EEVblog 1527 - Toshiba T1000LE DOS Vintage Laptop Repair HELL
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- čas přidán 11. 06. 2024
- This Ebay Toshiba T1000LE vintage DOS In ROM laptop repair turned out looking promising until, well, it didn't...
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00:00 - THE laptop that cointed the term Notebook, the Toshiba T1000 series
05:46 - It obsoleted the Tandy 100 and Tandy 200
07:00 - Powering up
10:16 - Opening up had a few issues - OOPS
12:12 - The first suspect
17:55 - Bad caps?
20:50 - Suspect process
23:18 - Backup battery SRAM problem
24:12 - Thermal camera
26:32 - Extra sneaky PSU
33:27 - Under the microscope, this looks BAD!
37:00 - Yuck!
44:28 - BUSTED
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#ElectronicsCreators #Repair #vintage - Věda a technologie
These old Toshibas are shockingly bad - both in layout / design and the caps and trace thickness on PSU section. I started looking at a T1200 (yet to revisit with microscope soon) and I spent hours messing around trying to get the PSU section up and running properly. I suspect I may not be able to fix it... Considering how old it is, I was shocked at the trace and via size on the T1200 PSU board (it has just one separate PSU board unlike the T1000). I can hardly see them with magnification...
Everyone on the forums say similar things. Convoluted PSU, no schematic, corroded traces, yuck.
@@EEVblog These Toshibas series will not power on without a charged battery, hence the red flashing led. The trick is to power the laptop directly through the battery terminals with 7.2V to 9V DC. If the battery voltage is any higher or lower than 7.2V to 9V then the laptop will not power on or will shutdown instantly. Using the battery terminals to power the laptop will bypass much of the over complicated main power switching circuit. Also the hard disk caddy needs to be fitted as there is a microswitch that prevents the laptop from powering on when it is removed. The back light and invertor is likely to be bad too but a 12V LED strip works as an improved upgrade to replace them. The back light inverter can overload the power circuit so good idea to disconnect that before powering up. Good luck with it as I've found the power circuit to be almost impossible to repair but had success using the methods that I've explained.
@@arnolduk123 I hope Dave will go for that. Don't fix the original PSU but instead use simulated battery power.
@@michael.a.covington Yeah, these laptops were designed to run directly from battery power and most of the power circuit is used to keep the battery charged.
@@EEVblog honestly you messed up... Put in capacitors that actually go with this system with the actual correct voltage instead of the surface mount ones you used.
45:06 - "People are probably screamin' at me!"
I was one of those people xD
I had planned on letting you know about the cracked caps (which I had thought were diodes) if you didn't notice them before the end of the video.
I was product manager with Toshiba in The Netherlands from 1989 until 1994. Interesting times. So many revolutionary inventions; small harddisks, pcmcia, first color TFT (T4400 series), hefty competition with Compaq, dramatic price drops etc.
The sub battery is for “AutoResume”, i.e. instant power on, remember that MS-DOS had no support for standby.
On the Back side is a physical broken diode or some thing.
C517 below the coil between C520 and C521 40:45 found at 45:01 😅
C520 visibly cracked in half
Yup, and the one near the speaker too on the same side of the board..
T1000? Conner drive? Dude ya wasted perfectly good Terminator joks
Yup, I feel ashamed.
I'm also noticing under the marking R513 that there is another black component that has a decent crack through it as well
He eventually noticed the components with the giant cracks in them. I suspect our beloved host could possibly benefit from some reallocation of available resources, trading a bit of high speed output for some additional input bandwidth...
@@StubbyPhillips I'm kinda wondering if it's not a field of view thing. The Tagarno is a physical microscope, right? He might not be seeing as much through the eyepieces as we're seeing on camera.
You need to use your senses before anything else, amazing how many things can be repaired by just looking properly , cant beleive you didnt see those cracked caps in all honesty. With all due respect, you can have all the knowledge in the world but if you dont have that fault finding brain/eyes/senses , youll be there all day
@@reacey It's true he could have seen it earlier, but you tend to look for the usual suspects first. Cracked components is definitely not the first thing you think of or look for, especially in a laptop. It might very well be the first time he sees that in 30 years. So it's really not that surprising that he didn't look at it first. It's worth wondering how this happened, because it's very unusual that such small components crack like that. We would expect them to melt under heat, not crack. It's surprising that several components failed like that.
