Hi, welcome to one more episode of the Assemblies
podcast. I'' m Chris Torrence and I have an unique guest today It'' s Mike McGinnis from the open Apple
podcast as well as also drop 3 inches and also Mike inform us Why we'' re here the real special guest is this revision zero Apple II That no one has had the ability to detect or take care of yet. And so we thought we would give it a try today And if it doesn'' t work, then you ' ll take it to KansasFest and also we'' ll let John Morris Is that his name? Yeah, yeah, we'' ll allowed John Morris have a run of it since I hear he can repair virtually anything Anyway And also what'' s what ' s really what
are the symptoms? Oh, When we transform it on you ' ll get a screen full trash and also the duplicated beeping No, I was you understand knowing you the power it beeps as soon as and also then mosts likely to the boot up sequence This is beeps over and over unless you hold the reset essential down and also then it obtains peaceful As well as you release and also it begins again.Well,.
we'' ll show you. All right. By the means, this is Serial number five absolutely no two five so.
it'' s in the later run of the alteration absolutely no I think there resembled six thousand.
made or something and the board number is 5 2 no six. It does not have the original power.
supply. I think a lot of the components of the initial other than a couple of the Dynamic RAM chips which I had to replace because when we.
pulled them up from the board that the legs just degenerated So those are not original, however everything else is I think.
so awesome. Yeah, let'' s start. All right. We'' ll plug it in and see what happens Nothing yet That'' s eco-friendly well, yet does that look yeah,.
that'' s it'. Do you believe it ' s real display? That ' s well I assume perhaps the video clip. link is a bit loose back here I'' m not sure that ' s fascinating, yet we struck the reset But that is
the Apple to be we. stifle right it acts and well I'also which I think we ' ll see those soon We have the initial drives.
that were purchased for this point And also whether these these are connected in.
or otherwise doesn'' t matter hmm when I release So Mike, just how did you obtain this device It was a lady whose husband was somebody like us.
and also had a basement packed with things and he died And also she didn'' t recognize what to do with any one of it and also we ' re chatting like Cellar your dimension full of This stuff a deck equipment.He had.
like chess games like electronic chess stuff He was actually that just every she.
had no concept what it was what it deserved Or just how to get rid of it and also you know, he had died like the.
year or two previously so she was still quite broken up regarding it And she sort of simply sent me this checklist of like below'' s All the things that I found in the basement.
so far.Can you inform me what to do with it? So I aided her sort stuff out tidy it. up obtain it on eBay and obtain it out of there Which wow actually valued and also. as a thank you she gave
me this amazing That ' s truly cool and also one of these drives here. has obtained a really little serial number that was purchased like a pair months after this was So Yeah So did it did it ever work or she said it yet But you ' ve never ever in fact it did not function when I obtained it Okay, it was this has been sitting as well as had. been being in their cellar for fairly some time Yeah, so it may have resembled three decades. back was the last time it
in fact appropriate yeah We first removed all of the chips from the board. and after that cleansed the motherboard with a mix of 90% isopropyl alcohol as well as some contact cleaner And after that we also attempted exchanging out all the chips from. my Apple II plus, however nothing appeared to make a distinction Mike and I are going to make use of a logic probe to. try to evaluate a few of the pins on the Apple II board And this is a version LP 560 in instance you ' re. curious and also what I ' ve done is I'' ve hooked this approximately 5 volts from the Apple II and to do that I simply tied into the lower audio speaker pin. right here, which is plus 5 volts and after that for ground I ' ve tied into the right most pin on. the complementary video'adapter up below As well as you can see that I instead than attempting to affix the. alligator clips straight to the pins and also a risk shorting them I ' ve just used these little header. cords below simply to make it a little much safer so if we take the reasoning probe as well as we just touch it to say the ground line on the 6502 You can see that it beeps and after that we can just go. down the pins and also test to see which ones are functioning So for instance
the following one. below ' s the all set line.So that ' s high Below is the clock So both'lights are brightened and
then. it'' s blinking with a high pitch sound That
implies that it ' s a square wave that ' s. higher than 200 kilohertz.
So that ' s excellent and after that Let ' s go over to the various other'side of the board right here Pin 40 on the 6502 is the reset.
line. If I simply hold that down After that I strike reset You can see it goes reduced As well as now it'' s back high once again Currently that I'' ve hit reset it ' s doing that thing where it ' s. constantly warning as well as starting over and also over once more and also again So now we can see if we can figure out.
what'' s taking place from any of these other pins So as an example pin 34 is the read-write line And also you can see that every time it Does a reset then there'' s a shift for the.
read-write line and after that right here are the data pins for the 6502 So this is D0 D1 D2 D3 4 5 6 7 this is currently attend to line a 15 so this would certainly.
be the high little bit of the address line To test all the solder pads on this Apple II motherboard I'' m mosting likely to attempt a strategy.
recommended by Alan Environment-friendly on the Facebook web page And that was to put down a piece of.
light weight aluminum foil in addition to a soft cloth and after that with the motherboard in addition to it simply press the Favorable get in touch with on each pin and ensure that it makes.
contact with the solder pad under and also I you can see I'' ve got the black lead linked to the light weight aluminum foil and afterwards I'' m simply mosting likely to examine each.
one of these pins one after one more To make certain that I'' m getting get in touch with All right, so here'' s the rev absolutely no. Apple II looking substantially extra disheveled We didn'' t get it functioning Mike, what do you What do you have to claim? Well, we did a great deal of fixing at the very least as.
long as we recognize how to do we did a number of signal Checking out with your reasoning probe and The voltmeter still the exact same.
outcomes we swapped out the keyboard Power supply our supply we.
drew RAM chips we reset stuff the CPU We recognize is functioning because we examined pin.
40 and also 37 and also obtained the ideal signals out of that Yeah, we understand that we'' re getting some sort of automobile beginning big some kind of vehicle beginning because we when we put the disc two card in port six it does.
you know the it attempts to do the reset However yeah, I indicate, you understand towns have been shed and Millions are dead as well as at the very least one Apple II plus.
over there got given up to examine all this out, but I Believe I believe we'' re gon na need to accept us Greater minds than ours.Maybe John will certainly have. some ideas and also I ' m gon na head house at this moment But I ' m leaving this below. He ' s quiting. I appreciate your aid as well as some of the concepts However eventually we'' re still sort of.
where we were prior to you power it up and You understand, I imply still does the exact same thing Alright, so Mike and I were.
unable to fix his rev no Apple II So hopefully following episode.
we'' ll have a fix for the trouble and also Allow you recognize what occurred. Till then thanks for enjoying If I see this on ebay.com.
