The number of times I watched in horror, uttering *"hoh god"* under my breath at the freakish ways you wrestled with this poor machine make the title of this video very much earned.
I just LOVE retro computing... It is way more interesting... than these today's enthoos boasting about Threadrippers and RTX 4090s... I started with sister's boyfriend's Presario 700 which had Monster Truck Madness 2 on it...
@@mica7191 "Man I really hate modern computing because you can get a 64 core processor and a 4090 for $10,000 instead of, you know, a sub gigahertz processor, and 12mb of ram. Oh and I also love how every company was acting like apple today with proprietary parts for every line of computers." I like retro computing too. But y'all are blinded by nostalgia. Everything is wayyyyyyy better today.
@@TechnicalSpecter I will never understand some tech enthusiast channels like LinusTechTips... They are over the top... I will always have to afford a used pc... because I'm from a rural area in Croatia... and not from Canada like godmotherfucking Linus
The Tandy is acting like it's not getting enough power. I'd suggest doing a full recap of the other power supply also. One way to test weak power supply power is to unplug the HDD and see if that improves overall performance, as the HDD is the biggest power consumer in that machine; The backlight being the second-largest power consumer. Also consider testing and recapping the motherboard itself. And, while some people might balk, I'd suggest replacing EVERY electrolytic cap I see. Nothing lasts forever, and IMO, it would help to resolve a lot of electrical gremlins. It just depends on how much you want to invest in these machines.
You're not getting consistent power in. The noise your hearing is due to noise on your power lines interfering with the speaker, the reason you're hearing a difference in tone when accessing the floppy is likely evidence of this. The power supply needs some further work and it would be a good idea to recap the motherboard and have a close at the power rails to make each component is getting an adequate supply.
1701 means hard disk controller error. Light blinking and disk spinning down indicates the drive has an error code to report (which it is blinking out). The drive thus is not responding to commands and thus the controller reports an error.
There's almost never a good reason to jump a fuse. Either it's blown because there's some other faulty component that's drawing too much current, or there's some other problem that hasn't caused the fuse to blow. Either way, check the continuity of the fuse and if it's blown you need to figure out why it blew, not just replace it with a wire. If you do that and the problem is still there, it could possibly draw a lot more current and cause even more damage. First step is always thou shalt check voltages. You should be able to see if a rail is loaded down. The fact that the screen dims under load should be pretty visible on the multimeter. If you haven't already replaced all the caps in the power supply, that would be a good start. I'd also check the diodes and transistors, make sure they're not shorted something. Also check the transformer to make sure there's no shorted windings, or shorts between the windings. That capacitor falling on the motherboard could also have caused something to blow, which is now loading down a power rail as well. Anyway, that's a good start for your homework. Please turn in your copybook once you've completed the assigned exercises.
I was internally screaming all the time he did that, I mean checking the fuse and recapping the PSU should be the first thing when you see the screen flickering when something drawes power...
The screaming noise is probably due to poor filtering on the power rails. Could also be the cause of some of the other weirdness. This could easily be due to the other caps in the power supply being bad, despite not looking bad, and not filtering the power rails properly.
"Evil shenanigans!" "I swear to almighty I'll pistol-whip the next person who says 'shenanigans'." 🤣
2 ปีที่แล้ว +7
Im happy you decided to do a full recap! Visual inspection of caps just tells you they look nice, nothing more. When a friend donated a Macintosh Performa 450to me he tested it and it was working. I got it a few days later and it was stone dead. PSU caps where leaking everywhere and it was fresh! The problem was that o-rings dry up, they get hot during first power up and dont expand with the casing so they leak and die after that. Fixed the PSU, it powered up but the FDD had a lot of issues, one was leaky caps with corrosion. I was swabbing of the paint apple put on them during manufacturing, I wanted to read the specs printed on top of the SMD electrolytics hidden under the paint. The dam caps fell strait off LOL! Looked like traces and pads where gone, brown corrosion crap everywhere. Cleaned it off with vinegar and I found perfectly good copper under the corrosion. Recaped it, cleaned the heads (did not read or write properly), and eventually got i working properly again. Still have to do the MB but will do that once I found a replacement for the HDD. But I would not be surprised if the lose caps in your machine just detached them self's, old electrolyte seems pretty corrosive compared to more modern stuff and the legs just corrodes off the pads. Im sure you get it going with some fresh caps and probably a few more fixes, often other stuff are broken too, not just caps but lets hope not. Good luck and see you in part 2!
