Schematic for UM6561?

[lidnariq]

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.

[FARID]

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

[krzysiobal]

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.

[lidnariq]

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")

[FARID]

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

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

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")

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

And here is something interesting :

跟据文章描述，改N制只要把晶振换成21.47727MHz就行了。

Google translate :

According to the article described, change the N system as long as the crystal into 21.47727MHz on the line.

[krzysiobal]

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.

[lidnariq]

If [pin 19] is [P1 D2] Famicom microphone should I connect it GND (as suggested in Russian schematic) or leave it floating?

Either's fine.

—
Google OCRs the first two paragraphs of the data sheet as

在众多的中英电脑学习机中，用6561芯片开发出来的学习
机，可谓品牌众多。如“科王926”，“声霸”，“小霸王”，“小博士”
等，目前该芯片构成的学习机维修资料很少，本人从事UM6561
芯片的开发，维修多年，近一年又维修了一些中英文电脑学习
机，现将维修资料和检修实例整理出来与同行共享.

目前国内销售的UM6561集成块是UM6561 PAL / NTSC，
该芯片用26.601712MHz的晶振时，视频输出PAL彩色信号,
当使用21.47727MHz的晶振时，视频输出NTSC彩色电视信
号，这类中英文学习机在型号升级时（如486型到926型）从硬
件上看没有实质性的改变. 大多都是增加新的软件功能，也就是
学习卡中内容不同.

It does sound like it autodetects crystal frequency and switches between NTSC and Dendy behavior accordingly.

[krzysiobal]

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!

[Skyway1985]

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!

[krzysiobal]

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.

[Skyway1985]

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

[Fisher]

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

[VEG]

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).

Could you please show more photos of this board, from all sides? Also a photo of the famiclone itself also would be useful.

[FARID]

Last night I was digging google about UM6561 schematic and those Chinese docs, trying to find its original source.
I found this page : https://zhuanlan.zhihu.com/p/59418044 which has an interesting reference at the end of the web page :

【1】刘泾（1996）。《用UM6561芯片的中英文电脑学习机的原理与维修》。《电子报合订本下册》，第292页

The name of this reference matches to this page which I had before :

By using google translate :

[1] Liu Ye (1996). "Principle and Maintenance of Chinese and English Computer Learning Machine Using UM6561 Chip". "Newsletter Volume II", page 292

So it was from this book :

I dig more to see if I can find any PDF, so I found this website which is selling it :
http://222.186.171.228/search.php?word= ... rchby=isbn

it costs only 7 Yuan (=1$), but the problem is I can't buy online because of international sanction of Iran.
Can anyone buy and share it here?

[krzysiobal]

Nice wake-up after 2.5 years of inactivity, where have you been for that whole period of time?