Phillips VG8235 - Color video + V9958 Problems... | MSX Resource Center (Página 2/3)

Supporter (11)

08-11-2009, 22:13

hi again, guys...
Testes typing command VDP(10)=0...Don´t stop flicker...Rom 2+ is with VDP Int 60hz, but shakeing screen...Does anybody knows talk to me if VDP X-tal Frequency are same V9938 in V9958? I´m very suspicious whom no...8235 Encoder unit, in use with 9938, not recognize a blue signal...What´s happening?
Thanks, friends...
Cheers

Por Jipe

Paragon (1604)

09-11-2009, 16:59

i have modify a 8235 with V9958 and the video signal is very bad with waves on border
i modify the /csynch signal with the HB700 schematic
but before what's the model of your 8235 because exist different version
/00 /02 /19 /20 /22 /29 /36 /39

i work in a 8235 /19 AZERTY french

Por thewalll28

Supporter (11)

09-11-2009, 17:21

my philips vg8235 are 20 model...keyboard are qwerty...Whre´s find a hack in hb700?
thanks again

Por Jipe

Paragon (1604)

09-11-2009, 18:44

/20 is same /39 in french
i check the schematic of this model before reply

Por thewalll28

Supporter (11)

09-11-2009, 18:50

Jipe...
GREAT!!!! Flickers disappear !!! Simply I plugs CSYNC directly from V9958/pin6 and I turn on the computer...GREAT IDEA!!! Very, but very thank you...Now, i need only modified A520 to NTSC frequency...Another caos...Laughing...Thank you
Cheers

Por Jipe

Paragon (1604)

09-11-2009, 20:17

connect directly is dangerous for the v9958 if problem
in my version i modify the /CSYNC before Q15 ( in french version ) of 8235 /19
in your model see on schematic you fin Q13 with a R72 resistor (french version only) but not on MSX in (int and din version)
added all electronic component on your MSX and remove Q12
but dont connect R72 on /CSYNC , cut /CSYNC wire and connect R72 on CSYNC pin 6 VDP

Por RetroTechie

Paragon (1563)

09-11-2009, 23:39

connect directly is dangerous for the v9958 if problem
You shouldn't connect sensitive / difficult to replace IC's like a V9958 directly to outside world - good chance you'll have a dead V9958 soon (static charges etc). Put transistor buffers in between, or feed V9958 signals into computer-internal circuitry. If you're experimenting, then at least use some series resistors to limit peak currents.

Por thewalll28

Supporter (11)

11-11-2009, 07:41

Thanks for all, my friends...
I looks 8235/020 schematic and follow instructions to modified CSYNc signal...I only tested plugs directly...Only seem...
Thank you,
Cheers

Por galine

Rookie (25)

20-09-2010, 11:52

Hello, yesterday I try to mod my VG 8235/39 in msx2+ and I have this reaction have you a idea what's wrong with my modification?

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thank you in advance

Por galine

Rookie (25)

20-09-2010, 13:58

All is ok now I make a bad connection now is good I must follow the mod for a stable sync and not yellowed color.