You still have a power issue. That squealing is noise from the power supply. Bad filter caps, could be bad caps on the motherboard as well. The dimming of the display shows me that the voltages are sagging when the drive motors activate.
Seems like one of the drives is browning out the system. Or maybe the floppy controller. You should put volt-meters on all the voltage rails and measure them when its trying to do stuff.
Ok on fuses, you can use continuity checks on a multi-meter. Also with that much corrosion, you also need to check the continuity between traces on the board itself, because that level of corrosion most likely ate away some of the traces.
I'm watching this in horror, thinking "JUST CHECK THE CONTINUITY!!!, WHERE'S YOUR METER???? WTF????" , I'm currently at 8:03 so I don't know what happens next.
I was thinking the same thing. If you don't have a meter, I highly recommend one that beeps for continuity so you don't have to look away from the probes while testing.
The hard drive itself may have some leaky capacitors and/or the actuator motor may be frozen. Had both issues on some of my more ancient laptops. Dunno if these drives work now (as one machine is still dead and the others don't have a BIOS so I can even tell them that they *have* a hard drive), but at least the drives now pass their self test as in they spin up, wait another second, then the actuator arm moves around, parks itself, drive LED turns off and the drive stays on.
I would probably try measuring the power supply voltages. Most likely 5 and 12 volts with a teensy bit of -12 for the serial port. Replacing caps wholesale is not the very best strategy, better to measure them first with a cap and ESR meter. It’s best to have some guidance from the measurements. Ad one is likely to maybe goof up on replacing 10% of the parts so fewer repairs is better.
The 8086vic-20 chip architecture tells me the drive is a 720K floppy drive. Using a 720K boot floppy (not 1.44) should get you up and running. The physical difference you should be able to see is if there is a hole opposite the write-protect tab. I;ve had to cover the hole in the past to get the disk to get a 1.44 to format as a 720K. Of course, you could always install a 360K drive for testing on the bench. Tandy units tend to power over the data cable, so without seeing the connections on the drives themselves, a little difficult to know. If the HDD is dead, best to pull the card and drive for testing, that way the controller isn't hanging the bios on startup. It is possible the drives are working, just a LLF is needed. I suspect the light tube in the LCD may be worn out and is dragging down the power supply. They can be a pain to replace, but it is doable. If you need some tools, let me know and I"ll send you a few that you may be able to use. Let me know if you have issues/questions, as these 8-bit units (8086's) were how I started in the computing industry back in the day.
17:56 Perhaps back in the day or sometime in its life, someone pulled that capacitor off and replaced the card, but didn't continue disassembly to retrieve it. That's the only thing I can think of.
If it's anything like the early ZDS XT laptops, the hdd controller did not report in bios the drive size. Regarding the floppy used - was it single density? Some of those old laptops were single density only.
you should have gotten a 1400LT they are much more reliable and you can get a cf card adapter for it so you can keep both the dual floppies and still have a cf hdd. I did that to mines and its a blast using it!
Hey Sean. You absolutely need to recap those power supplies. They use esr parts which allows for rapid discharge, but they've long given up the ghost. Do not just buy random caps for this, need to match parts. I can help you with this if you need
Cute little computer. Floppy probably just needs a good clean, maybe has some sheered gear teeth. I would never expect such an ancient hard drive to just boot. Probably stiction or crashed heads. The 'voltage regulator' is most likely the step-up transformer for the backlight display. Remember to completely clean the boards before and after re-capping and watch out for loose pieces of solder. The power supply is still suspect and may not be delivering enough power to the drives.
