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General Category => Technical support - Hardware related => Topic started by: Rabs on 20:11, 09 October 23

Title: C141 and Screen "Shimmer"
Post by: Rabs on 20:11, 09 October 23
OK just completing a CPC6128 repair (new keyboard membrane and AY-3-8192 so not a cheap repair).

Just completing the final tests and I have noticed what I can only call a slight "shimmer" when using an RGB2HDMI converter. 

I don't see this "shimmer" when using a real CTM644 and I don't see it when using a different CPC6128.

So I am thinking C141 (appears something has taken a byte out of it).

Has anyone else seen this before?

C141_COMPONENT.jpgC141_SCHEMATIC.JPG
Title: Re: C141 and Screen "Shimmer"
Post by: SerErris on 23:39, 09 October 23
Seen other damages to disc capacitors. worth to exchange wiith any 220 nF version. 

Not sure if this is causing the shimmering.
Title: Re: C141 and Screen "Shimmer"
Post by: Rabs on 06:38, 10 October 23
Quick Auto Calibration on the RGB2HDMI fixed it. Well stopped the "shimmer".
Title: Re: C141 and Screen "Shimmer"
Post by: McArti0 on 07:36, 10 October 23
It is not nF for 16MHz dotpixel. It's pF
Title: Re: C141 and Screen "Shimmer"
Post by: SerErris on 17:19, 10 October 23
Quote from: McArti0 on 07:36, 10 October 23It is not nF for 16MHz dotpixel. It's pF
Yes your are absolute right ... how could I overlook that.

Quote from: Rabs on 06:38, 10 October 23Quick Auto Calibration on the RGB2HDMI fixed it. Well stopped the "shimmer".
That is actually something you learn if you have multiple CPC.

Yes every CPC is different and you need to run calibration for each of them. I have now 4 and none share the same settings.
Title: Re: C141 and Screen "Shimmer"
Post by: Bryce on 07:39, 11 October 23
Quote from: Rabs on 20:11, 09 October 23OK just completing a CPC6128 repair (new keyboard membrane and AY-3-8192 so not a cheap repair).

Just completing the final tests and I have noticed what I can only call a slight "shimmer" when using an RGB2HDMI converter.

I don't see this "shimmer" when using a real CTM644 and I don't see it when using a different CPC6128.

So I am thinking C141 (appears something has taken a byte out of it).

Has anyone else seen this before?

C141_COMPONENT.jpgC141_SCHEMATIC.JPG

I'd be more worried about the badly dried lower solder joint on the capacitor. That would have a bigger negative effect than the "bite".

Bryce.
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