ST314 drive replacement.

[stephen_usher]

Well, today's job is replacing the Chinon long button drive in my SF314 with a TDK (STFM) one as I damaged the Side 1 head many years ago.

I've transferred the drive access LED optic from the Chinon and the drive itself now fits, so my next job is to replace the cables on the adapter board and make them Shugart compatible. Wish me luck!

IMG_1615.jpg (47.39 KiB) Viewed 1313 times

IMG_1616.jpg (49.89 KiB) Viewed 1313 times

[exxos]

[stephen_usher]

Bother! The pin assignments I got off the 'Net were obviously wrong. When powered pin 11 is +5V, which is most certainly not "Ground".

I got this from AtariAge (poobah).

I'm going to have to do another search.

[tzok]

Just use the Atari 14-pin drive pinout and map these pins accordingly. You may also check if pin 3 is ground, then it is likely to be 1:1 to Atari FDD DIN connector pinout.


1 - Read Data
2 - Side Select
3 - GND
4 - Index
5 - Drive Select 0
6 - Drive Select 1
7 - GND
8 - Motor On
9 - Step Direction
10 - Step
11 - Write Data
12 - Write Gate
13 - Track 00
14 - Write Protect

[stephen_usher]

Just use the Atari 14-pin drive pinout and map these pins accordingly. You may also check if pin 3 is ground, then it is likely to be 1:1 to Atari FDD DIN connector pinout.

Unfortunately it's not a pin-for-pin mapping, it's an early Chinon non-standard connector apparently.

Anyway, seeing at there was a 2K ohm resistance between the +5V rail and pin 10 I risked plugging it all together. No smoke.

The drive is detected by TOS but the drive light comes on when the internal drive in the ST is accessed and the motor never runs.

The drive selection is supposed to be being done by the interface board I thought. Anyway, half there.

[tzok]

I meant - use the DIN connector pinout to map the wires in Chinnon connector to the appropriate signals, and then rewire them for a Shugart connector. Remember about the differences between PC Floppy and the Shugart standard (namely Motor ON and Drive Select lines).

1 - n.c.
2 - n.c.
3 - GND
4 - Head Load (n.c.)
5 - GND
6 - Drive Select 3 (n.c.)
7 - GND
8 - Index
9 - GND
10 - Drive Select 0
11 - GND
12 - Drive Select 1 (n.c.)
13 - GND
14 - Drive Select 2 (n.c.)
15 - GND
16 - Motor On
17 - GND
18 - Step Direction
19 - GND
20 - Step
21 - GND
22 - Write Data
23 - GND
24 - Write Gate
25 - GND
26 - Track 00
27 - GND
28 - Write Protect
29 - GND
30 - Read Data
31 - GND
32 - Side Select
33 - GND
34 - Ready (n.c.)

[stephen_usher]

As you can see in the image at the start of the thread, I have the supposed Chinon/Shugart mapping and that's what I used.

[tzok]

...but it is apparently wrong (or at least incomplete)

Instead of trying to fine a working pinout, just use DIN pinout and a multimeter to create a signal map for this 14 pin Chinon connector.

[stephen_usher]

I've done that but several of the lines are crontrolled by an IC. Those which are not check out correctly.

I'm wondering if I've mis-counted the wires on the ribbon cable for line 10, motor-on.

This debugging isn't being helped by a headache at the moment.

P.S. Nope. All check out correctly.

P.P.S. The drive I'm installing is a long-button STFM drive (TDK) that would use standard Shugart, not PC, pin-out as far as I'm aware.

P.P.P.S. The "Motor On" line is directly passed through from the connector, so it should "just work".

[stephen_usher]

Oh, so that variation is that it should be pin 16 and not 10. That and drive select is 10 and not 14.

That's a bit of a pain.

The strange thing is that the drive *IS* being selected, which suggests pin 14 is correct.