37:15 C520, blown tantalum cap
The sub battery is a feature that laptops had up until the late Pentium days. You could put the machine in standby, then yoink the main battery and swap in a fresh one. The sub battery (called standby battery in other machines) would keep the RAM refreshed for the short time needed to swap main batteries out. They also sometimes keep the CMOS settings, but it's not uncommon for a computer to have a separate battery just for that.
I believe my 2005 Dell has this feature but it doesn't seem to work right.
PDAs with Microsoft operating systems had dedicated memory batteries well into the 2000s, some models even had mechanical interlocks for replacing one battery at a time. Then Microsoft finally embraced the existence of flash memory, only to squander their market position by completely replacing their APIs multiple times in a few years. That last failed design is what's most hated about recent Windows products, besides obnoxious behavior towards customers and governments.
I had a T1100, and a T1200. The keyboard was lovely to use. The thing I remember the most was the smell that had something really special about it as it reminded me of the happy first contact with computers.
Ah the smell of gently simmering electrolyte perhaps?
@@DaveF. Why would you smell that back then? That's a thing you smell decades later when the caps fail.
@@8bitbubsy Its called a 'Joke'
@@andymouse Good 'Joke'.
@@8bitbubsy Thanks!
I have incorporated OKI 80C55-2 and 80C88 in our products for 30 years; still use them today.
I love remembering all the old systems I grew up with but I don't miss how slow everything was. 😄
For sure, and these days outside of running old games on original hardware, or the odd piece of defunked sofware till we hit the late XP era with DDR2 RAMthey really are not that usable. It also still blows my mind even at 42 having been a computer user since I was 2 when my family got a Commodore Vic-20, at how even a cheap sub $200 Android tablet these days puts older desktop systems even from the XP era to shame.
@@CommodoreFan64 Yeah and phones. The ability to casually edit 4K, play 3D games or run n-body simulations. Phones newer than 2019 can run an xbox360 emulator which may not sound that impressive given the console age but at such low wattages on a portable device with emulator overheads really is. Give it another 20 years and phones will probably have ray tracing chips.
Definite need to add jumpers, lot of work! C520 broken, if someone got a good one, please help to check the value.
I also noticed C520 as well. Definitely doesn't look healthy. Edit: Seems like Dave noticed.
@@szabotihamer I'm glad he found it. I was jabbing at the screen
@@-Kal- Me too!!
@@-Kal- m
I have a couple of these machines as well as a T1200, T1000 and a couple of T1000XE's.
It's a love-hate relationship. I love the look&feel and the history behind them but every single one you get has the same problem.
The Elna and NipponChemicon caps used in the DC-DC converters all just start leaking from the bottom and the electrolyte does the rest.
No way to judge it from the outside of the machine or even from the top of the board.
On top of that, what looks like minor damage may lead you down a very, very deep rabbit hole.
I've fixed all 3 of my T1000LE's and they still work after a couple of years.
In the mean time I've fixed, amongst others, two T1600 and reverse-engineered the PSU PCB's for them along the way.
Feel free to send me a message if you need any information or just want to exchange thoughts (see my YT community or about page).
I have 3 of these to check component values, etc. if need be.
I've spent countless hours searching the web and staring at these boards so I'd like to think I know a thing or two about them.
It's worth the time to repair for YT, always great to see a nice juicy repair.
PS. if you want to see a rabbit hole check my Keithley 2001 DMM vids. I needed a holiday afterwards!
oh, i missed it. have a look right away
Not when I have so many other videos I have a backlog of unfortunately.
Dave, C520 (large black SMD cap) on the underside looks like it has a large crack through it.
Regarding copper traces, use a thin tin-plated copper wire and solder it from point a, bend the wire along the trace, solder the wire in the trace towards point b. It will be nice that way.
Whoa! These ELNA RSH series "Long-Life" capacitors are the same ones that plagued the Adcom GFA-565 audio power amplifier. It's a wonderful amplifier, but these leaky capacitors caused every single one of them to fail, often causing a large DC voltage to appear at the speaker terminals, often blowing out a speaker.
