GUIDE: Telling apart good Genesis 1s and Genesis 2s from bad ones.

[MaxWar]

Mwahahah!

Finally got my hands on a Model 2 VA3
Had to email pictures to about 25 ebay sellers before I found one.
Out of all these model 2 consoles, only 2 were 3/4, and only one was Va3.

Now I can check if it has the clean CCAM sound of the VA4 or if it is more like a Va0,1,1.8.
It has the 5660 ASIC though, so my hopes are not too high

For those not knowing what Im talking about, I found that the 5960 found in the VA4 was the champion of low noise on the sound output.

[omp]

Not a bad board the va3. Mine is in pieces but can be overclocked unlike the va2.3.

[MaxWar]

And the VA4 cannot be overclocked Either. Which is what I dont like about it. If the VA3 has the nice sound of the VA4 + overclockability, then It becomes a win board to me. We shall see

[omp]

VA4 no overclock either? That's a bit of jolly interesting.

I still use a VA2.3 for daily duties though, have a few of those including one with that bloody Samsung Encoder. I would like to upgrade that to a CXA1645 minimum or give the CXA2075 a go.

But we are in the process of prepping our house for sale/saving for next one so that is way way way way way way down the line. It might get done when my son is old enough to swing a soldering iron (he is currently 18 months old). I think that would be a useful skill for him to learn.

[MaxWar]

VA4 is a GOAC model so the 68k is integrated and Afaik they do not support overclocking. Is this similar with the VA2.3? ( never opened one ).
By analogy to what the model 1 VA7 was, the VA4 is kind of like a model 3 in a model 2 case, although it still has 32X and SCD compatibility.

The VA3 however, despite being a 3/4 motherboard, is similar to early model 2 ( va0 - va1.8) but on a more compact form and has a better sound circuit.

I will try the CCAM on my VA3 tonight and see how it behaves. It has the crappy samsung video encoder but that can be fixed, not that I will bother If i find out that the VA3 has the same VDP noise level as other Model 2 on its sound output.

[villahed94]

VA4 is a GOAC model so the 68k is integrated and Afaik they do not support overclocking. Is this similar with the VA2.3? ( never opened one ).
By analogy to what the model 1 VA7 was, the VA4 is kind of like a model 3 in a model 2 case, although it still has 32X and SCD compatibility.

The VA3 however, despite being a 3/4 motherboard, is similar to early model 2 ( va0 - va1.8) but on a more compact form and has a better sound circuit.

I will try the CCAM on my VA3 tonight and see how it behaves. It has the crappy samsung video encoder but that can be fixed, not that I will bother If i find out that the VA3 has the same VDP noise level as other Model 2 on its sound output.

The VA2 and VA2.3 MD2s have a different VDP made by Toshiba. It's basically a 5660 sans FM (Yamaha wouldn't give them their secret, would they?), thus the need for a discrete YM2612 on those.

[MaxWar]

The VA2 and VA2.3 MD2s have a different VDP made by Toshiba. It's basically a 5660 sans FM (Yamaha wouldn't give them their secret, would they?), thus the need for a discrete YM2612 on those.

Interesting, but then It still has a discrete 68k CPU? What exactly is preventing it from being overclocked?


Ok I just installed CCAM on my Model 2 VA3 and made recordings. Same identical result as my VA1 model 2 Same exact noise pattern.
Not too surprising I guess, they share the same ASIC.
Seems like the VA4 is truly the magic one, sadly it cannot be overclocked.

Too bad, uh? I made a recording of the Stock VA3 too, and alot of the VDP noise seems to be filtered out. Somehow I do not think it is only the lowpass, there is something else going on.

[Drakon]

Interesting, but then It still has a discrete 68k CPU? What exactly is preventing it from being overclocked?


Ok I just installed CCAM on my Model 2 VA3 and made recordings. Same identical result as my VA1 model 2 Same exact noise pattern.
Not too surprising I guess, they share the same ASIC.
Seems like the VA4 is truly the magic one, sadly it cannot be overclocked.

Too bad, uh? I made a recording of the Stock VA3 too, and alot of the VDP noise seems to be filtered out. Somehow I do not think it is only the lowpass, there is something else going on.

You should be able to overclock anything with a separate 68k. Just find the clock trace and wire it into a switch.

[villahed94]

According to Sega's official documents, the VA6 board without EXT port (Non-HDG) is actually called VA6.5 . Basically the same as a VA6.

[parafin]

Hi friends. Got MD1 Japan. Can You tell me revision of motherboard. I think it is early one between 1-3 but exactly?

[Ace]

Your attachment doesn't work. Reupload to image to an image hosting site and link it here.

[villahed94]

Hi friends. Got MD1 Japan. Can You tell me revision of motherboard. I think it is early one between 1-3 but exactly?

You sir, have acquired a VA0 Model 1. It's the oldest Megadrive revision in existance.
Please tell us its serial number.

[parafin]

wow its granny one S/N 88M80658 its jp region
It works great but one point I want fix. Stereo jack have clack sound. Its clack on same volume level: when volume low its very hear, when loud not realy. What You think maybe it's old capacitors?

PS sorry for my bad English

[villahed94]

That is a motherboard problem common to all revisions up to VA2. Sega miscalculated the gain in the amp circuit and thus it's waay too loud for the headphone amplifier, causing that clicky sound at low volumes. BTW, those early revisions have less filtering than later Model 1s.
I'd still recommend performing a cpacitor replacement, just as a preventive measure.

[parafin]

Is there solution for this proublem, maybe add filter to disable this clicky sound?