Famicom World

Family Computer => Technical & Repair Assistance => Topic started by: urufuNoFamicom on February 08, 2019, 12:09:51 PM



Title: Blank Screen; what's broken?! [Famicom RF]
Post by: urufuNoFamicom on February 08, 2019, 12:09:51 PM
So i bought an untested original Famicom for pretty cheap, that was bought in a lot sell by the seller, to use in a personal project, and im trying to see if it works.

They sent a copy of Dragon Quest III with it (which was nice of them), but it doesn't seem to work.

I'm using the NES-003 RF adapter, and my tv (old plasma) is set to channel 96 (thank you "cable" mode). Power adapter is pin-negative, 9v, 850mA DC.

When i turn on the console, the screen is "blank"; that is, it outputs to the TV (static is replaced), but it's just a black(ish) screen.

I'm assuming this is the behavior of a system with no cartridge? I've cleaned and inspected both the cartridge and header pins, and nothing seems awry. Looking inside the unit there's nothing out of the ordinary looking either (though i didn't inspect the board's topside).

So my question is: is it the cartridge or the FAMICOM, and how can i tell?


Title: Re: Blank Screen; System or Cartridge? [Famicom RF]
Post by: FAMICOM_87 on February 08, 2019, 04:34:05 PM
any pictures? check the cables between RF power unit and main board .


Title: Re: Blank Screen; System or Cartridge? [Famicom RF]
Post by: togemet2 on February 08, 2019, 08:51:33 PM
Try cleaning the cartridge pins with rubbing alcohol (contact cleaner should work fine too).


Title: Re: Blank Screen; System or Cartridge? [Famicom RF]
Post by: urufuNoFamicom on February 08, 2019, 11:08:01 PM
Try cleaning the cartridge pins with rubbing alcohol (contact cleaner should work fine too).

I used an general purpose alcohol wipe (for electronics and glasses) on both the console and game contacts with no luck. Cleaned them fairly good though.

any pictures? check the cables between RF power unit and main board .

What do you mean exactly? As in check the internal cabling? I don't think it's a power issue (wouldn't it not output anything at all if the console wasn't powered? The screen is static when the system is off).

Nothing looks out of the ordinary with it, inside and out, though i could give the internals a more thorough look.

I'll take pictures of the board when I'm home.


Title: Re: Blank Screen; System or Cartridge? [Famicom RF]
Post by: FAMICOM_87 on February 09, 2019, 07:24:04 AM
you will get a solid black screen even if video signal from main board and RF power board is disconnected, so get multi-meter and check it, also check if you getting good 5V out of 7805, you you getting lower then about 4.5V that might be an issue too .
There is another possibility, bad RAM chips :(  or CPU/PPU.
Touch them to feel if any getting unusually  :fire: hot during operation  :gamer:


Title: Re: Blank Screen; System or Cartridge? [Famicom RF]
Post by: urufuNoFamicom on February 09, 2019, 12:08:53 PM
you will get a solid black screen even if video signal from main board and RF power board is disconnected, so get multi-meter and check it, also check if you getting good 5V out of 7805, you you getting lower then about 4.5V that might be an issue too .
There is another possibility, bad RAM chips :(  or CPU/PPU.
Touch them to feel if any getting unusually  :fire: hot during operation  :gamer:

I would, but, i can't find it.

The console internals don't match teardowns I've found. All the teardowns seem to have boards from the late 80s, but mine is from 1984. It has all the markings of a legitimate system, but the PSU is different (but still stamped 1983 Nintendo Co. Ltd)

I'll keep looking around for a proper image so i know what to test.


Edit 1: I found it, and it's got the right voltage. 5v on one pin, 9v on another (using a 9v supply) and 0v on the center (ground).

What next?

Edit 2: whilst plugged in, none of the chips on board heat up. Cartridge problem?

Edit 3: A friend informed me that the Famicom will output mic audio to the TV when a cartridge is inserted, and it works! So at least audio is working. Seeing as audio works but theres no sound from the game, does this mean it's the cartridge? Or could something else still be bad?


Title: Re: Blank Screen; System or Cartridge? [Famicom RF]
Post by: togemet2 on February 09, 2019, 08:14:24 PM
You could always just buy a $2 cartridge from ebay. Or even another copy of Dragon Quest III. Those are really cheap.


Title: Re: Blank Screen; System or Cartridge? [Famicom RF]
Post by: FAMICOM_87 on February 10, 2019, 08:29:20 AM
yes may be the  :redcart: is broken  :fire: try another one  ::)
 


Title: Re: Blank Screen; System or Cartridge? [Famicom RF]
Post by: urufuNoFamicom on February 10, 2019, 10:35:33 AM
I have TENNIS being shipped in from Japan, but it won't be here for a couple of weeks.


Title: Re: Blank Screen; System or Cartridge? [Famicom RF]
Post by: FAMICOM_87 on February 10, 2019, 12:06:42 PM
don't you have any china pirate 60pin  :redcart: ? they works too in most part  :gamer:


Title: Re: Blank Screen; System or Cartridge? [Famicom RF]
Post by: P on February 10, 2019, 05:12:43 PM
I'm assuming this is the behavior of a system with no cartridge?
The exact behaviour varies for each Famicom. This could be many things.

any pictures? check the cables between RF power unit and main board .
What do you mean exactly? As in check the internal cabling? I don't think it's a power issue (wouldn't it not output anything at all if the console wasn't powered? The screen is static when the system is off).
A partly working AC-adapters is a common problem. Oxidated pins on cartridge and/or console is another.

