Thanks for the tips! I had found something that I suspected was an optical sensor, but wasn't too sure. And cleaning it out as best I could didn't change anything. Of course, I couldn't get at the thing very well. And, as Tony pointed out, common-sense wiring of the thing would mean the problem couldn't have been just a dirty lens. The good news is that I have a working drive to compare against, so tracing the problem shouldn't be that hard. Maybe this weekend... ] Date: Mon, 10 Nov 1997 10:28:14 +0000 (GMT) ] From: Tony Duell <ard(a)odin.phy.bris.ac.uk> ] Subject: Re: Qume? ] ] On Mon, 10 Nov 1997, Bill Yakowenko wrote: blah, blah, blah... ] Lots of useful bits deleted... ] ] ... It shouldn't be too hard to trace the signal from the ] phototransistor to the Trk00 pin through the logic chips, though. You'd think so. The last time I tried fixing these drives (a couple years ago) I was trying to work backwards from the select LED. Had big problems tracing the circuit because the traces go under chips, and often turn corners under there, so you can't see which ones go where. And I was paranoid about using a continuity-checker for fear of putting voltage someplace where it could do damage. (Was that being excessive?) On the other hand, it should be trivial to measure voltage of the Trk00 signal at the connector, and see if it was getting that far. Divide and conquer - the first secret of debugging. ] ] -tony ] Date: Mon, 10 Nov 1997 09:05:15 -0800 (PST) ] From: Tim Shoppa <shoppa(a)alph02.triumf.ca> ] Subject: Re: Qume? ] ] > ...got service manuals?... ] ] I wish I did. What model do you have? I'm looking for manuals ] for the Qume Datatrack 8 (DSDD, full-height.) They are DT/8's, full height, I think DSDD (a megabyte per floppy). ] But lacking a manual, you still can trace the circuitry by hand; ] it's all SSI TTL, discrete components, and a couple of simple ] analog chips. Yup. Sounds easy. If I wasn't so @#!% paranoid with the meter. ] ] Tim. (shoppa(a)triumf.ca) ] Date: Mon, 10 Nov 1997 17:33:51 +0000 (GMT) ] From: Tony Duell <ard(a)odin.phy.bris.ac.uk> ] Subject: Re: Qume? ] ... ] Still blowing dust out of the sensor can't do any harm, and it's something ] that I'd do first anyway, as it can't help the problem. ] Will try it again, disassembling the thing if necessary to get access. ] ] -tony Thanks guys! Bill.