@@JosiahGould There was a post on Hackaday last week showing how someone built a PCMCIA wifi card using an RP2040. I've found a standard Pi fits nicely in the case from a US Robotics Speedster modem, and can connect a hardware serial port on the GPIO pins.
Urgh... I got shivers remembering trying to play Catacomb 3D on a 286 with a screen similar to this. It was a blurry headache inducing mess of neon red streaks.
Maybe you could temporarily substitute the PSU by an old AT or ATX one, just to see if it's a power issue. Also, those fuses really should be left as if there is a problem you don't risk passing high voltage to the main board. In a bind, you could just hot-wire a barrel fuse in it's place.
My temporary fuse replacement is usually a single tiny strand of wire, which is basically a fuse without the glass/container, or a piece of solder, because it melts pretty quickly if there's a problem.
New subscriber here! This fight remembered me a lot trying to work out my parents 286..386 and 486 in my teens even not being a tech guy. My dad actually is a IT guy and had some of these machines around for our use at home (like laser printers in mid 90s) . Thanks for the memories!
A good rule of thumb when it comes to blown fuses is to always assume something blew it. With that in mind, bypassing one with a wire link like that is usually a bad idea, and you're lucky you didn't blow up something else on the PSU. The first thing to do would be to look for dead shorts from any of the voltage rails to ground, and across AC. Then, check the diodes and the legs of any transistors, power regulators, etc for shorts. If everything looks good, unplug everything from the PSU and stick another similarly-rated fuse in the circuit and see if that one blows. too. If it doesn't, start looking for shorts on the input side of things. The first rule of electronics troubleshooting is always check voltages. After you get your fuse problem squared away, check the +12v, +5, -5v, if it exists, and any other rails indicated by the service manual or any other documentation you can find. Often, a screen will dim or a hard drive will fail to spin up because they're getting several volts under spec. Leaky and dead caps can certainly cause this problem, but resistors can also drift out of spec, and voltage regulators often fail. A lot of PSUs have trim pots that allow you to adjust the rail voltages up & down, which might take care of the problem, too.
Sometimes to check just how bad the PSU is, i try to replace it by wiring up a standard PC PSU, however that implies figuring out the voltages for each pin.
i just fixed up a pentium 100 laptop and its working nicely, upgraded the ram to 40mb (32mb module + 8mb onboard), and a 32gb 2.5 IDE SSD from amazon. i have Windows 95 C on it.
This reminds me of PSUs inside an X68000. You should consider making a custom PCB that holds a PicoPSU. That will make the unit work correctly forever with modern protection that this PSU doesn’t have.
Why wouldn't you just measure the fuse? Should be a dead short end to end... You could be causing damage as there was a reason for the fuse to blow in the first place if it was blown...
AR: I'm gonna bypass these fuses with little bits of wire me, who has an ASE in electrical systems: That is so incredibly stupid on so many different levels
Wow, I had one of those, it was my first ever laptop. I got it for free because it had a dead charging circuit, I replaced a burned out resister and it started working again, so I guess it cost me 12 cents. I used it for years.
aren't those technically luggable computers? i have a zenith portable that looks like a big laptop, heavy weighs a bit more than 10 pounds. has no battery, runs on 110volts. only battery it had was a cmos battery which i removed, thank god it didnt leak on the board
Nice! And I hear you on the PC Convertible.. it's a CHUNK! IBM later fixed at least one sin by adding a backlit display, but as to why they didn't release the initial model with a backlit display is beyond me!
I am old enough to recall all sorts of the luggable computers back in the 1980s and even back then i thought it was kinda ridiculous to hauling the heavy things around.
I would totally concur about it being a power issue. The fact that the whining changes when you change the Vreg, the dimming when drives are accessed etc. all screams unstable power. Methinks that 2nd power supply has issues.
i think i wanted one of these when they were new. i'd stare the Consumers Distributing catalogue wondering how i'd ever have money to buy one. i was probably nine years old.