The electrolyte actually soaks into the fiberglass PCB, and it causes it to become slightly conductive, which causes the front end of the amplifier to amplify nearby DC rail voltages, and the amp can go up to 83VDC.
For some reason Elna has fanboys, I've always hated them, pure garbage.
Ouch, making the PCB fiberglass conductive is horrible and would require a complete rebuild of any affected device, just to restore the basic functionality of being a PCB.
Only saving grace would be if your observation was merely a paper based cheap PCB material getting soaked in anything wet, while actual fiberglass boards are safe from that particular danger.
T1000LE? A mimetic poly-alloy. None of that living tissue over a metal endoskeleton rubbish.
(I'm sorry Dave, I'm afraid I really had to drop some pop-culture references - but Dirty Harry is yours)
And hmm, seeing a Conner disk in a T-1000? Can't be a coincidence!
Lovely old laptop - shows how far we've gone since WayBackWhen! I hacked with some late '90s Toshiba Satellite, and a Thinkpad 380ED, but nothing that old.
Oh the mobo, a thing of beauty and a joy for ever. Too much rosin leftover for my taste though.
Unassuming CPU indeed. Who would have thought?
14:54 these xtals in a DIP package are a fascinating thing in itself, now that I've seen that in the Open Circuits book.
Electrolytic come-a-gutser, as always - what else would you expect? I would still bend the leads and put them through holes for extra mechanical rigidity.
Extreme discombobulation going on there on the backside! I wonder where this corrosion (hey now, hey now, now...) came from. Catch you later with this laptop, I hope! I'd love to see the launch.
These old laptops are amazing thank-you for the post awesome stuff 😀😀
I've got a T3100 with the orange gas plasma display. I had to buy two complete machines to get enough working parts to make one working one. really nice display.
There is a lot of corrosion caused by leaked capacitors, which is pretty typical for caps from that era, especially if they are "high quality" brands. They leak out instead of drying out, so if they are not replaced (or removed) before they definitely fails, they cause a huge mess of electrolyte, corrosion and similar things on the PCB, which is typically non reparable issue. I prefer capacitors that dry out instead of leaking, which are typically the cheap ones. They are more often to fail, but also much easier to repair. In my opinion, that leakage caused a short between the windings of that big inductor (L501 or what), so I think this one should be at least rewound. Next thing are that broken SMT capacitors, which is in my opinion caused by slightly higher voltage like >7V on the 5V line (that capacitors are typically 6.3V), which, if occurred (and we know this happened), fried almost all TTL logic, so I think this device is completely nonrepairable. Which is something very typical for these old toshiba laptops.
And well, plastic housing of these devices was painted. It was a huge pain in the ass past then, because almost every repair resulted into some minor paint rip offs caused by bending or stretching that housing. Plastics are flexible, but the paint is not. That was a terrible idea, but, well, this was how things was made past then.
WordPerfect was all I ever needed. The split-screen mode where you could see every formatting mark was very handy. Now, if I ever have to modify a Word document there's a 99% chance I'm going to end up wrecking the whole thing.
J.R.R Martin apparently still writes on one of those. Perhaps that's why it seems to never be coming out... like he wrote 90% of his last novel and his oooooolde laptop went kaput, and unrepairable.
you most likely already know this, but in modern word processors like Libreoffice and MS Office, you can enable the formatting display "¶" to see exactly what the program is doing
My room mate in University had one of those laptops. He got it because it could accept an accessory card, that accessory card was a text-to-speech system. So cool back in the day.
“How bad do you want it?” For real, cool machine but it would take a labor of love to salvage it
We had several hundred T1100+ dual floppy laptops for field engineer use in the late 1980’s, near zero failures of the units themselves but the mains to dc power supplies from Toshiba were notoriously bad, running hot and with thermal fuse failures. We gave up on Toshiba replacements and eventually designed and manufactured a new one in house.
These are the videos I enjoy watching the most your tear down and repair and mailbag videos I plainly remember one about a marine GPS unit with super Caps in it or the handheld sat phone several years ago I watched those
Can't wait for the sequel!
