Sega-Naomi

Hi there.



Picked up an universal lately and that strange monitor problem just appeared.



It starts just normal and after smth like 30 secs after the game is loaded i can hear that noise coming from the monitor, a bit like the noise that a degauss makes when you press the button. Immediately after that the colors are weird :







An Idea anyone ?

sounds like either the degauss ptc is shorting or if you have a manual degauss switch then there is a problem with that or the wiring

Well i must add that when i press the demag button the picture becomes normal again.. but for 2 or 3 minutes then it starts again.

After you hit the degauss button, wait about 10 seconds, then turn the machine off. Disconnect the degauss plug from the monitor chassis and start the cab back up to see if the color issues happen again. I bet it will be fine, which means there is something wrong with the degauss circuit, either the button in the psu is faulty (shoring out) or possibly the thermistor used in the coil circuit?

Gonna try that tomorrow or Friday. Thanks for the help.

Got some time to do some testing.



Checked the voltage => ok

Disconnected degauss plug from the chassis => still the same.



:smt012

well i actually think the shadow mask is damaged inside the tube,that would explain the degauss situation

has this cabinet fallen over or been hit with anything

grantspain wrote:well I actually think the shadow mask is damaged inside the tube,that would explain the degauss situation

has this cabinet fallen over or been hit with anything

Not to my knowledge.

This is strange sometimes the problem will appear 2 mins after the cab is powered up and sometimes 1 hour after.

with the degauss disconnected and it still does it proves that its a tube fault

I read somewhere that mask damage is not uniform nor circular and this is the case. Annoying.