This video demonstrates troubleshooting and repair of an Acorn Archimedes A3020 computer's IDE hard drive interface, revealing that the 74HCT573 logic chip was replaced with a 74HC573 (which lacks TTL compatibility), and that a broken trace between the HCT573 and HC573 chips was causing the IDE recognition failure; the repair process involves using an oscilloscope to identify signal issues, reflowing solder connections, and potentially replacing the logic chips with genuine HCT versions to restore proper IDE communication.
Deep Dive
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Deep Dive
Acorn Archimedes A3020 part 2: video issues and IDE messesAdded:
Everyone, and welcome to the Retro Channel, and we're back with the Acorn A3020. Uh this is the second video that I've done on this machine. Uh if you want to see the previous video, I'll throw a link to that up there, and also in the video description. But, as a brief recap of that video, uh we first unboxed this thing. This was donated by Mike from Texas, uh who sent it over to me in Australia. So, we did a bit of an unboxing, and also took the covers off, had a poke around inside, inspected some of the damage because uh these machines do normally have a NiCad battery installed, and that had leaked on the motherboard, and um destroyed some of the traces. So, repair work has been done to this machine, and it is more or less functional. However, we did run into a couple of issues with the video output uh in the last video. So, that's the first thing that I want to try and take care of. And apparently, there is an issue with this machine recognizing the uh hard drive or the IDE interface.
Uh there is a little IDE to flash adapter inside this machine, but apparently, the machine itself can't recognize it. So, it may be that some of those repairs uh have either failed over time or just weren't carried out completely in the first place. So, uh we'll also be hopefully taking a look at the um IDE issue. But, uh first of all, we need to sort out the display issues.
Now, before we hook this thing back up, there were a couple of other things that I've learned since filming that first video that I wanted to quickly cover. Um most of these come from Mike, um who gave me a bit more history about this machine. Um one of them was the actual top cover itself is actually from an A3010.
Uh I mentioned in the first video that I thought there may have been like a failed retro writing process cuz there do seem to be streaks in part of the top cover. But, as it turns out, because this cover came from an A3010, and they have uh a bunch of sort of screen print stuff all along the top part here, in order to make this look more like a 3020, that stuff was removed and obviously the badge was changed to an A3020. So, um yeah, it's not a failed retrobright. It's literally just slightly wider bits of the case where um that screen printing was. For the most part, you can't really see it. I mean, you'd probably struggle to see it on camera. I can only see it if I look at the case at certain angles. So, yeah, not a big deal. I think the um original top half of this case was broken and that's why it was replaced with an A3010 case. Uh obviously, the bottom half of the case is the original A3020 case because the A3010 has different ports on the back. And from this angle, you can probably see the top half of the case is slightly wider than the bottom half.
Um Mike also mentioned that this Logitech mouse has been modified to work with the Acorn. So, originally, these mice um they're like a PC bus mouse. So, you'd actually have an ISA card that this would plug into on a, you know, IBM compatible PC. But, this one has been modified to work with the Acorn and I think Adrian did a video um showing how to modify one of these to work with one of the Acorns cuz um even though it's got a fairly standard PS/2 mini-DIN style jack, the Acorn uses a slightly different pinout from the regular PS/2 style. So, yeah, this mouse is already been modified, hence why it doesn't need an adapter. But, normally, these mice wouldn't work if you plug them straight into an Archimedes.
Mike also mentioned that these little logic ICs here, uh these are 74HC573s and there's some 74HCT573s in this bag as well. Uh these are just in case the ones on the motherboard, which look to be in a pretty rough state from that battery damage, they're just included in case they need to be replaced. Uh I think I misidentified one of those logic ICs as like a 74HC74, but that's just because some of the printing had rubbed off, and obviously I can't read. So, um yeah. Just in case we need to replace either of those two logic ICs, Mike did include a whole bunch of them, which is very nice. And speaking of the battery, I was a bit confused by the battery that was in this machine. Uh I wasn't sure if it was the original or not, because uh it's like a little coin cell battery as well, except it's a nickel metal hydride battery, rather than a NiCad battery. So, yes, it has been replaced, and I think I managed to get a voltage out of it of like 1.3 V, which is actually normal for that particular battery. And apparently, if um the battery was completely dead, um the um machine wouldn't hold its configuration settings, and uh I think we'd get I think on boot up, we'd get a red border, um which we didn't see in the first video. Although, then again, uh all the colors were screwed up in the first video, so um yeah. That's the first thing I'm going to try and sort out is this video problem, because um after talking to Mike, he said, you know, he didn't have any issues with the video output. So, I think it's just something stupid that I'm doing. And keep in mind, I know nothing about these computers. Uh like I said in the first video, I've never played around with an Archimedes, so um I don't really know what I'm doing, but um I'm very willing to learn. So, let's get this thing plugged in, see if we've still got that same video issue, and if so, try and sort it out.
