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Everything posted by Taijigamer

  1. Hope u get it sorted, man. Check this thread out for info on diagnosing and fixing FZ-10 psu http://forum.3doplanet.ru/viewtopic.php?f=17&t=209&start=60 It's in Russian but easy to translat with Google. Those guys know their stuff. Going back to your original problem, I've been reading around and a lot of people have come forward with this issue although some get the 3DO logo for a brief second before a black screen. The same symptoms are replicated when I power on my FZ-1 without the cd drive connected. The console must do a POST before booting the Bios. Maybe a failing laser also causes an issue with booting. These consoles are now almost 25 years old so a laser replacement and a recap are inevitable. Good luck.
  2. Ah man, that sucks. Have u checked the 2A fuse? Just replace Q001 and Q002 and hopefully u should be back on track. From your tests we can see that the VP536 is fine so the problem points towards the ROM chip for not firing up the Bios. This could be bad caps. It looks like u need to replace the caps, replace the laser and fix the psu. Not too much work Good luck.
  3. Unfortunately there is very little official documentation on the 3DO. I have tried to find the service manual but no luck so we have to troubleshoot as best we can. The first reading on your list should be 5~V AC, not DC. Your multimeter may have been looking for DC and got a 0v. Sounds like your Vp536 is fine. Next would be to check the voltage out on pins 32 (Luma), 34 (CVBS) and 36 (Chroma) of your VP536. This will tell if the graphics chip and encoder are pumping out video signals. Also check the voltage regulators on the mobo. We know the psu is good. If they are all good then it can point back to your CD drive. Has it ever been able to boot games or to the bios? Have u tried different retail games, are they for the same region? Have u tried getting a new laser? It's strange that it won't boot to bios. The other culprit could be bad capacitors which could be stopping the CPU/ bios chip from working properly.
  4. Have u checked voltage at the ribbon connector between psu and motherboard? there should be about 3x 9v and 6x 5v connections. Have u checked voltages at the regulators on the mobo? Also check the VAA points on the VP536 encoder. If all turns out ok then the next best bet is a cap replacement.
  5. What's wrong with your current 3DO? Sometimes some faulty 3DOs turn up on eBay for a good price but mostly they are overpriced.
  6. My mistake. The pixel clk equation threw me off course. U are absolutely right, the pixel clk is that of the system, in this case the system is using a square pixel clk (14.75mhz PAL, 12.52mhz NTSE). So clk12i/o should be good to go and shouldn't require buffering. Square pixel refer to the pixel aspect ratio though, not the shape of the waveform. Sometimes the blanking level is also referred to as the back porch (probably erroneously). It's voltage level should be the same and therefore may provide your blank level reference. I've looked at your board designs, very nice. The data sheet recommends double terminating the Analogue outputs with a 75ohm resistor which I see u have done. It is also recommend with RGB to add a 75ohm resistor in serial along with a 220uF capacitor to maintain the 75ohm impedence and filter unwanted DC signals.
  7. Very interesting idea. A couple of points to add, if I may. U mention buffering for TTL, the data sheet says it is TTL compatible, it isn't a requirement though. The levels of the digital RGB, sync and blank should be fine without the need for extra circuitry. The ADV7125 doesn't use a square pixel clk as far as I can see so using clk12i maybe out. U might needs a dedicated pixel clk, which would need buffering potentially. Sync can be stripped from luma and either sent straight to to/ monitor or fed back into ADV7125. If sent back to chip, it will be put into Green signal as Sync on Green which may be undesirable for some TVs/ monitors. If sent direct to TV, it will be 2 clk cycles out from RGB due to a pipeline delay in the DAC. Not sure what effect this will have but is something to consider. If sync is used directly, Sync pin on ADV7125 needs to be tied to GND. Also the VP536 produces HS and VS separately do maybe it's possible to get RGBHV working on a VGA monitor? Regarding blanking, again doesn't need to be TTL buffered. The LM1881 also strips Backporch from the video signal, this might be useable to provide blank level but I'm not sure. At this point some experimenting may be in order. Finally, regarding the Analogue out lines, u have tied them to ground using 75ohm resistors I assume. U may also need 75ohm resistor and 220uF capacitors in serial with those lines, this could be incorporated at the pcb end or in the SCART connector if using SCART. Hope this helps, I'm working on a 3DO at the moment with the BT910x chips so I may look at using one of your designs to experiment with. I'll let U know my findings.
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