HB-F1XV black screen

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By Manuel

Ascended (15829)

Manuel's picture

27-10-2019, 23:27

Thanks for this dump info, fallen1! I adjusted the openMSX Sony HB-F1XV configuration to use the proper sections out of this EPROM dump directly.

Note that it appears the ROM layout is the same as for the Sony HB-F1XDJ. (The BIOS too, didn't check the other ROM parts.)

By fallen1

Resident (43)

fallen1's picture

28-10-2019, 14:45

I'm glad it was of some use. Yes, I saw a discussion that those two models have the same guts, just a different case.

By fallen1

Resident (43)

fallen1's picture

28-10-2019, 15:02

I made some progress: Got the spare octal latch 74LS373 for the data bus and ... it got destroyed immediately because I'm a dumbass and didn't measure the voltages in the socket - on my defense, I had all ICs that are in socket out so I "expected" there to be 0V - yet there were spikes up to 5.9V

That was the last drop, I desoldered all resistor arrays (all were pullups), disconected VCC+D0 for the large ROM + VDP, removed CPU, ram, rom, fdc, the data bus buffer and octal latch to get a nice 0V on D0... or to pinpoint the problem to the SMDs on the bottom (S1985 + Sony mb670836 ICs).
Still there were 2V on D0 ... so I had to desolder one of the D0 lines. Tried mb670836's D0 and you guessed it, there were still 2V on D0 Evil
Just to confirm that there is nothing wrong with my measurements, lifted also S1985's D0 leg and now it sits at 0V... (I always connected 4 data lines to see differences - D0-D3)

So unless someone has a working S1985, I'm pretty much done here Running Naked in a Field of Flowers

By fallen1

Resident (43)

fallen1's picture

06-11-2019, 22:00

Yes, I tried repair-bas some time ago but he refused as there were too many people fiddling around with that device.
Tried asking locally too, but there is no MSX group where I live also no one was willing to look at it...

So I continued looking for the issue - what was not pulling the D0 down but the rest yes. After countless hours, I got it running today - got the dense sockets by mail and tried to socket VDP first, then desoldered the 2nd ROM board and I never thought I will be so happy to see my ugly wavy blue screen. It was distorted and wavy - yet the MSX logo and RAM (from the megaflashrom) were visible so there was hope now :)

The distorted screen was caused by the VRAMS (already in sockets, almost everything is in sockets now :) - just switched them around until it started working (yes, stupid but worked).

Some time ago (when the machine was working), I ordered the CXA1145M as there was lot of leakage around it and I thought it can be the cause of not-working composite-out & could somehow affect the RGB that is passing thru. The pads were corroded so after cleanup, soldered the new chip, booted - and wawes were gone :RNFF:

Got the SRAM for 512kb mod today too, so did the mod to 256kb first and it gets detected fine (also along with the megaflashrom) so when I get the transistor&diode, I'll do the rest.

But of course, if a ROM chip is out, something will not work - and it doesn't. The basic does not load for some reason - just blue screen. When using the megaflashrom, I get message below. When I use a game, the screen stays white.

It's actually this - https://www.msx.org/wiki/Sony_HBI-J1 - which I was hoping would not be needed :(
Is there a solution to this? Can I copy something to the megaflashrom so it boots?

(double-checked - when I put the T5277 (ROM daughter board) back in, it won't boot)

Thanks

By gdx

Prophet (3087)

gdx's picture

07-11-2019, 02:10

Quote:

I got it running today - got the dense sockets by mail and tried to socket VDP first, then desoldered the 2nd ROM board and I never thought I will be so happy to see my ugly wavy blue screen.

Is the 2nd ROM the 381000-20 or the ROM on the left? I see both on the picture.

I was thinking on the left it is the ROM of the MSX-Music (16KB), and the 381000-20 contains probably: The Bios, Basic, Sub-ROM and Disk-ROM (64KB). The small board that is removed on the right surely contains: the MSX-JE, Kanji driver and Kanji-ROM. But the 381000-20 is a 128kB ROM. So it must contain also the Kanji driver and an unused area.

By Pentarou

Master (226)

Pentarou's picture

07-11-2019, 07:07

So the D0 problem was just a red herring and the culprit was the Kanji module?

By fallen1

Resident (43)

fallen1's picture

07-11-2019, 09:00

gdx wrote:

Is the 2nd ROM the 381000-20 or the ROM on the left? I see both on the picture.

It's the daughter board dipped in epoxide resin - the big black T5277. (on the left is the CPU with signals sticker I put there for faster reference)

gdx wrote:

I was thinking on the left it is the ROM of the MSX-Music (16KB), and the 381000-20 contains probably: The Bios, Basic, Sub-ROM and Disk-ROM (64KB). The small board that is removed on the right surely contains: the MSX-JE, Kanji driver and Kanji-ROM. But the 381000-20 is a 128kB ROM. So it must contain also the Kanji driver and an unused area.

I dumped the 831000 ROM - the mapping is on previous page of this thread. There should be all necessary inside to get me a basic prompt, but it won't. BlueMSX has a firmware file called f1xvfirm.rom which is 1M - the same size as the daughter board - so maybe that is what is missing?

By fallen1

Resident (43)

fallen1's picture

07-11-2019, 09:13

Pentarou wrote:

So the D0 problem was just a red herring and the culprit was the Kanji module?

Nono, the Kanji module was shot on D0 and pulling it high all the time (+ RAM on D0).
Will try to hook it up on breadboard today and see if I can confirm it. Also will try to get rid of the resin, as there are too suspicious looking 8 small bulges underneath - and one of those may be the cause (I would expect the problem to be in an AND array of some sorts that enables bus on /CE, but those are 1 IC ...). Not sure how this will go...

Pentarou wrote:

Unfortunately blueMSX uses splitted ROM files.
Maybe a dump of the original ROM, even if it has stuck bits, can be useful to recognize the ROM layout?

You absolutely need these:
Main ROM/f1xvbios.rom = 32Kb
Kanji driver/f1xvkdr.rom??? = 32kb
Sub ROM/f1vext.rom = 16Kb

The rest are optional, i.e. The machine will still boot and give you the basic prompt without them:
Disk ROM/f1xvdisk.rom = 16kb
MSX Music/f1xvmus.rom = 16kb

Got them all now but it doesn't load the basic unfortunately. There are 38 pins - 20 address (1MB), 8 data, VCC,VSS,/CE,/RD,/RESET - still more signals missing, so perhaps it does more than just memory?

Thanks

By gdx

Prophet (3087)

gdx's picture

07-11-2019, 09:39

fallen1 wrote:

I dumped the 831000 ROM - the mapping is on previous page of this thread. There should be all necessary inside to get me a basic prompt, but it won't. BlueMSX has a firmware file called f1xvfirm.rom which is 1M - the same size as the daughter board - so maybe that is what is missing?

Ok, I skipped page 2. The daughter board is defective so you may need to remove the Kanji driver from the 831000 ROM, that may be the problem.

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