Compaq Portable 1 Restoration (Part one)

Hello, and welcome back to The 8-Bit Guy. So, for quite a while, I've been eager to do a documentary series on the first days of Compaq Computer Corporation. But, there have been 3 very specific machines that I wanted And, I've been on the lookout for these machines for quite a while. Well, I even have finally acquired all three of them.

Unfortunately, all three of them are broken and every one three of them do require cosmetic restoration also. So, this is often getting to be the primary of a series of restoration episodes and I'll be starting, with this guy. This is often The Compaq Portable 1.Of course, really it's just called the Compaq portable but we quite retroactively call it the one to differentiate it from the amount two and three. This is often quite almost like the Osborne within the way that it's packaged. But, This machine is quite special for a couple of different reasons.

One, I actually knew somebody who had one among these back in my high school time. But, this was also the primary commercially successful IBM compatible computer. Also because the first commercial successful IBM personal computer, so this is often a reasonably interesting piece of history So, I actually picked this computer up a couple of weeks ago at the retro computer gathering that we neutralize Dallas periodically. And, I used to be told it doesn't work. But, I even have not tried turning it on yet. So, let's probe this thing. Taking a glance at the outside of this thing, it's pretty dirty everywhere. 

However, it doesn't appear as if anything which will be hard to wash and that I don't even think it needs any retro rite. I'm almost sure what to try to to about the thread coming off this leather handle, though ..

However, taking a glance at the keyboard, things could also be different here. The keys definitely appear as if they have retro rite. In order that should be fun. But on the brilliant side, it isn't missing any keys. Well, I assume we should always plug this thing in and see what it does. Well, here goes nothing. I hear a lover. But there's no activity on the screen and that I don't hear any beeps or movement of floppy drives. I'll check the brightness. No difference.

OK, I think we will assume it's dead. Let's see if we will revive it. So, there are 5 internal snaps to get rid of this cover. What you would like to try to to is pop the primary one, then place something in There like another screwdriver to stay it from snapping backtrack. 

Then go right down to subsequent one and repeat. Eventually, once you get to the last one, the panel will come off. It's like there's already a broken snap. I don't see But, all the remainder of them seem to be good. This thing is pretty neat. It's like each function of the pc has its own little metal cage and And it's like they're mounted on little rubber shock absorbers, which is pretty cool! And it's like they're mounted on little rubber shock absorbers, which is pretty cool!

I wanted to start out with the cardboard socket cage, but these are a number of the foremost annoying screws ever. They're flat-tipped, but the slit is just too skinny for an honest sized screwdriver to suit. And that I just wans And while I had better luck thereupon, it had been still difficult to get rid of this stuff because there isn't much to grip onto. If the heads were just a touch bit taller, that might have helped tons. 

OK, let's remove the duvet. So, unlike other portable computers, this one is basically a bit like a desktop thereby it's 5 ISA expansion sockets. And 4 out of the 5 slots are filled Next, I'll remove this HV panel. Tons of those covers are just designed to slip off if you loosen the screws a touch. And there we go.

I'll also remove this bottom case cover. The primary troubleshooting step I always absorb the case of a dead computer is to get rid of anything that isn't essential, so I'll start with this. 

It appears to be some quite networking IBM MultiMate interface, never heard of this. Next thing is, what appears to be a parallel interface card. Next up is an old MFM disk drive controller card. All right, so I noticed there's this tiny LED power indicator on the computer But watch what happens once I power this thing up. Yeah, it flashes real quick, then you hear the fan come on. I noticed the fan itself is powered from AC power, so it isn't really directive of the facility supply working . So I'm getting to measure the voltage at the board. See that?

When I power it on, there ’s a brief burst of power, then it dies, a bit like with the LED.

OK, so I'm getting to keep disconnecting stuff. This is often the cable that runs the interior monitor. So I'm getting to remove the video card. Then I'm getting to remove the floppy card. Then I'm just getting to unplug the facility to the floppy drive and disk drive. The thought here is, I feel the capacitors within the power supply are weak, and that I want to scale back the load on the facility supply.

OK, here ’s the facility LED again, let ’s try the facility.

Hey, we've power!

Of course, we aren’t getting to see anything on the screen because there ’s no video card! So, let ’s stick the CGA card back in there.

However, nothing happened and in fact we were back to the flashing LED again. I felt like maybe the power supply was weak and there just wasn't enough amps to get past that initial starting phase. And I really wanted to see if the motherboard worked before going any further, so I got a crazy idea to use another power supply and sort of jump start the thing by giving it a few extra amps. I even asked a few other experts if this would be a bad idea and nobody could think of a good reason not to. 

I used some paperclips and just bent them into the right shape so that I could jump all 4 leads from the two power supplies.

Yeah, I think that will work.

Ok, I ’ll start by firing up the external supply.

