SEGA Mega Drive (Genesis) II - Black Screen Repair

[@MichaelWilliams-ff7kb]

Thank you for this video, it has been very helpful. I used a PC sound card oscilloscope on my console and reached the same conclusion. I am yet to find a PAL master crystal though.

[@Four_X]

Glad it helped!, those master crystal are SEGA custom crystals you'll only find them in a PAL Master System or Mega Drive.

[@MorganJustGames]

Another successful repair. Well done Mr X.

[@Four_X]

Thanks Jamie. Always a good day when you save a retro system from the scrap pile.

[@LtRaziel]

"There's only one culprit that the problem could be... It's either this chip or the master crystal." You've taught me things about mega drives, so let's take a moment to talk about maths....

[@maxwarfield6699]

Hello again! Just wondering if perhaps, you could help me identify that little black component, that sits next to the voltage regulator? It’s marked CF1 on the pcb itself but on it, is written: RC 04 u. Looked all over the web and all I could find is that CF might stand for crystal filter OR current follower - as I am a complete NOOB, I have never heard of either of these two things - so, what is this four pin device? Any insight will be greatly appreciated. Thank you kindly

[@Four_X]

I think it's marked FB1, it's a ferrite bead. There used to suppress and dissipate high frequency noise. if you look at the SEGA Mega Drive II Schematic here gamesx.com/wiki/lib/exe/fetch.php?media=schematics:genesis-2-md-2-schematic-1_of_4.png You'll see it in series with the Crystal Oscillator (OSC1).

[@maxwarfield6699]

@@Four_X No, no, on my NTSC board it’s located right next to the voltage regulator but on your PAL board, the component I’m referring too is sitting right next to the power jack, that you glued and reflowed. It’s a small black device with four pins, it looks like an opto-coupler [opto-isolator] and even yours, is marked CF1- you can clearly see it at 1:30 min of your video, just right of your thumb - what is that thing? Please let me know, I’ve looked all over the web, I’ve found nothing and I think I’m going crazy! Thank you kindly for replying. Cheers!

[@Four_X]

​@@maxwarfield6699 Sorry I don't know why the hell I was looking at the Crystal Oscillator (OSC1). That component labelled CF1 is an Inductor, Chock. you can see it on the SEGA Mega Drive II Schematic here gamesx.com/wiki/lib/exe/fetch.php?media=schematics:genesis-2-md-2-schematic-4_of_4.png, It's used to block higher-frequency (noise) while allowing direct current (DC) it can also block lower-frequencies of alternating current (AC). It's basically acting as a noise filter just in case your input power supply is noisy.

[@maxwarfield6699]

@@Four_X So, the CF could stand for “choke-filter”? And it’s replacing a notch-filter [inductor+capacitor]? Do you know how one might test this device? Please let me know, if you do. And again, thank you for replying - I’m learning a lot. Cheers!

[@PhilipBryden]

This knowledge is golden. Thanks for sharing.

[@darkprince5714]

I don fucking understand from start to finish but i enjoy watching it

[@ademline2010]

Hello, I have 1 gamestar 16 bit console and the black screen is faulty. I want to ask something about finding the solution. Do we need to check the voltage input pins of the integrated and chips for a motherboard that does not start in general? My second question is, how do you know the voltage input pins of this chip or IC? By the way, I don't have an oscilloscope. I need to get the result with the multimeter. thanks

[@Four_X]

It going to be difficult if you're just using a multimeter and don't have a oscilloscope to check the signal, you could get a logic probe and do it that way. Most chips will have a pinout online just google the chip ID number.

[@shahrukh8211]

I don’t have the oscilloscope and i have the same exact model With the same exact problem and i have done everything from visual checking and cleaning . What so you suggest i can check things from a normal multi meter.

[@Four_X]

Get yourself a Logic Probe, there not expensive and check signals like clock, reset, interrupts ect, check the RAM and look for any stuck (High, Low or Floating) signals.

[@vgplayersandhaters518]

first off Great video, Ok so what settings did you have your scope set to when looking for the Signals from the IC's. i just got a analog Scope and still not too familiar on what to set it to. I am working on a Sega nomad that is not doing anything and the VDP gets hotter then anything else on the board when i power it up. the system was working but i made a mistake when trying to fix the regulator(system took 11V for a bit until i noticed what i had done wrong. anyway i was trying to check some clock signals but not sure if i have it set up right. any suggestions would be Great,

[@eddkippax8110]

I've an SMD 2 just like this, needed the usual power repair. But I have black screen. Following your video closely I've tested most things. The crystal, the Z chip etc. There is no obvious signs of capacitor failure, corrosion or broken traces. Of course I've cleaned the cart port and all of the board. What I have noticed on the CPU is where I should have 5v I only have 0.11v... on start up for one second I get an initial reading of 5v then it drops off to 0.11v do you think the CPU may be at fault? The Sega outputs static briefly and static sound through speakers then back to black screen. Your video was great you have some cool equipment!

[@Four_X]

Sounds like a shorted component to me.

[@eddkippax8110]

@@Four_X do you do a repair service? Though probably not cost effective... I'm more curious than anything

[@riogonchar9883]

@Four X, wow this is amazing! In my case each time I touch the video cord (Heprkin HDTV Cable ) where it connects to my Sega Genesis 2, the colors on the screen get screwed, or I get the black screen or no sound. Do you think it is the same problem that I can fix with D Sole Wrinkle? PS: I never done it in my life before, so I am a bit scared :D

[@Four_X]

It's going to be one of two things. 1) dirty DIN pins on the video output connector. 2) dry joint's (solder) on the DIN's video output connection to the PCB.

