Unknow Brazilian Monitor - Help

[m.andrade1]

Hello Friends
Got this Brazilian monitor call "Eletrocyan" possible a clone from some china assembly like Wey-la, i have an overall good colors and screen but recently on some very bright areas it makes some image distortion, like the above, anyone know if some specific capacitor can be replaced, to minimize this problem, didnt want to re-cap it all, any tips will be very apreciated. !
Using Ati-4350 + jpac + Calamity CRT_Emudrivers Windows XP + Groovymame







Thatīs the problem distortion on very white areas:

[Paradroid]

The monitor might not actually be defective. Rather, this kind of behavior may be a design limitation.

Many consumer TVs also do quite poorly with this test (I have seen similar but less severe results with Philips and Grundig TVs) while some high-end TVs (e.g. Loewe) do very well with it. I have seen a Sony BVM that didn't even flinch when running this test! The geometry stayed perfect.

The in-game screenshot you posted looks awesome to me. Great color and focus! I wouldn't worry so much about that Nokia test pattern  unless you're convinced the monitor didn't do that to start with.

[m.andrade1]

Hello Paradroid
Thank you so much for your feedback, i think you are right i will start to worry about with cap-kit when the monitor became very bad, now will go on like this.
Thanks
Marcos

[lilshawn]

this is called "BLOOMING" the surge in the B+ causes a voltage change which affects the horizontal and vertical scan.

Turing the brightness DOWN will help alot. don't forget, this is a CRT not a super bright plasma display. it's not going to be eye melting bright.

if the monitor is quite old, consider changing the B+ cap with a new one to help smooth out the voltage changes (the biggest black capacitor next the the heatsink) it may be getting weak.

if those things don't help, you have a power regulation problem that will require a schematic to diagnose and fix.

[m.andrade1]

Hello lilshawn
Thank you so much for your help, you mean change this black 220Uf 250v cap especific, could reduce the Blooming ?

Thanks
Marcos

[lilshawn]

it could be the one. if the chassis has not been worked on before, it's probably a good idea to replace all the capacitors. as they get old, they lose their ability to store and deliver power properly, causing all sorts of issues.

these capacitors could be several years old now... good name brand capacitors (nichicon, panasonic, etc) have a lifetime of a few thousand HOURS. (about 5000) these off brand capacitors (hitano, capxon, etc) would likely be way less than that.

I recommend replacing all the "big" capacitors like the large low voltage 1000/1500/2200uF sized caps and the high voltage capacitors (100/200/250 volt) with new capacitors. I wouldn't worry about the smaller 1/10 uf that are under 50 volts, they are probably still okay.

after you change them, i feel much of the issues you are seeing will be considerably reduced.

[m.andrade1]

Hello lilshawn
Thank you so much again ! you are absolute right, will focus on the biggest capacitors, then will test, maybe will save some job if the image becomes better, dont need to cap it all, in overal i already get a good colors and screen qualitiy, the only thing is those white bright areas with these "blooming" effect that are making me crazy.






Thanks a lot
Marcos

[lilshawn]

It's always going to bloom a little bit. It's just the nature of the way the monitor works. But replacing weakened caps will certainly help reduce the amount it does.