0x0008 - An Overdue IBM 5150 Repair

It's time for me to get my 5150 up and running.
I've been putting this off for far too long. I had some kind of mental hurdle I had to get over to finally push myself to do this one. The ambiguity of the symptoms and the measurements I got made me less than confident in this repair.
So I'm not 100% convinced this is the forever solution, but for now all I can say is that it seems fixed. Now I'm really looking forward to getting the other PSUs refurbished and getting the second 5150 going for CGA. I know it's a stupid limit to put on myself, but it makes for a good artificial motivation to actually get it done.
Playlists of more stuff like this:
Computers: • Computers
Repairs: • Repair
1980s: • 1980s
Other Links
KZbin: / akbkuku
Github: github.com/AkB...
Thingiverse: www.thingivers...
Patreon: / akbkuku
Discord: / discord

[@CattoRayTube]

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

[@jimmartin8853]

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.

[@frugalprepper]

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!

[@mjsimons9757]

I picked up a couple of 5150s surplus around the same time. Upped the memory and added a 20 MG hard drive (close to $200 bucks). My big move from a Radio Shaft Color Computer to my first real computer. Fun times.

[@infinitecanadian]

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

[@LightTheUnicorn]

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!

[@mbe102]

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

[@PileOfEmptyTapes]

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.

[@tyttuut]

(obligatory Druaga2 joke)

[@akkudakkupl]

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

[@HoJunP]

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!

[@ducksonplays4190]

Actually 2nd XD

[@80486DX2]

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.

[@hakemon]

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.

[@TechTangents]

I was able to get the 3rd party PSU to power up with just the HDD. But I can't remember if I ever tried turning it on with no load. So it may just always turn on. I've tried both PSUs in a 5150 though and they don't do anything.

[@Membrane556]

I find the best thing for a load is to put a DC bulb of around 10 watts on the +12 and +5 rails.

[@PiddeBas]

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

[@Voidsworn]

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.

[@LoganDark4357]

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

[@spartin212013]

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

[@guycrew728]

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

[@ropersonline]

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.

[@TechTangents]

I cut out some other shots where I attempted to power up both 5150 with the original PSUs and the fans don't even kick. The HDD was just a smaller way of demonstrating it for the video.

[@LoLSmileyFACE650]

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

[@Toad_Hugger]

I approve of your Artyom profile picture! :P

[@LoLSmileyFACE650]

@@Toad_Hugger thank you! metro 2033 for life

[@jaanarturviirsalu7627]

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

[@eduardoavila646]

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.

[@TechTangents]

Typically, resistance will be measured by running a constant current through the target while measuring the voltage across the target. In the case of a DC resistance measurement on a capacitor you get something that looks like a resistance, but theoretically, should not be. The capacitor will begin to charge as the constant current is applied, this will create a voltage difference between the positive and negative terminals. As the capacitor reaches it's maximum charge the current flow into it will slow down which looks like the resistance is increasing. Eventually the capacitor will be fully charged and no longer pull current. At this point the voltage will be the same on both terminals and it will look like an open circuit. However, nothing is perfect. The dielectric material between the plates in the capacitor will not be infinitely resistive. So there will eventually be a point at which it could be measured as a DC resistance. That amount should be extremely high. I was checking to make sure the dielectric had not degraded to the point of allowing a significant current to pass through.

[@eduardoavila646]

Thx for the info! So if i have a 16v capacitor with 6300uf, i could try that applying 12v to it? Or It would need to be its nominal voltage?

[@TechTangents]

You're talking about constant voltage. Which is different from constant current. It's not really possible to measure a capacitor with a typical multi-meter(not even the fancy ones I use in my videos) that's why separate ESR meters exist. A more complex testing method is required for capacitors than just applying power and reading a voltage. There are some very affordable capacitor testers out there though. This one is usually recommended and it easily available on ebay: kzbin.info/www/bejne/bXPVZH9nd51jpdk

[@eduardoavila646]

Oh, my mistake! I am messing the whole morning with voltages and i am seeing them everywhere now. Thx, i will try to get one.

[@ByteSizeThoughts]

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

[@christopherbartleson8918]

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

[@luha628]

What an awesome video! Great work as always.

[@SqualidsargeStudios]

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

[@RetroSpector78]

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.

[@johnfrancisdoe1563]

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).

[@JessicaFEREM]

Honestly a very good first video imo

[@j.beofeld2575]

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

[@smalltownMainer]

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

[@smalltownMainer]

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

[@smalltownMainer]

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

[@shreyaskul]

There is audio lag issue :/

[@mjsimons9757]

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.

[@MasterControl90original]

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.

[@memadmax69]

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

[@xephorce]

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?

[@TechTangents]

I've never heard of someone DIY'ing a DLP printer. I don't know if there is a community around that yet, I would try to see if there is. There are a lot of people trying different things right now, so there may have been someone who has tried that already.

[@xephorce]

thanks for the reply. I figure it should be easyish lol. only one axis to worry about when printing. the DLP tv is just sitting in the back room doing nothing lol. I figure as long as I can get it to focus correctly it shouldn't be too hard. might have to buy a lens and a mirror maybe modify some kind of enclosure. I will look for some groups to get some ideas. thanks again for the reply.

