VOGONS


First post, by keropi

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Hiya!

Some time ago I bought a Chinon FR-506 1.2MB fdd :

IMG02772-20130929-2105_zps2e0b723a.jpg

I can't get it to recognize disks, after I while DOS just throws the classic "general failure reading drive A:" ... now this drive has a number of jumpers on it and I am not certain it was used in a DOS/PC machine by the previous owner... tried searching but did not find anything useful, at least nothing I could use since my knowledge on 5.25" FDDs is very limited.

Can anyone here tell me what jumpers to set? Here are a couple of shots:

IMG02769-20130929-2105_zps2d19f8a9.jpg

IMG02771-20130929-2105_zpsc771ece6.jpg

If I have confirmation that the drive is set-up correctly then I would know whether to keep it or bin it... it's the only floppy drive on my test 486 machine btw.

Thanks in advance for any info/help! 😊

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Reply 1 of 9, by ratfink

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I think I had this problem once with a 5.25 drive. It turned out to be a small ribbon cable dislodged on the drive [not the main cable connecting to the motherboard, but another small cable].

I'm sure you tried different media, bios settings and floppy cable orientations 😉.

Reply 2 of 9, by keropi

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didn't check for any ribbons (good thinking there, thanks amigo!) but I did check different disks... the drive also takes it's sweet time to release booting to C: , that's why I suspect a jumper error... and when you try to access a floppy disk you can hear it doing many retries, not the usual 2-3 before the DOS error comes up.
In BIOS I just configured it as "5.25" 1.2MB" and there is no way to insert the cable wrong. I tested with 360kb disks btw.

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Reply 3 of 9, by Old Thrashbarg

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OK... change the jumper from DS0 to DS1, see if it works just from that.

TM is probably termination. It should be installed if the drive is on the end of the cable, removed if it's in the middle of the cable. IU just controls the function of the front LED light, shouldn't need to mess with that one. MS1 and MS2 are for motor speed selection (i.e., 300/360RPM)... I doubt you'll need to change those, but then again I don't know what the actual settings correspond to on that drive, so if all else fails, you could try different combinations of those two. D-R should be the ready setting, it changes whether the drive uses a ready signal on pin 34... open probably means it's disabled, and PCs don't use it, so you shouldn't need to change that one. FG I don't know, but it looks to be unpopulated anyway.

Reply 4 of 9, by keropi

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tried several settings , still could not make the drive read... well it could be dead...
thanks for all your help!

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Reply 6 of 9, by keropi

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some light cleaning, yes... won't bother with them anymore though 😉

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Reply 7 of 9, by jwt27

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Since this is the top result on Google for this drive, I'll add the correct jumper settings here:
TM: closed for drive A, open for drive B
DS0: open
DS1: closed
DS2: open
DS3: open
IU: open
MS1: closed
D-R: closed
MS2: open

TM are the termination resistors, which must be enabled only for the last drive on the cable, normally drive A. DS1 is the standard Drive Select number for IBM PC/compatibles. D-R selects the function of pin 34, Disk Changed if open, Drive Ready if closed. IU enables the In Use signal, which is, ironically, never actually used.
Enabling both MS1 and MS2 selects automatic motor speed switching. MS2 enables it, and MS1 inverts the signal from pin 2 (or else it spins at 360rpm for DD and 300rpm for HD discs). Don't know if this has any use anymore, maybe some ancient controllers still work with it...

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Reply 8 of 9, by keropi

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^ thanks for that!
Will test the drive again at some point 😉

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Reply 9 of 9, by maxtherabbit

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Pretty sure D-R *closed* enables disk changed and open is ready. Mt drive came with D-R closed and the disk changed signal is working in DOS as intended.