Home Featured #68 Mike Maginnis’ Rev 0 Apple II

#68 Mike Maginnis’ Rev 0 Apple II

#68 Mike Maginnis’ Rev 0 Apple II

Hi, welcome to another episode of the Assemblies
podcast. I'' m Chris Torrence and I have an unique visitor today It'' s Mike McGinnis from the open Apple
podcast as well as likewise drop 3 inches and Mike tell us Why we'' re below the actual unique guest is this revision no Apple II That no one has had the ability to diagnose or fix yet. As well as so we assumed we would certainly give it a shot today And if it doesn'' t work, then you ' ll take it to KansasFest as well as we'' ll let John Morris Is that his name? Yeah, yeah, we'' ll allowed John Morris have a run of it because I hear he can fix virtually anything Anyway And what'' s what ' s really what
are the symptoms? Oh, When we turn it on you ' ll obtain a screen complete trash and the duplicated warning No, I was you understand understanding you the power it beeps as soon as and after that goes to the boot up series This is beeps over and over unless you hold the reset key down and after that it obtains peaceful As well as you let go and also it starts again.Well,.

we'' ll show you. All. So incidentally, this is Serial number 5 absolutely no 2 5 so.
it'' s in the later run of the alteration zero I think there resembled 6 thousand.
made or something and also the board number is Five 2 absolutely no six. It does not have the initial power.
supply. I believe the majority of the parts of the initial other than a couple of the Dynamic RAM chips which I had to change because when we.
pulled them up from the board that the legs just degenerated So those are not original, but everything else is I assume.
so great. Yeah, let'' s get started. All right. We'' ll plug it in as well as see what happens Nothing yet That'' s green well, yet does that look yeah,.

s it.Do you think it'' s real screen? That'' s well I assume perhaps the video.
connection is a bit loose back right here I'' m uncertain that ' s interesting, yet we hit the reset But that is
the Apple to be we. stifle right it acts and also well I'likewise which I guess we ' ll see those soon We have the initial drives.
that were acquired for this thing As well as whether these these are plugged in.
or not doesn'' t matter hmm when I let go So Mike, how did you obtain this maker It was a female whose partner was someone like us.
as well as had a cellar loaded with things and he passed away And she didn'' t understand what to do with any of it and we ' re chatting like Cellar your dimension filled up with This stuff a deck equipment.He had.

like chess video games like electronic chess stuff He was truly that simply every she.
had no concept what it was what it deserved Or just how to obtain rid of it as well as you recognize, he had actually passed away like the.
year or so in the past so she was still pretty damaged up concerning it And she sort of just sent me this list of like here'' s All the things that I found in the basement.
until now. Can you inform me what to do with it? So I aided her kind things out clean it.
up obtain it on ebay.com and also obtain it out of there Which wow truly appreciated as well as.
as a thank you she gave me this amazing That'' s really awesome and also among these drives below.
has got a truly little identification number that was purchased like a pair months hereafter was So Yeah So did it did it ever before work or she said it yet However you'' ve never ever in fact it did not work when I got it Okay, it was this has been sitting and also had.
been resting in their basement for fairly time Yeah, so it might have resembled 30 years.
back was the last time it really ideal yeah We first eliminated every one of the chips from the board.
and after that cleaned up the motherboard with a mix of 90% isopropyl alcohol in addition to some get in touch with cleaner And after that we additionally attempted exchanging out all the chips from.
my Apple II plus, but nothing appeared to make a distinction Mike and also I are going to make use of a logic probe to.
try to examine several of the pins on the Apple II board And also this is a design 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 connected right into the bottom speaker pin. here, which is plus five volts as well as after that for ground I ' ve connected into the right most pin on.
the auxiliary video port up here And you can see that I instead than attempting to connect the.
alligator clips directly to the pins and also a danger shorting them I'' ve just made use of these little header.
cables below just to make it a little more secure so if we take the reasoning probe as well as we just touch it to claim the ground line on the 6502 You can see that it beeps and afterwards we can simply go.
down the pins and examination to see which ones are working So for instance the following one.
here'' s the ready line.So that ' s high Right here is the clock So both lights are lit up and afterwards. it ' s blinking with a high pitch sound That implies that it'' s a square wave that'' s. higher than 200 kilohertz. That'' s great and after that Let'' s go over to the various other side of the board below Pin 40 on the 6502 is the reset.
line. So if I just hold that down After that I hit reset You can see it goes low And also currently it'' s back high once more Now that I'' ve hit reset it ' s doing that thing where it ' s. constantly beeping and also beginning over as well as over once again and once more So now we can see if we can determine.
what'' s going on from any one of these various other pins So as an example pin 34 is the read-write line And you can see that each time it Does a reset then there'' s a shift for the.
read-write line as well as after that here are the data pins for the 6502 So this is D0 D1 D2 D3 4 5 6 7 this is currently deal with line a 15 so this would.
be the high little bit of the address line To evaluate all the solder pads on this Apple II motherboard I'' m mosting likely to attempt a method.
suggested by Alan Eco-friendly on the Facebook page Which was to lay down an item of.
aluminum foil in addition to a soft cloth and after that with the motherboard on top of it just push the Positive contact on each pin and also make certain that it makes.
contact with the solder pad on the bottom and I you can see I'' ve obtained the black lead hooked up to the aluminum foil and afterwards I'' m just going to evaluate each.
among these pins one after another To ensure that I'' m getting call All right, so here'' s the rev zero. Apple II looking significantly much more disheveled We didn'' t obtain it functioning Mike, what do you What do you have to state? Well, we did a great deal of fixing at the very least as.
much as we know exactly how to do we did a bunch of signal Reviewing with your logic probe and The voltmeter still the same.
outcomes we switched out the keyboard Power supply our supply we.
drew RAM chips we reset things the CPU We understand is working since we checked pin.
40 and 37 as well as got the right signals out of that Yeah, we understand that we'' re getting some type of car start big some sort of auto start since we when we placed the disc two card in port six it does.
you recognize the it tries to do the reset But yeah, I indicate, you know towns have actually been melted as well as Millions are dead and also at least one Apple II plus.
over there got given up to examine all this out, yet I Assume I believe we'' re gon na have to accept us Greater minds than ours.Maybe John will have. some thoughts and also I ' m gon na head residence at this factor Yet I ' m leaving this below. He ' s quiting. I appreciate your help as well as some of the concepts Yet ultimately we'' re still sort of.
where we were before you power it up and You understand, I indicate still does the same point Alright, so Mike and I were.
incapable to fix his rev absolutely no Apple II So ideally following episode.
we'' ll have a repair for the trouble and Let you recognize what occurred. So up until after that thanks for enjoying If I see this on eBay.