Oh yeah, that's a recurring subject that unfortunately many sellers who actually don't have proper knowledge try to sell as safe. I had a sort of horror history that I relate here. I'm also not sure about Mega Drive's safety, as a friend supposedly had damaged one by intense use of a Chinese Everdri...
Hi. Sorry for the long absence. I tried to "warm-up" the PCB with the same results. This is the expected behavior because 368 is an inverting buffer. Interesting. I thought it should behave as an open collector. Maybe a pull-down or pull-up here can make a big difference? Next thing to try out. Here...
That is an identical Phantom clone, too? Yes. You said that one of the problematic carts is a repro that you had made, did you try you try to store a different game (or controller test program) on that cart? Yes. 1) your mainboard (or all phantom-series mainboards in general) In another Phantom, I ...
Maybe the buffer ICs are damaged now? 74HC368 Strangely on my cce copy of Gradius even if I remove the buffer ICs the control acts as if all the buttons are pressed, resulting on the gray test screen. If you want to know how to fix the problem, you should look more into what is special about those ...
As I've seem on your YT channel, your mother language is probably spanish, right? The schematic is very well designed and simple to follow. You can post your doubts here and I'm sure people here will be happy to help. But try first to follow the signal with an amplifier, as suggested by Lidnariq. Th...
Now I can see it, thanks. :-) Basically you had put the left channel post amplifier output on the right channel output capacitor. I'm not sure if in this kind circuit is a good idea to do these trial and error stuff but, does it make any difference if you plug it on the C66 instead of the C65? Again...
Unfortunately, I'm not able to see the image that you have posted. Looks like you are plugging the output of the left post amplifier to the positive of an output capacitor. There is a big chance of some problem on the transistors Q16 and Q17 or on the circuit around them. Have you tried another know...
Which pin of the IC you had put on what pin of wich capacitor? The problem may be a bad electrolytic capacitor. Since they're 20+ years exchanging them is a good idea. There's also a small circuit with a transistor and some other components, that you can test with a small amplifier as Lidnariq sugge...
I agree with you.
To save a connector on the expansion port, they did that mess.
I tried to cut the traces and got the same results.
By the way, the games that I'm trying have nothing connected to these pins.
Still didn't understand why washing the board made it work fine for a while.
AFAIK this chip uses the standard 64Kbit SRAM pinout, so you should be fine with any other 64Kbit IC. You can get one of these on many games that use CHR RAM instead of ROM, like Contra and Megaman. Also many japanese RPGs that save use one of them. Some old ISA network and modem cards also use it. ...