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Power supply problem on touchscreen contoller

I have an old IRIS 4d/35 system with touchscreen capabilities and display is CRT type.

Recently we upgraded the system to run on LCD displays where we needed to provide the touchscreen controller with a separate power supply since the power for the controller was previously drawn from the CRT power supply.

However when a new switching power supply was used the touchscreen did not work. Reverting back to the supply from the CRT works flawlessly.

The supplies required for the touchscreen controller are 12V, -12V and 5V. The CRT power supply had a common ground and so does the new switching power supply.

Any idea what could be the problem with the new power supply. Any advise would be very much appreciated.
 
I've checked on this and this is what I found.

The original power supply is proving 5V - 2A, +12V - 0.3A, -12V - 0.2A
While the replacement power supply 5V - 4A, +12V - 2A, -12V - 0.5A

Has the common ground of the +12V and +5V effect on the -12V in anyway?
 
M

mike

Jan 1, 1970
0
I've checked on this and this is what I found.

The original power supply is proving 5V - 2A, +12V - 0.3A, -12V - 0.2A
While the replacement power supply 5V - 4A, +12V - 2A, -12V - 0.5A

Has the common ground of the +12V and +5V effect on the -12V in anyway?
What do you mean by proving?
Do you mean "reading the labels on the power supplies?"
With the system operating, what voltages did you measure?
If you got the right voltmeter readings, look with a scope
to see if it's really DC.
Power supplies have a minimum load requirement. Sometimes
that's supplied inside. Other times, you're required to provide
some minimum external load for everything to work out right.

However when a new switching power supply was used the touchscreen did
not work. Reverting back to the supply from the CRT works flawlessly.

Exactly what was the symptom of "did not work?"

Does this mean that you left the touch screen attached to the LCD and only
swapped out the power supply?

Depending on the mechanical configuration, noise from the LCD backlight
might
affect the touch screen. You can check this by distancing the touch
from the lcd.
 
What do you mean by proving?

Do you mean "reading the labels on the power supplies?"

With the system operating, what voltages did you measure?

If you got the right voltmeter readings, look with a scope

to see if it's really DC.

Power supplies have a minimum load requirement. Sometimes

that's supplied inside. Other times, you're required to provide

some minimum external load for everything to work out right.



However when a new switching power supply was used the touchscreen did

not work. Reverting back to the supply from the CRT works flawlessly.



Exactly what was the symptom of "did not work?"



Does this mean that you left the touch screen attached to the LCD and only

swapped out the power supply?



Depending on the mechanical configuration, noise from the LCD backlight

might

affect the touch screen. You can check this by distancing the touch

from the lcd.


What do you mean by proving? Sorry that was a spelling mistake. I meant providing.

Exactly what was the symptom of "did not work?"
The touchscreen did not respond to any touch inputs.
Does this mean that you left the touch screen attached to the LCD and only

swapped out the power supply?
Yes that's what I did.

Will check the output with a scope since the voltages are not far apart in comparison.
 
N

N_Cook

Jan 1, 1970
0
I have an old IRIS 4d/35 system with touchscreen capabilities and display is CRT type.

Recently we upgraded the system to run on LCD displays where we needed to
provide the touchscreen controller with a separate power supply since the
power for the controller was previously drawn from the CRT power supply.
However when a new switching power supply was used the touchscreen did
not work. Reverting back to the supply from the CRT works flawlessly.
The supplies required for the touchscreen controller are 12V, -12V and
5V. The CRT power supply had a common ground and so does the new switching
power supply.
Any idea what could be the problem with the new power supply. Any advise
would be very much appreciated.

Does the touchscreen use a high "static" voltage (ultimately via the CRT
accelerating voltage) as part of its operation ?
 
I have an old IRIS 4d/35 system with touchscreen capabilities and display is CRT type.



Recently we upgraded the system to run on LCD displays where we needed to provide the touchscreen controller with a separate power supply since the power for the controller was previously drawn from the CRT power supply.



However when a new switching power supply was used the touchscreen did not work. Reverting back to the supply from the CRT works flawlessly.



The supplies required for the touchscreen controller are 12V, -12V and 5V. The CRT power supply had a common ground and so does the new switching power supply.



Any idea what could be the problem with the new power supply. Any advise would be very much appreciated.


When we upgraded from CRT to LCD the touchscreen was upgraded at the same time. I suspect the problem is with the power supply as reverting back to the original solves the problem.
 
C

Cydrome Leader

Jan 1, 1970
0
I have an old IRIS 4d/35 system with touchscreen capabilities and display is CRT type.

somehow your post was stuck somewhere for about 15 years.

not sure about the touch screen problem though.

I have to ask- what is this thing still being used for??
 
[email protected] wrote:









Are you saying the touchscreen placed on the LCD panel works

fine when powered by the old power supply? If so, then that eliminates

the LCD drive signals as a concern for fouling up the signals on the

touch panel. CRTs have some noise on the front, but the shadow mask

generally isolates the front from a lot of noise. LCDs are REALLY

noisy beasts, with 50V pulses on a zillion "wires" on the front

of the panel.



But, assuming it really is only the power supply that is different, then

it is either the power-up sequence or noise. Possibly the new supply

voltages come up in a different sequence than the old one, or there

is noise on one or more of the voltages.



Jon

Will check on the sequence on power up, thanks Jon.
 
I have an old IRIS 4d/35 system with touchscreen capabilities and display is CRT type.



Recently we upgraded the system to run on LCD displays where we needed to provide the touchscreen controller with a separate power supply since the power for the controller was previously drawn from the CRT power supply.



However when a new switching power supply was used the touchscreen did not work. Reverting back to the supply from the CRT works flawlessly.



The supplies required for the touchscreen controller are 12V, -12V and 5V. The CRT power supply had a common ground and so does the new switching power supply.



Any idea what could be the problem with the new power supply. Any advise would be very much appreciated.
 
somehow your post was stuck somewhere for about 15 years.



not sure about the touch screen problem though.



I have to ask- what is this thing still being used for??

Cydrome,

the 4d/35 is being used on a flight simulator. The company is planning to replace the iris system but I would still have to maintain the old simulator.
 
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