Tatsujin PCB working randomly

[geekmiki]

Hi,

I just got a Tatsujin PCB that is giving me quite some trouble.

When I fire up the PCB for the first time, I get this:



5V has of course been adjusted and is fine:



Then I have to turn off and on the cab a couple of times before the PCB finally boots up and goes through RAM test, which it passes:



Then today during one of the unsuccessful boot ups I got this:



After that RAM error, it finally worked.

I have checked that all the EPROMs are well seated and that the PCB has no trace damage.

Could it be cap related? Any clue on this random errors and boot problems?

Thank you in advance!

[system11]

Try it on another cab, it seems similar to the problem I sometimes have with certain types of power supply, causing trouble for the reset circuit.

[geekmiki]

I forgot to mention that the PCB has been tested on my two cabs (Astro City and Egret II) and that it has the same behavior on both.
Btw, it's the only PCB that has this kind of problem on my cabs.

[system11]

Check capacitors C16 and C17.

[geekmiki]

I replaced C1 and C16 which were the ones I had (470uF 16V) and it seemed to be working when I plugged it in again.

I'll check again today to see if I got rid of the random booting, if not I'll order the others and start replacing.

Thanks for your advice system11!

[system11]

None of the others will make any difference, just C16 and C17, and C16 was the most likely.

[system11]

So how did it go?

[geekmiki]

Hi,

It's still working fine! You were right it was C16, since I haven't changed any other caps but C1 and C16.

Thanks again for your help system11!

[system11]

Cool, it's a common problem on Flying Shark boards too, they look exactly like that when the cap goes as it kills the power-on reset.