Nice work - yet again. I agree with your "optimistic perspective" method of repair. I noticed that early on when I first started watching your C64 and 1541 repair videos, and one of the main reasons I'm a subscriber -- there's always that good vibe... relax, GadgetUK will get it fixed.
Another fine repair. The different frequency crystal changed the Colorburst signal contained in the composite video and your TV could no longer decode this information hence the black and white picture. Nice scope by the way, those HAMEG'S are brilliant analog scopes. My uncle owed one just like yours back in the day, he taught me how to use a scope on that very model, just seeing it brought a tear to my eye as it made me think of my uncle (who is sadly no longer around).
Yes - that's the reason, Colorburst - it was on the tip of my tongue during filming but I just drew a blank =/ HAMEG scopes are great! This one has some nice features related specifically to TV stuff, but I've never used those functions. Sorry to hear about your uncle =(
Cool you got it working. Do you like the crystal measure/tester ? Julian has videos on it where he mods it I think, have you tried that ? Something about the crystal input circuits.
Yes - It was the same kit he used! I've posted a link up top! I did that same mod he suggested (changing one of the 22pF caps for a 47pF cap, and that solves the problem). I haven't experienced any of the wierd problems he had with temperature fluxations though!?! It needs an amplifier adding to act as a frequency counter, rather than a crystal tester. I did order the components and have a go at making that amp but couldn't get anywhere with it. I will revisit that at some point.
The frequency counter was thanks to a video I saw on Julian Iletts channel btw:- ruclips.net/video/z7Fv9QqiqZ0/видео.html When I mentioned the two 74 logic chips at the start - they are actually CMOS. 40H368's.
Depends how the internal trimmer is wired up - if it's a parallel capacitor to the oscillator, it will lower the frequency; so if you chose a crystal with lower frequency than originally, you're stuck, unless you do something else. The way this cartridge works to my knowledge, it has video ROM, not an RAM expansion. There's two separate memory buses going into the cartridge on NES, well you knew this already, but the CHR bus can carry either ROM or SRAM. When CHR cartridge half is ROM, the console internal 2K VRAM would necessarily be used for tile background attribute map, but the sprite attribute array is internal register set to the PPU chip.
Thanks for pointing that out! It makes sense now you mention it! I also supect the cap won't make that much difference to the frequency anway - but I will have a tinker when I get more time. Thanks for the info about PPU ROM and SRAM acess there - It has been almost 17 years since I worked on the NES emulator and a lot has been forgotten.
It's just a cheap frequency counter kit - Julian Ilett covered a kit on his channel! I completely forgot to mention where I got that kit. See his 2nd video here:- ruclips.net/video/z7Fv9QqiqZ0/видео.html
I have found two Japanese dogbone controllers with failed 4021 shift registers/encoders. Replacing them fixed the problem and reinstalling them transferred the problem, so mine were definitely failed (not just a solder short).
GadgetUK164 No problem. I was buying a lot of "junk" and "broken" dogbones back then. Luckily, 4021 chips are dirt cheap from eBay so I didn't even have to salvage them from other controllers. Also noticed that the very last revision (the one they stopped producing in the early 2000s) had a SMD 4021 shift register. Luckily, that one had a different problem. Oddly, I've found Japanese and US dogbones that were simply disconnected inside with no significant stresses evident on the cable (definitely wasn't pulled through the posts). Easy fix, but no wonder Nintendo hesitated to use internal disconnects for the older controllers. ;)
My famicom have a slightly different power/modulator board as well. Not really difficult to figure out, thankfully! I have some slight jailbar noise in the picture, not sure if it is worth the hassle to do the extra noise removal mods. Have read they don't always work.
The two things I've found that help with the jailbars a bit are 1) grounded copper tape under the PPU, and 2) adding an additional 47uF cap across the VCC and ground (as shown in my Famicom restores). There might be other things beyond that - if you find any, please let me know!
Could do the cap, sounds simple enough. One of the other things I've read, besides the copper tape, is cutting a trace and rerouting the composite video signal. Apparently the trace is very close to another which causes noise. Had a link to it, I'll do some digging and see if I can find it.
Hey Gadget, maybe teaching granny to suck eggs, but Adam of OneCircuit (ruclips.net/channel/UC0Bzak63p0W4bL1mp8txEVA) is very good at fixing logic based problems, he deals mainly with arcade boards, but it's all applicable, his videos are really good as he talks through every step he's doing really rather well on his repair vids. Even if it's not applicable to consoles per sé, it's interesting viewing non the less as he goes in depth about ROMs, RAM, MUX etc. etc.
Thanks! The problem is my logic analyser is crap lol! I sub to OneCircuit - he does some interesting repairs =D I have another logic analyser here though - so should be able to get that working when I have some more time. I am not stuck with a problem etc - I just wanted to show the CPU reading from the ROM and to talk through some of how the NES works, and why its such a great system to learn from.
![Blox Fruits Dragon Rework Update [Full Stream]](http://i.ytimg.com/vi/EqDAp8udhm0/mqdefault.jpg)
Part 3 - ruclips.net/video/rbkJbb2YVNw/видео.html
Part 1 - ruclips.net/video/o7dp4FDIAoE/видео.html
Nice work - yet again. I agree with your "optimistic perspective" method of repair. I noticed that early on when I first started watching your C64 and 1541 repair videos, and one of the main reasons I'm a subscriber -- there's always that good vibe... relax, GadgetUK will get it fixed.
