SD512 with HB201P stucks | MSX Resource Center (Page 2/5)

Prophet (3646)

23-08-2018, 16:58

odaman68000 wrote:

In my opinion, jumper cut and connect cutted pin to GND with 10Kohm register.
It will disable firmware ROM completely.
10Kohm can be 1Kohm and so on, it’s just for safe, it prevent short circuit.

OMG! If you connect the /CS pin of that ROM to GND with a 10K resistor, it will cause bus contention and quickly fry everything on the machine.

Connect it to the +5V via a 4K7 resistor. That will disable the built-in software.

By Pentarou

Hero (516)

23-08-2018, 17:03

Whatever you do, could you post the solution that has worked and maybe a photo of the area? This will help if other people need to fix this common problem.

Quote:

I tried with J5 and receive a black screen.

What did you do with J5? You opened or closed it?

Quote:

In my opinion, jumper cut and connect cutted pin to GND with 10Kohm register.

All those inputs select pin that you see (CS,CE,OE) have a small circle so they are active low. When connected to GND (directly or via a resistor) they are active, you want the opposite.
Sometimes just cutting those lines is enough, because it leaves the devices in an undefined state that *may* work for your purpose, but the correct way to disable the input signal would be to connect it (via resistor) to VCC.

By Lao Mu

Supporter (13)

23-08-2018, 18:22

Quote:

I tried with J5 and receive a black screen.

What did you do with J5? You opened or closed it?

It was closed and I open it. That results in a blk, screen after powering on again.

Quote:

In my opinion, jumper cut and connect cutted pin to GND with 10Kohm register.

All those inputs select pin that you see (CS,CE,OE) have a small circle so they are active low. When connected to GND (directly or via a resistor) they are active, you want the opposite.
Sometimes just cutting those lines is enough, because it leaves the devices in an undefined state that *may* work for your purpose, but the correct way to disable the input signal would be to connect it (via resistor) to VCC.

I will give that a trial this WE .

By Lao Mu

Supporter (13)

23-08-2018, 18:47

Hi,
I checked the IC8 chip and found it to be a TMM23128P. This is the detail drawing:

https://msx.pics/image/UL6Cm

I am unsure if it is really enough to cut Pin 27...as there is a second CS on Pin 20.
I did not expect it to be so difficult ....

By Pentarou

Hero (516)

23-08-2018, 19:43

"Programmable chip select" !?!?

Quote:

I am unsure if it is really enough to cut Pin 27...as there is a second CS on Pin 20.

One should be enough. It worked for Odaman68000...

If that doesn't work, cut all the pins and remove the ROM

By Lao Mu

Supporter (13)

23-08-2018, 23:44

Hi again,

i got now the situation I wanted. I cut Pin 27 connect to 5V first and power on ...but the maschine boots up in this application menu. After that I cut Pin 20 also and connect it to 5V. Then it boots up straight into basic with 28815 bytes free.
I power off and plug in the SD512 and power on again....but it stucks again in this Microsoft Screen again.

Slowly I get the feeling that my SD512 is the problem... I tried it with a 4GB SD & a 2GB SD.

Time to sleep now... lets see how it works out tomorrow.

By odaman68000

Rookie (25)

24-08-2018, 09:34

Hi, I’m sorry so much, if I have enough time, I can examine more...

I succeeded running SD512 on HB-101, but recently, it started stuck again.
I suspect the reason why SD512 stucks is, SD512 cartridge connector’s contact failure.
It’s not gold-plated, very poor contact.
It oftenly stucks while booting with random strings on boot screen sometimes goes good, many times goes wrong...

I can’t know your SD512 situation, but there’s such possibility.
You suceeded disabling application firmware on boot, so SD512 should run.

I want to fix my SD512, but contact failure can not be fixed...

By odaman68000

Rookie (25)

24-08-2018, 09:48

Hi again, I forgot to write one thing.

Do you have any minitor program which can dump hex binary on memory?
Many monitor have a feature which changing the slot.

If you can, change the slot to SD512 plugged slot, and check the 4000h.
If SD512 connected well, you will see 41h, 42h pair on 4000-4001h.

MSX-AIDS, Molitor, or other monitor program will help you.

By Pentarou

Hero (516)

24-08-2018, 11:09

Lao Mu wrote:

I power off and plug in the SD512 and power on again....but it stucks again in this Microsoft Screen again.

If you boot without an SD card do you get Nextor basic? If you don't then your card could be defective.

odaman68000 wrote:

I want to fix my SD512, but contact failure can not be fixed...

If you think that's the problem just clean the contacts.

By Lao Mu

Supporter (13)

24-08-2018, 12:21

Hi,

thx again....if I plug in the SD512 and power on the maschine it stucks in greeting screen "MSX Version 1.0 etc."

Thsi happens with SD card or without. Unfortunately I just start with MSX and do not have enorgh ressources to test.
I will buy a few ROM games on Ebay later to test the ROM slots and a tapedeck..

@Odamann: I will check all contacts...from the view they are like new. On both, the SD512 and the HB201P.