Disk eject problem using FDD-Drive Swapper

[X-Col]

Hi All,

calling any users of the FDD-Drive Swapper, I need your assistance in troubleshooting an issue I have relating to the software disk eject signal.

I installed the drive swapper according to the instructions and it works flawlessly with the FDX68. However, when I switch back to the real floppy drives I have a strange issue;

i.e. whenever the software sends an eject signal to drive 0, both drives are ejected.
For example;
-once the disk1 of Choujin is loaded it should go on to load disk 2 (for midi support). However, once disk 1 is finished loading, 'both' disks are ejected.
-when Akumajō Dracula finishes loading the first disk it should only eject drive 0 as disk 2 (in drive 1) is for saving your game. However, once disk 1 is finished loading 'both' disks are ejected.

This problem does not occur with the actual FDX68 emulator - both of the above games work as intended (only drive 0 is ejected).
The floppy drives work perfectly without the FDD-Drive Swapper attached, but then I can't use the FDX68.... :-(

I have posted this problem a while ago in the FDX68 problem thread, but decided to post a separate topic in the hope someone will spot it and assist, or someone will reach out to Michael for me.

Failing that, if anyone has any idea what might be happening to cause this issue?...

[X-Col]

My X68000 model is Ace HD

The FDD-Drive Swapper board is MC01-0010C TypeC Rev1.0

It has two 74LS257 quad multiplexers on it to control the switching of 'option select' & 'drive select' signals. I'm wondering if one of them is faulty? Could this cause the issue I describe?

Update: I have resolved this issue. Will update with the solution soon,  it may help someone else...

[leonk]

Can you post the fix here? 

[X-Col]

Can you post the fix here? 

No problem, I didn't think anyone was interested or I would have posted earlier.

You just need to cut two traces on the 'Option Select' adapter board and join them with 390R resistors.

How you do this is up to you. I actually added the resistors to the FDD Drive Swapper itself (see pictures)

Here is my 'Option Select' adapter with cut traces (a bit out focus, apologies; you are only cutting the 2 traces - top left): https://drive.google.com/file/d/1D3erPd8oWasee50pXZJqaRaTJ7MTRCpR/view?usp=sharing

Here is my FDD-Drive Swapper with resistors in place (note the picture is just to illustrate where the resistors are placed, use 390R resistors): https://drive.google.com/file/d/13pyMuqgcv7SQYyb5uxB2qAgCqteIBXAv/view?usp=sharing

The above picture shows 330R resistors, but the problem still remained intermittently. 390R resistors cured the problem completely.

You could actually use SMD resistors and place them on the 'Option Select' adapter itself ;-)

I am assuming the option select signal is too strong after going through the multiplexers, resulting in the issue I describe.

Note: Just to be clear, only do this on the 'Option Select' side, leave the adapter on the 'Drive Select' side intact.