All right, everything should be plugged in, and once again, I'm using the OSSC to do the video capture. Um so, it should be set to the right input. Let's power this thing on.
Uh can we see that display in the camera? I think so. Let's just see what that does.
A bunch of nothing.
All right, the keyboard's giving me four flashing lights.
All right, I can see there's a little LED mounted to um this GoTek here, which is also giving me four flashing lights.
And now it seems to have stopped.
Um so the disk LED was flashing at me. The power LED is a solid green, so we've definitely got power.
Did I connect something the wrong way?
Let's just disconnect this GoTek.
Or at least uh disconnect it entirely, may as well.
Let's try that again.
Oh, we're getting something.
31.48 kHz at 59.96 Oh, and we got a beep from the speaker.
Okay, I must have just plugged the GoTek in the wrong way. Thankfully, doesn't look like I damaged anything, but yes, we still have that green and blue screen, which definitely isn't right. Uh it should be like gray.
So, I don't think it's a cable issue. I mean, I could grab another VGA cable, but I've used this cable before and it's never had a problem. Um could also be something to do with the OSSC.
Uh I think last time I used this was over a year ago, so maybe I just need to jump into the settings on this thing.
Good thing I still have the remote kicking around. Does it have batteries?
It does.
I do not remember what buttons I need to press. Uh is that menu? Okay.
Video in processing, let's start there.
Oh.
Okay, so I think the last time I was using this uh was the NES Luma code video, and it is still set to NES Lumacode. Yeah, prior to the previous video on this machine, I haven't used the OSSC for probably over a year, so I'm surprised that it actually holds on to those settings. I'm very much more used to the RetroTINK, which immediately forgets everything the moment you unplug it or power it off. So, um yeah, okay, that probably Yeah.
Some foolishness on my part, clearly. Um so, yeah, that looks a lot more what I'd expect to see.
Um maybe I should just go in here and just reset all the settings. I'm sure that's possible somehow. Reset settings.
Let's just do that. Okay.
All right, everything looks a whole lot better. Um let's poke around the OS once again and see what we can find. Well, I'm kind of glad that I didn't have to go troubleshooting anything in the um video circuit, cuz I can see a lot of corrosion did make its way over here, but I guess it hasn't really affected anything apart from breaking a couple of traces here, which look to have been already bodged, so don't have to worry too much there, I guess. All right, let's jump back in here. So, apparently, if I hit heading to configure, I think I can set this to make the hard drive show up somewhere. Um Keep forgetting that everything just pops up in the taskbar once you sort of open it. Um All right, disk.
So, I'm guessing that's telling us Oop.
Oh, okay. I can just I can add my own disk. Well, okay, let's try and add a hard disk.
Changing the number of disks is potentially dangerous. Uh I don't think we're going to break anything at the moment.
Okay.
Disk number understood. Has it been formatted? I'm pretty sure it has.
I mean, that kind of looks right. I don't know why the GoTek didn't work.
Maybe I just plugged that in wrong. I'm just going to just going to shut this down now that we've sorted out that video issue, which I felt was going to take a lot longer.
Let's just plug the GoTek back in. I'm pretty sure the cable's the right way around. It did already have this twist in it. So, I just assumed that it was going to fall back in a similar sort of placement.
Yeah, so now I'm getting flashing lights on that drive LED and uh nothing on the GoTek display. So, maybe I have plugged this in backwards.
Oh, of course, GoTek probably needs external power. That might also make it happy.
