CX5MII/128 converision

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By retrocanada76

Champion (509)

retrocanada76's picture

01-05-2016, 07:41

Can't find the transistors here. Can i replace 2SA933S and 2SC1740
for 2N3906 and 2N3904 respectively?

By maxis

Champion (512)

maxis's picture

01-05-2016, 09:31

retrocanada76 wrote:

Can't find the transistors here. Can i replace 2SA933S and 2SC1740
for 2N3906 and 2N3904 respectively?

Yes, you can substitue 3906 and 3904, but the pinout doesn't match the original.
Otherwise the original transistors you can by @ ALIEXPRESS.COM

By alali.ahmed.t

Supporter (14)

alali.ahmed.t's picture

29-04-2022, 01:08

It is good to see this thread. I managed to upgrade my Japanese YIS-503II to MSX2 without RTC, with the help of Alexey. I am in the middle of converting it to MSX2+ .. I installed V9958 and modified the wiring successfully and it is working well on MSX2 without RTC. The problem I am having is the subrom with RTC doesn't want to boot, I checked all my components and I don't see any problem. The only thing I noticed is that the RTC chip is warm.

I have not done any wiring from RTC to subrom yet. Does the Japanese machine also need that?

By alali.ahmed.t

Supporter (14)

alali.ahmed.t's picture

13-05-2022, 18:57

Just wanted to updated, I changed the RTC chip as my checks indicated it was not functioning very well, voltage on it was less than 5V. Now the machine works very well, I moved and finished the conversion to MSX2+ successfully. Thanx to Alexey from RBSC for all his support.

I also found out that my MSX Yamaha board was similar to CX5 ones, so the A14 on the subrom to the Z80 was not enabled which will limit the subrom to only have 16kb, but all that was changed once I upgraded to MSX2+.

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