Disk drive and Virtual 2315 Cartridge Facility accomplishments

NEW 48V BULB IN THE UNLOCK LIGHT WORKS PROPERLY

My bulbs came in and I inserted one in the IBM 1130. When powered up, the Unlock light will be lit indicating that the receiver can be opened to slide cartridges in and out of the drive. As soon as the Run switch is activated and the drive begins spinning, the Unlock light will extinguish and stay off until after the drive comes to a halt. 

VOLTAGE CHECKS BEFORE CONNECTING THE RK-05 EMULATOR TO 1130/2310 SIGNALS

I put a meter on all the signal lines that will be connected to the RK-05 emulator circuits to verify that they don't produce voltages that will cause problems for the interface circuitry in the emulator. I found three pins that recorded voltages around 6V, the rest are all 3V or less. 

Pin B13 from the disk drive is the Write Data and Clock signal, an input to the drive which is output by the emulator. The emulator uses an open collector driver gate which is insensitive to the fact that the pin has a pullup to 6V. 

Pin B03 from the 1130 controller logic is the Read Data input to the 1130, which is output by the emulator using a open collector driver gate. Again, it is a pullup voltage that won't affect the RK-05 circuits. 

Pin D10 from the 1130 controller logic is Write Gate output from the 1130, which is an input to the RK-05. I observed a voltage of just over 6V on the pin, which worries me because the SN74LVC244A chip has a specified range of 0 to 5.5V for its inputs and an absolute max, must avoid voltage of 6.5V. 

I am going to mull over whether I need to do anything for this signal or just hope that it doesn't overstress the level converter chip in the emulator. 

REPAIRED B12 PIN IN CONNECTOR TO 2310 DRIVE

After close examination with a microscope I could see the cause of the poor connectivity for the opening for B12. The connector uses individual sockets that have tabs which are bent inward to press against the pin when the connector is pushed onto the backplane. I can see this in all the other sockets but the one for B12 has its tabs pushed outward so that they don't contact the pin. 

Its hard to see to the sockets marked 2, 6 and 8 have tabs bent inward in the rectangular opening but socket 4 has flat sides. B12 is connected to socket 4.

I desoldered and carefully removed the socket from the connector shell, where I was able to gently reform the tabs on the socket to provide a reliable firm connection. 

Socket shell partly removed for B12

Socket shell with tabs not yet reformed inward

I then reinstalled the socket and soldered it up. Testing with the connector provided that the connection for B12 is now working properly. 

LOCATION BEING CONSIDERED TO MOUNT RK-05 EMULATOR BOX AND POWER SUPPLY

I will create a mounting so that this is accessible when the right side door of the 1130 is swung open. The interface card will sit behind it and a bit above. The power supply will be behind it against the housing for the peripheral cable connectors.