Try to find a service manual for it if you can. The Tandy service manuals were very useful, and quite thorough for the most part. I used one of the LT1400's back in the day to write work procedures for our division on the boat.
The board of "getting old stuff on the internet ltd." needs a status report on that Tandy! There is a critical shortage of old stuff on the internet! Just today, I had a conversation with two redditors, *not using old stuff!*
Oh wow, I also have a 1400FD that needs some repairs. I have a PDF version of the service manual for the 1400LT that might be applicable to the other 2 in the series.
If I were testing a system with the PSU open/dismantled, I would plug it into a power strip which is switched off, turn the power switch on the computer on, and THEN turn on the power strip. That way your hands are away from the PSU when switching the system on.
That's worrying. I should check mine to make sure the caps aren't leaking. Last time I opened it up was probably about 7 or 8 years ago and it looked fine.
I have the 286 version of this the 2830? 2840? hd . The power dc boards on these suck, they never age well. Ive tried a couple times to fix mine, and still doesn't want to boot. Stupid watchdog circuit is unobtanium. Maybe I'll try again soon. I can get it to boot bypassing the dc to dc board.
Unstable supply voltage/dead caps. You hear all that noise through the speaker because of all that electrical noise on one (or more) power lines.
“I’ll just bypass these fuses here” - Death
That's getting into 8-bit guy troubleshooting right there 😂
"I have no idea if theyre blown or not" So test continuity with a multimeter?
Glad I wasn't the only one yelling at the screen. 🙂
This right here...
Yup
The number of times I watched in horror, uttering *"hoh god"* under my breath at the freakish ways you wrestled with this poor machine make the title of this video very much earned.
R.I.P. the harddrive that fell over
Good old trinity... Apple II, Commodore PET, and Tandy TRS-80
I just LOVE retro computing... It is way more interesting... than these today's enthoos boasting about Threadrippers and RTX 4090s... I started with sister's boyfriend's Presario 700 which had Monster Truck Madness 2 on it...
@@mica7191 "Man I really hate modern computing because you can get a 64 core processor and a 4090 for $10,000 instead of, you know, a sub gigahertz processor, and 12mb of ram. Oh and I also love how every company was acting like apple today with proprietary parts for every line of computers." I like retro computing too. But y'all are blinded by nostalgia. Everything is wayyyyyyy better today.
@@TechnicalSpecter I will never understand some tech enthusiast channels like LinusTechTips... They are over the top... I will always have to afford a used pc... because I'm from a rural area in Croatia... and not from Canada like godmotherfucking Linus
The Tandy is acting like it's not getting enough power. I'd suggest doing a full recap of the other power supply also. One way to test weak power supply power is to unplug the HDD and see if that improves overall performance, as the HDD is the biggest power consumer in that machine; The backlight being the second-largest power consumer.
Also consider testing and recapping the motherboard itself. And, while some people might balk, I'd suggest replacing EVERY electrolytic cap I see. Nothing lasts forever, and IMO, it would help to resolve a lot of electrical gremlins. It just depends on how much you want to invest in these machines.
You're not getting consistent power in. The noise your hearing is due to noise on your power lines interfering with the speaker, the reason you're hearing a difference in tone when accessing the floppy is likely evidence of this. The power supply needs some further work and it would be a good idea to recap the motherboard and have a close at the power rails to make each component is getting an adequate supply.
The one that only lets the fan spin for a split second before turning off again might be caused by shorted tantalum capacitors on the motherboard.
1701 means hard disk controller error. Light blinking and disk spinning down indicates the drive has an error code to report (which it is blinking out). The drive thus is not responding to commands and thus the controller reports an error.
As a certain youtuber named Alec often says: "Through the magic of buying 2 of them!"
I thought it might be a deliberately off-brand reference.
that was exactly my thought!
