Hi, in part 2 of my IBM XT video, we are going to be tackling the Tandon floppy drive that was unable to read a single disk. Enjoy #IBM #Floppy #Tandon
Nice Video, Inductor is a colour code 'Brown-Black-Brown" , and is given in uH, So its a 100uH inductor. A thing to know about TanTal capacitors. They are one of the best and durable But a few reminders. They absolutely can not handle over voltage. If it say's 10V, Thats the limit also. Than reverse polarity or AC it is also direct finito. That's why you NEVER start up old equipment after a long stay without power. The aluminium one you replaced will not last as long as the TanTal version. Check also DATASheets of the Aluminiums. A lot of variation in life span. From 1000h till up 10.000h. Difference in costs few cents. Always startup only the power supply, without any thing of the computer it self. The start-up over Voltage are there to make lot of damage. Every electronic device with main power you have to first at least reform the supply capacitors. Reformation is simple with a series resistor of app. 47k and slowely turn up the voltage. That way the internal isolation will come back. Time? App half an hour. Internet look-up "Reform Capacitor" . Talking about PWM-Power supply's and the 400V at the mains. Mostly the low voltage capacitors will withstand the power-up sequence.
To fix the floppy lever, you just need a couple drops of lubricant in the track it slides in. I use silicone lubricant for this but I'm sure some grease would work fine.
Modern electronics are also entirely repairable. You just gotta have the know how. I always see this 'it was better back then' - 'unlike modern electronics'. All this tells me is you haven't tried.
@@cybercat1531 I kind of agree, nothing is unrepairable with the right tools etc, but the big deal with more modern stuff is the availability of custom or pre-programmed parts, as far as I remember all the components in that Tandon drive are off the shelf parts that you could order from Digikey etc (they may be obsolete now but were so widely used I'm pretty sure you can still buy them NOS)
@@cybercat1531 Repairable if you have specialist Tools and skills like Louis Rosmann. My Pentium 3 board with bad AGP slot is probably toast. My father has some electronics skills (I don't) but diagnosing and fixing it is beyond his capacity. The board sort of does something, but it always fails with a video memory issue, doens't display anything an all the caps look fine. The AGP slot doesn't look damaged either. It's got some sort an obscure issue that is not reasonbly fixable by a hobbiest. This floppy drive is a part of the good old days when you could just use a standard soldering iron and work with trough-hole parts instead of needing some specialist tools. It's be something my 74 year-old father could fix. Modern electronics sadly are made to be thrown away be design.
Binge-watching endearing a I'm not going to say a lockdown or self isolation but in these times is a real thing you've got the time so why not binge watch something binge do something but not in excess and as long as it's not something that you shouldn't be binge to doing in the first place in terms of help flies Etc yeah it will happen in times like these to binge watch good time to have Netflix or other streaming services wish I had RU-vid premium as well as of course enough money on hand for RU-vid movies this is not a plug for this either but I have none of the above but do have Netflix so something to watch always Esther should be in life.
Nice!... thanks for sharing. My first computer was an IBM XT 'Industrial' model. I bought it from a workmate in 1996 for $350. It was basically an XT motherboard built into a bigger cabinet with air-vent filters and stuff like that for dusty industry environments. It came with an IBM CGA monitor and model "F" keyboard. It had it's original 10 meg hard-drive and full-height 360K floppy drive and 640 k of RAM and MSDOS 5 and some games, and SuperStor version 1.2 which compressed that 10 megs into a whopping 20 megs of hard-drive space. :-)
Really liking your videos. I've just bought myself a 5160 that's non-functional, so these videos are prepping me with a lot of knowledge I may need to get it working again!
15:32 you have 1986 model of IBM PC XT, its newer model with newer bios (faster memory counter on start). These models were included with model M keyboard instead of model F
In 4:43, you seem to start with a wrong assumption: "... as soon as a disk was being inserted, ... it wasn't able to move its heads anymore". I am quite confident that the drive was *able* to move its head even with a disk inserted. But the drive was never told to move its head. When DOS or the BIOS tries to read a disk, the first thing they are going to read is the boot sector (with the BIOS parameter block) or the first FAT sector (with the media ID byte). Both of these sectors are on track 0 - and the POST process already moved the head there. So no need to move the head. Obviously, reading the sector failed. Error recovery includes recalibrating the drive, i.e. stepping outwards until the head is at track 0. As the head is already at track 0, recalibrating is a no-op. After recalibration, the head is moved back to the requested track, which is (again) track 0, so no need to move the head after recalibration. Without the ability to detect the format (160/180/320/360KiB) of the disk, DOS is not going to request anything off track 0, so no step pulses to the drive in operation. That's why you don't get any head movement in DOS, but you got head movement from during the POST, which will step the drive even if no data can be read.
Having put together a few assembly videos myself, I know how much extra work it is to shoot video of the repair. Thank you for continuing to make these videos. That said, I'm shocked you got a perfect format out of a single-sided disk in a double-sided drive ;-) Also, the keyboard you have was an option for the 1986 BIOS XT, which is the only XT BIOS that has support for the extra keys (F11, F12, etc.).
Thank you for keeping up the content! It's been enjoyable to watch. One of the things I've learned over the years of working on this style of equipment is: "If I think its a simple repair, something else will go wrong." I try to fix as many different kinds of electronics as I can, but older PCs from the Pentium MMX to the Pentium 3 era are my favorite to work on. Such a good variety
Couple of people advised against lubricating the rails for the heads. Just a good cleaning but no real lubrication needed for this particular mechanism. (I did apply some white grease but didn’t make any difference in sound).
