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.
can be problem video dac chip
(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.
is your chip sega marked code 315-6145 or 315-6258 ?
(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.)
usually similar problem from video dac.
can you check audio ? audio could work
(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.
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
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.
hi Gillbert
Thx for good info. and how can find that DAC ? any web site or etc ?
i have 8 DC for same issue
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.
that dc used iside arcade cabinet with jamma
i will replace and check again.
thx
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)
(17.05.2017 00:35)Gillbert писал(а): [ -> ]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.
I found the shematics
here
VIDEO DAC
CE402: 47uF 10v
GPU AND VRAM
CE203: 100uF 10v
Sounds about right?
CE402 is 47uF 16v
CE203 is correct
(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 =)
that caps are tantalum but, you can use electrolytic for temporary test only