HB-G900D no video output

By sdsnatcher73

Paladin (929)

sdsnatcher73's picture

03-06-2020, 13:05

Hi Guys,

I have purchased a Sony HB-G900D and it was sold defective but turns out the machine itself seems to work but I get no video output from the start connector. If I put e.g. Nemesis 3 in slot 1 or 2 I can here the game is running (the demo sounds start playing) but just no display. Also floppy disk is working and all keys on the keyboard give a keyclick (some need some convincing so the keyboard probably needs cleaning). I assume the VDP is working (otherwise the game would not run I think), so my guess is the genlocker part is defective as I suppose these machines are should work fine without the Videotizer module (it is marked optional in the Wiki), but I am not sure. I've tried all 4 combinations of the rear switches (PVM/PERI-TV and INTERLACED/NON-INTERLACED).

Any info on what could be going on is appreciated.

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By sdsnatcher73

Paladin (929)

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03-06-2020, 13:26

It’s alive:

My guess now is that the PVM/PERI-TV (which I believe stands for Peritel TV aka SCART TV) is broken... as the output stays fine on the PVM either way (and did not work on my old Sharp LCD TV which works with every MSX so far)

By sdsnatcher73

Paladin (929)

sdsnatcher73's picture

03-06-2020, 14:17

Oddly this HB-G900D came with a P (QWERTY) keyboard. But the ROM is QWERTZ. I will make dumps (as they do not seem to be available)...

By MSX4ever

Master (198)

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03-06-2020, 17:42

Did you tried the MSX command "set video 0,,0" ?

HB-G900D (P) has a command : _VSW (1), but i'm not sure if
this command special for the sony set is (HB-G900 and HBI-G900)

By sdsnatcher73

Paladin (929)

sdsnatcher73's picture

03-06-2020, 19:38

Unfortunately that did not help. It may have to do with the crystal in the machine somehow. The PAL output registers as

on my OSSC which it then can't output to my DVI screen. If I type VDP(10)=0 (blindly on a wrong layout keyboard) the OSSC starts to output video but it is

. Both seen on the low side but it seems for 60Hz still acceptable (and of course the PVM is much more tollerable). Also the machine seems to run at 3.75MHz which again is on the high side....

By lintweaker

Master (244)

lintweaker's picture

04-06-2020, 08:29

MSX4ever wrote:

Did you tried the MSX command "set video 0,,0" ?

HB-G900D (P) has a command : _VSW (1), but i'm not sure if
this command special for the sony set is (HB-G900 and HBI-G900)

Interesting command '_VSW(1)' I'll give it a try :-)

By lintweaker

Master (244)

lintweaker's picture

04-06-2020, 08:29

Nice looking machine! Seems very clean, good find.

By sdsnatcher73

Paladin (929)

sdsnatcher73's picture

04-06-2020, 21:17

Yes it does look very nice, the keyboard has yellowed quite a bit but some sunshine (when the rain has passed) will turn it back in time...

Anyway, I opened the machine and managed to get the sync back to 50/60Hz, I get an image now on the OSSC but the positioning is off. I think it needs to be tuned using an oscilloscope, I know just the guy who can help Wink at the same time I’ll change the main ROM so I don’t have to remember where all the special characters are Wink