I waited to the end to see if you saw those cracked caps! Good luck with this one!
As a bloke born in 2000, I find it fascinating the older technologies, there is something special about these older pieces. Probably doesn't help i'm an EE student who loves this stuff hehe
Please more videos of vintage computers!
rip it all out and put a pi in there. Figuring out the keyboard might be a pain but it can probably just be wired to a USB keyboard controller directly. The display might need to be replaced if you dont want to go down the rabbit hole of figuring the display out
Might make a nice serial terminal
I recently did an extensive repair on a liquid damaged PCB, had to strip off all larger components, add many bodge wires, replace multiple SMD transistors, rebuilt and got it fully working again. A lot of via's had failed - they aren't fully protected by the solder resist coating. I'm afraid the prospects for your Toshiba board don't look too good to me :(
Tiny traces, rotted vias. Could be a fun hobby project for someone to practice their micro repair, but in the areas where the corrosion has set in, you'd have to lift every chip or other component that may have a trace or via under it. And in doing so, potentially lift traces in the process. This era of things seem to have infuriatingly tiny and weak traces and pads (and poor adhesion to the board). In this situation, there is also a risk that a section of trace disappears completely and you have no idea it was ever there in order to fix it.
Yes, this one I would give up on. Corroded vias are worst, and this board has like a hundred to check/fix. Not even speaking of repairing the traces. It would take me countless hours for some very uncertain outcome. I've had my own experiences with NiCd juice corroding all SMT pads from the underside so whatever is left of the pads will instantly lift from the board. That was a pretty frustrating repair experience.
@@ShmblerBut was this NiCd leak from either battery or electrolyte leak from the ELSAs?
It’s easier to remake the board and order the BOM than repair with that level of corrosion
Had one of these. never worked. Same issue, caps leaked out and it's all because of the Quaternary Ammonium Salts issue which plagued those caps, the Elnas and others. there's reasons why ones that still rely on that tech are now relegated to special use cases, and are protected against leakage like this. This is the same issue that made apple surface mount caps go bad.
Best course of action would be to throw this in an ultrasonic cleaner and let that work the magic for a couple hours, and then rinse it in the dishwasher with non-corrosive detergent-- you'd be surprised how much cap gunk can be removed with just a touch of detergent! If you need the value of that tant that blew, I can probably go down to my board in the basement which I've kept after all these years and get you a reading off of it and I'll report back as time permits.
Wow. I had an SE. And Wordperfect 5.1. And... wait for it... Xtree Gold 😀. Anyone remember the Amiga 500 and Supremacy ?
c520 in the last section looks a bit split, and I'd be surprised if them traces still worked haha
WOW, wordperfect, I remember using that back in the 80s and early 90s. To get that cleaned up and repaired, your going to have to remove a fair bit of solder mask to ensure you dont have residual corrosives lurking under there.
I have a 110CT Windows 98 VHS Cassette-sized machine from almost the same era that I use to interface my oscilloscopes and analyzers (RS-232) when travelling, and it works just fine.
I actually set up a dual-boot DOS 6/Windows 98, and I use almost exclusively the DOS side. The hard drive is getting arthritic, and I actually had to open it at one time to un-stick it, so I'm looking into getting it replaced (hopefully with an SSD) but otherwise I can't complain. The battery even holds enough charge to move the device from one side of the room to the other whilst remaining connected - probably a good minute or so. Far more compute capacity than they used to go to the moon and back!
Sorry Dave, but I vote for you to continue down this rabbit hole because I found part one to be fascinating and entertaining.
That looks like the laptop my dad had. I loved it!
There are so many T1000 out there that do not work and cannot be repaired. But people love them. I would love to see a hack or development project to replace the innards with a new board and bring them back to life for fun.
I think I have one of the biggest collection of Chicony Acrobat laptops (I have 2 of them) and sadly both of them suffer similar issues. The capacitor plague was a terrible era in the history of electronics.
I was hoping that I can learn here how to fix my laptops, so I am really waiting for part 2. Thx for sharing the knowledge and expireence.