There's almost never a good reason to jump a fuse. Either it's blown because there's some other faulty component that's drawing too much current, or there's some other problem that hasn't caused the fuse to blow. Either way, check the continuity of the fuse and if it's blown you need to figure out why it blew, not just replace it with a wire. If you do that and the problem is still there, it could possibly draw a lot more current and cause even more damage.
First step is always thou shalt check voltages. You should be able to see if a rail is loaded down. The fact that the screen dims under load should be pretty visible on the multimeter. If you haven't already replaced all the caps in the power supply, that would be a good start. I'd also check the diodes and transistors, make sure they're not shorted something. Also check the transformer to make sure there's no shorted windings, or shorts between the windings.
That capacitor falling on the motherboard could also have caused something to blow, which is now loading down a power rail as well.
Anyway, that's a good start for your homework. Please turn in your copybook once you've completed the assigned exercises.
I was internally screaming all the time he did that, I mean checking the fuse and recapping the PSU should be the first thing when you see the screen flickering when something drawes power...
1701-C? Congrats on your Ambassador class Tandy.
My regards to Captain Garrett.
Maybe test the fuse with a multimeter first? You wouldn’t even have to take it out.
The screaming noise is probably due to poor filtering on the power rails. Could also be the cause of some of the other weirdness. This could easily be due to the other caps in the power supply being bad, despite not looking bad, and not filtering the power rails properly.
You and your time traveling shenanigans sneaking into Sep-Tandy at the last minute Action Retro. You win this round 😁
"Evil shenanigans!"
"I swear to almighty I'll pistol-whip the next person who says 'shenanigans'." 🤣
Im happy you decided to do a full recap!
Visual inspection of caps just tells you they look nice, nothing more.
When a friend donated a Macintosh Performa 450to me he tested it and it was working.
I got it a few days later and it was stone dead. PSU caps where leaking everywhere and it was fresh! The problem was that o-rings dry up, they get hot during first power up and dont expand with the casing so they leak and die after that.
Fixed the PSU, it powered up but the FDD had a lot of issues, one was leaky caps with corrosion.
I was swabbing of the paint apple put on them during manufacturing, I wanted to read the specs printed on top of the SMD electrolytics hidden under the paint.
The dam caps fell strait off LOL!
Looked like traces and pads where gone, brown corrosion crap everywhere. Cleaned it off with vinegar and I found perfectly good copper under the corrosion. Recaped it, cleaned the heads (did not read or write properly), and eventually got i working properly again.
Still have to do the MB but will do that once I found a replacement for the HDD.
But I would not be surprised if the lose caps in your machine just detached them self's, old electrolyte seems pretty corrosive compared to more modern stuff and the legs just corrodes off the pads.
Im sure you get it going with some fresh caps and probably a few more fixes, often other stuff are broken too, not just caps but lets hope not.
Good luck and see you in part 2!
You still have a power issue. That squealing is noise from the power supply. Bad filter caps, could be bad caps on the motherboard as well. The dimming of the display shows me that the voltages are sagging when the drive motors activate.
Technology Connections' "by the magic of buying two of them" has got to be the best way to solve a problem.
Seems like one of the drives is browning out the system. Or maybe the floppy controller. You should put volt-meters on all the voltage rails and measure them when its trying to do stuff.
Ok on fuses, you can use continuity checks on a multi-meter. Also with that much corrosion, you also need to check the continuity between traces on the board itself, because that level of corrosion most likely ate away some of the traces.
I'm watching this in horror, thinking "JUST CHECK THE CONTINUITY!!!, WHERE'S YOUR METER???? WTF????" , I'm currently at 8:03 so I don't know what happens next.
Especially vias, I've found...
Echo the comments above. I was so nervous…
I was thinking the same thing. If you don't have a meter, I highly recommend one that beeps for continuity so you don't have to look away from the probes while testing.
