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I wonder if this COB famiclone that krzysiobal found contains a UM6561.

There's a bunch of pins over there in the corner (18,19, maybe another one or two) that might not be supply pins and might change the behavior if tied high or low.

Seems to be the official datasheet of UM6561 :
http://bbs.a9vg.com/thread-5103544-1-1.html

I have spare UM6561 for testing


and there is direct connection only between those GND pins: 73, 60, 16.

Other pins marked as GND or NC in this schematics (32, 18, 19) might act as input pins. There is high probability of it, as multimeter on diode test shows some value for EACH of those pins with respect to GND, so they are internally connected.

The datasheet that Farid found for the UM6561 says that pin 19 is P1 D2 (i.e. famicom microphone).

I notice that he switched pin 32 from ground (in the initial pinout) to 5V (in his very first breadboarded picture, pin 32 is labelled "GND 5V")

If it is Famicom microphone should I connect it GND (as suggested in Russian schematic) or leave it floating?


It is definitely mislabeled in the Russian schematic since it is connected to other VCC pins internally.

And here is something interesting :

Google translate :

I confirm, pin 32 is connected to VCC. So out of those mysterious pins, only 18 is unknown, so it is probably pal/ntsc select.

Either's fine.

—
Google OCRs the first two paragraphs of the data sheet as
It does sound like it autodetects crystal frequency and switches between NTSC and Dendy behavior accordingly.

I just got one famiclone with glob-top UM6561 (soldered on add-on board), but there is also place for regular 80 pin SMD UM6561. What is weird, its pinout it shifted from original UM6561 (this pin1 = UM6561 pin2, this pin 2 = UM6561 pin3).



This board uses 26.601712 MHz crystal and has place for two jumpers - one marked as P/N and the other 50/60 (both were unsoldered, but soldering shorted each of them to GND).

Shorting P/N causes PAL screen to momentally switch to black/white, shorting 50/60 causes TV to lose sync (it is responsible for crystal selection).

So I did this clever switch and now I can in runtime switch between PAL and NTSC - curiously switching crystal during runtime does not cause CPU to break.

I was worried if connecting crystal with only one leg and putting second leg on long wire and switch will have problems, but nothing that happened!

sorry to resurrect an old thread, @krzysiobal does what you did work with a UM6561f-2? i have 2 game axe color, both in need of a um6561cf-1 both failed. but i got some um6561f-2 that only work with pal xtal, and run terrible. i want NTSC! could you advise me? which pins on the umc package are affected by what you did? or what pins need to connect? BTW im a fan of your pcb and repro work! want to buy some soon!

I have just done some test using my IQ502, UM6561CF-2 based famiclone console (with 26.601712 MHz chip):
1. Replacing the crystal with 21.47727 MHz causes TV lose sync and slower sound, so the chip does NOT have region crystal audo detect frequency
2. Pin 18 is NOT cabaple of switching region between PAL/NTSC. It is some kind of input (with itnernal pull-up to 5V), but when you apply 0V on it, console automatically hangs up. When you look on the scope at the M2 line when pin 18 is at 5V (or not connected to anything):


and when it is tied to 0V:


It seems to change the M2 appearance bit, but its further meaning is unknown.

3. Few weeks ago I had console also based on UM6561F-2 which had 21.47727 MHz crystal and was NTSC mode. Pin 18 was also not connected to anything, so probably the whole chip has the PAL/NTSC region set during the manufacturing process (and thats why some of them have UM6561BF / F / -1 / -2 markings)

So if you want to have PAL/NTSC switchable console, you need to obtain some glob-top clone with ability to add switch button.

Krzy, Thank you, that's EXACTLY what i thought and what i had observed. i installed a F-2 in my game axe to verify the board was fine and it was the NOAC that failed, and I could only get video with the 26mhz xtal. I've got a lead on some UM6561cf-1 from hong kong. looks like im going to have to shell out 25 usd per IC. Im ordering 5 in case of a failure in the future as i have 2 game axes with noac ram that failed due to poor ESD protection in the stock circuit. the 6561F-2 seems to be had for much cheaper, but i just can't adjust to Dendy PAL... lol

Any idea if these NOACs would work fine with 3.3v parts and not have problems in the future?