Advice on yoke (scan coil) / CRT replacement

A

Adrian Smith

Guest
I have an Iiyama Visionmaster Pro 410 with a severely scratched CRT face
which would not polish out. I replaced the entire CRT assembly including
scan coils with one from a scrap Dell P791 which uses the same type of tube
(Mitsubishi Natural Flat 17") but different coils. A quick check on the coil
resistances proved them to be the same readings as the original but I cannot
check their inductance. I connected the rotation coil and the coils for
convergence and found the image when powered up is sound geometry wise
indicating the scan coils are probably compatible.

However, the line output transistor seems to be running a few degrees hotter
than normal, but the unit worked fine for two days. The greyscale needs
adjusting slightly but this is not possible as I don't have Iiyama's
software to set it up.

It is too much hassle to swap the scan coils over between the two tubes and
I can live with the greyscale problem but would the monitor be OK long term
with these substitute coils? It was suggested to uprate the line output
transistor to a 25A transistor instead of the fitted 20A but I don't think
it will make much difference.

Any suggestions before I bin the old CRT?
Also does anyone have the service software for this monitor?

Any help would be greatly appreciated.

Adrian
 
What's a few degrees?

--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work. To
contact me, please use the feedback form on the S.E.R FAQ Web sites.



"Adrian Smith" <adrian-smith31@bollocksmail.com> writes:

I have an Iiyama Visionmaster Pro 410 with a severely scratched CRT face
which would not polish out. I replaced the entire CRT assembly including
scan coils with one from a scrap Dell P791 which uses the same type of tube
(Mitsubishi Natural Flat 17") but different coils. A quick check on the coil
resistances proved them to be the same readings as the original but I cannot
check their inductance. I connected the rotation coil and the coils for
convergence and found the image when powered up is sound geometry wise
indicating the scan coils are probably compatible.

However, the line output transistor seems to be running a few degrees hotter
than normal, but the unit worked fine for two days. The greyscale needs
adjusting slightly but this is not possible as I don't have Iiyama's
software to set it up.

It is too much hassle to swap the scan coils over between the two tubes and
I can live with the greyscale problem but would the monitor be OK long term
with these substitute coils? It was suggested to uprate the line output
transistor to a 25A transistor instead of the fitted 20A but I don't think
it will make much difference.

Any suggestions before I bin the old CRT?
Also does anyone have the service software for this monitor?

Any help would be greatly appreciated.

Adrian
Click to expand...
 
Degrees centigrade; the transistor is not too hot to touch but notably
hotter than another working unit with the original CRT.

"Sam Goldwasser" <sam@saul.cis.upenn.edu> wrote in message
news:6w4qtarph1.fsf@saul.cis.upenn.edu...
What's a few degrees?

--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work.
To
contact me, please use the feedback form on the S.E.R FAQ Web sites.



"Adrian Smith" <adrian-smith31@bollocksmail.com> writes:

I have an Iiyama Visionmaster Pro 410 with a severely scratched CRT face
which would not polish out. I replaced the entire CRT assembly including
scan coils with one from a scrap Dell P791 which uses the same type of
tube
(Mitsubishi Natural Flat 17") but different coils. A quick check on the
coil
resistances proved them to be the same readings as the original but I
cannot
check their inductance. I connected the rotation coil and the coils for
convergence and found the image when powered up is sound geometry wise
indicating the scan coils are probably compatible.

However, the line output transistor seems to be running a few degrees
hotter
than normal, but the unit worked fine for two days. The greyscale needs
adjusting slightly but this is not possible as I don't have Iiyama's
software to set it up.

It is too much hassle to swap the scan coils over between the two tubes
and
I can live with the greyscale problem but would the monitor be OK long
term
with these substitute coils? It was suggested to uprate the line output
transistor to a 25A transistor instead of the fitted 20A but I don't
think
it will make much difference.

Any suggestions before I bin the old CRT?
Also does anyone have the service software for this monitor?

Any help would be greatly appreciated.

Adrian
Click to expand...
 
Adrian Smith:
A 25 A transistor instead of a 20 A transistor WILL NOT solve the heat
problem........ the same amount of power will still be dissipated in the
form of heat..... the SAME amount of heat. Also, the gray scale problem
is NOT caused by scan coils but rather the CRT itself and the support
circuitry in the monitor...... usually there are adjustments..... over a
limited range... that will compensate for the RGB gun imbalance inherent in
CRTs.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
------------------------------


"Adrian Smith" <adrian-smith31@bollocksmail.com> wrote in message
news:1078065502.12380.0@damia.uk.clara.net...
Degrees centigrade; the transistor is not too hot to touch but notably
hotter than another working unit with the original CRT.

