Schneider G65 - picture on lower side of screen

Started by vipros, 22:29, 27 February 23

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

vipros

Greetings to everyone. My name is Sinisa.
I apologize if someone has already post this.
Part 1.
I recently became the proud owner of an Amstrad/Schneider CPC 6128. After the first switching-on, everything worked fine.
After while (second turn ON) the monitor (Schneider G65) did not work properly. The image on the monitor was on the lower side of the screen and could be moved with the help of the V-sync potentiometer, but not over the entire screen but only in the lower part.
After working for 10 min the monitor doesn't work anymore, it also doesn't provide power to C6128.
Part 2.
I'm pretty sure the monitor is the problem because I have one good monitor Amstrad G65 and everything works fine when I connect C6128 on that good monitor.
After checking the motherbord I figure that the  fuse 2A is dead. After replacing the fuse, monitor is again working with the same problems from the beginning of the story (picture is in the lower side of the screen).
Part 3.
I try to use my FlirOne thermal camera and I see that the transistor KTC1815 is on the fire. After a few minutes of work, other parts are also heated. Most of all - the "pasive" cooler.
Part 4.C
Checking the same temperatures on good monitor & and seeking advice.

All pictures are in the link:
https://photos.app.goo.gl/m4iWhGiDdWaKPNJA8


Best regards....


Bryce

There's probably a bad capacitor on the board that's shorting the power and blowing the fuse.

Bryce.

vipros

Hi Bryce, thank you for the advice.
I used a thermal imaging camera and took the measurement on the good Amstrad G65 monitor so I can make comparation to bad monitor.
I noticed a big difference in temperature on the IC UPC 1031H2  (Good monitor - around 50-60°C, bad one around 130°C)
This IC  is essentially a Vertical deflection device that oscillates a vertical signal and I have a problem with vertical sync.
You cannot view this attachment.

Now I just hope that the error is in that IC and not something else that affects that IC.
Also here is part list and circuit diagram.
You cannot view this attachment.
You cannot view this attachment.
Data sheet for   IC UPC 1031H2
You cannot view this attachment.
I will  replace that IC, but right away when I change IC, should I change the capacitors and which ones?
Best regards,
Sinisa










Bryce

Luckily, that IC is still easy to find and relatively cheap. I'd swap it first and monitor its temperature. If the new one is getting hot, I'd check all electrolytic capacitors associated with its function. Also check its supply voltage before swapping the new part in.

Bryce.

Powered by SMFPacks Menu Editor Mod