't what i fear. what really makes me sweat my
juices out is the tube itself, when i'm working on it while online i know
that there is a 25+ kv infront of me. one mistake and i might be history and
so i take emergency precautions while working with it. also i have proper
grounding which calms me down a little.

this is all i've got,

hope for the best solution.


thanx all

--
Message posted via ElectronicsKB.com
http://www.electronicskb.com/Uwe/For...epair/200808/1

"d6xkr via ElectronicsKB.com" u45258@uwe wrote in message
news:883aeb25e685c@uwe...
Arfa Daily wrote:
hi

[quoted text clipped - 43 lines]

thanx

Seems to me that the advice being given on that forum, whilst not
definitive, is never-the-less exactly right. I would suggest that the
first
thing to do would be to check the pincushion amp, and its drive. Also, if
any caps *have* leaked (and you are not confusing the glue that's often
found around their bases, with leaked electrolyte), then they need to be
replaced. Just because they had enough go in them to just about do their
job
three days ago, doesn't mean that one of them hasn't gasped its last
today.

To use a car analogy, you can drive around today with half a millimetre of
lining material on your brake pads, that stop the car today, and squeal
metal on metal tomorrow ...

The 24C08 is an EEPROM, where all of the setup parameters are stored. It's
not at all unusual for these to get corrupted in TV sets, and to produce
symptoms like you describe, which are not correctable. However, it's often
necessary to pre-program a new blank one with a basic set of parameters,
before it will work.

Finally, a warning. If you are not used to working on monitors, take
extreme
care, as they employ switchmode power supplies, which are (literally)
potentially lethal. Also the high voltage generation circuits for the CRT
can give you a nasty bite, as can the CRT itself, long after you have
switched off.

Arfa



hi and thanx for your reply.....

i'm sorry my post didn't show the fourth chip which is;

4. KA3842B and also there was a fifth one......
E009C

i wrote it's data on the back of the paper containing all the data of the
chips i found, it's data are;

5. PM02AF
LM this one i couldn't get any datasheet about
358N

the fourth chip is smps controller, this makes me know only three out of
five
chips and i don't know exactly which is the pincushion amp, or where is
it's
drive. it's kind of making me handicaped not having the service manual for
this piece of hardware. also i don't have the proper test equips, only an
avo
meter, the data sheets and my personal experience.

today i replace the caps that i suspected of having leaked, and the truth
to
be said, the pincushion became less by 8mm which is small but positive
result.
also i tried to replace the ATMEL 24C08 EEPROM with a new blank one, but i
got a white screen with horizontal bright lines across it, it looked like
a
writing paper and i didn't see any thing but shadows of what really was to
be
shown behind this new look so i turned back to the old one and every thing
is
fine relatively.

the first chip i mentioned "no. 1" is a big ic and since the begining i
suspected it but i don't have it's data sheet as to decide whether or not
to
replace it. also it's said to be discontinued which makes me unsure
whether
will i find it on the market or not.

as a matter of fact the monitor is eight years old and all of it's
capacitors
are probably if not surely much older, so it needs all of it's caps to be
replaced. but i need to have it working as not to be throwing mony away
for
nothing.

you are right about being extra careful while working with this type of
hardware, but the smps isn't what i fear. what really makes me sweat my
juices out is the tube itself, when i'm working on it while online i know
that there is a 25+ kv infront of me. one mistake and i might be history
and
so i take emergency precautions while working with it. also i have proper
grounding which calms me down a little.

this is all i've got,

hope for the best solution.


thanx all

--

Looking at www.eserviceinfo.com there are a lot of entries for Viewsonic
manuals. I only had a quick skim through, but there seemed to be lots of
listings for the e655 model which might be sufficiently similar to work by
??

The pincushion amp is likely to be discrete rather than a chip, and might be
based around FET on a small heatsink. Geometry correction waveforms are
often fed to it from that 'big' chip. I fear that you will not get too far
on this fault without a 'scope to look at the waveforms. I would absolutely
recommend against employing any kind of 'shotgun' approach at component
replacement, as you are likely to end up with more problems than you started
with.

As for the safety angle, I think you might be misunderstanding the relative
dangers of the HV generator circuitry, and the power supply. Whilst it is
true that the CRT's final anode will have around 25 kv on it, the source
impedance for this supply is relatively high. This means that the available
current at that voltage is quite limited. For sure, if you had a weak heart,
or managed to hang yourself right across that supply, receiving a shock from
it *might*, at a pinch, prove fatal. The much more likely outcome is a
stinging hand - probably with a cut across it where your hand collided with
the chassis during its rapid exit :-) - some words that are completely
new to your children :-) and wounded pride.

On the other hand, the switch mode power supply has around 380v dc on its
front end, and this is derived DIRECTLY from the incoming line voltage by a
bridge rectifier, so a relatively low impedance source with the current
limited *only* by the front end fuse, which is likely to be a 3 or 4 amp
ceramic type. This is enough to kill you. No joke. Fact.

