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+--- Тема: Faulty video-output: white flashing picture (/thread-2608.html)
Faulty video-output: white flashing picture - jacobsson - 15.05.2017 11:50
Hi.
I have a mainboard that functions properly except for the video output, I hear sound and the controller board works.
The video-output gives a flashing white screen, almost like an old dirty NES cartridge, any ideas where to begin troubleshooting?
I have soldering skills and tools.
RE: Faulty video-output: white flashing picture - aykiri1 - 15.05.2017 13:25
can be problem video dac chip
RE: Faulty video-output: white flashing picture - jacobsson - 15.05.2017 14:49
(15.05.2017 13:25)aykiri1 писал(а): can be problem video dac chip
You're probably right. Is there any good troubleshooting guide for measure test point voltages with a multimeter or so? Unfortunately I don't own an oscilloscope.
RE: Faulty video-output: white flashing picture - aykiri1 - 16.05.2017 10:41
is your chip sega marked code 315-6145 or 315-6258 ?
RE: Faulty video-output: white flashing picture - jacobsson - 16.05.2017 12:51
(16.05.2017 10:41)aykiri1 писал(а): is your chip sega marked code 315-6145 or 315-6258 ?
Let me check tonight, I'll come back to you!
Also good to know, since I haven't used this mainboard earlier I've already checked for screw marks around the video port and I could't find any (in case the former owner used a longer screw to install the GDROM).
(I guess the last resort would be to heatgun the mainboard with solder flux on the DAC pins and video output port.)
RE: Faulty video-output: white flashing picture - aykiri1 - 16.05.2017 14:04
usually similar problem from video dac.
can you check audio ? audio could work
RE: Faulty video-output: white flashing picture - jacobsson - 16.05.2017 16:54
(16.05.2017 14:04)aykiri1 писал(а): usually similar problem from video dac.
can you check audio ? audio could work
Audio works fine, I can hear the boot up sound and if I wait some time I can hear the cursor sound when pressing the D-pad.
RE: Faulty video-output: white flashing picture - aykiri1 - 16.05.2017 20:37
change that chip (if you can find it)
315-6145 (sega code) using usually sega va0 cards
315-6258 (sega code) using usually sega va1,2 cards
BU1426KS (IC custom code)
all codes equivalent
so i don't know where you can get that chips. so difficult
RE: Faulty video-output: white flashing picture - Gillbert - 16.05.2017 23:36
Most of times is really the DAC chip that is faulty, as aykiri1 have told.
But, as a last resort, replace CE203 and CE402, these capacitors are responsible for +Vcc filter of video circuit stages.
RE: Faulty video-output: white flashing picture - aykiri1 - 17.05.2017 00:22
hi Gillbert
Thx for good info. and how can find that DAC ? any web site or etc ?
i have 8 DC for same issue
RE: Faulty video-output: white flashing picture - Gillbert - 17.05.2017 00:35
8 DC's with that same issue? That's really too bad.
Anyway, it's worth to check the caps I mentioned, I already found two cases where the problem were the capacitors.Unfortunately is only possible to find that DAC chip on spare DC motherboards.
RE: Faulty video-output: white flashing picture - aykiri1 - 17.05.2017 00:45
that dc used iside arcade cabinet with jamma
i will replace and check again.
thx
RE: Faulty video-output: white flashing picture - jacobsson - 17.05.2017 11:07
Wow thanks for all the good info guys!
@aykiri1 8 faulty units with the same issue? Daaamn!
I didn't have the time to dig up my mainboard yesternight but I have a bunch of stuff to test, mainly changing those capacitors: CE203 & CE402. You don't happen to have the values for those at hand? (I'm at work thinking I might be able to pick those up the way home)
RE: Faulty video-output: white flashing picture - jacobsson - 17.05.2017 13:08
(17.05.2017 00:35)Gillbert писал(а): 8 DC's with that same issue? That's really too bad.I found the shematics here
Unfortunately is only possible to find that DAC chip on spare DC motherboards.
VIDEO DAC
CE402: 47uF 10v
GPU AND VRAM
CE203: 100uF 10v
Sounds about right?
RE: Faulty video-output: white flashing picture - aykiri1 - 17.05.2017 15:34
CE402 is 47uF 16v
CE203 is correct
RE: Faulty video-output: white flashing picture - jacobsson - 18.05.2017 10:53
(17.05.2017 15:34)aykiri1 писал(а): CE402 is 47uF 16v
CE203 is correct
Thanks! I've ordered them now, I'll come back to you within a month hopefully =)
RE: Faulty video-output: white flashing picture - aykiri1 - 18.05.2017 20:29
that caps are tantalum but, you can use electrolytic for temporary test only