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AVGA 3000, J-PAC, Blast w/ Nanao MS-2933 and Tri-sync setup
#341707 - 06/21/15 03:57 PM
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Hi,
I've been posting my fun over on http://forum.arcadeotaku.com/viewtopic.php?f=4&t=30924&p=427833#p427833.
Is it possible to configure the J-PAC jumpers to do the Hori/Vert Sync-> Composite sync + amp the levels, but to allow 15/24/31kHz with some permutation of the jumpers?
It seems I have to choose a single fixed-frequency.
The screen will auto-sync to 15/24/31kHz, but I need a J-PAC. It won't sync to a VGA signal over the DE-15 connector. The J-PAC seems to lock be in to one frequency at a time if I'm understanding the supported permutations (No jumpers = passthrough sync, 15/24/31 individually is that freq, and 15+31 is 15kHz with 31kHz vert sampling).
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Re: AVGA 3000, J-PAC, Blast w/ Nanao MS-2933 and Tri-sync setup
[Re: Tourniquet]
#341714 - 06/21/15 10:26 PM
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I'm not understanding what you're wanting. Also, it doesn't sample anything; it allows signal through or not.
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Scifi frauds. SF illuminates.
_________________
Culture General Contact Unit (Eccentric)
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Re: AVGA 3000, J-PAC, Blast w/ Nanao MS-2933 and Tri-sync setup
[Re: Traso]
#341715 - 06/21/15 10:40 PM
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> I'm not understanding what you're wanting.
Perhaps I'm way off base, here's my understanding of the J-PAC based on https://www.ultimarc.com/jpac2.html
The pattern of DIPs do the following (where the first is the one labelled 15kHz, second is the 24kHz, and third is the 31kHz. 1 is jumper present, 0 is not):
* 0,0,0 - no filtering of vert freq, no messing with sync. Assumed Composite in/out.
* 1,0,0 - allow _only_ 15kHz through. Convert Hori/Vert sync to Composite
* 0,1,0 - allow _only_ 24kHz through. ""
* 0,0,1 - allow _only_ 31kHz through. ""
* 1,0,1 - allow only 15kHz through. Convert Hori/Vert sync to Composite. "Divide line frequency by 2" (AKA resampling the vert sync).
What I'd like would be to allow 15,24,31kHz through (or anything, frankly, would suffice), but to do the Hori/Vert -> Composite sync, inversion etc.
(now I'm wondering is 1,1,0. 0,1,1 and 1,1,1 do anything useful and undocumented).
Edit: 1,1,1 certainly doesn't - it behaves the same as 1,0,1 as you might guess.
I guess the reason this isn't common is people either have a single-sync monitor, or they have something much more modern that takes a VGA signal and they can skip a J-PAC/JAMMASD entirely.
> Also, it doesn't sample anything; it allows signal through or not.
Yes, yes it does. See above. It samples the sync. The Video signal is left untouched though.
Edited by Tourniquet (06/21/15 11:41 PM)
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Re: AVGA 3000, J-PAC, Blast w/ Nanao MS-2933 and Tri-sync setup
[Re: Tourniquet]
#341860 - 06/25/15 08:18 PM
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> Yes, yes it does. See above. It samples the sync. The Video signal is left untouched though.
Okay.
Ummmm, none means it'll allow everything. That's what you want, right? On my candy/15khz monitor, I have 15/31 on, so that I get only those (the 31 being split like you said).
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Scifi frauds. SF illuminates.
_________________
Culture General Contact Unit (Eccentric)
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Re: AVGA 3000, J-PAC, Blast w/ Nanao MS-2933 and Tri-sync setup
[Re: Traso]
#341872 - 06/25/15 09:44 PM
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> > Yes, yes it does. See above. It samples the sync. The Video signal is left
> untouched though.
>
> Okay.
>
> Ummmm, none means it'll allow everything. That's what you want, right? On my
> candy/15khz monitor, I have 15/31 on, so that I get only those (the 31 being split
> like you said).
No. You can only put on one jumper at a time - the exception being the special 15+31 setting, that halves the vsync. It's not like picking and choosing which frequencies you want (though that's what I'm asking for).
No - removing all the jumpers is not the same as allowing them all through - it disables the VSync+HSync->CSync circuit too. Techncially, I wouldn't mind the protection of restricting it to 15-31kHz (or even the precise 15,24,31kHz frequencies).
You don't care about this, because you have only a single-sync monitor.
Others don't care, because their super-trinotron TV tubes, or PFX displays are more modern and can handle VGA inputs and h/vsync. My display is an early (v. good for its era) tri-sync.
I've discussed it with Andy W over email and he understands the problem, and reckons the hw could do it no problem, but it obviously need s anew chip. His suggestion was the one I had already arrived at - take the jumpers off and bridge the vert and hori sync, or else do something similar with the DSUB connector.
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Re: AVGA 3000, J-PAC, Blast w/ Nanao MS-2933 and Tri-sync setup
[Re: Tourniquet]
#341983 - 06/28/15 06:14 PM
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> I've discussed it with Andy W over email and he understands the problem, and reckons
> the hw could do it no problem, but it obviously need s anew chip. His suggestion was
> the one I had already arrived at - take the jumpers off and bridge the vert and hori
> sync, or else do something similar with the DSUB connector.
Happy conclusion - simply bridging the h/v-sync and removing the jumpers indeed fixes it. Just need to find a good way to do this.
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Re: AVGA 3000, J-PAC, Blast w/ Nanao MS-2933 and Tri-sync setup
[Re: Tourniquet]
#342084 - 07/02/15 08:13 PM
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> Happy conclusion - simply bridging the h/v-sync and removing the jumpers indeed fixes it. Just need to find a good way to do this.
Ah, I see (mostly). Groovy.
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Scifi frauds. SF illuminates.
_________________
Culture General Contact Unit (Eccentric)
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