Used T1000LE/T1900s as a kid, solid machines and can confirm the power supplies gave some trouble
I just remembered an old Tektronix report. It described their factory repair procedure. The very surprising statement was that the nearly first operation they did was to wash the scope in a dish washer, using distilled water! They followed that with a long (24 hour?) drying. That was maybe in the 1990's, possibly even earlier.
The other thing -- I relate any power indicator pulsation to the built in "hiccup" mode start, fail, retry due to overload somewhere after (or possibly within) the power supply. As to leaked capacitor fluids, my finding has been that rather than the usual high concentration IPA, a 5 to 10% IPA or even plain distilled water often works better. But a lengthy soaking may be required in any case.
Cool, I remember playing on one of these as a kid. My dad worked as a radio tech for Ministry of Transportation and Highways and used it program radio's among other things. The LCD was so slow it was not a gaming machine, especially if it was cold.
I used to play the Indycar racing game on a T1200. I thought it was amazingly cool to be able to take the computer to other places other than home and still play indycar. The screen though, so slow it was almost useless!
While some old HDDs tend to be surprisingly reliable, the Conner 2.5" drives were not. They, like some of their Quantum 3.5" contemporaries, suffer from sticky rubber bumpers that glue the head stack in place so the head will not move. If yours has this problem, carefully disassemble the drive (making sure to not get the also disintegrating rubber gasket on the platters), power it on, help the head stack to unlock using your fingers and then get the data off quickly. Only a temporary fix, unfortunately.
When I saw the title of this video I figured I should watch. I have a T1200XE that has the same symptoms. I guess I need to pull the motherboard now and see what the underside looks like. I do really want to get it working. It belonged to a buddy, and he gave me all his old computer stuff to add to my collection.
Last time I used these was in the mid-90's when it was running braille translation software to produce braille materials for a correspondence course. It worked fine for years despite the amount of paper dust it was exposed to.
There are a few traces needing help haha. Don't give up! Save this guy
Waaay back when, I started buying old laptops for $5-$10 at garage sales to teach myself laptop repair. This was the 2nd one I got. (The first was an old Zenith "portable".)
What I found was that it wouldn't boot without a working battery. I opened up the battery pack using an Xacto, replaced the NiCads with NiMHs. (Which required that I only charged them separately, not thru the machine.)
This laptop, with full 1M of memory and an 8086 processor, could run MS-Windows 2 nicely in protected mode.
Another problem I had was it didn't have a floppy. To get software on it I had to do a command line comm trick with a Laplink cable to load Laplink and then transfer stuff via the parallel port. Worked great, lots of fun. Had to go away during my downsizing move a couple years ago.
8086 doesn't have a protected mode--are you perhaps thinking of an 80286?
I bought a similar used one back then for "not so much" as I needed a backup/development place for a Psion 3 (Arm, pocket, on 2 AA batteries.) I have a similar system today as a side hobby to play with now and then.
Ooo, my first laptop when I was 7, still works..
I've never seen a MOSFET with green package. That's pretty cool!
be such a nightmare to repair that board but with patience anything can be fixed
I had (well still have in pieces) T1200, it was great when it worked, sadly it slowly decayed - first both floppy drives died, then LCD stopped working and finally mainboard kicked the bucket. It's certainly interesting laptop, but generic enough not to warrant full repair, altough the ALPS mechanical keyboard is great and I'm tempted to make adapter to connect it to newer PC.
As a japanese electronic component aficionado, the inside of this thing is an absolute beauty!
Yep. I have a similar model (think it was a T1000SE?) and tried repairing it doing exactly what you've done quite a few years ago. Stuck in the same boat. The capacitor leakage was much worse in my example
I know it will require a lot of time and work, but I and I guess plenty others do like watching someone resurrecting such a ancient piece of hardware back from the dead. Might be borderline madness this adventure but... still
I just started working on restoring a T1000 a few days ago! First single-board laptop on the US market, and my first computer as a kid. (My dad had one of the fancy new Windows 3.1 machines.) I've also picked up a T1200, and its guts are very similar to this.
Those brown ELNA / "LongLife" caps are notorious leakers. The T1200 has a whole bank of odd values and sizes on its power board, most of which are leaking. Both machines have other brands of caps in various places as well, but the bad ones are all those brown ones.
Did you ever get it going? I recapped mine and nothing. The components are so darn close on the T1000 circuit board.