The hard drive itself may have some leaky capacitors and/or the actuator motor may be frozen. Had both issues on some of my more ancient laptops. Dunno if these drives work now (as one machine is still dead and the others don't have a BIOS so I can even tell them that they *have* a hard drive), but at least the drives now pass their self test as in they spin up, wait another second, then the actuator arm moves around, parks itself, drive LED turns off and the drive stays on.
That floppy drive might be 720K. Try using a 720K boot disk.
always love me some questionable computer shenanigans! they really help me recently with what i've been dealing with in my life
That's the beautiful sound of electrical interference. There's probably a bunch of caps and resistors on the filter side of the psu that need help.
I would probably try measuring the power supply voltages. Most likely 5 and 12 volts with a teensy bit of -12 for the serial port. Replacing caps wholesale is not the very best strategy, better to measure them first with a cap and ESR meter. It’s best to have some guidance from the measurements. Ad one is likely to maybe goof up on replacing 10% of the parts so fewer repairs is better.
Why wouldn't you just test the fuse with a multimeter? Also, if the fuse is blown it might be for a reason.
Exactly
Bypassing fuses: "if he dies, he dies"
I find it interesting that this PSU is *completely different* from the one in my 1400LT, despite the rest of the system being so similar.
The 8086vic-20 chip architecture tells me the drive is a 720K floppy drive. Using a 720K boot floppy (not 1.44) should get you up and running. The physical difference you should be able to see is if there is a hole opposite the write-protect tab. I;ve had to cover the hole in the past to get the disk to get a 1.44 to format as a 720K. Of course, you could always install a 360K drive for testing on the bench. Tandy units tend to power over the data cable, so without seeing the connections on the drives themselves, a little difficult to know. If the HDD is dead, best to pull the card and drive for testing, that way the controller isn't hanging the bios on startup. It is possible the drives are working, just a LLF is needed. I suspect the light tube in the LCD may be worn out and is dragging down the power supply. They can be a pain to replace, but it is doable. If you need some tools, let me know and I"ll send you a few that you may be able to use. Let me know if you have issues/questions, as these 8-bit units (8086's) were how I started in the computing industry back in the day.
you are my favorite youtuber i love your humor and i love the shenanigan's that you put these older machines through
Sean: I got a Tandy!
Me: Oh neat! It'll be a Tandy 1000 or a 3000HD or...
Sean: It's a luggable
Me: So you have chosen death
17:56 Perhaps back in the day or sometime in its life, someone pulled that capacitor off and replaced the card, but didn't continue disassembly to retrieve it. That's the only thing I can think of.
If it's anything like the early ZDS XT laptops, the hdd controller did not report in bios the drive size.
Regarding the floppy used - was it single density? Some of those old laptops were single density only.
you should have gotten a 1400LT they are much more reliable and you can get a cf card adapter for it so you can keep both the dual floppies and still have a cf hdd. I did that to mines and its a blast using it!
2:33 - IBM really wanted that "sidecar" concept to be a thing...
20:10 "Re-Cap Everything!" should be on a shirt.
Hey Sean. You absolutely need to recap those power supplies. They use esr parts which allows for rapid discharge, but they've long given up the ghost. Do not just buy random caps for this, need to match parts. I can help you with this if you need
Of Rochester? Like the Medway town?
@@oldtechnobodycaresabout new york
Gotta love a good old Tandy. Really love how they look!
Cute little computer. Floppy probably just needs a good clean, maybe has some sheered gear teeth. I would never expect such an ancient hard drive to just boot. Probably stiction or crashed heads. The 'voltage regulator' is most likely the step-up transformer for the backlight display. Remember to completely clean the boards before and after re-capping and watch out for loose pieces of solder.
The power supply is still suspect and may not be delivering enough power to the drives.
I'd love to make a Raspberry Pi cyberdeck out of one of those.
Put the Pi on an expansion card to replace the modem. Full original hardware with the power of a Pi on a bootable card.
@@JosiahGould There was a post on Hackaday last week showing how someone built a PCMCIA wifi card using an RP2040. I've found a standard Pi fits nicely in the case from a US Robotics Speedster modem, and can connect a hardware serial port on the GPIO pins.
