Mtc900e stable but split image cause?

[stevebm1]

Any idea what is causing this,the image is stable and clear,but split in two?

 

[stevebm1]

It’s not the game pcb,as it is doing it with every game pcb I tried

 

[stevebm1]

Chassis has been recapped,hor pots changed,but problem is still there

 

[gunblade]

is it 900e or 900usa, do you have a photo of the rgb connecter

 

[stevebm1]

900E,it has the standard rgb connector,I have tried another chassis on the tube and it is fine,the image is correct,it’s just this one,I was testing that has the split image

 

[gunblade]

there are a few things going on with the chassis, red seems to have a fault and that half locked image.
the vertical hold and lin pots corrode and can give odd issues like this
the contrast is too high as well
it is possible a leaky transistor in the sync circuit is preventing full lock
all the usual standard mtc900e issues

 

[stevebm1]

The red issue is due to a dodgy pot on the neckcard,if you press the plastic case it solves the issue(I have a new one on the way in the post)

 

[stevebm1]

Blew out the ver lin potwith compressed air,and the picture now locks ok,just got to sort the red issue now

 

[gunblade]

these chassis suffer so much from age and corrosion, the pots and small signal transistors in particular plus the neck card drive transistors and glass diodes - these can become such a massive job

 

[tb2000]

Yeah, i've fixed them before where they've been on test and transistors have gone down one by one. For example, left one on for 30 minutes, transistor went on neckboard, another 20 minutes, one goes on the rgb mixer section, another 30 minutes, one goes on the neckboard, then it could go an hour before another goes down, and so on. If I get one like that I just tend to change all transistors on the neckboard (as when the BF871's go they often take out a resistor as well) and all transistors in the rgb mixer section. I had one a while ago that had a vertical size problem - changed the pot but it didn't really make much difference. Took a while to work it out but it turned out the new (new old stock) pot I put in was faulty!

 

[stevebm1]

Since I managed to sort out the. Hold problem,With the signal disconnected,i still get a red screen,I desoldered the red wire from the neckcard to see if that made a difference,but it still stay red now

 

[stevebm1]

Yeah, i've fixed them before where they've been on test and transistors have gone down one by one. For example, left one on for 30 minutes, transistor went on neckboard, another 20 minutes, one goes on the rgb mixer section, another 30 minutes, one goes on the neckboard, then it could go an hour before another goes down, and so on. If I get one like that I just tend to change all transistors on the neckboard (as when the BF871's go they often take out a resistor as well) and all transistors in the rgb mixer section. I had one a while ago that had a vertical size problem - changed the pot but it didn't really make much difference. Took a while to work it out but it turned out the new (new old stock) pot I put in was faulty!

What’s the location of the transistors that are the rgb mixer signal ones you and gunblade mention to check?