Edit 3: A friend informed me that the Famicom will output mic audio to the TV when a cartridge is inserted, and it works! So at least audio is working. Seeing as audio works but theres no sound from the game, does this mean it's the cartridge? Or could something else still be bad?
That means that the the mic works, the audio line is connected to the RF-board and that the audio pins on the cartridge are bridging correctly. It doesn't mean that the CPU and APU are working though.

Yeah trying other games to rule out the cartridge is your best bet I think.


Title: Re: Blank Screen; System or Cartridge? [Famicom RF]
Post by: Sydsydsyd on February 19, 2019, 10:12:15 AM
Can you upload pictures of the board? Maybe we can check it together  :)


Title: Re: Blank Screen; what's broken?! [Famicom RF]
Post by: urufuNoFamicom on February 20, 2019, 02:03:37 AM
Yeah trying other games to rule out the cartridge is your best bet I think.

So Tennis arrived, and the cartridge did not work. So it seems to be something with the console (CPU, PPU, SRAM). :(

Can you upload pictures of the board? Maybe we can check it together  :)

(https://i.imgur.com/7zWyliv.jpg) (https://i.imgur.com/Z2L2ONu.jpg) (https://i.imgur.com/4imiffq.jpg) (https://i.imgur.com/OlRimyD.jpg) (https://i.imgur.com/tpEHEte.jpg) (https://i.imgur.com/ukD66fJ.jpg)

Not sure where to go from here.


Edit:

(https://i.imgur.com/rGLxduu.jpg)

Would that be considered corroded? It looks a bit like "rust" on this one pin. Wondering if this↗︎ (https://youtu.be/o7dp4FDIAoE) is my issue?

Edit 2:

If it is SRAM, would this↗︎ (https://www.digikey.com/product-detail/en/idt-integrated-device-technology-inc/6116SA15TPG/800-2603-5-ND/2008361) work? It's a 6116 (2Kx8 16Kb) 24-DIP through-hole mounted SRAM chip. I feel like this would be a suitable replacement, but i can't find a spec sheet on the one in the system to compare. Edit 3: I found a spec sheet on one of the SRAMs used in another original FAMICOMs (not mine but same system; different manufacturers based on production date i assume) and they're identical except for the fact the IDT chip has a faster response time (15ns vs 150ns).


Title: Re: Blank Screen; what's broken?! [Famicom RF]
Post by: 80sFREAK on February 20, 2019, 02:11:47 PM
Clean PCB with IPA and reflow that chip.

added...

Looks like there is water damage. You should replace plastic trimmer(that green part around XTAL :) ), 22-27pF ceramic capacitor will do the job, if you don't have trimmer. And, yes, need good cleaning with IPA.


Title: Re: Blank Screen; what's broken?! [Famicom RF]
Post by: urufuNoFamicom on February 20, 2019, 10:11:26 PM
Could you perhaps circle in the image what needs replaced, and provide a part number or part specification if possible?  :help:


Title: Re: Blank Screen; what's broken?! [Famicom RF]
Post by: 80sFREAK on February 21, 2019, 01:57:34 PM
Bottom right corner of RP2A03 on your photos, there is "that green part".


Title: Re: Blank Screen; what's broken?! [Famicom RF]
Post by: urufuNoFamicom on February 25, 2019, 02:17:23 AM
Would this↗︎ (https://www.digikey.com/product-detail/en/vishay-bc-components/S220K25SL0N63L6R/1270PH-ND/2356806) work? Thinking about getting this and the SRAM chip↗︎ (https://www.digikey.com/product-detail/en/idt-integrated-device-technology-inc/6116SA15TPG/800-2603-5-ND/2008361) (might as well replace it), but my electronics knowledge is hit or miss.


Title: Re: Blank Screen; what's broken?! [Famicom RF]
Post by: 80sFREAK on February 25, 2019, 04:31:54 AM
Yes, variable ceramic capacitor should work.


Title: Re: Blank Screen; what's broken?! [Famicom RF]
Post by: urufuNoFamicom on February 25, 2019, 08:29:26 AM
Wait, so does it have to be a "variable" capacitor by name? Digikey has separate selections for those. And if I'm not mistaken in reading the datasheet for the linked capacitor, it can only go on 10%, which 1.1*22 (or 22 + 10%) is 24.2pF. Is the max being 27pF a requirement?

I found a replacement trimmer but it was like $4 :-X

Sorry if i sound like I don't know what I'm doing. My knowledge is usually project oriented, so it wildly varies based on what I'm dealing with. Just need to make sure I order the right part.


Title: Re: Blank Screen; what's broken?! [Famicom RF]
Post by: 80sFREAK on February 25, 2019, 09:27:28 AM
Do you have any scrap electronics around? Those cheap chinese made radio or tv or whatever with thru-hole components? Get just ceramic capacitor 22pF or 27pF and replace trimmer. K.I.S.S.


Title: Re: Blank Screen; what's broken?! [Famicom RF]
Post by: urufuNoFamicom on February 25, 2019, 11:46:05 AM
No, but you [inadvertently] answered my question anyways; the 22pF ceramic will do. I'll post whether the capacitor was the issue, as well as the SRAM if the capacitor swap fails to fix it.


Title: Re: Blank Screen; what's broken?! [Famicom RF]
Post by: 80sFREAK on February 25, 2019, 01:42:30 PM
You also might need to desolder XTAL(grey thermoshrink with 21.477 on it) and clean under and its bottom, where is pins. My guess, there is just no CLK, so everything is dead


Title: Re: Blank Screen; what's broken?! [Famicom RF]
Post by: urufuNoFamicom on February 25, 2019, 04:31:26 PM
I'll try that when I replace the capacitor. Going to hold off on the SRAM until i know for sure whether it's an issue, but i bought one just in case. Parts should arrive Friday if they ship on time. :)