MSX Turbo R jailbar fix - Help needed

Champion (296)

13-03-2018, 19:07

Hello mates, I've recently tried to fix my problem with jailbars video output on my MSX Turbo R A1GT with no success, I followed the steps from FR's MSX Files but i did something wrong, I've uploaded 2 pics to http://msx.pics to show you what I did. Maybe someone can help me to fix it, thank you in advance.

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Por Grauw

Ascended (10818)

13-03-2018, 19:38

That should do the trick. Worked for my GT as well as two other GTs I’ve recently had in my hands (applying audiofix).

Maybe the droplet of solder on J1 is not making contact? It looks a bit iffy, like a blob resting on top rather than welded with both sides of the pad. Try removing it, cleaning the pads (possibly rough it up a bit with a file), and applying one again. I would use a little less solder too.

Por Algorythms

Champion (288)

13-03-2018, 19:50

Looks like it could be a cold joint solder resulting in bad connection. As Grauw suggests, remove and try again after a clean up, and with a little less solder. The solder should flow onto the pads. But don't keep the soldering iron there too long eighter, as the heat might damage the pcb.
Also, are you sure you were actually seeing the RGB image before, not the composite video signal?

Por Grauw

Ascended (10818)

13-03-2018, 20:06

After cleaning the pads, it may also help to apply some flux if you have it (though most solder wire has a resin core). I did this on one of the GT’s, worked well. Be sure to clean off the residual flux after making the joint.

Because the contact has never been used there can be a coating on it either from the factory or just grease, preventing the solder from properly welding to it.

The essence of the fix is to output composite-sync on the DIN, rather than composite-video. The composite-video can be used as a sync signal, but does cause the jailbars. Luckily for us the turboR GT designers already seem to have anticipated this issue, so the fix is simple.

Would’ve been nice if it had been like this by default, but I guess it was a trade-off they chose to do due to removal of the composite video output to make room for the MIDI ports.

Por QBee Sam

Champion (296)

14-03-2018, 00:17

Thank you for the fast reply, I'll try to fix it tomorrow.

@Algorytms: The jailbars are less noticable on RGB but I used S-Video to capture video and the jailbars are cleary visible, the composite looks terrible in my GT, is not an option for me.

Por Grauw

Ascended (10818)

14-03-2018, 00:24

Ah, this only fixes jailbars on the RGB output.

Por QBee Sam

Champion (296)

20-03-2018, 00:15

Finally I removed the solder and replaced it with conductive pen, my idea was to improve the S-Video output, the RGB is good enough for me, so this fix really doesn't act like I thought. Anyway thank you very much for your help.

Por Grauw

Ascended (10818)

20-03-2018, 00:56

There may be an underlying issue with the composite video signal I guess, but what it is remains a mystery for now then.