Yeah, the machine seems to be unhappy about it.
Yeah, four flashes from the disk LED.
And then, I guess it gives up cuz it stops flashing, but it doesn't boot into the OS.
The GoTek display does say 004, so it appears Yeah, the GoTek is alive.
Uh Hmm.
What if we unplug that?
>> [snorts] >> Okay, yeah, that's strange. So, even with the um the GoTek disconnected, it's just getting power, the machine still refuses to boot.
That's that seems odd.
All right, maybe we should try the reset button. I know there's one.
It's on the side of the computer. It is recessed, so I need something to poke that.
All right, just hit reset.
Oop, looks like it's booting.
So, maybe that's an issue with the configuration, um cuz obviously this does store some settings in um uh non-volatile RAM.
So, yeah, it seems to boot after I hit the reset button, so maybe it's because I've put this hard drive here, but that doesn't really explain why it wouldn't boot before when I didn't have that hard drive there.
So, maybe we should get rid of that for now.
Okay.
I'm going to power this off. I'm not going to make any other changes.
I just want to see if it boots correctly.
Yes, okay. Seems to be booting normally.
So, why does it not like the GoTek anymore?
Yeah, it is not happy about having that GoTek there. That's strange.
All right, what if we try and boot that and then hit the reset button.
Okay, so turning it on and then hitting the reset button seems to have allowed it to boot properly.
And yeah, GoTek is there, so that's still working.
That's good. Kind of strange that I'd need to hit reset in order to make it boot.
Um definitely didn't need to do that the first time, like in the previous video, so yeah, that's a bit odd. Okay, so obviously trying to add the hard disk from here isn't going to work. Now, um a few people did mention that um I can get out into the command line by by F12.
Okay, it shows up right down the very bottom of the screen. It's almost cut off, but you can kind of see me typing down there. So, apparently, if we type configure, uh we have configuration options.
Okay.
Is it going to keep scrolling or is it just stuck?
Okay, so even though the image is slightly cut off, we can see that under floppies it says D and hard disk D IDE disk D.
And down the bottom it says where D is the decimal number, a hexadecimal number preceded by and or the base followed by underscore followed by the digits in the given base.
You got that?
Is the hard drive just not set up, but then why does it say floppy drives uh also not set up or they're just D with no number or anything?
What does that mean?
Uh let's try status.
What does this tell us?
Drive zero, floppies one, hard disk zero, IDE disk zero.
Step three.
And then yeah, use configure to set the options.
Um Okay, so I've added the IDE hard disk back in the um the GUI configure utility.
Let's go back into the command line.
See what it says now.
Um the same.
Oops, status.
All right, so now it does say ID is one.
So, I guess we have configured that. Uh I don't know how to get out of the command line.
One of the other F keys? Yeah, I I don't know how to go back to the GUI. So, just going to reset it.
That'll get us back there.
I'm sure I'll figure that out soon enough.
Okay, what is going on?
We don't have a flashing drive LED or disk LED.
Video output seems to be there.
Even though the screen says no video, the OS says C reckons there's video.
Oops.
Still full power cycle. Okay, we're getting that flashing LED again.
If I hit the reset button, it looks like it's now going to boot.
And our drive is still there. No doubt we can't access it, but you know, it's still Yeah, still shows up.
So, yeah.
Configuration options, but it doesn't like how do you actually change these options?
The only thing it seems Oops.
You hit shift, but yeah, that just kind of pushes us out of this. Like, do we actually configure anything from here?
Uh okay, do I just need to hit return twice?
>> [laughter] >> Okay. Yeah, I learned something.
Okay, I need to do some reading and work out what the normal procedure would be to set up the the IDE hard drives in these things. Um, I know Mike already tried to do that and you know, it didn't work for him. So, I don't think I'm going to have any more success. In fact, I can guarantee that I won't, but I need to just rule that out as a possibility.
Um, once that inevitably fails, then we'll pull this thing apart and inspect some of this repair work.
Okay, so the next step apparently is to use the HForm utility, which I guess is hard drive formatter, to correctly set up the hard drive and I assume there's nothing currently on that thing.
It is one of these little IDE flash adapters.
