Sharp MZ-2000 Upgrades
Amongst the machines I am currently renovating is a Sharp MZ-2000, the successor to the venerable Sharp MZ-80B. This machine not only provides the ability to run MZ-80B software but adds 48K VRAM for full colour output and all encapsulated in a very aesthetic design based on the Sharp MZ-80A casing.
Like most machines from Japan which werent intended for export, the power supply runs at 100V (it will operate at 110-120 so countries such as the USA have no issue). As this machine uses a transformer rather than the more recent switch mode supplies, it is easier to adapt to run off 220-240V.
Powering up with 220V-240V will see the transformer output after full wave bridge rectification rise by approx 2-2.4xx. This higher output will feed into a 100V capacitor which has plenty of headroom but after the fuses it becomes a little more critical. The components are rated max 35V for the capacitors and 40V for the regulator IC's so they will be at their limit. They may work 'as is' but the stress will eventually kill them. My solution is to put a mini high efficiency switching rectifier between the fuses F41/F21 which will lower the voltage, this should then allow a full range input of 110V-240V for the machine and it is easily removed if needed. The caveat to this is -5V line which uses a seperate unfused winding with half wave rectification and a smoothing capacitor rated at 16V. I will check the output from the half wave rectifier and if close to 16V, change this capacitor to a higher voltage rating.
I'm looking forward to upgrading this lovely machine with both of the tranZPUter SW designs to add additional functionality including 512K RAM, SD Card services and a faster CPU.
The MZ-2000 already has colour video output with 48K Graphics VRAM / Character VRAM when it has the optional VRAM card installed, so on this unit it makes sense to only install the tranZPUter SW v2.2 card, but for machines without the VRAM card, the tranZPUter SW-700 v1.3 is the ideal choice. I will work on both cards to cater for both possibilities.
One of the advantages in working with a real machine is knowledge gained. It is alright working from books and schematics but interacting with real hardware, at least from my point of view, offers a great deal more insight and you have a benchmark to compare an emulation against.
I have held off from finishing the MZ-2000 emulation in the Sharp MZ Series for a few reasons but now I have no excuse. Adapting the tranZPUter SW-700 v1.3 board I can upgrade the Video Module to match the VRAM card and have both to hand for comparison. Any changes I make to the CPLD/FPGA to make it operate in the MZ-2000 will no doubt feed back into the emulation.
The Sharp MZ-2000 prior to renovation, this is my new machine, it doesnt need so much work as it is a very clean example, just the electronics, monitor and tape deck need servicing and calibrating.
Work In Progress! Watch this space!
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