Yikes .. so, that was a bit unexpected. Let's watch that again. It looks like a tantalum capacitor on the video card exploded. You can see it right there, and you can also see the black mark it left on the metal bracket and even on the pin headers above it. Here's the interesting thing, now that the capacitor blew, the power supply actually starts up every single time now.

However, I'm still not getting any video. I decided to test the voltages again and this time I'm getting a steady 5.1 bolts, which is maybe just a bit high, but I don't think it would be a problem. And on the other rail I'm getting 12.4 voltages.

Again, a little high, but probably not an issue. All right, so I had to sleep on this and now it ’s morning and time to get back to work!

Now, let's just take an overview of where we're at in this troubleshooting situation. First of all, I thought the problem was the power supply. And, apparently it wasn't. Apparently the problem all along was this tantalum capacitor on the CGA card was shorted. And, I guess the power supply in here was simply too weak or its protection circuit was too precise to allow the current to flow through, where this power supply just barreled the power right on through until this thing blew out.

Interestingly enough, the power supply is working fine in here, now. And every time I fire this one, there is proper voltage at the motherboard, and at the Molex connectors for the floppy drive and the hard drive. So, I think the power supply may be good. But, there's still 3 wildcards. And that is, does this CGA card work?

I looked at this capacitor and it only appears to connect to this external header here and it doesn't appear to be anything critical on this card. So, I don't think that capacitor is a critical component, but I'm still not getting any video, either on the external or the internal monitor. So, that raises the questions of does this card work?

Does the motherboard work?

And does the internal CRT work?

I can tell you this, when I fire the computer on now, I see that the heater on the back of the CRT is glowing now. Which, is a good sign that does tend to indicate the CRT may be working. So, how do we troubleshoot this?

Well, we need to do a process of elimination. Now, I don't have a replacement motherboard that I can try, but I did make some phone calls last night and I made a late night run over to my friend DJ's house and he had these.

Now, these are CGA cards!

But, they're not just any CGA cards, they actually happen to be Compaq CGA cards with an internal header for running one of these internal monitors. 

Now, you may notice, it's a little bit shorter than the original card. I think this Is from maybe the second generation of these Compaq portables, so it's a little bit more compact. A lot of the chips are more consolidated. But, in theory, it should work. So, I'm going to stick this card in there and Let's see what it does. The internal header is in a different place, but I think the cable will reach. And it does, so there we go. Let's try it again.

Nothing. Still no video, no beeps, no signs of life. I also tried it on an external monitor just to be sure. Still nothing. The next thing I want to do is try one of these POST cards. And, no, I am not talking about a post card you send in the mail, but POST stands for power on self-test. This particular one is designed to work in an ISA slot or a PCI slot. 

Then it has a decoding for any error codes from the BIOS. Also, it has these little LEDs over here will show all of the initiatives and other information about the bus, including the reset line so you can see if that is stuck or not. So, I'm going to stick this down in Well, everything looks good, except there are no codes and still no activity.

Well, it's time to remove the motherboard. The way do this is to remove this little panel so that we can disconnect the power supply and the keyboard. And the board simply slides out like so. Well, here it is. The board is somewhat smaller than I expected.

I ’m a little mystified what these empty ROM sockets are for.

I hope I ’m not missing something important there.

I ’m going to go ahead and reseat all of the socketed ICs.

I ’m not going to remove them, just pry them up a tad bit and push them back down in.

I ’ll also do all the RAM chips .. speaking of, I noticed this one here in a socket, makes me wonder if this RAM chip has been replaced before.

I also noticed something else.

Check this out. The trace here is burned. This is most likely the 5 volt rail for the ISA sockets. So, I thought I should test continuity on the ISA sockets. And yep, it appears there is a break right in the middle. Looks like the 3 slots on the end here are the only ones getting power. So, I tried the POST card again in one of the dead sockets. And sure enough, you can see the LED for 5 volts is not lit up. So that socket is essentially dead until I repair it. So I thought I should try sticking the video card in one of the good sockets, and fortunately the internal video cable does reach. But, still, no dice. Computer is still dead.

OK, so I visited see my friend Raymond who is just like the Jedi master of electronics repairs. And, we were getting to check out repairing this board. And, he did check out it briefly, however, things quite took a touch little bit Of a turn when he was digging around on his shelf and ended up finding this. Which is, actually, the precise same board that goes in one among these Compaq machines. Don't know where it came from, he said he's had it there for years. the sole problem is he noticed there was some damaged traces here probably from something scratching it really deeply, so he added these little patch wires on there to unravel that problem, but we fired this cover on the bench and it did work!

OK, also some news on this CGA card. This is often the first CGA card and this is the one that had the capacitor that blew up. Now, when he actually tested this, he found that there was still a brief and therefore the short was actually on the 12 volt line, not the 5 volt line.

So, what meaning is meaning the trace on the motherboard actually ended up burning out before the capacitor did. He ended up replacing this capacitor and that we tested this on the bench also and this card is now working. cards that I picked up from my friend DJ?

