IBM
This IBM PC floppy drive won’t read disks (Tandon TM-100
This IBM PC floppy drive won’t read disks (Tandon TM-100 repair)
#IBM #floppy #drive #wont #read #disks #Tandon #TM100
“Adrian’s Digital Basement”
This 41 year old single sided floppy drive came from an early IBM PC 5150 and even has IBM branding on it. That makes it a bit …
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These kinds of repairs are so satisfying!
This sort of stuff gives me flashbacks of when I had to learn about disk formatting low level in the 90s by books from the library because nobody I my friend group knew why mac disks didn't work in IBM compatibles.
Ended up finding a System 7 program that would read IBM formatted disks on my Powerbook 100 so I could do homework on it because Word on the Mac was the GOAT.
When I first got into the IT field, I had one of those type drives in m,y work PC. Then we endeed up going with the much smaller type. They were pretty good drives.
Dousingle sided voiceover dub hits different.
EE here. I would certainly suspect noise could be causing your issue. Please take a look at how your failure rate immediately decreased when you attached the O-scope probe. Probes have a built-in capacitance that could act as a nice low-pass filter (Notice how most of the input filters have caps that are in the pF range). I'd give a quick look at the filtering and bypass caps on the board. Having said that, even if this is the case it could point to an op amp or switching device that is operating marginally thereby requiring the signals to be much "cleaner" than would normally be required.
If you were operating and repairing 40 year old computers in 1985, you'd be working on something like ENIAC.
the st johns + atari mashup… <chef's kiss>
If greaseweazle can do just about everything why can't it support using a floppy like a normal drive where you can see files, add files and delete from windows explorer, instead of just working with disk images?
Adrian's Digital Basement videos should replace most computer class teachers in elementary and high schools. If I had this growing up I would have learned so much more.
Cable offset can usually erase the current track. The write gate get turns on
For bench testing use a liner power supply.
Always better results..
PC controllers have better signal recovery circuits
For bench testing use a liner power supply.
Always better results..
For bench testing use a liner power supply.
Always better results..
I wonder, so was it just dirty power that was upsetting the grease weasle?
I've had those molex connector power supplies and have found that they are JUNK. T think they came with some IDE to SATA adapters that I had bought.
BTW, have you heard of a TinySA? It'd be fun to see the MFM signal on one of those. You see the two different frequency peaks and the bits would show up in the waterfall display.
I’m sure the schematics are online
Isn't that 286 board the one you overclocked? Is it possible the clock speed is throwing off the floppy interface? That failing, did you try the 286 without the xtide bios?
I actually have a late revision 5150 made in 1983 and it shipped with a single sided drive. It also just had 64K of RAM and MDA.
I managed to find mine as an unused boxed example so I know the drive is original. The manual in the box also contains DOS 2.1 on single sided disks.
I believe IBM continued to offer a single sided drive late into production as an ultra low cost option before finally being phased out in the XT
My Tandon TM-100 is still sitting on the shelf, so it's always fun to grab it and follow along with the video. It's a -2A model with a "48 TPI DSR" label under the latch, and a build date of 3-9-84. I've decided that's a US American date format, which means it's a little older than I am, so I don't feel quite as old as I would if it used the correct date format.
My guess the problems at the end were related to the XTIDE BIOS. If they've patched the floppy routines, it's possible those routines are bugged in a way that gets the drive into a bad state, and it's returning unexpected data that DOS doesn't understand.
WORN drive. Write Once Read Never
I look forward to you working on the high speed tape drive in the Coleco Adam! And the floppy drive
the 286 is the overclocked one? i guess the DMA controller is acting up due to the marginally too high speed. from my 286 NEAT chipset days i remember, while overclocking the DMA for floppies started giving error/freezes even before other stuff failed.
You NEED a PAT2
A bad write gate input “gate” can cause the drive into a constant write state, blowing all of the data
Adrian, you talk about misalignment of the tracks so much, but try to avoid the calibration like crazy. nice to see the other tests, but i would really put a known good disk and then calibrate the analogue signal for the highest output on the inner tracks.
Check the read amp chip with a scope..
Also there are a +,- power inverter for the read amp that often fails
U can use the decal on the bottom of the spindle. When at the correct speed the pattern will seem to stop.
There are two patterns. One for 60hz and one for 50hz
Dodgy motherboard DMAC can cause computer to hang when accessing a floppy drive.
Is the 286 motherboard the one with the broken slot?
Watch track 0
The dysan media would help a bunch!
It along with a scope can spot an alignment problem in seconds
I only found your channel a few weeks ago and I'd like to thank you for uploading some great content on vintage computers. Cheers!!
Lighter term resisters