HB-F1XV black screen

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By fallen1

Resident (43)

fallen1's picture

07-11-2019, 09:58

gdx wrote:

The daughter board is defective so you may need to remove the Kanji driver from the 831000 ROM, that may be the problem.

Thanks GDX, that makes sense - will first try to get the board running again (worst case it won't work) as my EEPROMs + programmer are still somewhere en route from China.
Isn't there a possibility to somehow put the missing kanji rom on the SD-card of the MegaFlashRom? I'm new to MSX so pardon my ignorance Smile

By gdx

Prophet (3085)

gdx's picture

07-11-2019, 10:03

Chip at left seems to be the FDC controller.

By Pentarou

Master (226)

Pentarou's picture

07-11-2019, 14:06

Maybe you can try to pull the ROM's highest address pin from the socket ant tie it to GND, this would leave BIOS+BASIC+ EXT+ DISK visible but would hide F1XVKDR.ROM (Kanji driver/basic would not load).
But I don't know if it will work, as the boot logo is in that ROM section. Maybe it's better to try it in an emu first.

fallen1 wrote:

There are 38 pins - 20 address (1MB), 8 data, VCC,VSS,/CE,/RD,/RESET - still more signals missing

Pinout is here.

By fallen1

Resident (43)

fallen1's picture

07-11-2019, 15:33

gdx wrote:

Chip at left seems to be the FDC controller.

Yes sorry, the leftmost IC is the FDC controller

By fallen1

Resident (43)

fallen1's picture

07-11-2019, 15:57

Pentarou wrote:

Maybe you can try to pull the ROM's highest address pin from the socket ant tie it to GND, this would leave BIOS+BASIC+ EXT+ DISK visible but would hide F1XVKDR.ROM (Kanji driver/basic would not load).
But I don't know if it will work, as the boot logo is in that ROM section. Maybe it's better to try it in an emu first.

fallen1 wrote:

There are 38 pins - 20 address (1MB), 8 data, VCC,VSS,/CE,/RD,/RESET - still more signals missing

Pinout is here.

I like the idea of blocking the - unfortunately, I de-socketed the ROM because of the 512k RAM upgrade (which works, yay) where the extra RAM is piggybacked on top of the ROM and it would not fit under the keyboard (socket + 2 chips stacked).
It could be done by bending the ROM A16 pin underneath the chip and connecting it to ground + prolong the RAM's pin to the address trace. If there is a way how to test it before, it would be great as I already stressed the pads enough. I have no clue how to test it via emulator, but if the secondary ROM recovery fails, I'll have to look into it (it would hide the MUS too unless some logic would be implemented with the two topmost address pins I guess)

Thanks guys

By Pentarou

Master (226)

Pentarou's picture

07-11-2019, 17:07

To test in emu: Make a new config with everything the same but change this:
3 1 2 4 42 "Machines/MSX2+ - Sony HB-F1XV/f1xvkdr.rom" ""
replace the f1xvkdr.rom with f1xcbios.rom (will be seen in that address space with ROM A16 pulled low).
And remove this:
0 3 0 6 40 "Machines/MSX2+ - Sony HB-F1XV/f1xvfirm.rom" ""

Please note that I don't use BlueMSX so I'm not 100% sure this is correct.

If you have enough space between the board and the bottom case, you could solder the SRAM chip on the underside of the PCB (reverse mount).
That would leave you enough space to still fit a socket for the ROM.

By fallen1

Resident (43)

fallen1's picture

07-11-2019, 20:18

Pentarou wrote:

To test in emu: Make a new config with everything the same but change this:
3 1 2 4 42 "Machines/MSX2+ - Sony HB-F1XV/f1xvkdr.rom" ""
replace the f1xvkdr.rom with f1xcbios.rom (will be seen in that address space with ROM A16 pulled low).
And remove this:
0 3 0 6 40 "Machines/MSX2+ - Sony HB-F1XV/f1xvfirm.rom" ""

Please note that I don't use BlueMSX so I'm not 100% sure this is correct.

Tried in BlueMSX and got black screen (CPU running and doing some instructions)
Tried also in openMSX - also black screen: replaced the Kanji driver in slot 3-1 with copy of bios - starting at 0x4000, size 0x8000 + removed contents of slot 0-3 + removed the "Kanji ROM" section.

When I remove the basic copy in 3-1, it starts. That means I need to make a copy of the ROM without the Kanji driver, but Thank you for the tips!

Pentarou wrote:

If you have enough space between the board and the bottom case, you could solder the SRAM chip on the underside of the PCB (reverse mount).
That would leave you enough space to still fit a socket for the ROM.

I saw VRAM upgrades done like that, but it would mean to bend the SRAM pins to the opposite direction, which will kill those pins I think (got spare mem so I can try).

Will check the secondary ROM now (as I don't have the EPROM/Programmer)

By fallen1

Resident (43)

fallen1's picture

07-11-2019, 23:23

fallen1 wrote:

Will check the secondary ROM now

When I connected the VCC+GND and set both /RESETs to high, there was 5V on D0 and 0.0V on the rest of data lines, so definitely a problem there...

The 8 bulges in the corner above pin 1 are 8x 4.7k resistors and unfortunately, all work fine. There are 8 more small parts
spread around the board, so will try to uncover those too - but I expect them to be caps for the larger ICs so not really relevant. Also uncovering the track of the D0 pin could reveal something - maybe point me to the latch IC ...

By fallen1

Resident (43)

fallen1's picture

09-11-2019, 00:58

So after some archeology, I uncovered this:


It seems to have following pin layout (D = data lines, so OUT, R = resistors, so IN):

The "?" is I assume OE and the part 8 latches.

Does someone recognise that pin layout? Is this a standard package?

The dimensions from pads to pads are 4.5mm x 3.5mm.

Thanks

By Manuel

Ascended (15821)

Manuel's picture

09-11-2019, 09:52

What are we looking at here?

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