ChanServ changed the topic of ##yamahasynths to: Channel dedicated to questions and discussion of Yamaha FM Synthesizer internals and corresponding REing. Discussion of synthesis methods similar to the Yamaha line of chips, Sound Blasters + clones, PCM chips like RF5C68, and CD theory of operation are also on-topic. Channel logs: https://freenode.irclog.whitequark.org/~h~yamahasynths
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<cr1901_modern> protosphere: Apropos of the thread, what's the purpose of the ATX connector?
<andlabs|2> ?
<andlabs|2> atx powered multimeter
<andlabs|2> lol
<andlabs|2> every time I see someone with an oscilloscope I think I should probably get one too
<andlabs|2> but I don't know which is the best to get; everyone has a different one
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<protosphere> cr1901_modern: I was just using it with an ATX to AT adapter
<protosphere> because it was what I had and it would work
<protosphere> (the power connector on the compaq board is just xt/at with some extra pins on either side)
<protosphere> I never got around to trying to figure out what was wrong with it in the end since I found I didn’t have my multimeter anyway
<protosphere> theres probably too much wrong with it for my level of knowledge anyway I imagine
<protosphere> the cpu seemingly doesn’t execute from rom and the cga card seems broken in other weird ways
<KitsuWhooa> <protosphere> the cpu seemingly doesn’t execute from rom <-- maybe it's held in reset?
<protosphere> https://twitter.com/protosphere_/status/1343119117545455616 the way it draws triangular sections across characters like that concerns me
<KitsuWhooa> I guess difficult to tell without a multimeter/scope, but still
<KitsuWhooa> I think that looks a bit like some bus lines are floating
<KitsuWhooa> Could be bad vram on the card or some cut/corroded traces
<protosphere> The way it’s drawing the blank sections is outside of the pixel grid though too
<KitsuWhooa> Anyway, regarding the cpu not executing, it's very possible there's a "power good" signal coming off the power supply, and unless that's tied to low or high, it won't start the cpu
<protosphere> yes the power good runs to some other ic that holds the cpu in reset
<protosphere> until that line goes high
<KitsuWhooa> I assume you can't check if the cpu is stuck in reset or not
<KitsuWhooa> ...or not
<protosphere> I do have a scope
<KitsuWhooa> Yeah I just saw in the photo and was like "whoops"
<protosphere> i just wanted to check if my cheap bench psu was a hazard before I went and did anything there
<protosphere> and I don’t have a multimeter on me
<KitsuWhooa> ah
<KitsuWhooa> For that video card, I'd suggest probing all the vram bus lines one by one as a starting point to see if anything weird is going on. Like signals rising really slowly or incorrect voltage levels.
<KitsuWhooa> Also, it's possible the video card requires negative voltage as well
<KitsuWhooa> *one of the negative voltage rails
<protosphere> Judging by some other accounts it just needs 5v/12v
<KitsuWhooa> that's what I'd expect too, but you never know
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