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SWTPC 6800 and CT-64 terminal

allmacs

Member
Joined
Dec 17, 2016
Messages
49
Location
South Carolina , United States
Hello I have issues with my CT-64 terminal. It seems that the vertical sync is out for some reason.
https://youtu.be/Q3re47AbHJk
I have replaced all components in the power supply. and several Capacitors and Resistors that seemed out on the CT-64 main board.
So far what I checked on the oscilloscope looks good. Whenever I find a component that seems out I order them new and the project halts until they are installed.
I am trying to find someone who knows these Computers. There is a person named Michael H., who made a SWTPC website , but it seems impossible to get a hold of him.
IMG_0068.jpg
 
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Mine has a distorted display which I don't think is the display, as when I feed the composite out into an external monitor I get the same results. There are also multiple logic faults. I get corrupt characters on the screen. Its on the back burner as I have lots more things to debug...
 
Mine has a distorted display which I don't think is the display, as when I feed the composite out into an external monitor I get the same results. There are also multiple logic faults. I get corrupt characters on the screen. Its on the back burner as I have lots more things to debug...

What do you think the cause is? Capacitors? Transformer? or bad IC's? Did you work on a computer like this before?
 
What do you think the cause is? Capacitors? Transformer? or bad IC's? Did you work on a computer like this before?

I suspect all of those, plus possible bad connections between the boards and between the ICs and sockets. I must admit I try and avoid actually messing at the component level, although I have built similar computers from components. In the day I built a 77-68 and the later 6809 system..

https://en.wikipedia.org/wiki/Newbear_77-68

.. and have built several radio receivers and transmitters. Current project is trying to fix a SCSI2SD where the USB socket has been ripped from the board. it was only held with hot melt glue so several bits of track wunt as well... :(:(:(:(
 
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