"Sam Goldwasser" <sam@saul.cis.upenn.edu> wrote in message
news:6w4qtarph1.fsf@saul.cis.upenn.edu...
What's a few degrees?

--- sam | Sci.Electronics.Repair FAQ Home Page:
http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Site Info:
http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work.
To
contact me, please use the feedback form on the S.E.R FAQ Web sites.



"Adrian Smith" <adrian-smith31@bollocksmail.com> writes:

I have an Iiyama Visionmaster Pro 410 with a severely scratched CRT
face
which would not polish out. I replaced the entire CRT assembly
including
scan coils with one from a scrap Dell P791 which uses the same type of
tube
(Mitsubishi Natural Flat 17") but different coils. A quick check on
the
coil
resistances proved them to be the same readings as the original but I
cannot
check their inductance. I connected the rotation coil and the coils
for
convergence and found the image when powered up is sound geometry wise
indicating the scan coils are probably compatible.

However, the line output transistor seems to be running a few degrees
hotter
than normal, but the unit worked fine for two days. The greyscale
needs
adjusting slightly but this is not possible as I don't have Iiyama's
software to set it up.

It is too much hassle to swap the scan coils over between the two
tubes
and
I can live with the greyscale problem but would the monitor be OK long
term
with these substitute coils? It was suggested to uprate the line
output
transistor to a 25A transistor instead of the fitted 20A but I don't
think
it will make much difference.

Any suggestions before I bin the old CRT?
Also does anyone have the service software for this monitor?

Any help would be greatly appreciated.

Adrian
Click to expand...
 
Hi,
Thanks for the info but the monitor has no adjustments for cut off and gain
of the guns as this is done via a service mode or via service software.
There is a connector on the mainboard labelled 'SC' which has nothing
connected. Two of the pins are the SDA and SCL lines of the I2C bus so I'm
guessing SC means Service Connector and some sort of service jig attaches to
this for adjustment.

Adrian

"Sofie" <sofie@olypen.com> wrote in message
news:10441v65sst561b@corp.supernews.com...
Adrian Smith:
A 25 A transistor instead of a 20 A transistor WILL NOT solve the heat
problem........ the same amount of power will still be dissipated in the
form of heat..... the SAME amount of heat. Also, the gray scale problem
is NOT caused by scan coils but rather the CRT itself and the support
circuitry in the monitor...... usually there are adjustments..... over a
limited range... that will compensate for the RGB gun imbalance inherent
in
CRTs.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
------------------------------


"Adrian Smith" <adrian-smith31@bollocksmail.com> wrote in message
news:1078065502.12380.0@damia.uk.clara.net...
Degrees centigrade; the transistor is not too hot to touch but notably
hotter than another working unit with the original CRT.

"Sam Goldwasser" <sam@saul.cis.upenn.edu> wrote in message
news:6w4qtarph1.fsf@saul.cis.upenn.edu...
What's a few degrees?

--- sam | Sci.Electronics.Repair FAQ Home Page:
http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Site Info:
http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer
work.
To
contact me, please use the feedback form on the S.E.R FAQ Web sites.



"Adrian Smith" <adrian-smith31@bollocksmail.com> writes:

I have an Iiyama Visionmaster Pro 410 with a severely scratched CRT
face
which would not polish out. I replaced the entire CRT assembly
including
scan coils with one from a scrap Dell P791 which uses the same type
of
tube
(Mitsubishi Natural Flat 17") but different coils. A quick check on
the
coil
resistances proved them to be the same readings as the original but
I
cannot
check their inductance. I connected the rotation coil and the coils
for
convergence and found the image when powered up is sound geometry
wise
indicating the scan coils are probably compatible.

However, the line output transistor seems to be running a few
degrees
hotter
than normal, but the unit worked fine for two days. The greyscale
needs
adjusting slightly but this is not possible as I don't have Iiyama's
software to set it up.

It is too much hassle to swap the scan coils over between the two
tubes
and
I can live with the greyscale problem but would the monitor be OK
long
term
with these substitute coils? It was suggested to uprate the line
output
transistor to a 25A transistor instead of the fitted 20A but I don't
think
it will make much difference.

Any suggestions before I bin the old CRT?
Also does anyone have the service software for this monitor?

Any help would be greatly appreciated.

Adrian
Click to expand...
 
