Jailbars on stock hardware. Is it normal?

[ACML]

I've noticed that even a stock 1200XL without the chroma even connected to the monitor jack will show jailbars on the monochrome Luma signal on my Samsung TV.  I've read threads on AA discussing jailbars and a lot of it points to a bleed of ground between Chroma and Luma.  That would not explain why I'm seeing jailbars on a stock 1200XL that does even have Chroma connected to the monitor jack.  Does a stock beige 800 have jailbars on a modern LED/LCD screen?  I always apply the ClearPic2002 video mod to my 1200XLs and I had initially thought it was introducing them (jailbars) since Chroma is now on the monitor jack.  Now I realize that the stock video circuit already has the jailbars in the Luma signal before I touch one component.  Besides, the ClearPic2002 mod only exchanges components and may alter paths, but does not add paths (no new traces or connections).  So, ClearPic2002 is not the cause of jailbars.  I think UAV gets around jailbars due to where it picks off video signals, but I've also read accounts on AA where UAV installs still have jailbars. In the end, the quality of the ClearPic2002 is amazing and I'm conscious of the faint jailbars, but it does not bother me enough to want to do more (just me).

 

 

[+-^CrossBow^-]

54 minutes ago, ACML said:

I've noticed that even a stock 1200XL without the chroma even connected to the monitor jack will show jailbars on the monochrome Luma signal on my Samsung TV.  I've read threads on AA discussing jailbars and a lot of it points to a bleed of ground between Chroma and Luma.  That would not explain why I'm seeing jailbars on a stock 1200XL that does even have Chroma connected to the monitor jack.  Does a stock beige 800 have jailbars on a modern LED/LCD screen?  I always apply the ClearPic2002 video mod to my 1200XLs and I had initially thought it was introducing them (jailbars) since Chroma is now on the monitor jack.  Now I realize that the stock video circuit already has the jailbars in the Luma signal before I touch one component.  Besides, the ClearPic2002 mod only exchanges components and may alter paths, but does not add paths (no new traces or connections).  So, ClearPic2002 is not the cause of jailbars.  I think UAV gets around jailbars due to where it picks off video signals, but I've also read accounts on AA where UAV installs still have jailbars. In the end, the quality of the ClearPic2002 is amazing and I'm conscious of the faint jailbars, but it does not bother me enough to want to do more (just me).

 

 

Well, on most 800xls that I've done the UAV seem to provide a much better picture with little to no jail bars. However, such was NOT the case with my 130xe. it had jail bars before the UAV and still had them after regardless of the cables I used etc. I did notice that once I removed the RF modulator (to make room for my VBXE RGB output), that the jail bars lessened considerably through the UAV. I've also read where the composite is to blame and I was still using it but had it running from the UAV to the composite pin on the monitor out port and disconnected the original so no idea.

 

 

[_The Doctor__]

The cable shielding, signal bleed, digital noise from RAM can all be a factor, however with the XE's Freddy chip the jail bars can be reduced by filling in missing timing circuit and missing cap in freddy domain. This is noted in a few threads.

Edited July 31, 2023 by _The Doctor__

[Rybags]

The common jailbars you see will usually coincide with the Refresh cycles.

Next up from that will coincide with character or half character boundaries (cycles)

 

This has been discussed before - I'm no electronics expert but suspect it's from a combination of things.  Upgrades such as VBXE and Sophia usually eliminate the problem completely.  Other fixes have varying level of success.

[+bob1200xl]

Jailbars seem to exist in the video of most 1200XLs. Whether you can see them depends on what monitor/display/cable you are using. The higher the bandwidth of the path, the more they stand out. What you need is a sharp filter with a steep bandpass.

 

my $.02...

 

Bob

 

[Rybags]

Can people with modern day remake machines that use the stock Antic and GTIA report here?  e.g. 1088 XEL and 576 NUC

 

I'd be interested to know how they compare.  Also, anyone with the 800XL remade motherboard.

[+DrVenkman]

9 hours ago, Rybags said:

Can people with modern day remake machines that use the stock Antic and GTIA report here?  e.g. 1088 XEL and 576 NUC

No jailbars at all on my 1088XEL, 1088XLD or 576NUC+. @mytek knows how to design a ground plane.

[Beeblebrox]

I plan to install a UGV in my 1200xl. So cheap and if all the installs I've done in XE machines is anything to go by it'll work a treat.

Edited August 1, 2023 by Beeblebrox

[+MrFish]

14 hours ago, Rybags said:

Also, anyone with the 800XL remade motherboard.

There's also the 130XE remade motherboard.