Well, it seems one among them worked and one among them didn't. I feel this is often the one that didn't work and it also had a capacitor that was shorted. It had been one among those self same little tantalum capacitors then he replaced that and now all three

of these CGA cards are now working.

However, albeit this board did stir up, and that we couldn't get any longer because we didn't have any disk drives or anything connected thereto, but there are some interesting differences during this board. First of all, it's an NEC V2 processor installed rather than the Intel 8088 and it's a totally compatible processor, actually it's actually just a touch bit superior. So, I assume we'll just leave that in there.

However, when it involves RAM that's where we've got a drag. 

Because, this board only has 256K of RAM, because these are 4164 chips and therefore the other board had 41256 chips in it. So, I'm getting to remove the RAM chips from this first board here. You know, this is often something I haven't wiped out over 20 years, swapping a whole bank of RAM like this. Believe it or not, this was quite common on IBM compatible motherboards of the age , Whether or not they be clones or the important thing.

SIMMs and DIMMs were uncommon on XT class machines and really didn't start becoming popular until 386 motherboards. So, this was how you upgraded the memory in early PC motherboards, one carve a time. So, this is often the factory configuration of this board, it comes with 128K soldered to the board, then two rows of expansion so you'll put up to 640K total on this board. There are two sets of DIP switches on this board, now my understanding is that this switch controls settings regarding things like floppy drives and what quite video card. 

These are wont to configure what proportion RAM is on the board, however, from what I've read, later versions of the BIOS actually ignore these and do a self-test to work out what proportion RAM is in, so we'll see how that works. Speaking of BIOS, watching the BIOS chip on the first board, it mentions copyright up to 1986, which is 4 years after this machine was designed.

But on the new board I just picked up, it goes all the thanks to 1987, meaning this is often probably the newest BIOS ever made for this machine. So, these are the 4164 chips I pulled out of the new board, and I'll definitely hang on to those as I think they're compatible with Commodore 64 and Apple II machines among others. Anyway. So, subsequent thing I want to try to to is take away this metal bracket from the old board and install it on the new board. Then I can install the board into the pc. I'm getting to plow ahead and use the first CGA card so a minimum of something of this may be original, right?

Well, let ’s power it up.

Well, all we get is a mistake message on the screen.

Still, I'll take that over what we had before, which was nothing in the least. Rummaging through the service manual, this appears to be a RAM error and it's telling me there's a drag with Bank 2, data bit 7. Since I Don't have any spares, I feel for the instant I'm just getting to put the old RAM back in there. So here we return, this point with the old RAM. Well, now we're getting a special error message. I'm unsure if this is often progress or not. It says it's a hardware error, but let me try inserting an MS-DOS boot disk and just see what happens.

OK, you'll see the LED on the disc drive illuminate, but it still didn’t help any. Same message.

OK, so time to disassemble the disc drive.

One thing I noticed directly is that the top would barely move in the least. It took tons of force to maneuver it. So, the primary thing I did was to relubricate everything, then I started working the top back and forth until eventually it became easy to maneuver. I think this was the source of the hardware error since the top couldn't seek or return to trace zero where the sensor is. So, here we go, yet again. The drive lights up and that I actually hear some activity. I feel it's booting. And it did. And just while I felt like progress was being made, I discovered yet one more problem. The keyboard, is totally dead.

However, I even have to admit I used to be kind of expecting this. I had been warned about this already. So, time to disassemble the keyboard. So, take a glance at this. There are little capacitive foam circles on each key.

However, you'll see that just touching them causes them to completely disintegrate. These things is completely gone. Every single key. These will need to get replaced. Still, I wanted to ascertain if the remainder of the keyboard worked, so I cleaned And, I used to be ready to type, but it's really difficult since half the time it shows 2 or 3 characters once I touch one among these pads. Still, I used to be ready to coax it into loading Planet X3. And it's pretty good in CGA green-screen mode.

Of course, it's nearly impossible to play without a properly working keyboard. Alright guys, so I even have been performing on this computer for 7 days straight. And that I realize it doesn't seem that way once you watch a 20 minute video, but yeah this has been one among the foremost challenging troubleshooting processes I've had to travel through for quite a while. A part of the rationale is just thanks to lack of experience with this machine and also thanks to lack of spare parts. Which, Actually, it's quite a miracle that I used to be ready to find the spare parts that I did, so don't look a present horse within the mouth.

However, it's like I'm getting to be waiting a minimum of another fortnight for delivery on the parts I want to end restoring the keyboard. So, I'm getting to plow ahead and put this away for now, then we'll have a neighborhood 2 begin when those parts show up then hopefully we will get this thing completely working. I feel we're over Capitol Hill. Meaning, all of the hard part is behind us. So, anyway, this may probably find yourself being a 3 parter, because partially 3 are going to be the particular documentary, quite like I did with the Osborne. So, hope to ascertain you around then, and thanks for watching!