Viewsonic E790 With Undocumented Features

[Nate Smith]

This moniter appears to have developed a zoom function, i dont know
exactly what else to call it, esp when it is turned of cold or waking
up from low power mode... picture randomly expanding/shrinking by 5 or
10 percent... whats your take on this? power supply regulation? bad
caps?

Thanks
Nate

 

[Joe Smith]

Flyback
joe

 

[Spudley]

Yes, poor power supply regulation, probably due to bad caps.

 

[Jerry G.]

Poor power supply regulation due to some components starting to fail, many
times be a number of capacitors. This type of symptom can also be attributed
to poor high voltage regulation as well. The primary power supply must be
verified first.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
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This moniter appears to have developed a zoom function, i dont know
exactly what else to call it, esp when it is turned of cold or waking
up from low power mode... picture randomly expanding/shrinking by 5 or
10 percent... whats your take on this? power supply regulation? bad
caps?

Thanks
Nate

 

[James Sweet]

Yes, poor power supply regulation, probably due to bad caps.

Does just the horizintal width expand? If so replace the 4N35 optoisolator
in the power supply before it takes out the vertical output chip. If this is
the same guts as the PF series this is a very common problem. I've used a
4N26 as a replacement a few times as it's all I had and it worked fine.

 

[Nate Smith]

Does just the horizintal width expand? If so replace the 4N35 optoisolator
in the power supply before it takes out the vertical output chip. If this is
the same guts as the PF series this is a very common problem. I've used a
4N26 as a replacement a few times as it's all I had and it worked fine.

Nope, its vertical also.. which is what led me away from deflection
issues...

Nate

 

[Nate Smith]

Will an ESR meter check caps in circuit? Where can I get a good one
without breaking the bank?

Nate

 

[James Sweet]

Will an ESR meter check caps in circuit? Where can I get a good one
without breaking the bank?

Nate

Yes it will, I've got the CapWizard that I've been happy with, but the Dick
Smith one is a lot cheaper and supposedly pretty good, I just hadn't heard
of it at the time.

You should still check the power supply, pick an output and tack solder a
wire to it and another to ground. Clip a DMM to it and monitor the voltage
while you use the monitor and see if it creeps up.