Sounds of the Tandon TM502

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Tandon-Microtek TM502
Country of Origin: USA
Introduced: Unknown
Interface: ST-412 (MFM nominal)
Capacity: 10MB
Form: 5.25 HH (1")
CHS: 306 / 4 / 17
LZN: 307
WPC: 128
Track-track: 16.3ms
Linear access: 58.7ms
Random access: 98.0ms
Rotational: 3600RPM
Media: Metallic, inline TF heads
Disks: 2
Actuation: Rotary band swingarm stepper
Feedback: None
Lift/Lock/Park: None
Brake: Electromechanical
Service life: Unknown
Related models: TM501 (1 disk), TM503 (3 disk)
Failures: Unknown
Settings: No link at this time
My thoughts:
The TM500 lineup was Tandon's response to Seagate's ST-400 series. Evident by the lack of examples available, the TM500 did not fare very well. It seems like early Tandy 1000 machines which included hard disks included TM502s, but later ones did not, and it seems very few were sold otherwise. Like many companies, Tandon sold a single platter 5MB version of their drive, the TM501, which is hideously rare, and just like Seagate, Disctron, and CMI, Tandon also sold a 3 platter 15MB version, the TM503, which seems to have been selected as an option for the TRS-80 external disk drive units. Sadly, my TM503 gave up during filming, and I am down to just one last Tandon TM500 drive in my lineup which works - This TM502. I recommend the competition over Tandon's mechanism any day.

[@Teraforce88]

I must say, this drive certainly *sounds* like a high quality drive in good condition: it's spindle bearings are very quiet, as is the stepper motor, especially during short seeks. The seek times themselves are also better than the equivalent CMI, Disctron, and Shugart drives from the era. Too bad the real-world reliability isn't there...

[@TheDiskMaster]

@@Teraforce88 It happens. That, along with their poor sales numbers makes them a bit uncommon as well. Tandon didn't get these into the hands of OEMs and so these never moved.

[@bobjoe2827]

Tandon's manual lists the TM-502 as an 85ms seek time drive (with the fluid damper) which would have been just as fast as a ST-412, and faster than the MiniScribe 2012. I have never seen a Tandon that had the fluid damper still intact after all of these years, so perhaps that plays into the performance loss of these drives. The Tandon TM-500 series drives were the OEM drive for the Columbia data products MPC-1600-4 as well as many external hard drive enclosures (but not IBM, probably because they are difficult to fit into an XT's drive bay). The TM-500 series are among the easiest ST-412 class hard drives to service (especially head/platter swaps and stepper band replacements) and are in my opinion the best drives Tandon produced, however all Tandon drives were made to be cheap to manufacture and have just enough quality to be adequate in their function, so they are not a good choice of drive to use nowadays.

[@TheDiskMaster]

I had intended to do a recording run of three platter drives all at once: The CM-5619, D519, ST-419, TM-503, and the CM-5616C, but the ST-419 and Tandon TM-503 laid down and died during testing. I haven't been able to get either to start back up properly - Even with the replacement 419 board you sent me. Generally, drives with configurations other than 2 platters are pretty uncommon.

[@bobjoe2827]

@@TheDiskMaster I had a Tandon TM-502 that refused to work (even LLF) after running it through Spinrite's speed tests. The problem ended up being a broken head coil wire on head 0 and a head stack swap with a parts unit brought the drive back to normal operation. I wish you better luck on your TM-503 and ST-419, hopefully it will turn out to be something simple.

[@TheDiskMaster]

@@bobjoe2827 I'm not sure. The ST-419 will spin up but does not recalibrate to track 0 and never becomes ready. The TM-503 had it's spindle motor fail.

[@bobjoe2827]

@@TheDiskMaster The 419 could be a bad stepper motor (I tested that board on my ST-419 before I sent it) or possibly a failed track 0 sensor. If you are up to it, I do have a working spare spindle motor for the TM-503 with pretty good bearings

[@TheDiskMaster]

​@@bobjoe2827Hmm, that might be worth doing. TM503s aren't very common. I'll have to clear off some of my other projects first. I don't think it's the track 0 sensor, I'm thinking it might be the hall sensor for the spindle. No idea at this time, I've put the drive to the side for now.

[@douro20]

I actually had a TM502 at one point. It came out of the same industrial enclosure my TM100-2A floppy disk drive came from. I believe it was unused. Yeah they're terrible performers but at least they were better built than their later drives.

[@TheDiskMaster]

@@douro20 Just about anything is better built than the Tandon TM-252 and their voice coil drives.

[@thegeforce6625]

@@TheDiskMasterwait so did Tandon make voice coil drives at one point?

[@TheDiskMaster]

​@@thegeforce6625A couple, I've shown one on this channel even, the Tandon TM702AT. The entire TM700 range is voice coil.

[@Mathmos252]

morse code??? 2:39

[@TheDiskMaster]

No, that's the sound of the stepping motor actuating the head stack.

[@Mathmos252]

@@TheDiskMaster i know lol Xd , i meant that It sounds like morse code😭😭😭

[@TheDiskMaster]

​@@Mathmos252Not really, there aren't any gaps or patterns to it. It would just be gibberish if any of it was decodable at all.

[@leecremeans5446]

Tandon didn't get good until after Western Digital bought them...

[@JankPods0201]

Neither before. The other TM series of drives, Such as the TM252, 262, and 362 were mediocre and were unreliable.

[@TheDiskMaster]

@@leecremeans5446 Tandon was never good. Western Digital continued to produce the exact same Tandon mechanism with extremely minor changes until the more modern voice coil designs were ready for market.

[@TheDiskMaster]

@@JankPods0201 All Tandon drives have the initials TM. The TM-252 is actually an earlier drive, based on the chassis you see here but slimmed down for half height operation.