I have two broken Toshiba T1000SE laptops very similar to this which I've tried to get up and running but without any luck. I recapped all of the capacitors but couldn't get them to boot. I thought it was just my shoddy soldering skills but it looks like there is more to it! A problem I've had is the wire connectors with the LED and charge boards are really brittle and I ended up breaking one when disassembling / reassembling :(
I'll be looking forward to a part 2 to see if you can get it working!
I also have an original Toshiba T1000 which is a completely different piece of hardware and switches on OK. It also has a power issue with it dropping out when attempting to use the floppy drive but boots to ROM DOS just fine.
Yes Dave, do the Tandy 200 video!
Sad dead puppy, but as always an exciting video. I like repair vidoes. Thx Dave
oh-oh! i have two of thems here^^ some memories of my work at France Telecom, in 1990's ^^
I have the SE version if i remember well, but no hard drive inside. I should check... ;)
HI DAVE. ALL CAPS JOE HERE
THANKS FOR THE VIDEO. THAT LED FLASHES WHEN IT CAN'T DETECT A BATTERY AND THAT BATTERY IS BEYOND FLAT AND IT CAN'T SEE IT AT ALL SO IT'S FLASHING THE LED
No need to SHOUT. 🙄
That keyboard is beautiful.
oh my, this is brand new!!!
I had the same problem with those Elna RSH series caps on a power supply for a spectrum analyzer (Advantest R3271). Half the board was covered in leaked electrolyte and there was corrosion everywhere. I managed to repair some traces but I wasn't successful repairing the board. Unfortunately, the power supply is the only part for which there is no schematic in the service manual...
You got loads of working dumpster dive monitors and TV's Dave, maybe use one as a monitor for the camera when you are recording?
I had one that had a trackball on the right side of the screen. If i remember it right the ball was there toshiba text was and the mouse buttons were on the other side on the lid. Windows 3.0 was really funky to use because screen ghosted so much.
Hi, The T800 is Terminator, this is the T1000, it must be Arnold's strong cousin... good luck with the repair.
if you look at 37:50 you can see c524,c521 and c520 markings on board you can see big line or big crack inside black chip.could that be fault?
You didn't watch the whole video
Ah this gives me PTSD from a T1900 - a later model but similar symptoms and a bastard to take apart and repair. Again, some people swore by re-capping alone but myself and others never got theirs working. And it didn't even have board damage like your T1000! These things are definitely not for the faint of heart 😬
@37:20 Dave, C520 Diode is CRACKED in half. You missed it.
Keep watching...
@@EEVblog we were all screaming at you about that one and the other one 😂
@@EEVblog we were all screaming at you about that one and the other one 😂
I have one of those, it didn't boot when we moved last year, but I might have had the wrong power supply. I think it flashes a green light though.
Pretty sure it's painted metal on the back of the monitor.
Dave! C520! LOOOOOK!
I feel like I've been watching a pantomime show!
Dave, over there! No the other way!
- Yes, I WAS shouting at the TV.
Need to take a nap now..... 😬
I have this same model, unfortunately it was in bad condition, the internal battery leaked and literally destroyed the main board. I cleaned it up and some day I will try to fix it.
Nice video, try to power the main bord with another power supply with the adequate rail voltages
I taught my high school students WP5.1 and remember that overlay!
My step father had the loan of a T1000SE in, wait for it, 1995, I was only just starting to learn about IBM PCs then, so I knew nothing about DOS and very little about Windows, if anything. So I didn't know the SE had DOS in ROM. I'd kind of like to find a T1000 LE or SE, that's in working condition.
I had the little brother (by age) of this, T1200XE, all thru my university years.
Part 2 please, you can save it, find some time, it doesn't need to be soon
My oldest computer is a Compaq Armada 7770DMT from 1997.
It´s very impressive how quick computers developed within a few years back then.
It has a 233mhz pentium mmx, maxed out at 144mb ram total and currently i have a 100gb ide hdd installed.
It runs Windows 98SE very well, however it also makes a great DOS gaming machine thanks to it´s full vga graphics support and ESS audio drive with full soundblaster compatibility.