Adrian Smith:
Yes, the monitor circuitry DOES have adjustments for gray scale tracking
but, as you discovered, these adjustments are carried out in software just
like many models consumer televisions in the past 10 years or so. .... no
matter whether or not the gray scale is aligned via physical controls or
through software.... they are adjustments never the less.
At the current low prices of new CRT based computer monitors these days you
might be best advised to stop wasting your time and money and just replace
it with a new one..... or a used monitor may be available usually at good
prices at computer repair places, etc.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
-------------------------




"Adrian Smith" <adrian-smith31@bollocksmail.com> wrote in message
news:1078070255.10795.0@doris.uk.clara.net...
Hi,
Thanks for the info but the monitor has no adjustments for cut off and
gain
of the guns as this is done via a service mode or via service software.
There is a connector on the mainboard labelled 'SC' which has nothing
connected. Two of the pins are the SDA and SCL lines of the I2C bus so I'm
guessing SC means Service Connector and some sort of service jig attaches
to
this for adjustment.

Adrian

"Sofie" <sofie@olypen.com> wrote in message
news:10441v65sst561b@corp.supernews.com...
Adrian Smith:
A 25 A transistor instead of a 20 A transistor WILL NOT solve the heat
problem........ the same amount of power will still be dissipated in the
form of heat..... the SAME amount of heat. Also, the gray scale
problem
is NOT caused by scan coils but rather the CRT itself and the support
circuitry in the monitor...... usually there are adjustments..... over
a
limited range... that will compensate for the RGB gun imbalance
inherent
in
CRTs.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
------------------------------


"Adrian Smith" <adrian-smith31@bollocksmail.com> wrote in message
news:1078065502.12380.0@damia.uk.clara.net...
Degrees centigrade; the transistor is not too hot to touch but notably
hotter than another working unit with the original CRT.

"Sam Goldwasser" <sam@saul.cis.upenn.edu> wrote in message
news:6w4qtarph1.fsf@saul.cis.upenn.edu...
What's a few degrees?

--- sam | Sci.Electronics.Repair FAQ Home Page:
http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Site Info:
http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer
work.
To
contact me, please use the feedback form on the S.E.R FAQ Web sites.



"Adrian Smith" <adrian-smith31@bollocksmail.com> writes:

I have an Iiyama Visionmaster Pro 410 with a severely scratched
CRT
face
which would not polish out. I replaced the entire CRT assembly
including
scan coils with one from a scrap Dell P791 which uses the same
type
of
tube
(Mitsubishi Natural Flat 17") but different coils. A quick check
on
the
coil
resistances proved them to be the same readings as the original
but
I
cannot
check their inductance. I connected the rotation coil and the
coils
for
convergence and found the image when powered up is sound geometry
wise
indicating the scan coils are probably compatible.

However, the line output transistor seems to be running a few
degrees
hotter
than normal, but the unit worked fine for two days. The greyscale
needs
adjusting slightly but this is not possible as I don't have
Iiyama's
software to set it up.

It is too much hassle to swap the scan coils over between the two
tubes
and
I can live with the greyscale problem but would the monitor be OK
long
term
with these substitute coils? It was suggested to uprate the line
output
transistor to a 25A transistor instead of the fitted 20A but I
don't
think
it will make much difference.

Any suggestions before I bin the old CRT?
Also does anyone have the service software for this monitor?

Any help would be greatly appreciated.

Adrian
Click to expand...
 
"Adrian Smith" <adrian-smith31@bollocksmail.com> writes:

RE: How hot the HOT?

Degrees centigrade; the transistor is not too hot to touch but notably
hotter than another working unit with the original CRT.
Click to expand...
If it's not too hot to hold your finger on it (insulated of course!), it's
probably OK. Did you install it with heatsink compound and/or a heat
conducting pad?

--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work. To
contact me, please use the feedback form on the S.E.R FAQ Web sites.
 
Hi,
Its mounted as originally with a thermal transfer insulating pad. Although
very warm, its not too hot to touch and you can leave your finger on it
without burning so I guess I am worrying over nothing.
Thanks for your help.

As for the greyscale problem, a circuitry hack will probably work if I can
just find a datasheet for the video IC...
Its all good experience...

Adrian

"Sam Goldwasser" <sam@saul.cis.upenn.edu> wrote in message
news:6wbrnhbf9x.fsf@saul.cis.upenn.edu...
"Adrian Smith" <adrian-smith31@bollocksmail.com> writes:

RE: How hot the HOT?

Degrees centigrade; the transistor is not too hot to touch but notably
hotter than another working unit with the original CRT.

If it's not too hot to hold your finger on it (insulated of course!), it's
probably OK. Did you install it with heatsink compound and/or a heat
conducting pad?

--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work.
To
contact me, please use the feedback form on the S.E.R FAQ Web sites.
Click to expand...
 
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