So please take care around that area. Use an isolation transformer if you
have one. Makes life a little bit safer.

Arfa

Arfa Daily wrote:
hi

[quoted text clipped - 95 lines]

thanx all

Looking at www.eserviceinfo.com there are a lot of entries for Viewsonic
manuals. I only had a quick skim through, but there seemed to be lots of
listings for the e655 model which might be sufficiently similar to work by
??

The pincushion amp is likely to be discrete rather than a chip, and might be
based around FET on a small heatsink. Geometry correction waveforms are
often fed to it from that 'big' chip. I fear that you will not get too far
on this fault without a 'scope to look at the waveforms. I would absolutely
recommend against employing any kind of 'shotgun' approach at component
replacement, as you are likely to end up with more problems than you started
with.

As for the safety angle, I think you might be misunderstanding the relative
dangers of the HV generator circuitry, and the power supply. Whilst it is
true that the CRT's final anode will have around 25 kv on it, the source
impedance for this supply is relatively high. This means that the available
current at that voltage is quite limited. For sure, if you had a weak heart,
or managed to hang yourself right across that supply, receiving a shock from
it *might*, at a pinch, prove fatal. The much more likely outcome is a
stinging hand - probably with a cut across it where your hand collided with
the chassis during its rapid exit :-) - some words that are completely
new to your children :-) and wounded pride.

On the other hand, the switch mode power supply has around 380v dc on its
front end, and this is derived DIRECTLY from the incoming line voltage by a
bridge rectifier, so a relatively low impedance source with the current
limited *only* by the front end fuse, which is likely to be a 3 or 4 amp
ceramic type. This is enough to kill you. No joke. Fact.

So please take care around that area. Use an isolation transformer if you
have one. Makes life a little bit safer.

Arfa


hi

this is today's update...

i actually took the ridiculous desition of replacing all the electrolitic
caps as they are the first suspect of any damage to an old circuit. nothing
really changed, i think that the image quality increased but i'm not sure. i
also replaced ic no. 5 because while googling i found some datasheet that
says it's a dual op-amp so i thought that this would be the culprit, but
nothing so far.

an oscilloscope is a very very nice tool to have, but actually i'll be stuck
for a long while with the shotgun policy -which worked with me several. as
you are more knowledgable than me about monitors, i'll imagine that you're a
psychic and you can see inside my pistol and tell me whether the bullet is
close or far. i'll tell you all the details you need, you only have to give
the directions.

actually i don't have children, so don't worry about whatever vocab -i'm not
a minor either :-).

i'll follow this post with another listing all the discrete large triple
legged comonents, whether with heatsinks or not. and i'll try to google thier
datasheets also so stay tuned.

also please try to reply earlier because i waited for your opinion today
morning, and it could have taken a good part in my desition.

ok...

bye.

--
Message posted via ElectronicsKB.com
http://www.electronicskb.com/Uwe/For...epair/200808/1

On Mon, 04 Aug 2008 22:05:59 GMT, "d6xkr" u45258@uwe wrote:

hi


my monitor has pin cushion effect problem, and the picture edges are out of
the view. the monitor controls don't solve it as the (horizontal size)/
(pincushion\trapezoid) controls don't have effect anymore.

Em,. Two thoughts one look for a big diode in front of the line output
transistor or close to the Line OutPut Transformer. When these break
down, they cause the width to go out.The screen gets really wide.

If the screen height is collapsing maybe check for something like a
TDA1675 and associated components, in particular diodes.

Best regards,

Robin

Robin Taylor wrote:
hi

my monitor has pin cushion effect problem, and the picture edges are out of
the view. the monitor controls don't solve it as the (horizontal size)/
(pincushion\trapezoid) controls don't have effect anymore.

Em,. Two thoughts one look for a big diode in front of the line output
transistor or close to the Line OutPut Transformer. When these break
down, they cause the width to go out.The screen gets really wide.

If the screen height is collapsing maybe check for something like a
TDA1675 and associated components, in particular diodes.

Best regards,

Robin

this is the follow up with the discrete transistors i found inisde the
monitor. there are exactly five components of this description, three are
FETs and two are BJTs, and all the rest transistors inside are small TO-92
BJTs, all of them are BJTs. the FETs are all near the power collection, one
just right after the big 220uf/400v cap and it have a big heatsink, i guess
it's a chopper, the second looks nearly the same and is located just beside
the smps transformer, i guess it's a chopper too. the last one is without a
heatsink and is locate nearer to the tube connectors.

