0x0008 - An Overdue IBM 5150 Repair 

Unintended summary of many AkBKukU projects at 11:16: "so let me recap everything I have here right now."

For those coming along looking to fix their 5150's with problems. Back when I was a boy (DJ reference) my job was to repair these things. First, these came with a 63 watt power supply. One of the power supply lines going to the motherboard is called the "Power Good". If you don't connect the motherboard or provide a power good signal, the power supply will not start up. It be dead. Second, the tantalum caps on the PC boards will usually let you know when they're bad. They turn into a flaming fireball and automatically remove themselves. No user input needed. Put a 2 pin in backwards and get the same results. Third, when working on the floppy drives. On the bottom is a timing pattern for both 50 and 60 hertz strobes. Use a florescent light to check and adjust the speed. If it's off the drive won't read disks. Good luck.

All it took was the term 'IBM 5150' and hearing you for about 5 seconds to subscribe.

It's amazing. I became a computer tech in 1992 full time and learned DOS 2.11 and Basic on a 5150 in high school. Back when I became a computer tech, these old 8088 / 8086 computers were just considered junk. I spent days sometimes hauling these old computers out of companies by the van load to the dump after doing a workstation upgrade. I wish I would have kept some of them now!

So much 5150 in one video! Fantastic work on getting that one running as a rather “base system”, always lovely to see those up and running again. And hell yeah, amber phosphor monitors are so damn cool!

Capacitor ESR and leakage basically are independent. High ESR means the electrolyte is dried out / gone, high leakage indicates bad spots in the dielectric. Old caps may exhibit either, both, or neither. An ESR meter will tell you nothing about leakage, and a leakage tester nothing about ESR. Tantalums actually can be very durable, but their low ESR and small size means they are easily damaged by high inrush currents unless derated substantially. This was not common knowledge in the very early '80s, so particularly devices designed by people who were inclined to skimp on capacitors saw a fair share of failures.

I found your channel a few days ago and I love it!

Jesus, that fast forward sound at 3:30 scared the shit out of me lmao.

What an awesome video! Great work as always.

I knew i have heard your voice before! im excited to watch your vids!

(obligatory Druaga2 joke)

The 47n caps are power decoupling, you could swap them for 100n with no problems.

Nice one! Great vid, I am on the lookout for my first IBM here in Australia but they are quite uncommon!

5:45 I thought some capacitors is going to release magic smoke and firework, but glad that doesn't happen to you :D it happened to me with my IBM 5155. have to replace 2 shorted tantalum capacitor on motherboard and 1 on CGA card to get it working.

I was already stoked on your Amdek...and then that CGS shows up....

Oh I'm first comment😂 I accidently found your channel and I'm really impressed that you're fixing such an old electronics. I really like your videos. Please keep posting these good videos!

Honestly a very good first video imo

If you hadn't said anything I probably wouldn't even have noticed that this actually is some of your first footage

Lol, I love the VHS Fast forward and resume sounds. :D

Oh, I love that site. I have a 5160 that I received from one of my professors. Shortly after getting it, I turned it on, turned it off, then turned it ...nope. Dead. I used that site to troubleshoot and found it was a failed CGA video card. which I repaired. It was a bad tantalum capacitor, so I replaced them all.

You've got a new subscriber right here!!!

Awesome video

When you connect your ohmmeter to the power input, you are basically measuring the power consumption of everything plugged in, but at a wrong voltage. So there should be current running through, and the resistance should drop when you plug in more parts. Unless you have a manual that states what the ohm reading should be *at a specific ohmmeter test voltage or current* , you won't get much from that test unless it shows a dead short. As for the power supply, I wonder if the old handbooks contain enough detail to wire an ATX to PC/G adapter cable, letting you use a modern PSU (If it has the extra voltages that are often unused on modern boards).

Just a heads up, those old 5150 power supplies won't power up without a heavy load. Even a single hard drive and CD-ROM drive wouldn't power one up I was repairing, it required a load on both the molex and motherboard connectors to get it to run. They are super picky about their loads.

Your LCR meter still has the protective film on the screen!

thanks !! i have the same problem in a 5150 64k - 256k, i will try to fix, only the speaker make a louder sound and not start the pc, only one time run, and never more. thanks again.

I had he exact same thing with this IBM floppy controller. My multimeter flagged a continuity beep between GND and 5V as soon as it was inserted on my IBM 5150. The exact same thing occurred on my IBM 5155. Oddly enough, using the same floppy controllers on an XT clone didn’t have the issue. I ended up using another (non IBM floppy controller) on my 5150 cause I was afraid of shorting something. But after watching this I’m beginning to think this might be just a “normal” IBM thing.

not gonna lie. that amber colored monitor is awesome. it makes me think of fallout new vegas lol -Says guy with gas mask icon

8:00: Most of the 5150 PSUs do not power on unless there is enough of a load connected; that could be a drive or a board, or even several things if necessary. That's not necessarily a fault. It's just the nature of the thing. I dimly seem to recall that that was even documented somewhere. I'm not even convinced that your original PSU has failed - that's a modern load connected at 9:30, which may not have been what was needed. I'm also not convinced the other PSU at 10:43 is actually faulty - again, that's a modern load, and the mainboard is unplugged there. If memory serves, it does seem to help to give the PSU a rest after failed switch-ons, and retry only much later with a Goldilocks amount of load on it. That behaviour too is probably normal and not a fault. Again, I am not convinced that the PSUs at 11:50 have failed. The clone PSU probably is simply less picky. Replacing the tantalum capacitors was probably helpful regardless or at the very least not harmful. Those really are notorious, even to the point of potentially producing literal fireworks when they fail. You're a little bit brave or foolhardy to hold old tantalum caps in your fingers. 21:16: Exactly right, the new tantal caps will likely be reliably good for a lot longer. Btw., ESD can be a real bummer with those old DRAM DIPs which can be more sensitive than modern chips, and you're being very cavalier. Careful now.

