Problems adapting from 26 to the 34 pins of a 7-segments digit gotek (amstrad pc 5086, 5286, 5386)

[Maidnet]

Hi there! Greetings from Spain!

I have an AMSTRAD PC 5286. All the AMSTRAD 5000's PC series has a 1'44 MB CiTIZEN Floppy disk, model UIDA-38A (The exact model can change, but in my case is that). That floppy disk drive has a 26 pins connexion, and this is broken. To find another floppy drive with 26 pins that works, is very hard and expensive. I purchased an 26 PINS TO 34 PINS adapter from ALIEXPRESS to try to solve this problem (the same for all the AMSTRAD 5000 Series).

Link here:
https://es.aliexpress.com/item/10050036 ... pt=glo2esp


I have also a 7 segments digit GOTEK, model SFRKC30.AT3 (from amigastore.eu). I have purchased that in a second hand web, with the standard pins connections for AMIGA and PC (JC connected, S1 connected)

Initially, the GOTEK works fine. But cannot detect the disk change, with which is impossible to install directly any program with more of one disk. I can force the disk change in MS-DOS (Norton Commander, by example), but when the installation program is an .EXE or something, I don't have any physical mode to force the disk change, and the program installation fails.

The same thing happens with a traditional 3'5'' floppy drive that I've tried. I've been looking at the wiring diagrams on the internet, I've tried to connect some pins at the adaptor, but I haven't been able to do anything. I don't really know what I'm doing and if I'm doing it right either he-he

Can someone please help me to configure the adapter (or the GOTEK instead) so that the disk change detection works with the 26 to 34 pins adaption in the AMSTRAD 5286? I don't know if this happens in others PC systems...

Thank you very much!!

[Maidnet]

Ok, after a whole weekend reading forums and documentation, I managed to solve the problem. Apparently the cable configuration is different for some computers, like the Compaq SLT/286, and there are floppy drives with different pinout. This Compaq model and the AMSTRAD 5000 series share a 26-pin CITIZEN floppy drive. Although the model of the floppy drive is different (there are several similar models with very similar characteristics) I thought that they would probably share the same pinout. I found this in a forum about the pinout of the Citizen OSDA 53B floppy drive:

Code: Select all

01=GND					02=/STEP
03=GND					04=/WDATA
05=GND					06=/WGATE
07=GND					08=/TRK0
09=GND(no pin)				10=/WPROT
11=GND					12=/RDATA
13=GND					14=/HDSEL
15=GND					16=/DSKCHG
17=/RPM_LC-H/L				18=VCC (5Vdc)
19=/DENSITY_SELECT			20=/INDEX
21=VCC (5Vdc)				22=/DIR
23=???					24=/DRV1 ??? 
25=???					26=/MED1 ???

I don't understand much, but apparently this is not very common among the already uncommon 26-pin floppy drives. It seems that the converters use the standard pinout, and with this type of drives, the disk change signal is lost.

By connecting pin 16 of the 26-pin cable to pin 34 of the 34-pin cable, the signal arrives correctly and is detected, so the disk change is updated on the PC. The gotek now works perfectly.

I don't know if this will help anyone, but I leave it here for the future or in case you want to update the list of supported equipment.