BUT on the other hand the BJTs are locate just beside the tube connectors,
particularly beside a plug that is 1x4 grid of connectors, the wires in it
are brown-yellow-blue-red from right to left.
so i guess one of these transistors or both of them are responisble for what
happened.

thier numbers are;

1. C5248 2. 0669A both of them are NPN

the one FET that is near the tube connectors is;

3. 1RFG30

i googled for datasheets, the only one i found was no. 1's datasheet, it
states that it's "High-Voltage Switching (Audio output amplifier transistor,
stabilized power supply transistor)"
and i think this is the one. the thing is i tested the BJTs and they seemed
to be operational, i'm not sure but i know how to test a BJT with an avo
meter.

also the no. 1 transistor is attached to a metal frame mounted on the pcb
with tin solder, rather than attached to a heatsink.

i'll try to replace them and see what happens, i hope i find them all on the
market. i don't know what viewsonic was thinking, manufacturing it's products
with these ancient components. it seems as they manufactured these things in
the ice age, then stored them into the ice, and when the ice melted by the
global warming, they got them out and began selling.

whatever..........

as for the image, actually it's not collapsed i'd rather say that it's
widened but not so much. it looks like a chair that someone was sitting on
then stood and the cushion on the chair didn't return back to it's normal
shape. it just stayed compressed inside, the image just looks like that, with
it's outer corners wider than the middle and spreading outside the view. they
call this simptom pincshion effect, also if you were following the horizontal
size doesn't have any effect whatsoever.

actually there is that diode just after the smps transformer but i don't know
exactly if it is operational or not as it didn't grab my attention. i'll
check on it in the morning.

thanx for the ideas

--
Message posted via ElectronicsKB.com
http://www.electronicskb.com/Uwe/For...epair/200808/1

On Wed, 06 Aug 2008 23:27:21 GMT, "d6xkr via ElectronicsKB.com"
u45258@uwe wrote:

actually there is that diode just after the smps transformer but i don't know
exactly if it is operational or not as it didn't grab my attention. i'll
check on it in the morning.


The Diodes after the the SMPSU are secondary rectifiers, they're most
probably ok.

You are looking for a big diode like this:
http://www.nxp.com/acrobat_download/...ts/BY448_2.pdf
near the line output transistor, this is the transistor most likely
screwed to the aluminium box/heatsink surounding the line output
transformer. http://en.wikipedia.org/wiki/Flyback_transformer

I have seen this diode fail, in a few monitors, when it fails it
effects width and east/west correct,(pincusion).
All this said its been at least 10 years since I was fixing monitors.


Good luck,

Robin

Robin Taylor wrote:
actually there is that diode just after the smps transformer but i don't know
exactly if it is operational or not as it didn't grab my attention. i'll
check on it in the morning.

The Diodes after the the SMPSU are secondary rectifiers, they're most
probably ok.

You are looking for a big diode like this:
http://www.nxp.com/acrobat_download/...ts/BY448_2.pdf
near the line output transistor, this is the transistor most likely
screwed to the aluminium box/heatsink surounding the line output
transformer. http://en.wikipedia.org/wiki/Flyback_transformer

I have seen this diode fail, in a few monitors, when it fails it
effects width and east/west correct,(pincusion).
All this said its been at least 10 years since I was fixing monitors.

Good luck,

Robin

i red this paper which gave me an idea about the larger picture of horizontal
sync. http://www.repairfaq.org/sam/reppic/horiz-tv.pdf, and i think it said
the same as you suggested, there is a problem with a peripheral component
around the flyback transformer. i also checked on the flyback trans. and the
components around it, i found the damper diode and it checked right it's
operational, but it looks like a regular diode except for it's a little bulky
and brownish in color. i found also another diode that looks like the one the
datasheet you posted mentioned, it has a glass casing and it's oval in shape
but it's very small and white and it's operational too.

the numbers of both the diodes are;

1. rg4a bulky one 2. 33ipn small one

finding that every thing is fine with these, i tried to check every component
around the flyback transformer. every thing checked ok, nothing seemed
damaged, there were two more diodes and they were ok, there was a coil and it
checked ok too. and a n-p-n BJT and it checked ok too. an elecrolytic
capacitor was there too and it was fine, but i'll recheck on it again may be
replace it, i already got a new spare one.

not only this i checked on all the FETs on the pcb and they all were n-
channel type and they were fine. i have diode checker in my multi-meter and
it shows the biasing voltage if the diode is operational. all of the solid
state devices i've checked were ok. all the BJTs around were ok too, and the
diodes that were away from the flyback transformer were ok too. everything
just looks fine, no burnes, no exploding or leaking devices, or damaged not
even a small resistor, which adds much to my confusion. does this have any
thing to do with damage to the flyback trans. itself?

hope any solution that fixes this situation appears in the horizon.

thanx

--
Message posted via ElectronicsKB.com
http://www.electronicskb.com/Uwe/For...epair/200808/1

On Thu, 07 Aug 2008 14:52:48 GMT, "d6xkr via ElectronicsKB.com"
u45258@uwe wrote:

rg4a bulky one

sounds likey... They are not always in that round package, sometimes
the are just large cylndrical types same pagage as a large rectifier.

