Author Topic: 60Hz PCW  (Read 679 times)

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Offline PulkoMandy

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60Hz PCW
« on: 08:10, 18 February 16 »
Hi there,

While experimenting with putting a PCW motherboard outside the PCW case, I managed once or twice to get it to boot in 60Hz mode. However, I am still not sure what triggered that and I can't find any hint to this in the hardware schematics nor the programming reference.

How does the PCW switch between 50 and 60Hz modes? Are the US versions (if such a thing exists) using 60Hz?

Offline Habi

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Re: 60Hz PCW
« Reply #1 on: 12:44, 18 February 16 »

Hello.


There is no official information about all of this, I’m sorry.


However, if you take a look to the schematics you’ll see that some of the GA pins that are used for communicate with the printer controller are used also to read configuration on boot (memory size). It’s safe there because it takes some time for it to boot and while it does its pins are high impedance, so the state can be forced with pull resistors.


In fact, NPCSEC and A0 are connected through a 10K resistor to LK1 and LK2, which in turn switches to +5V or GND (pullup or pulldown) for memory size selection.


My principal suspect here is NBOOT. Normally it has a pullup resistor, but there are some boards without it. I haven’t had time to test this until now but if you can, please be my guest and publish your results. :)


Cheers.