And I [snorts] assume it's already blank. So, let's try and use that utility. Mike said that it was on the GoTek somewhere. So, I just need to find I guess which disk image it's actually set to.
HForm.
And HForm 2.48. I assume we just run this one.
Format which drive? Okay, yes, it is drive four. It's really annoying me that this is cut off on the edge of the screen.
All right, now we can see everything.
Okay, so it looks like it can see the flash drive.
465 cylinders, 520 heads, 544 sectors per track. So, does that mean that it's already been set up and I shouldn't touch this?
Yeah, we're going to touch it anyway.
Let's um Let's just set it to the smallest possible configuration. Obviously, that's for an actual Kona hard drive, but we'll try this.
Uh let's go with A.
Do a format, proper format. Soak test the hard drive. No, we won't worry about that.
Not at the moment.
You sure you want this to be drive?
Yes.
Okay.
Well, it looks like it's formatting it, but we don't actually know if it's working.
HForm failed. Disk not understood. Has it been formatted?
Okay.
And now it's just kicked us out. Okay, I've been playing around with all the options in this HForm program, and yeah, none of them seem to allow this um IDE flash drive to work properly. So, I don't know if it's just I'm not specifying the right um parameters or whatever, but um yeah, it nothing really seems to work. So, I'm thinking I might try and pull the current one that's in the machine out of there and stick in the other uh flash adapter that I've got here, just in case there's an issue with this one that's currently in the machine. Uh I'm pretty sure I also have some compact flash cards and some little adapters that will connect to the um little 44-pin connector inside this. So, um I guess I could also try that as well. So, let's um let's disassemble this a bit, pull that current flash adapter out, stick the other one in, see if that makes any difference. It is sort of weird that yeah, the um the description for the device that it gives is, you know, a bit of a garbled mess, as is the firmware version, but that may be just that um the Acorn's not expecting to see something like a um flash adapter in it, which isn't a surprise. Um so, yeah, let's power this thing off, take the covers off, swap out these um IDE flash cards and see if that makes any difference.
Somehow doubt it though.
No doubt Mike has already tried this.
All right, there it is. So, let's pop this one out. I'm pretty sure it's the same as the one in the bag.
Um this is also another one that Mike provided, so uh I assume he's tried both of them. Well, this one says it's 1 GB size. This one doesn't say what size it is.
Can probably decipher it from the part numbers, but yeah, I don't know.
Uh they look more or less the same, so not really expecting any different results, but I think this is worth a shot.
All right, the other IDE flash is installed. Let's see if this makes any difference. Somehow doubt it.
Looks like the machine is booting, so that's a good start. At least it's not flashing the um disco IDE.
Really doubt the drive is just going to work. No.
Yeah, okay. So, I think that's pretty much exactly the same as what we got from the um the other IDE flash, so uh let's just try formatting this one.
Uh we'll just go with option four.
Really doubt this is going to work, but give it a go.
Uh I set it to be a bootable disk. I don't think that's going to matter cuz it's probably not going to work.
Yeah, disk not understood. Has it been formatted?
I tried.
Okay, let's uh swap to a normal compact flash card, see if that does anything different. I somehow doubt it though.
Uh I did find a 16 gig compact flash card, and I thought I had an adapter that um fit one of these. Well, it does fit the flash card, but it's got male pin headers on the end, and we need female pin headers. And uh I don't think I've got like a gender changer, and I'm not even sure if that would actually work correctly. Um obviously, I don't deal a lot with um you know, compact flash cards and IDE flash cards and that kind of thing. Um but I did find another one of these IDE flash cards in my stash, so I guess we can also try this as well.
Somehow doubt it's going to make any difference. Um these jumpers set the same? Yes.
And this one is a 2-gig version. Um I don't think that's really going to help cuz I'm pretty sure the Archimedes can't see, well, the RISC OS version in this machine can't see anything over like 500 meg or 512 megabytes, so it's probably not going to make much of a difference, but >> [gasps] >> uh it's worth a shot.
I'm going to take everything back out again.
In fact, that's probably enough.
Just need to stick that on there.
Okay, let's see.
Is it going to look the same as the other ones?