Frustrating but you are making progress. Looking forward towards your next video! Thanks for sharing
Urgh... I got shivers remembering trying to play Catacomb 3D on a 286 with a screen similar to this. It was a blurry headache inducing mess of neon red streaks.
The sounds this thing makes reminds me so much of the SavestoLink terminals in alien...
Maybe you could temporarily substitute the PSU by an old AT or ATX one, just to see if it's a power issue. Also, those fuses really should be left as if there is a problem you don't risk passing high voltage to the main board. In a bind, you could just hot-wire a barrel fuse in it's place.
My temporary fuse replacement is usually a single tiny strand of wire, which is basically a fuse without the glass/container, or a piece of solder, because it melts pretty quickly if there's a problem.
I take it you did a continuity test on that fuse and it was open, which is why you temporarily replaced it with wire.
could it be...
that square rectangle thought to be a fuse is also a filter? I hear low voltage power emanating from the power supply.
I really appreciate the capture of (mostly) the whole process. Good times!
Gotta love the "I don't care how you make it work, just make it work or else!" engineering of the old machines. ;)
1701-C ... Dude, looks like you've got Enterprise hardware goin on there... ;)
New subscriber here! This fight remembered me a lot trying to work out my parents 286..386 and 486 in my teens even not being a tech guy. My dad actually is a IT guy and had some of these machines around for our use at home (like laser printers in mid 90s) . Thanks for the memories!
The thing I love about your repair videos is that you share the same bemused frustration I do when I hit another dead end. Good work though!
A good rule of thumb when it comes to blown fuses is to always assume something blew it. With that in mind, bypassing one with a wire link like that is usually a bad idea, and you're lucky you didn't blow up something else on the PSU. The first thing to do would be to look for dead shorts from any of the voltage rails to ground, and across AC. Then, check the diodes and the legs of any transistors, power regulators, etc for shorts. If everything looks good, unplug everything from the PSU and stick another similarly-rated fuse in the circuit and see if that one blows. too. If it doesn't, start looking for shorts on the input side of things.
The first rule of electronics troubleshooting is always check voltages. After you get your fuse problem squared away, check the +12v, +5, -5v, if it exists, and any other rails indicated by the service manual or any other documentation you can find. Often, a screen will dim or a hard drive will fail to spin up because they're getting several volts under spec. Leaky and dead caps can certainly cause this problem, but resistors can also drift out of spec, and voltage regulators often fail. A lot of PSUs have trim pots that allow you to adjust the rail voltages up & down, which might take care of the problem, too.
Sometimes to check just how bad the PSU is, i try to replace it by wiring up a standard PC PSU, however that implies figuring out the voltages for each pin.
i just fixed up a pentium 100 laptop and its working nicely, upgraded the ram to 40mb (32mb module + 8mb onboard), and a 32gb 2.5 IDE SSD from amazon. i have Windows 95 C on it.
This reminds me of PSUs inside an X68000. You should consider making a custom PCB that holds a PicoPSU. That will make the unit work correctly forever with modern protection that this PSU doesn’t have.
Why wouldn't you just measure the fuse? Should be a dead short end to end... You could be causing damage as there was a reason for the fuse to blow in the first place if it was blown...
Omg. That's the model... I've been looking for this long lost gem of my childhood.
Only 25 years old and I love this channel and old tech. Love your awkward skits
Have you tried big hammer? Computers fear the big hammer
SepTandy lives on, and we look forward to future shenanigans in getting this machine restored to former glory!
this thing is really built like a small PC in a portable case! it's really cool
AR: I'm gonna bypass these fuses with little bits of wire
me, who has an ASE in electrical systems: That is so incredibly stupid on so many different levels
I've always liked the design language of Tandy portables/laptops.
Oh no! He's learned the true power of Technology Connections - That is, the power of buying TWO OF THEM!
