I really enjoyed watching this Steve. Very refreshing to see a man openly walk through his thoughts and emotions without fear of getting it wrong. Helped me realise I'm not the only one who doubts himself when taking on problems I don't always have the immediate answers to. I'd love to see a follow up video, I get the feeling you're not going to give up on this! Thanks again. 😊
Was looking for ways on how to level up my repairing game past just replacing parts and learned a lot of tricks and things to buy from you and even your mistakes- thanks for doing these and not pretending like you know everything, these are my favorite
Hi Steve, that capacitor is most likely used for decoupling on a power rail and added as a modification at the manufacturers. It could be to solve a stability or intermittent issue. You might find that it became a standard part of the PCB in later revisions of the board. This is common to see on boards as a modification to solve an issue. Sometimes referred to as a "Bodge component". It could also have been left off of the PCB design by accident.
I could more or less watch you repair just about anything and enjoy it MASSIVELY. Thanks so much for some very entertaining and informative videos. I'm even becoming more comfortable with working on some of my own gear, and you're very much a part of the reason why, and I very much appreciate it!
I'm an amateur on a budget. I'm used to watching pros do amazing videos on mods and repairs and I think I like your videos just as much. Great job, I feel like you were close.
I believe what you have there is a system that was once modded and someone has removed the mod then sold the unit. The cut traces, solder blobs on chip pins and the capacitor on the video output all scream a mod job. I would look up videos on how you do video mods to the system and see if you can trace back all the steps and see if something is still disconnected.
I was thinking the exact same thing. Often mods even require to cut certain traces. Which would explain at least some of it. Usually something working then shutting off indicates a semiconductor getting warm and stop working. But I honestly think it's the chip at this point.
Sega systems come from the factory or sega repair with strange additions like capacitors and things. I've seen it on alot of the older sega systems I've been in.
Rubbish. I've seen too many vintage hifi pcb's from equipment I'm 100% sure they were never opened having "modified redesign" from factory to know this could be a (let's call it) a "revision 0" board. Combine that with possible dodgy quality control on both pcb manufacturing and "friday afternoon factory repair" and there you have it.
It looks like pin 7 on the rgb chip is a selector pin to set the chip to ntsc or pal. If you ground it it's set to pal, if you set it high it's ntsc. It's not connected to anything on the working unit because leaving it floating has the same effect as grounding it because it's not set high. My first clue was that on the pinout diagram pal has a line over it. That means it's set to low for pal. I also realized how old this video is so I'm searching your channel to see if you figured it out. And I found it
meant to replay this video, my understanding is the Z80 controls sound, meant to see if the unit crashes at the point sound starts playing when compared to the working unit. There's also a diagnostic cartridge available, which may have helped. Anyway keep the video's coming they are always a good watch.
Found your channel during some time off work and having always enjoyed fault finding and fixing things I’ve proceeded to binge pretty much all your videos. Having started on my own Megadrive 1 with a black screen of death I feel your pain on removing the cart slot but having found broken traces underneath was quite the feeling of success! Though I did a bit more trace damage than you did. Keep up the good work.
those dark spots under the solder mask on the traces is usually a telltale sign of corrosion. Whenever you see it, always scrape it clear, tin it with solder, and apply fresh mask.
when my megadrive had the same issue, I reflowed every joint and cleaned the cart slot with wet and dry sand paper soaked in lighter fluid folded around an old credit card,, then tightened the pins with a fine watch makers screwdriver. That did the trick. However, there was always one cartridge that wouldn't work in it, but it would in my other console. It was an Aklaim made cartridge and I read they can have compatibility issues with some board revisions. Try doing the above and try different cartridges.
The reason mastersystem 2 were used to mod. Is because of the cartridge slot covers. They were easy to cut away the sides, so japanse cartridges would fit. These are round shaped at the corners in stead of European curved ones. If you look at the cartridge slot from the inside of the plastic housing, you will see cutlines were to remove the plastic.to enable Japanese, American cartridges. Therefore these system two's were the preferred system to use. This resulted in system 2 with a switch to switch between 50and 60 herz. And maybe there lies the problem with the black screen.
Awesome video your train of thought is exactly like mine, congrats for the perseverance as I would have chucked it a long time ago lol fingers crossed for a revisit 🤞
When looking at a diagram a line above the pin name means it is active low. The pin is a switch low for NTSC high for PAL or vis versa. A permanently low signal can be achieved by tying it to ground and a high can be achieved by tying the rail to an appropriate power rail. Also I would check the capacitor you found to be shorted to ground on both sides with it out of circuit. If that reads okay out of circuit then the chip that it goes to is more than likely faulty. It could be on a very low resistance line which newer CPU's and graphics chips have. However they are higher wattage devices and I doubt a megadrive would need any high wattages.
This is really useful info, thank you so much. I have been dreaming about that capacitor, as it was the only thing I think I left unsolved. I will definitely be going back to it. Thanks again, it's really appreciated! 👍
Your FNIRSI oscilloscope can measure 5mhz max. Keep the limitations in mind and this will be a very valuable tool. The bigger one, the 1014D can do way more, goes for under $200.