Thanks =D Much appreciated! =D
Another fine repair. The different frequency crystal changed the Colorburst signal contained in the composite video and your TV could no longer decode this information hence the black and white picture.
Nice scope by the way, those HAMEG'S are brilliant analog scopes. My uncle owed one just like yours back in the day, he taught me how to use a scope on that very model, just seeing it brought a tear to my eye as it made me think of my uncle (who is sadly no longer around).
Yes - that's the reason, Colorburst - it was on the tip of my tongue during filming but I just drew a blank =/ HAMEG scopes are great! This one has some nice features related specifically to TV stuff, but I've never used those functions. Sorry to hear about your uncle =(
Cool you got it working. Do you like the crystal measure/tester ? Julian has videos on it where he mods it I think, have you tried that ? Something about the crystal input circuits.
Yes - It was the same kit he used! I've posted a link up top! I did that same mod he suggested (changing one of the 22pF caps for a 47pF cap, and that solves the problem). I haven't experienced any of the wierd problems he had with temperature fluxations though!?! It needs an amplifier adding to act as a frequency counter, rather than a crystal tester. I did order the components and have a go at making that amp but couldn't get anywhere with it. I will revisit that at some point.
The frequency counter was thanks to a video I saw on Julian Iletts channel btw:- ruclips.net/video/z7Fv9QqiqZ0/видео.html When I mentioned the two 74 logic chips at the start - they are actually CMOS. 40H368's.
GadgetUK164 Thanks
Depends how the internal trimmer is wired up - if it's a parallel capacitor to the oscillator, it will lower the frequency; so if you chose a crystal with lower frequency than originally, you're stuck, unless you do something else.
The way this cartridge works to my knowledge, it has video ROM, not an RAM expansion. There's two separate memory buses going into the cartridge on NES, well you knew this already, but the CHR bus can carry either ROM or SRAM. When CHR cartridge half is ROM, the console internal 2K VRAM would necessarily be used for tile background attribute map, but the sprite attribute array is internal register set to the PPU chip.
Thanks for pointing that out! It makes sense now you mention it! I also supect the cap won't make that much difference to the frequency anway - but I will have a tinker when I get more time. Thanks for the info about PPU ROM and SRAM acess there - It has been almost 17 years since I worked on the NES emulator and a lot has been forgotten.
Great vid. What was that unit you used to test the crystal? . I would like to get one myself.
It's just a cheap frequency counter kit - Julian Ilett covered a kit on his channel! I completely forgot to mention where I got that kit. See his 2nd video here:- ruclips.net/video/z7Fv9QqiqZ0/видео.html
I have found two Japanese dogbone controllers with failed 4021 shift registers/encoders. Replacing them fixed the problem and reinstalling them transferred the problem, so mine were definitely failed (not just a solder short).
Thanks for the info - very interesting =D
GadgetUK164 No problem. I was buying a lot of "junk" and "broken" dogbones back then. Luckily, 4021 chips are dirt cheap from eBay so I didn't even have to salvage them from other controllers. Also noticed that the very last revision (the one they stopped producing in the early 2000s) had a SMD 4021 shift register. Luckily, that one had a different problem. Oddly, I've found Japanese and US dogbones that were simply disconnected inside with no significant stresses evident on the cable (definitely wasn't pulled through the posts). Easy fix, but no wonder Nintendo hesitated to use internal disconnects for the older controllers. ;)
Amazing repairs. Thanks for sharing.
Thanks =D
My famicom have a slightly different power/modulator board as well. Not really difficult to figure out, thankfully! I have some slight jailbar noise in the picture, not sure if it is worth the hassle to do the extra noise removal mods. Have read they don't always work.
The two things I've found that help with the jailbars a bit are 1) grounded copper tape under the PPU, and 2) adding an additional 47uF cap across the VCC and ground (as shown in my Famicom restores). There might be other things beyond that - if you find any, please let me know!
Could do the cap, sounds simple enough. One of the other things I've
read, besides the copper tape, is cutting a trace and rerouting the
composite video signal. Apparently the trace is very close to another
which causes noise. Had a link to it, I'll do some digging and see if I
can find it.
Thanks - that's a great page! I might give those mods a try on one of them, just to see what difference it makes.
Would be great to see if it is worth the time. Hope you'll make a video with the results. :-)
Fantastic!
Btw, my gba is fixed. It was the fuse as you said. Thanks.
That's great =D
Where can I buy the proper sram for the famicom? Even the ppu and cpu, my system is now only giving a grey screen.
eBay or AliExpress probably!
I’ve just acquired a famicom with a dead power supply. There doesn’t appear to be any corrosion, just doesnt turn on at all
Possibly the 7805 regulator or power socket?
Hey Gadget, maybe teaching granny to suck eggs, but Adam of OneCircuit (ruclips.net/channel/UC0Bzak63p0W4bL1mp8txEVA) is very good at fixing logic based problems, he deals mainly with arcade boards, but it's all applicable, his videos are really good as he talks through every step he's doing really rather well on his repair vids. Even if it's not applicable to consoles per sé, it's interesting viewing non the less as he goes in depth about ROMs, RAM, MUX etc. etc.
Thanks! The problem is my logic analyser is crap lol! I sub to OneCircuit - he does some interesting repairs =D I have another logic analyser here though - so should be able to get that working when I have some more time. I am not stuck with a problem etc - I just wanted to show the CPU reading from the ROM and to talk through some of how the NES works, and why its such a great system to learn from.