Sega saturn tectoy VA13 Mod Palm-M to NTSC

[ralfs]

Did I do something wrong? Because the console doesn't give an image and neither does the disk drive work

1- Remove the jumper from Jp2 and place it on Jp1

2- Change the 14,302mhz Crystal (x1) for a 14,318mhz crystal

3- Change the Crystal x5 to a 20mh one

4- Put a 2k2 Resistor on R142 and we will connect leg 7 of the IC21 to leg 12 with a jumper


Pictures

i.imgur.com/flbBIiC_d.webp?maxwidth=640&shape=thumb&fidelity=medium


i.imgur.com/HojTQn4_d.webp?maxwidth=640&shape=thumb&fidelity=medium


i.imgur.com/8ePlELk_d.webp?maxwidth=640&shape=thumb&fidelity=medium


i.imgur.com/W7537tH_d.webp?maxwidth=640&shape=thumb&fidelity=medium

[zyrobs]

Does it work if you undo your mod? Unless you butchered something, just putting back the old X1 crystal should show if things work or not (although the cd drive may not work with the wrong crystal).

[ralfs]

Jun 10, 2021 16:52:31 GMT zyrobs said:

Does it work if you undo your mod? Unless you butchered something, just putting back the old X1 crystal should show if things work or not (although the cd drive may not work with the wrong crystal).

I replaced the power supply capacitors and when I turned on the fuse exploded. I'm providing a new psu, as soon as I have it I'll give you feedback. Thanks

[zyrobs]

Ouch. You either put in one of the caps backwards or put too much solder and some traces shorted.
Normally you can get it back to life by replacing the fuse and the blown varistor next to it, of course you'll also need to make sure the caps are right this time, and there are no glaringly obvious shorts (like the two AC lines for example).

[ralfs]

Jun 11, 2021 1:39:29 GMT zyrobs said:

Ouch. You either put in one of the caps backwards or put too much solder and some traces shorted.
Normally you can get it back to life by replacing the fuse and the blown varistor next to it, of course you'll also need to make sure the caps are right this time, and there are no glaringly obvious shorts (like the two AC lines for example).

I replaced it with a new psu and it still has a black screen and the drive doesn't work. Now a high-pitched noise from the TV speaker also comes out

[zyrobs]

What happens if you restore the crystals?

Are you sure you didn't accidentally short out the motherboard somewhere?

[ralfs]

Jun 16, 2021 20:23:04 GMT zyrobs said:

What happens if you restore the crystals?

Are you sure you didn't accidentally short out the motherboard somewhere?

I managed to resolve it. It was the 20mhz Crystal, I changed it for another 20mhz one in good condition

But the image still has the problem it had before transcoding which is a gray horizontal line that covers the entire screen and is like a scanline. The strange thing is that in the Sega logo the image is normal

[ralfs]

I replaced all the motherboard capacitors and the problem persists. I do not know what else to do

[zyrobs]

Are you using a RGB Scart cable or composite/s-video?
What happens if you completely disconnect the AV encoder pin 6 (not 7)? Judging by that video I'm guessing the color subcarrier is not set up right, but that will only affect composite/s-video, and not RGB. If you disconnect the av encoders pin 6, there won't be any subcarrier input and consequently no color in the composite/s-video signal. But if this fixes the screen jumping/greying then you know that that was the issue.

edit: looking at your pics again, have you connected Vcc to pin 6? It should be connected to pin 7... pin 6 is the color subcarrier input (3.579545 MHz for NTSC, 3.575611 MHz for PAL-M, you might want to measure it to make sure), and Pin 7 is the NTSC/PAL selector pin (Vcc for NTSC, GND for PAL).

[ralfs]

I just looked here, it was connected to pin 7



The image was already gray before making the mod to ntsc.The composite cable is also gray, I'm using a scart cable with this converter.



Another assumption would be that the vdp1 chip or memories are bad. Look at how the objects become transparent in the back of the game.

[zyrobs]

Yeah, there's definitely some flickering there. I'd try to check the connections for the two framebuffer chips (IC12, IC13), as well as the connection between the VDP1 and VDP2 (pins 128-140 on the VDP1, 91-101 on the VDP2, I think).
It's like every other frame the VDP1 is missing, which would imply that the VDP2 can't refresh from one of the framebuffers.

Also, what happens if you put the old crystals back?

[ralfs]

When I put the old crystals the problem persists

[zyrobs]

Well there doesn't seem to be any damage on that part... At this point you'd have to measure each connection and test each part one by one, and measure the clock signals going into each chip (memory, vdps, the horizontal and vertical syncs, etc). One guy just this week had a problem where a trace was rotted under one of the chips, so just because everything looks fine does not mean that it's all good. Or maybe the wire and that resistor you put in there are too big and accidentally touch something they shouldn't.

It does look like a VDP1 issue since all the flickering parts in your video are VDP1 parts, including the FMV. The Sega logo did not flicker because it was all VDP2.

Unfortunately I can't be of more help without having the board in my hands.

[ralfs]

Jul 8, 2021 23:04:17 GMT zyrobs said:

Well there doesn't seem to be any damage on that part... At this point you'd have to measure each connection and test each part one by one, and measure the clock signals going into each chip (memory, vdps, the horizontal and vertical syncs, etc). One guy just this week had a problem where a trace was rotted under one of the chips, so just because everything looks fine does not mean that it's all good. Or maybe the wire and that resistor you put in there are too big and accidentally touch something they shouldn't.

It does look like a VDP1 issue since all the flickering parts in your video are VDP1 parts, including the FMV. The Sega logo did not flicker because it was all VDP2.

Unfortunately I can't be of more help without having the board in my hands

Thanks a lot for the help. If I can fix it, I'll give you news. Thanks!