Yeah, pretty much.
Um just go with four again.
I don't think it really matters cuz once again, it's probably isn't going to work.
Disc not understood. Yep, not a surprise. Okay, I need to take a little break, figure out if I'm actually doing all this correctly or if there's certain parameters that I need to specify, and then we'll um come back and try again, assuming that there is something stupid that I'm doing, which wouldn't be a surprise cuz like I said, I have no clue about these machines. So, I'm going to do some research, um probably get get touch with Mike just to um you know, pick his brain about this kind of stuff.
Um I'm sure some of you watching who are very very familiar with these machines will know exactly what to do and exactly what I'm doing wrong. But like I said, I have absolutely no idea what I'm doing.
So excuse me for one moment.
Okay, I did get in touch with Mike and he confirmed that he saw the same issues especially the the device description and also firmware version is a bit of a mess and yeah, the configuration of 897 cylinders, 528 heads and 63 sectors per track is definitely wrong as well. That would make this drive up to I don't know 120 gigabytes or something and it's definitely not that. So I did try formatting this using the other option. I did actually try this before off camera but didn't have any luck but we'll try it one more time. So 63 sectors per track should be fine.
Heads we want to go 16 not 500 and whatever and cylinders if we go for 1021 that should put this drive just below the 503 megabyte threshold.
So we'll go for a format.
Won't soak test. Let's make it bootable.
I know it's not going to work anyway but we'll give it a shot.
Yeah, obviously that didn't work.
Well, either way we know this is not working properly. So let's power this thing off and take a closer look at the damage that's been caused by the leaking battery.
So here's our battery damaged area and like I said in the first video, I think the previous owner, the person who had it before Mike actually did these repairs. So I think for the most part they look okay. Obviously some parts look a little bit ugly but uh for the most part they seem to be working although with the IDE connector not working, I guess we're not fully out of the woods. So I think I mentioned in the first video I thought this was a 7474.
This is actually the 74HC573 and this one here is the 74HCT573.
So, both of these pretty much handle stuff going to the IDE connector and if we take a look at the schematics we can see that clearly. So, here's our IDE hard disk connector and if we follow some of these traces down here you can see IC46 which is the HC573 and IC45 which is the HCT. These both interface with the hard drive connector so yeah, it's not out of the question that one of these might be broken.
So, even though part of me is itching just to remove these and redo this whole area, let's have a look with the oscilloscope first see if we can spot what is going wrong here. Okay, so we've just hooked up the GoTek and the flash device just so we can see what happens when everything is connected. Hopefully we won't need the keyboard to actually spot some obvious activity but let's just pick I don't know, this pin and yes, we do have something going on there.
So, that kind of looks fairly normal.
Let's have a look at some of the other pins.
So, of course I'm not actually looking at the schematics at the moment. I'm just literally poking at all the the pins on this chip just to see if we spot anything odd. This one does look a bit strange but Oh.
Okay.
That has activity when we move the mouse. That's fun.
So, if you look at IC45 I was poking around to the right hand side of the chip which would actually be I guess this side. Looks like the uh schematic isn't that well drawn. I think underneath that true is the actual pin numbers. In fact, I can just kind of make out 19 18 17 blah blah blah. So, they're connected uh directly to the data bus. So, it's not a surprise that we're going to see extra activity on there.
Um but obviously only when it needs to actually talk to the hard drive. I'm guessing that's when um the pin one, which is output enable, is going to go low. Let's look at pin one.
And there's already activity on there.
So, I guess that's not the full story cuz don't think it would be trying to access the um the hard drive that often. There is also a pin 11 on the schematics, which is labeled E. Uh let's just quickly look up what A573 actually is.
Okay, octal transparent D-type latches with three-state outputs. So, I'm guessing pin 11 is a latch of some sort.
Yeah, it's labeled LE, which I guess means latch enable. So, all right, here we go. So, output enable, if it goes low and latch enable is high, will cause the data input to appear on the data output. And it looks like when latch enable goes low, then uh it doesn't matter what's on the data input, the data output will be the same as whatever was previously there.
And of course, if output enable goes high, then um everything's ignored and the output just goes into high impedance mode.
