Tech : Space Invaders / Invaders Part 2

[John Bennett]

[ukvac] Tech : Space Invaders / Invaders Part 2
Essentially the question is, is there any difference between a taito CVN sound board and a PVN sound board?
The PVN board set will run CVN roms with the custom installed or removed, but the CVN sound board (with the 24 pin socket and MB14241 data shifter added) doesn't work with the PVN ROM board. I've tried adding the socket and a MB14241 to two CVN sound boards and the both seem to be in continuous reset mode at around 2Hz.

The only difference I can see on the board sets is the addition of the name reset (hiscore) control line heading into one of the LS153 muxes ...

Have I missed anything? Is there some sneaky mod that taito made to stop this being done?
Thanks,
Steve
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DATA Imported from archives: originally posted by (steve@coule.freeserve.co.uk)

 

[P-Man]

Re: [ukvac] Tech : Space Invaders / Invaders Part 2
Added a MB14241 to a CVN sound board? i'd like to know how you did this?
there is no provision for it on the pcb??

The only ghastly thing i can think of is that you have shoehorned the
mb14241 into the regular pitch socket provisioned for on the SN76477... but
you surely couldn't have done that?

unless you have a CVN sound board i havn't seen before (and that'd be a
first

Andy Welburn
www.andys-arcade.com

 

[John Bennett]

RE: [ukvac] Tech : Space Invaders / Invaders Part 2
>>Added a MB14241 to a CVN sound board? i'd like to know how you did this?

I put it in location 3, exactly the same place as on a PVN part 2 set ...

>>The only ghastly thing i can think of is that you have shoehorned the
mb14241 into the regular pitch socket provisioned for on the SN76477... but
you surely couldn't have done that?

Ha! Does that work? ;-)

>>unless you have a CVN sound board i havn't seen before (and that'd be a
first

Seems like it's a first ... well, and a second, I have two exactly the same L@@K almost RARE. They have paper taito labels CVN00018 and are silk screened CVN00014.


The PCB is 99.5% identical to a PVN00004 sound board .. .it seems to have the high score reset input circuitry added but I can't see any other differences. However, both my CVN sound boards reset 2 times per second when attempting to run the part 2 ROMs with the MB14241 in place, but both CVN sound boards work fine with standard SICV ROMS.

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[Dave2084]

Re: [ukvac] Tech : Space Invaders / Invaders Part 2
At 07:06 pm 9 12 2003, you wrote:
>Added a MB14241 to a CVN sound board? i'd like to know how you did this?
>there is no provision for it on the pcb??

There are some CVN sound boards that look like the PVN version but have no
MB14241 fitted (just holes in the PCB) and the high score reset button
input is missing.

>The only ghastly thing i can think of is that you have shoehorned the
>mb14241 into the regular pitch socket provisioned for on the SN76477... but
>you surely couldn't have done that?

???

>unless you have a CVN sound board i havn't seen before (and that'd be a
>first

I've had about 10 of these!
Wanna buy one?

;o)

I've never been able to figure out why SI part 2 does not work on these
either ....

Dave Langley
www.robotron-2084.co.uk

 

[P-Man]

Re: [ukvac] Tech : Space Invaders / Invaders Part 2
yep, Dave Langley pointed this out to me along with sending me a few pics of
the pcb...

I may have come across this pcb before, but it might have already been
populated with the custom shifter and i just mistook it for a regular PVN
board... other than that, i don't believe i have come across one with a
blank space, otherwise i would have gone out of my way to investigate why it
was empty....

I've done tonnes of space invaders pcbs as repairs, so i don't know why its
just i havn't come cross that flavour before when you and dave sem to have
seen plenty.... strange..

so, ignore me.. i couldn't tell you the answer to your question anyway...
I deal with TVN's and PVN's day in day out, don't see too many CVN's
really.. plus sometimes they are just complete mixnmatched sets made up of a
combination of the lot.

bearing in mind there are about 5-6 versions of each of the 3 pcbs in that
set... there's a lot to keep track of

Andy Welburn
www.andys-arcade.com