@@RetroSpector78 No, it needs a small amount of silicon grease on the rails to move smoothly. This is floppy repair 101 (clean the heads, lube the rails). Of course, use a small amount. Also, get a silicone spray and spritz a small amount in the plastic latch assembly to make it smoother.
@@michvod No. do not use silicone spray, it creeps and wrecks some plastics, if you absolutely must lubricate it use a plastics compatible grease, the kind intended for use on VCR/CD mechanisms
Very nice, happy you got it working again! I've never attempted to repair a floppy before, so this is quite useful. Good, detailed footage, great job. Now, if only I could find an IBM PC that doesn't cost a fortune, that'd be great. My dream is finding a model 5170 with EGA (or PGA! a man can dream, right) with a matching model M-keyboard. That was the first IBM I got to play with, back in high school, 1987-ish. :)
Between the plastic of the floppy disk, the knob that locks the floppy disk I put a little oil between the plastic rail, it was perfect and it made no more noise and closes well
I've said it before and I'll say it again, it is so cool that you are fixing up these old components and PCs - another excellent video! As for the opening mechanism, wouldn't something like lithium grease work?
When I first started into computers. I remember having disks formatted to the wrong size. I can't remember why. But you just had to specify what size on the format command in dos. Plus it was not a stable format anyway. Then I remember something about a 720k drive formatting at 360k unless you used I think a driveparm? command in the config.sys? Way to many years ago. If my brain is working. I think you can stick certain 1.44mb floppy drive in it and it will just format to 720k. aka backwards compatible.
If there is an inductor before the short (capacitor), it will act as a fuse. If unsure, measure the voltage on the new capacitor before taking everything apart (and messing up the alignment). If something blows and stops, then there is most likely something that got sacrificed and needs to be replaced. Sometimes it is a fuse, other time it could be a blown 0 ohm resistor or a blown track off the PCB :) I am still not sure, why you took the track 0 microswitch out, as you measured it before in situ and found it to be perfect ;)
Some shots were out of sequence. Just wanted to take a look at it and thought at some point it wasn’t positioned correctly (there is a small amount of flex depending on how it is fastened, and that could influence the track zero detection. At a certain point I was willing to try everything :) in retrospect these things always seem so easy. But this thing was sitting on my desk for over a week :)
Plastic-on-plastic? Try PTFE Grease (commonly available as "SuperLube"). It's safe for plastics, and is even the only type of grease approved for use inside food products (slush ice machines, for example). It's an inert, thick grease, which is among the safest types out there. (Some PTFE-based lubricants are known under the trademark Teflon)
I don't have a Tandon drive but I do have a CPI drive and I don't believe it had a lot of hours put on it. It was in an external interface box with a Tandon TM502 hard disk and a pair of large linear power supplies in it. I no longer have the hard disk but I do have both the power supplies and the floppy drive is in my 5150.
I might be wrong, but isn't the 'inductor' he took from a donor board actually a zero ohm resistor (effectively a link, but in resistor package for pick-n-place machines)? 1.4 ohm could just be the leads. Kinda like one of these: au.mouser.com/ProductDetail/Yageo/ZOR-25-T-52-0R?qs=sGAEpiMZZMtlubZbdhIBIFoOGUvNp40aunNMsQF%2F4bY%3D
You sound like you have some interest in Tandon floppy drives so I wish to ask a question. I have a Tandon TM65 2L circa 1985. I had repaired and had working in a Amstrad PC1512 which I was thrilled about. It needed a new glass type diode that was only allowing 0.005 volts through. I replaced it with a 0.6 volt diode and all was good. Then in a brilliant move I thought I'd try it in a Dell that I have and that ruined it. I am pretty sure this old Tandon doesn't have the high voltage gate that the newer floppy's have so they can share an ATA cable, you know the one with the twist that swaps the Motor ON with the Drive Select for pins 16 and 10. Well Motor ON needs 5v and Drive Select uses 0.4 volts so I think I damaged the DIP28 control chip. The one in question is # 977509-001. Are you familiar with it? Is it the same as the Western digital one that is #WD 177X. The 977509-001 is made by Cherry Semi Conductors and bought out 3 years ago by Onsemi. I should point out the drive was working just like yours not reading disks after it got damaged. Worked fine before the DELL. Any help with this would be appreciated.
I was actually looking for the keyboard for this computer, convinced it came with a model F. Spent 2 days looking until this model M caught my eye... and then I remembered..... nice to have this old model M matched with this computer.
I don't think adjusting track zero is not as simple as you show. Some controllers jump the stepper motor to a set phase after it rams into the stop. This means that the set screw has to be set so that it's at the center of that phase cycle. Then track zero on both sides is adjusted by adjusting the head position.
It looks so weird watching somebody doing these maintenance and repairs as a hobby, not as a “must” to get the computer up and running because you have stuff to do the next day and you really need that machine.
Pausing video, my first guess would be extra friction from the disk surface itself. Bad bearings, dry rails, lube up and go. Resuming video. Inductors are cheap, don't just bypass them. Also where is your LCR meter?
For future reference, you don't really need to use the full term "floppy disk drive" every time you mention the drive. Once you've introduced it to us in long form, then until you have to compare it with another type of drive, such as a hard disk drive, then all you need to say after that for a while is "disk drive" or just "drive." Saying the full term every time is like saying someone's first, middle, and last name every single time you refer to them, which sounds pretty silly.