*magic
Wow, I had one of those, it was my first ever laptop. I got it for free because it had a dead charging circuit, I replaced a burned out resister and it started working again, so I guess it cost me 12 cents. I used it for years.
I think we should all chip in and get him a multimeter. 🙂
Are you trying to boot 1.44 floppys in a 720K drive?
aren't those technically luggable computers? i have a zenith portable that looks like a big laptop, heavy weighs a bit more than 10 pounds. has no battery, runs on 110volts. only battery it had was a cmos battery which i removed, thank god it didnt leak on the board
I will say that the message "Disk Boot Failure" comes from the boot sector.
Nice! And I hear you on the PC Convertible.. it's a CHUNK! IBM later fixed at least one sin by adding a backlit display, but as to why they didn't release the initial model with a backlit display is beyond me!
I am old enough to recall all sorts of the luggable computers back in the 1980s and even back then i thought it was kinda ridiculous to hauling the heavy things around.
The first two videos I've watched of this channel are of you trying (and failing) to revive a dead laptop. It's very funny desu.
At 18:40 is that white board Sean with magnifying glasses or Bubbles from trailer park boys
I would totally concur about it being a power issue. The fact that the whining changes when you change the Vreg, the dimming when drives are accessed etc. all screams unstable power. Methinks that 2nd power supply has issues.
For American Samoa your upload almost hit Sep. 30th... missed it by 3 hrs.
The colour of the back light is a really nice on mine. It also goes a lot brighter than what it looks in this video.
i think i wanted one of these when they were new. i'd stare the Consumers Distributing catalogue wondering how i'd ever have money to buy one. i was probably nine years old.
"Fan spin!" Louis Rossman would be proud.
Try to find a service manual for it if you can. The Tandy service manuals were very useful, and quite thorough for the most part. I used one of the LT1400's back in the day to write work procedures for our division on the boat.
I found an XT-IDE Compact Flash card that fits in the expansion slot of the 1400LT, pretty useful for the dual-floppy systems.
The board of "getting old stuff on the internet ltd." needs a status report on that Tandy! There is a critical shortage of old stuff on the internet! Just today, I had a conversation with two redditors, *not using old stuff!*
Bought one of these earlier this year. Got so fed up trying to fix it that I sold it on after a couple of months. So cool but so janky.
The 286 systems are even worse! I have 3 and not 1 works...
It's September 31, 2022, so you're good!
I wonder where you get all these amazing retro PCs 💪🙏
This was my very first laptop. Memories, but I would not go back to it ever.
Oh wow, I also have a 1400FD that needs some repairs. I have a PDF version of the service manual for the 1400LT that might be applicable to the other 2 in the series.
If I were testing a system with the PSU open/dismantled, I would plug it into a power strip which is switched off, turn the power switch on the computer on, and THEN turn on the power strip. That way your hands are away from the PSU when switching the system on.
The demons inside the computer are screaming
That poor Tandies(sp?), I hope they finally get together and produce a working Tandy
Take a shot every time he says "heh" xD.
A battle of epic proportions.
I own a tandy 2800HD these laptops are center pin negative so please be careful when attemping to power them up without the original power supply!
Never just jump a fuse. Check it with a multimeter first. Get the appropriate fuse or an equivalent.
That hard drive controller card was...de-cap-itated.
Weren't those things used in the movie "Hackers"?
That's worrying. I should check mine to make sure the caps aren't leaking. Last time I opened it up was probably about 7 or 8 years ago and it looked fine.
>.> what funny linux things are you gonna do on an 8088..
All I want to do is this: I just want to find 11,780 capacitors, which is one more that we have
I have the 286 version of this the 2830? 2840? hd . The power dc boards on these suck, they never age well. Ive tried a couple times to fix mine, and still doesn't want to boot. Stupid watchdog circuit is unobtanium. Maybe I'll try again soon. I can get it to boot bypassing the dc to dc board.
I've got a Tandy 1400 LT (it's the same machine, just with an extra floppy drive and no HDD.) Mine works just fine :).
I like the low lighting.