AX-370 Black Screen with RTC ROM

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By alali.ahmed.t

Expert (72)

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15-08-2022, 18:11

Recently, I had black screen upon turning on my Sakhar AX-370. I troubleshooted it and I can verify the following:

- Turns on and run all the way normally using CBIOS ROM without any problem
- Turns on and run all the way normally using MSX1 ROM without any problem.
- Turns on and runs all the way normally using MSX2 ROM without RTC.
- Black screen on he original MSX2 ROM chip that it came with the machine (Arabic MSX2 with RTC)
- Black screen on any MSX2 or MSX2+ ROM that uses RTC.
- I never install the batteries if that makes any difference.

How do I troubleshoot the RTC while the machine is ON since it is part of the T9769 chip?

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By Mork

Rookie (26)

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15-08-2022, 21:13

How do you switch between the different roms and what is RTC?

By alali.ahmed.t

Expert (72)

alali.ahmed.t's picture

16-08-2022, 00:24

Mork wrote:

How do you switch between the different roms and what is RTC?

I de-soldered the NEC 2MB rom IC that was on the machine and installed an IC socket to allow me move the IC easily. Since this MSX has 9958 Video chip, it is easy to convert it to MSX2+ by programming 2MB IC (I used Winbond W27C020) and then installing it, you don't need any further modification but you need to know where to put the data on that W27C020 in order for the machine to work properly. I put the information on one of the threads, I can look for it.

By alali.ahmed.t

Expert (72)

alali.ahmed.t's picture

16-08-2022, 00:28

Oh RTC is Real Time Clock.

Here is the link to the thread that has the information I put to convert the machine to MSX2+

AX-370 Modification

By Mork

Rookie (26)

Mork's picture

16-08-2022, 09:18

Great!
Maybe I could get running the Yamaha YRM-504 in that way too.
Also it would be fine to have the Basic-Hardware-Scroll commands to do Softscrolling. I am at the begin of programming the 9958...
Where did you get the needed ROM-Files for converting the machine to MSX2+ ?

By alali.ahmed.t

Expert (72)

alali.ahmed.t's picture

19-08-2022, 17:22

Some of the roms can be found in BlueMsx "Share roms" folder. Look for it. But, if you want specific roms from specific machine, then there is a website that I can give it to you in PM later when I get home. I don't know how to do PM on this forum any more by the way but I will try to find a way

By alali.ahmed.t

Expert (72)

alali.ahmed.t's picture

20-08-2022, 02:34

Ok, I found the problem pin 20 (OSCIN) of the chip T9769 was not making contact. I used the soldering gun to put it back and now the machine is working very well.

By Mork

Rookie (26)

Mork's picture

22-08-2022, 13:19

Hi - I already bought new desoldering wire and my soldering iron is hot!
But I also don´t know how to send PMs on this forum...

By alali.ahmed.t

Expert (72)

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22-08-2022, 17:42

Give me your email and I will send you the information you need

By Mork

Rookie (26)

Mork's picture

23-08-2022, 16:11

Hi, it's: [mod: hidden by request of OP]

By mars2000you

Enlighted (6317)

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22-08-2022, 23:41

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