So, let's have a look at pin 11, which should be this one on the corner. So, there is activity there. So, looks like, you know, it is trying to talk to the hard drive, uh even though we're not trying to use the hard drive.
Okay, so let's just have a look from pins two to nine to see if there's normal activity on those pins cuz that would be coming from the hard drive.
So, pin two looks mostly okay. There is a little sort of runt pulse, but don't think that's going to be affecting anything.
Pin three does have a bodge wire attached to it.
Let me just sort of try and push that out of the way a little bit.
Pin three Pin three appears to have no activity.
Uh okay, so there is activity on the HC chip, but if we go straight across to the HCT chip, which uh I can see by these traces in between is directly connected.
Yeah, we're not seeing proper activity there. So, that's definitely got to be a problem.
Uh let's just continue through the rest of them.
All right, that looks normal.
Normal.
Pretty normal. They all have that little runt pulse, but yeah, I guess that's normal. Yeah, so it does appear that um the third pin down on the HCT573 is a problem. Not seeing anything there.
That's the one with the budge wire coming off it.
So, that would be BD9.
Uh and we do see activity on pin 18 of the HC45, which is also BD9. So, um there's only a tiny bit of trace between those two. So, the trace must be broken there. Uh I'm not sure.
I guess this budge wire is then taking this BD9 signal over to the IDE connector. So, that should be at pin four. Let's um I can't really probe that right now.
Let's power this off.
Remove the IDE interface. Okay, let's just see.
Pin six on the IDE connector should be connected here.
And it is not.
Ha. But it's kind of funny. It is budging the connection from the HCT over to pin six, but we've [snorts] actually got a break between pin six of this and pin whatever it is, 18 of the HC. So, this small bit of trace isn't actually connected properly.
So, I'm not going to go pulling everything out just yet. Let's just try and remove this bodge wire to get it out of the way.
See what we can see underneath.
I think just doing that may have actually reconnected that pin to the trace. I'm pretty sure pin three here was just floating slightly above the trace, and I think just me doing that may have reconnected it.
I know, it hasn't. Yeah, even though that trace looks intact, it's got to be broken in there somewhere.
I think our best bet here is just to flood the area with some liquid flux and just try and reflow some of these pins. See if that helps the situation.
Could also quite easily make it worse.
Yes.
Already getting solder bridges, but um there is quite a lot of solder in there.
I'm surprised there aren't a lot more bridges.
So, I'm just going to keep doing this until I manage to sort of drag the solder out.
Hopefully.
Getting there.
I'm just wiping the solder that gets onto the tip off in the brass wool.
And now I'm going to get carried away because yeah, solder really is pretty ugly, so I'd like to try and clean up this area a little bit more.
All right, let's stop there. Let's see if we've got a connection from pin six of the IDE connector over to pin three of the HCT.
Oh, of course we do not because that's this bodge wire.
All right, we'll reconnect that in a second. Let's see if we've got a connection from pin three of the HCT to pin 18.
And I'm blocking the shot here, but pin 18 of the HC and we do.
Okay, so if we reinstall this bodge wire, in theory, that should fix our problem.
Okay, I've just cleaned up the end of that bodge wire. I'm just going to tin it with a bit of solder.
I might actually bring it in over the top of the chip.
All right, our bodge is reconnected, so we should see, even though you can't see the multimeter, can I bring it into shot? Just Uh we should see a connection from pin six of the IDE connector to pin 18 of the HC.
Yep, and of course pin three of the HCT.
All right.
Did that solve the problem?
Or are we still going to find more problems? Um just given how this looks, um dare I say we might find some more problems, but let's just try this out and see what happens. I'm keen to know.
All right, let's run H form again.
Device four.
Uh it is still a mess with the description and firmware version, so and yeah, we've got 528 heads.
Don't think that's possible.
Um even though this is obviously a flash device, so it doesn't actually have any physical heads or cylinders or whatever, but um yeah.
Doesn't seem right.
Let's just use one of the presets um just so we can get some activity going over here.
Um yeah, sure, whatever.
Okay.
While it's doing that, let's bring up the scope again and just poke around.
So, obviously pin one um chip select is doing stuff.
Pin two, ooh.
