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Schematic for UM6561?

Posted: Thu Jan 05, 2017 1:09 pm
by FARID
Well first of all HAPPY NEW YEAR :beer:

I want to make a mini Famicom clone by using UM6561 + two EPROM so that I can run simple NROM games on it.
I am testing the circuit on a breadboard :

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I found a Dendy schematic which is based on UM6561 but it seems it has some errors in it :
(capacitor signs are Russian : MK=uF / H=nF / n=pF)

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Fortunately I have a Famicom clone named FUMA-001 which uses the same chip :

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By comparing them I found out that their circuit is very different so I have to compare them with another famous Famicom schematic :

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Also I want to omit RF and its related parts so that the whole thing become more compact.

Re: Schematic for UM6561?

Posted: Thu Jan 05, 2017 1:25 pm
by FARID
Dendy :
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Fuma :
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Famicom :
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80sFREAK :
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Output :
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console5.com :
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Output :
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Audio

Posted: Thu Jan 05, 2017 1:33 pm
by FARID

Re: Schematic for UM6561?

Posted: Thu Jan 05, 2017 1:38 pm
by FARID
7805 official datasheet suggest to use 0.1uF and 0.33uF but in Dendy and Famicom they used 47uF and 470uF :

Dendy :
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Fuma (it seems caps are swapped wrongly?) :
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7805 Datasheet :
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Re: Schematic for UM6561?

Posted: Thu Jan 05, 2017 1:46 pm
by FARID
Dendy (suggests to use 470nF (=0.47uF) Electrolytic capacitor) :
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Fuma (uses 100nF Ceramic capacitor) :
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Famicom (suggests to use 0.47uF Electrolytic capacitor) :
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so which one should I use?

Re: Schematic for UM6561?

Posted: Thu Jan 05, 2017 1:53 pm
by FARID
Famicom :
Image

Dendy (both caps for crystal are 30pF) :
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Fuma (Caps are different 39pF and 12pF) :
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Re: Schematic for UM6561?

Posted: Thu Jan 05, 2017 1:56 pm
by lidnariq
FARID wrote:7805 official datasheet suggest to use 0.1uF and 0.33uF but in Dendy and Famicom they used 47uF and 470uF :
I've seen different specified capacitances there, depending on the nature of the input voltage and the technology of the capacitor.

Larger capacitances are needed when you have full- (or half-) wave rectified AC and the capacitor has to hold enough power to keep everything running for up to 10ms between mains.

On the low side, a better ESR will improve AV quality.
FARID wrote:Dendy (suggests to use 470nF (=0.47uF) Electrolytic capacitor) :
Fuma (uses 100nF Ceramic capacitor) :
Famicom (suggests to use 0.47uF Electrolytic capacitor) :
so which one should I use?
On the 2A03 (I can't speak for the Dendy parts), the reset pin has a depletion NMOS pullup inside. When I measured mine, that pin emits somewhere between 20 and 50 µA continuously, only vaguely a function of the output and supply voltages.

The choice of capacitor only determines how long the CPU is held in reset after power up or after the user presses the reset button. A larger value will take longer.

The specific value doesn't seem to matter much, as long as the CPU comes out of reset consistently.

Re: Schematic for UM6561?

Posted: Fri Jan 06, 2017 12:13 pm
by FARID
It works fine :

https://youtu.be/P-ByTSWdE84

Schematic Rev 2 :
- Better circuit for Video output
- Fixed some mistakes

Suffix info :
UM6561F-1 - NTSC
UM6561F-2 - PAL-B
UM6561F-3 - PAL-M
UM6561F-4 - PAL-N

Source : http://www.emu-land.net/forum/index.php ... #msg959563

Re: Schematic for UM6561?

Posted: Tue Jan 17, 2017 3:27 pm
by FARID
I designed a PCB for my new project (United Famicom = Famicom + TxROM)
Which parts should be separated because of noise?

Re: Schematic for UM6561?

Posted: Tue Jan 17, 2017 4:00 pm
by lidnariq
Most of the system is low-speed 5V digital, and thus pretty immune to any kind of crosstalk.

However, the analog signals—audio and video—are quite sensitive. Coax is probably overkill, but you wouldn't go wrong with the PCB equivalent (ground traces on both sides of the signal, and ground fill underneath)

Re: Schematic for UM6561?

Posted: Sat Jan 28, 2017 4:13 pm
by FARID
So here is the United Famicom Rev 1.0 :
https://youtu.be/SadSu7zy3zw

The PCB costed about 50$

Re: Schematic for UM6561?

Posted: Sat Jan 28, 2017 4:56 pm
by krzysiobal
What's the point of making so long traces (GND polygon pour underneath helps from getting noise?)

How do u metalize holes?

Re: Schematic for UM6561?

Posted: Sun Jan 29, 2017 3:13 am
by FARID
What's the point of making so long traces
At first I wanted to use SMD to DIP adapter but later I decided not to use it and solder the chip directly to the main board, that is why that part seems a little awkward.
GND polygon pour underneath helps from getting noise?
Jero on nesdev IRC channel gave me two pdf regarding how to mix analog and digital parts to reduce the noise.
How do u metalize holes?
I didn't make the PCB at home, and as I said it costed 50$.

Re: Schematic for UM6561?

Posted: Thu Aug 24, 2017 12:38 pm
by muramasa
Thanks for the schematics Farid. I do have a question though can the UM6561 be used in a NTSC system if I select a different crystal?

Re: Schematic for UM6561?

Posted: Fri Aug 25, 2017 5:11 am
by FARID
muramasa wrote:Thanks for the schematics Farid. I do have a question though can the UM6561 be used in a NTSC system if I select a different crystal?
Sorry I have no idea about it.
But I can test it if you give me the proper info.