Nanao MS8-26SU Blank Screen Question...

[channel27]

Can anyone enlighten me on this

[Jess--]

in your situation I would be checking the earth lines on the video leads between your game board and the monitor before anything else.

my next port of call would be to have a good look around the board on the neck of the tube looking for dry joints.

Next time it fails on you try these 2 things.... 1 wiggle the leads between the game and monitor, 2. with the plastic handle of a screwdriver LIGHTLY tap the board on the neck of the tube (I really do mean lightly this is by far the most delicate area on a monitor).

[channel27]

Thanks Jess,
I checked all the conections with a multimeter and they seem fine so I took the chassis out to look for dry joints. This too looked fine so I cleaned the pcb up a bit (mainly to stop the girlfriend moaning about the state of my hands and subsequent state of everything I touched in the house

[Jess--]

the fact that you were getting a grey screen when you turned up the brightness showed that the anode was up and running ok, along with the actual drive circuits for the colour guns. what you were describing was loss of input to the video amps, normally this would only affect one colour (unless it was loss of ground between th game and monitor or a supply line to the amplifiers), that was why I pointed you in the direction of your cabling and the tube base,

hopefuly just by moving it around and cleaning it up you have knocked the dry joint and it is now working again, if it goes wrong on you again have a very good look around the tube base

[channel27]

Thanks again Jess for the reply,
It is happening again yes. It seems that the cycle goes like this... I discharge the monitor, take out the chassis, fiddle with it a bit  , put it back in and the picture runs well. However, the more times I turn it on and off the less chance I have of getting a picture on the screen and it takes longer and longer to "settle" until it wont come on at all. I'm guessing there's a dry joint somewhere on the neck board that I couldnt see. Is it normal that with a dry joint, discharging the monitor and taking the chassis out would temporarily cause the monitor to work? I guess it depends the severity of the dry joint and which components it is on i suppose?
Thanks again,
Channel27

[Ken Layton]

Jomac in Australia is the Nanao expert. I suggest contacting him. I think he has photos of what to do to correct this problem.

[Jomac]

Channel27 , 
As frustrating and complicated as this problem seems it is very simple to fix yourself.

Solution: Resolder Q572 even if it looks ok , forget about measuring and checking anything else , this is 100% causing your problem.
In later versions they tried silicone on the transistor to prevent these connection issue's but as you will see it didn't work.

Jomac

[channel27]

I'll do that straight away when I get home,
Thanks Jomac, you're a star!

[channel27]

Hi,
I did that and now it's working great, Thanks to all who replied