Pin two does not look happy.
Didn't look like that before.
Pin three also doesn't look happy. Pin four doesn't look happy.
Ew, have I made things far worse?
Am I just not getting a good ground? I think we've got a decent ground.
Um Hm, and the formatting is apparently completed, but yeah, all of these look very unhappy now. That's not good.
Why has it gone like that?
Pin 11 still has, you know, regular-looking activity, so that's our latch enable.
But yeah, all these things going over to the hard drive, which is pins three to nine, all look very screwy now.
Obviously, we won't see an issue on the actual data bus side because the system was working. Uh if there was a problem over here, um the system almost certainly wouldn't boot.
But um yeah, on the output side that's going to the hard drive, yeah, that I I can't see how that's right.
Yeah, even back on the desktop, these don't look right. Um Did we have the IDE device connected when we were probing this before? I don't think we did. Let's remove that.
Power this back on.
Probe those again.
Yeah, it still looks really screwy.
So, seems like I made things worse.
I don't know how, but I managed to do it.
Okay, I think what we need to do is remove both of those ICs, clean up the area, check all the traces going in and out of that area, and then reinstall a couple of fresh ICs which Mike kindly provided.
Let's get that done.
All right, I've just removed all the nuts holding the ports along the back, so we should finally be able to free this board from its metal cage.
And let's take a look on the underside.
Oh, it's actually not that bad.
So, yeah, I think the battery did more damage to the top side, and obviously also this metal shield. Um, yeah.
But, that's all cosmetic. We don't really care about that right now.
So, I really want to remove both these chips, but I know if I hit this area with hot air, it's also going to desolder all these bridge wires. Um, I guess I don't really have a lot of choice.
All right, let's see if we can actually protect this stuff back here.
Uh, actually, I might move that cap out of the way cuz it's uh it's going to get pretty toasty in that area even with the Kapton tape, and um that cap's just it's kind of in the way, so let's get that out of the way.
All right, that cap is out of the way, so we should be able to get a bit of tape over this stuff a little bit easier.
Of course, I also don't want to melt the floppy drive connector.
Uh everything else around here is probably okay. Let's remove that little bodge wire and then blast this with some hot air, see if we can get these ICs off cleanly.
There's one.
This one could get messy with all those bodges on the side.
Yikes.
All right, let's get all this old solder out of the way.
See what we're dealing with.
Okay, so it looks like we've got one loose pad there, but I did actually spot that when I was reflowing this chip, so yeah, that's fine.
Uh looks like this one is trying to come loose, but it's still mostly intact. And of course, we've got a few missing pads over here, which is where all those bodges were connecting to, so yeah, no surprise that there were so many bodges on that side.
Uh and of course, a bunch of burnt flux and other crap.
Um maybe we should try Let's try the soft brush.
Try not to disturb anything too much.
And of course the brush is just spreading everything around, but uh that's why I sort of wipe it off on a cloth cuz it sort of absorbs all the crap and then it can all come out on this.
But um it's actually not too bad under there. I thought it would be quite a bit worse.
I mean it's not great.
It's just not a horror show.
Not quite.
I did just lose that pad, but that's okay.
I might just run the braid over all these vias cuz they are looking pretty unhappy.
I don't want them to >> [sighs] >> slowly decay.
At least try and get them somewhat shiny.
So dare I say we were missing the connection from these traces over to the actual pins of the IC. Obviously there were bodges from the pins of the IC over to these vias, but um yeah, if these pads were already gone, then it stands to reason that uh there was nothing connecting to all of these traces going back under the chip. So I reckon that's probably what was wrong, but I'm curious to see if these ICs are still working. So let me clean them up and we'll try and test them.
So we'll use this IC tester which I've seen Lee from More Fun Making It Use, and it seems to be pretty good at telling the difference between LS, HC, and HCT chips. So let's see what this tells us. assuming I can get this IC in here.
Let's try that.
Aha!
74HC573, and this is This is actually the 74HCT, so either this can't tell the difference or this chip has been remarked. I don't know if it's the original one that was in there, but um yeah.
It is at least functional. I just don't know if it's really a HCT chip or just a HC. And um obviously this other one is the actual HC chip.
