Zaxxon's floppy drive interface

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acsi
Posts:22
Joined:Sat Jan 12, 2013 12:40 pm
Zaxxon's floppy drive interface

Post by acsi » Thu Aug 29, 2019 4:56 am

Hi,

Does anyone know if there are any other adjustments that can be made on this device apart from the 2 blue pots by the edge connector?

Mine's struggling with my HxC drive.

bluearcus
Posts:69
Joined:Wed Sep 07, 2016 4:45 pm

Re: Zaxxon's floppy drive interface

Post by bluearcus » Fri Dec 13, 2019 11:30 pm

Adjustment procedure is as follows I believe. There are two variable resistors and a variable cap to tweak.

Pull the WD2797 pin 22 to GND to force it in to test mode.
You now need to adjust three timing / frequency values.

Firstly the main data separator clock

This is done by looking at the VCO clock which in test mode appears on WD2797 DIRC pin16
Adjust it to freq 250kHz using the variable capacitor which is connected to pin 24 CLK

Then the read pulse width must be set

In test mode RPW can be measured on pin WD2797 TG43 pin29
Adjust it to a pulse width of 450nS using Variable resistor R9 which is connected to pin 18 RPW

Finally the write precompensation timing should be adjusted

WPW pulse width can be measured in WD2797 test mode on the WD pin 31
Adjust it to a pulse width of 250nS using Variable resistor R10 which is connected to pin 33 WPW

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