Seagate Elite "reverse surging" noise

[Patrik Schindler]

Hello Jules,

Am 14.11.2020 um 18:01 schrieb Jules Richardson via cctalk <cctalk at classiccmp.org>:

> I picked up a couple of 9GB Seagate Elite SCSI disks the other day (model 410800N, 1995-vintage but 5.25" FH units).

Nice. I also have three of them from the time when a German Dealer (Alternate) was selling stock to get rid of them in the late 1990’s. Was just 100 Deutschmarks back then.

> On the other, however, it makes a sound that I can best describe as "reverse surging", where every 5 seconds or thereabouts there's a very brief lowering in tone before the "normal" sound resumes.

Hm. Can’t recall of having heard what you describe.

> Anyone familiar with the Elite range know if "some of them just do that", or if it's likely to be some form of fault (which may only get worse)?

See comments of other fellow list members.

> However, if the speed really was fluctuating to the point that I could hear it then I'm surprised that I'm not getting read/write problems.

If Seagate derived the clock for matching read data into bits, the actual speed isn’t critical. Without analyzing the circuit board, I can’t tell for sure.

You can easily search for a mobile phone app providing a low-latency frequency reading or better some kind of spectrum analysator using the internal mic to see if there’s an actual fluctuation in frequency or just amplitude (volume) of the drive’s noise. If the differences are faint, it could be hard to tell these two apart. 

:wq! PoC