[@planesguineapigs1712]

Wonder if there is some form of ground fault

[@rasz]

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.

[@jrmcferren]

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.

[@datashed]

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

[@8088argentina]

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.

[@neuman356]

Try some 2component epoxy on that latch?

[@copperhamster]

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.

[@eduardoavila646]

Is loktite still good in the us? Here where i live they sell loktite, but its as effective as water. Not even my fingers it glues hard anymore. I only buy generic tekbond ones, that seem to be halfway between the old loktite and the new unneffective one.

[@copperhamster]

I was watching a video the other day, and loktite was what he tested as best. I primarily use superglue for quick setting something I've epoxied, as I said.

[@eduardoavila646]

Copper Hamster Oh. I was asking because its common to products that are good in the us be bad arouns here... Example: Dell laptops are good in the us, here they are expensive disposable pcs. Hp laptops never were good here, but my hp mini that i got in the us survived thousands of shorts in the usb, experiences, falls, extreme conditions, and lasted about 8 years, when i wantes to upgrade his atom, but didnt saw the new tdp and the board burned. Now incredibly, even without a processor i can switch its board on, and use it as a powerbank. But the hps from here die misterioslly months after bought. Thyx for the info anyway!

[@matthijsjanse3275]

wasnt its resistance 170 kohm

[@CattoRayTube]

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

[@TechTangents]

I think it was just draped along my neck. I literally can't remember the last time I got a haircut. My hair and I have come to an agreement on the optimal length. It stopped getting longer, and I stopped cutting it.

[@alexsinclair2012]

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

[@1980sGamer]

I know that profile picture...

[@alexsinclair2012]

OwO _no pants~_

[@1980sGamer]

Knew it. ;D

[@1980sGamer]

Oh yes, of all the things in the world you think this is "disgusting?' Okay then...

[@1980sGamer]

I think you need to get a grip my friend. There are far worse things that you could be getting offended over. But instead you choose to waste your time here.

[@MichaelRusso]

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

[@DiskWizard001]

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

[@BigSchu22]

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

[@datashed]

J.B. Weld all the way!!!

[@Kizmox]

As Druaga1 fan i find this amazing

[@JimLeonard]

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.

[@steingat]

Would you be interested in a Hercules compatible Graphics Card ?

[@TechTangents]

That would be a cool direction to take the monochrome system. I hadn't really considered trying to get a card like that for it.

[@austinramsay]

Still have it? Picking up a 5150 with a 5151 monochrome tomorrow

[@uncreative_name48]

Awosme vid man!

[@Just_A_Toaster852]

Awosme usr namme man!

[@uncreative_name48]

I would say the same, but the Pentium Dual Core was a bit lest of an inferno lol

[@Just_A_Toaster852]

I prefer being called a nuclear reactor vs an inferno

[@uncreative_name48]

lol ok "nuclear reactor"

[@Just_A_Toaster852]

Yep made fun of your spelling while misspelling things worse

[@mohinderkaur6671]

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

[@MrTruth-yn7pq]

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

[@mr.invisible1873]

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

[@chibichabot9293]

Awesome video

[@johneygd]

Painfull but great restoration.

[@Blitterbug]

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

[@srfrg9707]

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

[@yueibm]

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

[@sunnohh]

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

[@TechTangents]

I was making a double joke, the tables have actually turned since Intel now produces AMD64 compatible CPUs.

[@SUPERBOBESPONJA1000]

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

[@GAnimeRO]

14:55 spider infiltrator spotted

[@DavidScheiber]

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

[@HalianTheProtogen]

I'm not a fan of the VCR sound.

[@JoaoVitor-cw2vg]

360p squad, maybe the first one

[@johnfrancisdoe1563]

Joao Vitor Sorry, the MDA only goes to 350, CGA goes to 200.

[@carolbaker5775]

John Francis Doe jeez 360p is the video quality you get when you are on a KZbin video for the first 10 mins its up

[@WhileyisaEskiboy]

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

[@hubzcaps]

awsome

[@sergeantsucc909]

Neat.

[@cyberp0et]

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) kzbin.info/www/bejne/sKvKe5mMd7Ssoq8

[@hans429]

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

[@linksmith1057]

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.

[@ig33ku]

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

[@philiptech]

Under 50 views club

[@WhileyisaEskiboy]

Phil Pierce I see you have many followers and many videos you release daily.........

[@nrdesign1991]

That horribly bent card...

[@TechTangents]

It is unsettling. I could try bending the front and back of the case out to see if that helps give it some room. The "CGA 5150" doesn't fit nearly as snug, so it's definitely something up with that one.

[@Camper_Samu]

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

[@hazelpedemonte4464]

(It was an IBM 5100, but still...) El. Psy. Congroo.

[@SyntheticParadise]

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

[@jangelelcangry]

te equivocaste. :-)

[@GO-ky3wi]

Where are the hot chicks

[@soldierofjudgement0477]

51 likes at this point... HMMMMMMMMM