Okay, I think that's in.
Yeah, same thing. 74HC573.
All right, let's see what these replacement chips come up as. We'll just separate the two original ones.
And this is supposed to be a HCT573.
Ooh, and the markings do look very similar on both of these, so are these all fakes?
Are they all genuine?
All right, let's see what a new chip says.
Same thing. HC573.
Okay, yeah. So, this chip is the one that was on the board, and this is the one that came in the bag of chips, and they look exactly the same. Even the um the batch or date code is the same on both of them. So, dare I say the original chips that were on the board have already been replaced with these ones. And um these may not be genuine HCT chips.
Yeah, looking at the other bag of chips, we also have exactly the same HC versions. So, yeah, I think both of the chips that were originally on the board have been replaced by the ones in these bags. And um it should be okay for the HC one, but if the board requires a HCT version, then um these are not going to work properly. So, that could also be our issue.
Just stick one of these new ones in the tester just to see.
Yeah, 74 HC573.
So, that tells us that these two chips were not the original ones that were on this board and somebody has already replaced them. But, um >> [snorts] >> yeah, if this is not a genuine HCT chip, then that's going to be a problem. Um I think it's also highly likely that one of these traces, especially the ones running under the HCT chip, could have been an issue as well. So, I think I'm going to need to order um or at least try and source some genuine HCT chips and also try and reconnect some of these traces.
So, even though we're not sure about this chip, I do want to put the HC chip back in place cuz um everything looks pretty good over here. So, we shouldn't need to ever remove it again. And I have already checked all these vias to make sure they're actually making continuity to the other side of the board and they all seem fine. So, let's at least put that back into place and then we'll have a think about what to do with this one.
May as well use one of the new chips out of the bag. We'll just make sure that it's actually working before we go installing it. Yep, cool.
HC573. So, let's stick this one here. Uh of course, I'll have to just bodge a little connection between this pin and uh this trace right here, but that should be pretty straightforward.
I'm just going to try and extend this leg out a little bit so that hopefully we can get it to reach over to the rest of that trace.
All right. Doesn't look like much, but that might just be enough.
Let me just tack in this corner pin.
And I'm going to put it a little bit further across to the right just so this leg can hopefully reach over to that trace.
Um that should be good enough.
I think that's got it.
Yes, we do have a connection there.
So, that should be fine as long as I don't disturb it too much.
All right, that should be our HC back in place. I'm just going to check all these connections again.
And also check for shorts, of course.
All right, all our connections are good and we don't have any shorts. So, this chip is okay.
This one is going to be a bit more of a challenge, especially if I want to easily remove it and replace it with something else. So, um yeah, I think I'm going to run some bodge wires from these wires over to these resistors cuz obviously the traces go underneath this chip and then over to here.
Uh at least that'll sort of bypass these missing pads.
Uh of course, I'll still have to work out a solution where I actually managed to attach the legs to the rest of these traces, but um we'll we'll get there. We'll figure something out.
Hm, as tempting as it is to keep on working on this, I know that um if these HCT chips turn out to be the actual problem, that I'm just going to have to remove this thing again. So, um that'll obviously [clears throat] involve hot air and probably undoing all the bodges that I'm about to put in from these pads over to these resistors. So, I think first what I'm going to do is source more of these genuine HCT chips and then we'll continue on from there. So, um as this video is probably already long enough, um I'm just going to leave it here for this one and we'll pick this up again in the next part of this series and um hopefully get a working hard drive. Um so, yeah, if you have any suggestions or know anything else about um installing one of these IDE flash modules in an Acorn Archimedes, please leave it in the comments. Um for example, do you know if the description normally shows up garbled or is it supposed to say something more legible?
Um, and yeah, of course any other ideas or suggestions about these machines would be most welcome. So, um, yeah, we're going to leave it here for this one. Thank you all for watching and a massive thanks to the people that support the channel on Patreon. If you want to do the same and get ad-free early access to these videos along with discounts on my electron store and some occasional behind-the-scenes access and of course keep the channel running, be sure to check out the link below to the Patreon page. Um, that is it for this one. Thank you all for watching. I will catch you in the next one. Bye.
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