It can do 32 bit colors at 800x600 native resolution. I think it has 2 or 4 mb video ram but lacks of 3d acceleration support.
@37:35, did u see the cracked component near the “C520” label???
so many memories from this! some great, some the stuff wes craven could use to make a new horror film from... I had several connor drives back in the day.. still have a 40mb somewhere and last time it was powered up (about 5 years ago it still worked!) most of them developed bad sectors galore.
I have a box of 4mb expansion cards somewhere (like 100 of them) I got at an IT liquidation sale in the early 2000s, cant remember if they fit this or not.
I do remember these being an utter nightmare to work on.
Senior college thesis written in WP 5.1 in 1991. Got the 5-1/4 floppies around someplace.... Never owned or used (employer's) laptop until 2001 I think. Traveling engineers (not me) would sometimes have them. Now of course hardly any desktops in use at my company except some on production testers.
Tantalum caps could have popped from OV. My company has had a derating of 50% on those and avoid if possible in designs. MLC caps have replaced the need for a lot of them now though.
i cant wait to see that beautiful screen ^_^
Wow, good memories. I had the version without a harddisk and just a floppy. Memory expansion was using a PCMIA card with a wopping 2 MB (if i remember correct).
Yes tantalum capacitors are marked positive how do I know this… I purchased a SATA to msata adapter off eBay and it didn't work right. Traced it to the capacitor replaced the capacitor powered up and have a nice fireworks show glad I bought extras.
I haven't seen that much fireworks since I plugged in a AT power supply and the power switch cable shorted live 120V! When I was like 6-8.
Yep it will not be a simple repair... It will be an EPIC repair.
Hey Dave just saw a video about a Bendix MG-1 Central Air Data Computer: It mentioned your similar video you have to see how they got in.
43:06 not sure if you saw but those large capacitors (C520 and one near R517) look to be cracked too
I'm guessing the keyboard was supposed to be lifted from the F-key side, gently unhooking the plastic catch near the space bar. The releasing may have become slightly stuck from capacitor goo.
Ok, you tried without the battery. That was my first thought right off the bat. I have seen bad batteries cause low voltage (and lack of booting).
I had one of those way way back.
hold on to it for years to run software that refused to work on faster CPUs (yes that used to be a problem)
At 32:55 the residue is, as you later identified, leaked out electrolyte from the capacitors. I had this a lot when I repaired old Macintoshes. Give it a thorough clean with hot soapy water and a rinse with pure isopropyl. Some connections may require re-soldering to work again.
Looking at the bad traces at 38:15, I’d say the board is BER. This when I usually gave up a capacitor-corroded board after following a long rabbit-hole with my first terrible one. On capacitor-corroded boards, as the corrosion often destroys traces under chips and often vias too, you don’t have a chance especially if you don’t have massive amounts of time and a schematic.
the cracked C520 Dave, Dave! how did you miss that for half the video
Try providing the bus rail voltages directly maybe, just to see if it still even works. Then you can go backwards?
At 37:34 an exploded cap is visible, it is named C520. And another one without name near R513 is split too. Clean that board in the ultrasonic.
Damage from leaky capacitors and NiCD's are a major concern when working with vintage computers.
Only positive is that the repair work gets pretty straightforward, cleaning and restoring vias and traces.
ELNA capacitors are pretty much no-brainer, you replace them when you see them and you don't even bother measuring them. I fixed an AT power supply recently, all ELNA ones were dead, one even shot the alu can to the space and all that was left was a roll of paper :) All other caps were fine, even after some 25 years or so.
It's actually good to see ELNA caps in a non-working device, you know instantly where the problem is.
Hi Dave! Yeah that looks crusty! Something that might not be a total PIA to scope out , and there seems to be devided opinion and misunderstanding on. Is the "throttle commander" (removes engine lag from cars with electric gas pedal) is it trash like the obd2 watsits. I figure a pedal position sensor is a potentiometer, then engine management operates throttle gently to meet EPA standard.
How can something that connects between sensor and controller make the output actually more responsive other than making the absolute value higher.
I hope they work because I've just spent 200 quid on one to try and make an stick shift opel mpv maneuver with some sort of modicum of finesse. Instead of having to book an appointment with the biting point.