Has anybody tried this? Would it work?

[t-scene]

I have a model 2 VA1 with the Sony CXA1145. If I upgraded to the CXA2075 would the composite out be as good as the 32x?

[fr@ser]

A fujitsu MB3514 is i think ,nigh on identical to the sony 1145 pin config.

[electrochip]

I have a model 2 VA1 with the Sony CXA1145. If I upgraded to the CXA2075 would the composite out be as good as the 32x?

It would be better with the CXA2075, but once you use a 32X it uses it's own encoder so it doesn't matter what you use in the Genesis in that situation.

[mcurkman]

I have a model 2 VA1 with the Sony CXA1145. If I upgraded to the CXA2075 would the composite out be as good as the 32x?

with the CXA2075 it looks better than with the 32X attached. It is a much sharper composite with better colors than the 32X.

There you go.

[electrochip]

I looked over the CXA2075 swap I did and not much changed. First it was a MB3514 that I swapped out, but it should work just fine if you have the CXA1145. The MB3514 are both surface mount chips, so they are small and require some skill to remove and solder in. There are 24 pins on the chips but not all are used.

1 soldered
2 soldered
3 soldered
4 soldered
5 lifted and not soldered
6 soldered
7 soldered
8 lifted and not soldered
9 lifted and not soldered
10 soldered
11 lifted and not soldered
12 soldered
13 lifted and not soldered
14 lifted and not soldered
15 lifted and not soldered
16 lifted and not soldered
17 lifted and solder a 3.32k ohm resistor with 1% tolerance from here to pin 12
18 lifted and not soldered
19 soldered
20 soldered
21 soldered
22 soldered
23 soldered
24 soldered

If you want to pull S-Video from it, solder a 75 ohm resistor and a 220uf (10V or more) electrolytic capacitor from pins 15 and 16 and solder them to your connector. Just like the CXA1645 S-video mod.

[mcurkman]

I looked over the CXA2075 swap I did and not much changed. First it was a MB3514 that I swapped out, but it should work just fine if you have the CXA1145. The MB3514 are both surface mount chips, so they are small and require some skill to remove and solder in. There are 24 pins on the chips but not all are used.

1 soldered
2 soldered
3 soldered
4 soldered
5 lifted and not soldered
6 soldered
7 soldered
8 lifted and not soldered
9 lifted and not soldered
10 soldered
11 lifted and not soldered
12 soldered
13 lifted and not soldered
14 lifted and not soldered
15 lifted and not soldered
16 lifted and not soldered
17 lifted and solder a 3.32k ohm resistor with 1% tolerance from here to pin 12
18 lifted and not soldered
19 soldered
20 soldered
21 soldered
22 soldered
23 soldered
24 soldered

If you want to pull S-Video from it, solder a 75 ohm resistor and a 220uf (10V or more) electrolytic capacitor from pins 15 and 16 and solder them to your connector. Just like the CXA1645 S-video mod.

Can you do this on a 32x too?

[t-scene]

Im pretty sure the 32x has a custom Sega video encoder. Maybe electrochip can verify this.

[electrochip]

Can you do this on a 32x too?

No, 32X is custom and it won't work. You would have to build the whole RGB to NTSC circuit (check the datasheets) to convert the RGB from the 32X into composite or S-Video from the CXA2075.

[mcurkman]

Does anybody have the pinout for the video encoder in the 32x?

[Xeniczone]

I remember someone saying what the chip was on the 32X. It was a custom chip that was a combination between an encoder, and mixers.

I can't remember exactly, but if someone wanted to to build one they could possibly do it by building the mixing circuit and adding an CXA2075.

[Barone]

I looked over the CXA2075 swap I did and not much changed. First it was a MB3514 that I swapped out, but it should work just fine if you have the CXA1145. The MB3514 are both surface mount chips, so they are small and require some skill to remove and solder in. There are 24 pins on the chips but not all are used.

1 soldered
2 soldered
3 soldered
4 soldered
5 lifted and not soldered
6 soldered
7 soldered
8 lifted and not soldered
9 lifted and not soldered
10 soldered
11 lifted and not soldered
12 soldered
13 lifted and not soldered
14 lifted and not soldered
15 lifted and not soldered
16 lifted and not soldered
17 lifted and solder a 3.32k ohm resistor with 1% tolerance from here to pin 12
18 lifted and not soldered
19 soldered
20 soldered
21 soldered
22 soldered
23 soldered
24 soldered

If you want to pull S-Video from it, solder a 75 ohm resistor and a 220uf (10V or more) electrolytic capacitor from pins 15 and 16 and solder them to your connector. Just like the CXA1645 S-video mod.

I did it exactly...
Replaced a CXA1145 for one CXA2075 and I got a bad looking image...
Like humm... Very noisy... There's no noticeable noise on black or gray colors but the others look fucked up by some kind of noise... The image is not flipping and is colored but with bad noise.
All the pins are well connected and tested, and I use the resistor exactly as you described. The old XTal used as sub-carrier signal is connected to, should I disconnect it? Or should I place some component between the Xtal and the SCIN pin of the cxa2075?

I did it in a Model 1 Japanese Mega Drive VA5/VA6.

Help me, please...

[Drakon]

I did this. I removed the ka whatever chip. The cxa1145 was a drop in replacement. I also wired up a cxa1645 (was a lot more complicated). both the 1145 and the 1645 rendered video pretty much the same quality as the genesis model 1 with a 1145 or 1645. They actually look slightly better on the model 1.

regarding jailbars I found a fix. I left the cxa1145 in my model 1 genesis. I took the rgb + sync at the av out port and wired those into my cxa1645 circuit. This produces the best looking genesis s-video I've ever seen. Super clean.

Here's my lazy schematic



the green pcb is actually a cxa1645 kit for av famicoms but it works on the genesis too. You can order the kit from here:

http://homepage3.nifty.com/F-LABO/ProductsList.html

"■ ＮＥＷファミコン マルチＡＶ化キット２　(音声分離回路用部品なし)
　１キット　６０００円（送料・振替手数料は別途）　
"

is the product you want I used sutocorp.com to proxy order it.

The reason I have extra resistors on the s-video out is because passing the video through both the cxa1145 and the cxa1645 causes the picture to amp to a level that's too strong. Both the colour and brightness were too strong so I just added resistors until they both looked perfect.

I also built my own cxa1645 circuit and it seemed to work fine but then I noticed that sonic 2 the blue background in the first stage you could see it refreshing which was super annoying. Something about this kit circuit fixes that issue I'm too lazy to bother rebuilding the video circuit on this kit.

The video circuit is basically just a cxa1645m, a lm1881n to clean up the sync, a crystal oscillator, a bunch of resistors and caps, and a coil?

I also ordered some cxa2075 chips and looking at the pinouts.....



you should be able to drop a 2075 into a circuit wired up for a 1645. Can't wait for my 2075s to show up so I can just drop them into my existing circuits and see the difference.

[tony]

Can these boxes also support composite out? For example, I have a model 1 I'd like to improve the composite quality of. How would that compare against the Genny 3?

EDIT: In response to Electrochip's CXA2075 box.

[Drakon]

I'm interested in buying electrochips cxa2075 box. I tried dropping a 2075 into my 1645 circuit and it's not working right. Is it possible I can get your schematic electrochip? If you'd rather just sell me a cxa2075 box that would be fine too