[@riogonchar9883]

@Four X Update! I looked at my DIN pins as you advised, they were sparkling clean, but I still blew H20 in it as hard as I could :D and wiped the outer metal ring with a cloth and it seem that the problem is gone :D. Phew, hopefully I dont ever have to work the (solder) :D. thanks for your help!

[@JohnSmith-qn3ob]

Is the crystal really dead or did it just need to be resoldered?

[@Four_X]

It was dead as a doornail. Ha.

[@mickb69]

That was some impressive shit! I've just bought an old mk 1 master system and its got black screen. Off back to the shop though.

[@drhidayath]

Did you fix it?

[@Matless]

Hi! interesting video, maybe you can help me.. I have a video issue with my megadrive2, it's fully working except it doesn't show the red channel in RGB. It's connected with rgb scart, i've checked the cable is ok, checked the continuity traces in motherboard from the pins of the connector to the IC11 video encoder to IC6 (pin35) processor... All seems ok, I have continuity. If i connect in composite i see the red, in rgb no. Did you have any suggestions? Is definitely the rgb encoder damaged or can I check other things? Thank you soooo much!

[@erwinvb70]

I have exactly the same issues, flaky power connector and black screen on the Mega Drive I bought on a market last weekend. Wonder how common it is for these crystals to go bad, but I guess it’s probably a combination of bad design and rough handling of these old consoles where a hard bump may fracture the internals if these crystals. Still have to do measurements if mine has the same issue.. will be a challenge to find a replacement for it if it’s actually this component.

[@Four_X]

Good luck with the repair, let me know it you get it working.

[@erwinvb70]

I cleaned out the cartridge slot according your demonstration and the console came alive. I had no audio, but that turned out the PAL I/G switch in the RF modulator was broken and stuck on PAL I, unless I pressed really hard on it.

[@maxwarfield6699]

Complete noob here: I’ve recently acquired an oscilloscope and I’m learning how to use it so, in your case [this video] are you set on AC or Dc coupling? Also, are you on AC or DC trigger? Let me know, I want to learn. Thank you kindly

[@Four_X]

I'm working on a device that is mainly operating at TTL levels (5v Logic) so my scope is set to DC Coupled. The SEGA Mega drive also has analog audio. If I was hunting down a problem on the analog audio side I would have my scope set to AC Coupled.

[@maxwarfield6699]

@@Four_X You say the Sega mega drive has analog audio, again I’m a NOOB so, Isn’t audio always observed on AC coupled, because it behaves like a sinewave? And what other kind of audio is there, digital? Thank you so much for your reply, btw. I like your approach to electronic repairs, you don’t just spew-out a bunch of electronic jargon, you take your time and go about it logically, I like that, I think you’re a good teacher and that’s why I’m now subscribed to your channel. Anyhoo, kudos sir! And thanks again.

[@Four_X]

​@@maxwarfield6699 "so, Isn’t audio always observed on AC coupled, because it behaves like a sinewave". Correct most of the time, However the are occasion when looking at and Audio Signal with a Oscilloscope set to DC Coupled will be advantageous. One of those occasions would be to see if there was any DC offset to the Audio signal. This would at minimum cause distortion to the Audio and indicate there is something wrong somewhere. It's never good practice to couple two devices (I.E. CD Player to a Amplifier) with a DC offset, especially a device that is going to be amplified. A device outputting a high DC offset could also damage the Amplifier. This is also the same with Analog Video. If you watch my “Sinclair ZX Spectrum+ (Plus) 48K - Repair, Mod & Restore” video here kzbin.info/www/bejne/mXablHashrSnY80 at 17:30 you see me perform a Composite video mod and I explain why you have to use a Capacitor to eliminate the DC offset from the Composite video signal when connecting the Composite video signal to a TV.

[@user-wj9xq7ig2v]

I only wish these things were worth a little more they deserve to be saved but it often doesn't make sense to spend time on a bare console that can often be easily replaced for $20.

[@Four_X]

It's still a great day when you can save a retro system.

[@rubenbragado8187]

Muchas gracias por el vídeo,aunque no te entiendo más o menos he comprendido lo que tenia mal,el cristal de cuarzo.

[@Four_X]

I think i can understand, Yes it was a bad cristal.

[@abobonickname5696]

This problem so easy to fix but no one was able to fix it in Nigeria back in the 90s. I never saw a working mega drive 2 as all of them have this same issue. We just only look for the original genesis which can pretty much last forever.

[@robertleuty]

Hi I've just bought MK1 MD and it got a black screen like the one in video I've cleaned the slot no joy how much would I be paying someone to fix do you think thanks. I like your video I would have a go but no gear lol

[@RiotRetroGaming]

I was thinking the reset button was faulty and being held down. And the date on that board I turned 13! it's my birth date haha cool 😂 Good video.... "UNTIL DA NEXT WON" LOOOOL

[@Four_X]

The reset button doesn’t work like that in a sega Mega Drive Ant. The (315-5660) custom sega chip inside the Mega Drive II only triggers a system reset on a falling edge of a low from the reset button. Therefore it wouldn't matter if the reset button was held down it would only invoke a reset once. The Mega Drive II would only reset again once you let go and pressed the reset button again and the (315-5660) custom sega chip recognized a falling edge from the reset button.

[@NeOGiSOnE]

I have the same problem with a sega CDX possible the « Crystal »?

[@intbn]

@FourX2k3: My Mk 1 Megadrive goes dark a few seconds after I plug it in, before that, it's perfect, tried a second SCART, same problem, tried a second TV, same again, the cables not broke, TV configuration is all default, tried game mode and natural etc, made no difference, I'm in Ireland (EU), it's a Mk 1 PAL-I "High definition graphics - stereo sound" 1600-05 model Do you or anyone know what the problem/fix is?

[@rscelectrical7091]

Nice screen captures 😎

[@americanboathead5390]

Wish i had a chrystal lying around!!