How did that resistance measurement works? You use A psu to charge it up and at the same time measure it with a multimeter? What voltages did you use? I also need to measure some capacitors, but i only have a generic mutimeter.

As Druaga1 fan i find this amazing

Which piece of hewlet packard test equipment were you using in this video?

Painfull but great restoration.

while you hand was in there and the drive made its noise did it jump you a little?

while reaching for the speaker plug the drive came on and it looked like you pulled your hand out quick lol

You haven't lived until you owned and used a 5150 as your daily driver. Yup kids, those were the days... Notice, I didn't say good old days.

just for reference - tantalums go DEAD short, as in 0 ohm short and a LOUD bang with lots of smoke, no point checking their ESR imo. 33 ohm is what, 150mA on 5V rail? totally fine. Not to mention your normal reading was 150 Kilo ohms for naked board, not ohms. That 200-1300ohm cited on a website was probably for whole system with all cards in. Repairing those power supplies could be an interesting video.

whats the 3rd leg for if you can replace it with a 2 leg cap?

Use epoxy fiber-glassing resin marine grade for your plastic parts.

awsome

A solution to the broken floppy part. Ever thought about 3D printing the part?

I wouldn't go too much into that monochrome monitor unless you can have someone test the CRT. A TV shop should still have the equipment to test the tube. A dim image is an indicator to a possible weak CRT.

Oh this brings back memories. Or maybe nightmares. Some (not many) PC/AT power supplies needed a load on +5V or +12V to power on. We used to have a little plugin salvaged off a dead hard drive with a couple of 100k ohm resistors to ground. There's superglue and then their is superglue. Loktite and iirc Crazyglue are some of the best. I would use a tiny amount of loktite to hold the part in place while the epoxy I'd use set myself.

How do you replace the 3 pin capacitor with a 2 pin capacitor?

Apply non-shortciruit protected 5v power supply. shorted cap should clear itself a small spark. fault fixed

Neat.

Awosme vid man!

My very first PC case (not computer) I ever had.

Wonder if there is some form of ground fault

The sound @ 3:24 is a commodore 64 tape drive(or maybe some other tape drive) running.... GG, have fun, lol

I have been researching building my own 3d printer completely DIY style. I have a few options. extrusions types seem easy enough but I have an old DLP based rear projections TV, I have thought about trying to make a DLP style 3d printer. what are your thoughts on this idea? Have you looked at anything like this before? if so do you have any suggestions?

I've never found super glue to work well at all with plastic, especially small pieces like that. Maybe epoxy?

I think I never seen a single 5150 with a bit bent Isa card in it... Those early cga card are pretty much bent 99,9% of the time.

There is audio lag issue :/

PSU requires load to start up, that's why your first PSU didn't start up on the bench even though it worked in the system.

Try some 2component epoxy on that latch?

Could have told you cyanoacrylate would never hold a stress joint! Araldite is always the way to go...

On the 5170 PC/AT, machines not optioned with a hard drive came with a loading resistor. www.vcfed.org/forum/archive/index.php/t-22760.html

3d printers are the way forward! Be cool if you do print the part to watch you design and print it

wasnt its resistance 170 kohm

Acetone usualy works better than super glue when one has broken plastic pieces to glue together.

X86 is the architecture, amd no longer makes exact intel designs is a more accurate statement....on that note, subscribed!

3d print replacement floppy drive piece maybe? EDIT: nvm, you already said your gonna do that

05:53 Wait, you got a haircut?! I remember it being much longer!

I have 2 of those Teac drives (In scrapped bits).. If you need that latch assembly I can send it to you

14:55 spider infiltrator spotted

Would you be interested in a Hercules compatible Graphics Card ?

in the rewind sound i suggest to put it lower is very loud comparated to you voice so having high volume and that is kidda irritaring

AkBKukU: Are you the non-stoner, electronics whiz twin brother from another mother of Druaga 1 by chance?

Gorgeous machine! They were quite expensive back then. I had no idea those were capacitors 16:30 I got myself a Sinclair Spectrum Romanian clone (HC 91+) in 1994. That was my first ever computer. Of course it was not a PC, it was a HC (home computer). Very limited, running only BASIC programing language and BASIC software could be loaded from a cassette tape or if you had a floppy drive. I have uploaded a crappy video with that HC making it on GOOGLE :p i also uploaded some photos on Flickr (link is in the description of the video) ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-zzgJfVBOylM.html

360p squad, maybe the first one

I'm not a fan of the VCR sound.

Superglue,Superglue does what ever a super glues...

3:28 RIP headphone users...ow that HDD is loud

Ahh explains why you sound like Druaga1 lol............. but the format is short and scripted like LGR lol... i was sooo confused.

That horribly bent card...

No one made Steins; Gate jokes in the comments... I'm surprised.

Under 50 views club

¿Soy el único que habla español? Parece que sí je, je.

Ah tantalum capacitors. Nasty little fire starters. You could always tell in our PCB fab when someone installed one backwards and I didn't catch it in visual inspection before powering it up. Usually, the way you would know is by the loud pop of the cap exploding followed by my "HOLY FUCK!" shortly afterwards. That said, I've never seen reference designators that are all the same like that. That is very bizarre. Oh, and it's also funny to see someone else do the heat-up-and-drop technique to get out parts.

51 likes at this point... HMMMMMMMMM

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