How to Use an A2320

[raoulduke]

Thanks; as I said, I really don't know... I'm taking that discussion at face value - as I said because I just don't have the knowledge.  If someone has one of those silverboxes and can check the cap that'd possibly be useful; but I think it's got different circuitry.  [And I couldn't make out a rating in the pics on the site Matt_H posted.]

I mean... I guess putting a cap with too high a rating isn't likely to do damage, right?  (Whereas I think the other way around possibly could?)  I'm happy to experiment a little; wait and what would it possibly damage - the monitor?  I honestly don't care about that.

[raoulduke]

I appreciate it.  Thanks.  I have spare PCB; I guess I'll buy a female vga connector - or I may have one, actually.

One last question: The 9-pin vga has a sync ground and separate R, G, and B grounds; the 15-pin vga only has one ground (that hits multiple pins).  So should I just 'tie up' all the separate grounds and just put them all to the single ground of the 15-pin?

[raoulduke]

[Well that's my plan for the grounds.]

Yeah so much for last question... Re: the A2320 and recapping, if I'm reading this: (http://www.mouser.com/catalog/supplier/library/pdf/avxmultilayerceramicld.pdf) correctly, it seems to be that the codes are highly dependent on the type of cap.  And I don't know enough to differentiate the caps on the a2320; they should all be visible in the hi-res pics posted earlier [at least to see the types].

The only one that looks substantially different in type from the others is the "101".  And one of mine looks "chipped" or maybe even zapped, subtly though.  So that one would be what I'd replace first and then test before recapping the rest.  Anyway, any help would be much appreciated, but I want to leave the list up in case anyone else wants to recap in the future.

// I don't know if any of the first bit is right...

Code         / #of Caps / Meaning
A5E 104M / 13           / 5V 0.1uf; +/- 20%; tolerance control
476 +16k / 2             / 16V 47 uf
101          / 3             / 0.1nf
019 A5M   / 4             / 5V ?; AVX; +/-20%
334 E5Z    / 3             / 5V 0.33uf; +80%; tol. cntl.
102 C5K    / 1             /
101 A1[4?] / 1
040 ACF    / 1
043 AAM   / 1
045 ACP    / 1
001 AMF    / 1
010 ANP    / 1

And then those two electrolytic caps are 16V 470uf.

[raoulduke]

"Normally," though, I think they're wired together anyway.  Usually that second row and then a few first and third row pins are wired together.  I can't find my d-sub female connector (to evidence that thought), but: http://www.blogcdn.com/www.engadget.com/media/2006/11/vga_pinout.jpg .  But I can wire them specifically to the pins near the R, G, B; no biggie.  [I am a little curious if that explains a quality issue with my ST adapter, though.]

[raoulduke]

Cool.  Thanks.  I couldn't find 5v 100uf caps at mouser or digikey, so I'm going to go with 6.3v.

I think I'll actually make a little PCB connector board and leave the cables detachable on both ends.  I've had not great luck with my 8 or 9-wire Atari ST bus mouse adapter.

[raoulduke]

Didn't work [my VGA adapter]... I guess there's a small possibility that I wired it wrong (which I think is unlikely, though) and that starting from scratch would help.

Actually the only thing I couldn't try is the Dell CRT monitor I bought that has (by a wide margin) the widest scanning range - bc it has a male VGA plug and my ... apparatus ... also has a male VGA plug.  So I think I'll start there (with an adapter).

I recapped the two electrolytic 470uf 16V caps on the A2320 but that had no obvious effect.  I bought these 101(-labeled) caps but the ones I got only have two axials/leads and the originals have three.  Is one a ground?  I assume I should just look for another set of caps that have 3?

[raoulduke]

Could I be misunderstanding the purpose of all this?  I just wanted a higher resolution display mode.  Currently I'm also locked into max 16 colors.  I just assumed this was a limitation of composite output mode.

[raoulduke]

Can you explain the chip ram DMA bandwidth issue?  Or is there an easy link that would explain it?