If it isnt the diode.. then maybe one of the big pulse caps...
http://www.cricklewoodelectronics.co...cat=153&page=1
Unless you have an ass kick component tester, and I'm gussing you
don't, substitution is the only way to prove them good, this is where
having a huge box full of old monitor boards would come in handy...
;-)

Good Luck

Robin

"d6xkr via ElectronicsKB.com" u45258@uwe wrote in message
news:885177717897a@uwe...
Robin Taylor wrote:
actually there is that diode just after the smps transformer but i don't
know
exactly if it is operational or not as it didn't grab my attention. i'll
check on it in the morning.

The Diodes after the the SMPSU are secondary rectifiers, they're most
probably ok.

You are looking for a big diode like this:
http://www.nxp.com/acrobat_download/...ts/BY448_2.pdf
near the line output transistor, this is the transistor most likely
screwed to the aluminium box/heatsink surounding the line output
transformer. http://en.wikipedia.org/wiki/Flyback_transformer

I have seen this diode fail, in a few monitors, when it fails it
effects width and east/west correct,(pincusion).
All this said its been at least 10 years since I was fixing monitors.

Good luck,

Robin

i red this paper which gave me an idea about the larger picture of
horizontal
sync. http://www.repairfaq.org/sam/reppic/horiz-tv.pdf, and i think it
said
the same as you suggested, there is a problem with a peripheral component
around the flyback transformer. i also checked on the flyback trans. and
the
components around it, i found the damper diode and it checked right it's
operational, but it looks like a regular diode except for it's a little
bulky
and brownish in color. i found also another diode that looks like the one
the
datasheet you posted mentioned, it has a glass casing and it's oval in
shape
but it's very small and white and it's operational too.

the numbers of both the diodes are;

1. rg4a bulky one 2. 33ipn small one

finding that every thing is fine with these, i tried to check every
component
around the flyback transformer. every thing checked ok, nothing seemed
damaged, there were two more diodes and they were ok, there was a coil and
it
checked ok too. and a n-p-n BJT and it checked ok too. an elecrolytic
capacitor was there too and it was fine, but i'll recheck on it again may
be
replace it, i already got a new spare one.

not only this i checked on all the FETs on the pcb and they all were n-
channel type and they were fine. i have diode checker in my multi-meter
and
it shows the biasing voltage if the diode is operational. all of the solid
state devices i've checked were ok. all the BJTs around were ok too, and
the
diodes that were away from the flyback transformer were ok too. everything
just looks fine, no burnes, no exploding or leaking devices, or damaged
not
even a small resistor, which adds much to my confusion. does this have any
thing to do with damage to the flyback trans. itself?

hope any solution that fixes this situation appears in the horizon.

thanx

--
Message posted via ElectronicsKB.com
http://www.electronicskb.com/Uwe/For...epair/200808/1

To be honest, I think that you have reached the point where you can't go
much further without a set of schematics and a 'scope. You need to see how
E-W raster correction modulation is achieved, and then to see why it's not
happening. It's usually not quite as straightforward on computer monitors,
as it is on a TV set. This is because the TV set runs at a constant line
rate, so only one condition needs to be corrected for, whereas a monitor has
to run at a number of different line and frame rates. As the line rate
changes, so does the tuning of the flyback transformer, and the deflection
yoke. This results in major width and geometry variations. To compensate for
all these conditions, the E-W correction often takes the form of a FET
modulator stage for the line output HT supply. This is driven from the sync
processor and timebase chip (often a big one at the front of the chassis)
which draws its correction data from the EEPROM. When you change the
parameters via the front panel user controls, these are stored back in the
EEPROM by the same chip. Brightness and contrast data are also stored in
here, as well as auto grey scale and beam current data, which is why the new
blank chip that you tried, didn't work.

I don't know what else to suggest that you do. Did you look on
eserviceinfo.com to see if the Viewsonic with almost the same model number
that's listed, was similar ?

This site claims to have the e653 manual for free, but they need you to sign
up for their newsletter

http://www.protech2u.com/download.html

Arfa

Arfa Daily wrote:

To be honest, I think that you have reached the point where you can't go
much further without a set of schematics and a 'scope.

He may just be lucky if he finds the Fet or darlington which drive the
EW-correction and if this is shorted. Often there is an inductivity in
the collector path to block horizontal frequency - this may be burnt
then, too, sometimes opened.

You need to see how
E-W raster correction modulation is achieved,

Good explanation.

I don't know what else to suggest that you do. Did you look on
eserviceinfo.com to see if the Viewsonic with almost the same model number
that's listed, was similar ?

I was often surprised to find almost identical modules in different
models :-).

Regards,
H.