I had the same issue with a MD2. I looked everything.... Looking the pins of IC's on the schematic i had found that reset signal was "on" on the CPU (i dont remember It was the z80 or the motorola) but that order was sent by the IC6, the 315-5660... Never knew if i was right. Nice video!!!! 👍
I have/had the same issue as you have( that is why I watched your vid), only I did not have any broken traces I also have the same cartridge slot as you have, and what helped for me was pushing down in the holes on top of the cartridge port on the pins with some tweezers so the pins would be compressed a bit and protrude some more in the cartridge slot. everywhere I have read that black screens is the cartridge slot, turns out it was right. ps. Do not push in the pins to far so they do not buckle.
Hi, I just bought a package of 2 megadrives and games and had the same issue on both consoles, no picture, no sound but power was on. I used electronic cleaning spray on the cartridge slot and the game and both work now. ( well I fear this wont be an easy fix for StezStix Fix too because he already had a picture for a milisecond )
Don't give up! You are probably very close to fixing the console and it is quite entertaining to watch :) Reminds me when I've spent 4 days on a Game Gear that did not read games. I have even read the service manual like 2-3 times. In the end, I have found a single broken trace when checking the connections of the cartridge connector by the service manual. You don't want to know how much time I have spent cleaning that cartridge connector thinking that it must be a dirty pin... :)
Haha, I know the feeling. I could tell I was getting closer with this one, but I had been working on it for 2 full days and had to send it somewhere. I'll definitely go back to it. I can't sleep at night! 😁
Wondering if it might not be the power regulator. You get a very small window where the system is running but when everything else kicks in it's too demanding for the aged regulator and dies? The fact that you get that licence screen seems to indicate that the video encoder is just fine, or at least "good enough" that it shouldn't be the cause of the system shutting down.
Did you ever end up figuring out what was wrong with this? I started messing around with electronics and soldering about a year ago and now I'm trying my luck at making a handheld Genesis, which I guess is a Nomad lol. I love watching your videos, they teach people to be persistent and to follow hunches that are often the answer to a problem.
I know than I come here way too late for you but my comment can still be useful for anyone who watch this video ^^ For the capacitor, I've seen much uglier from factory. If the brand and/or series of the capacitor matches the other ones, it probably comes from factory as well. Also, the aspect of the soldering can be a clue : most of the time, brighter means later. - @10:04 Yes, it's the Z80. - Oscillators are often used with harmonics of the base frequency, not the base frequency itself. - If the main quartz/oscillator is not working, you won't have anything on the screen. So, if you have "produced by/or under license..." wihout any difference with a working console, then many things are working properly. - @28:59 Your iron is too hot, so it melts the glue of the trace and thus lift it. Also, the white/beige things near the pads show that the iron is hot enough to create bubbles within the PCB (delamination). Definitely too hot. - About choosing an oscilloscope, be sure that it can see the signal properly : to see a 50MHz signal, then choosing an oscilloscope that can see at least twice this frequency, 100MHz here . Nowadays you have excellent 200Mhz rated products from Siglent or Rigol below 300€. For a tool like this it is very cheap. - @44:56 For this kind of chip the choice of the video standard is done with the pin tied to Vcc OR ground. Check in the datasheet if available.
Out of curiosity, when it turned on then blanked out, did you ever put a thermal camera on it to check to see for anything overheating? That should always be the first step when turning something on. Was there ever a part 3?
@@StezStixFix If the short across the IC pins via what looks like a solder bridge, doesn't have a copper track under the solder bridge, then it's highly likely the bridge was made by mistake, there is also a slim chance the bridge is a revision, Mod or Hack via the manufacturer or some previous Gullible owner, I say Gullible because there are a few bad Mods and hack Videos out there, that do what is claimed but in doing so are probably the cause for also damaging ones unit..
Makes sense. I would prefer it to be standard, so if there have been any modifications, then I would be taking them out anyhow. I'm 99% certain the bridge wasn't supposed to be there. It was a blob, not a carefully soldered bridge. And there was no copper track underneath that I could see. Plus there is plenty of room above the chip to have another trace that joins to the trace next to it, so unless it was a mistake when manufacturing the board, I can't see it being right. I will be taking another look at the board tomorrow, so will analyse it properly!
GREAT! I'm so relieved you expected a copper track, Just goes show you're one seriously quick study, prompting me to mull over The Simpsons Mafia Dude as he conveys "I Like THAT" 😎
by look, the voltage is dropping when the power demand goes up. (hence the flash of picture and poof) i know you did a very good amount of eyeballing, but still i would say, check for any potential solder bridges, it could also be polarity is switched. You could also try measure VI curve. If you can.
Hey Steve, the rule I have for electrolytic capacitors is if around two or three smaller caps measures a resistance above 1Ω then I replace them. New electrolytic caps should have very low resistance usually .5Ω or lower
Please explain, are you measuring them on diode mode? Are measuring them out of circuit? Are talking about SMD caps? I don’t think 0.5 Ohms for any cap is even possible, it’s usually way higher. Please explain, I’m trying to learn. Thank you
In my experience, when measuring the output frequency from oscillators you would do better with a dedicated frequency counter that can handle the frequencies involved. Scopes can measure frequency but they tend to be some what limited in bandwidth and hence max frequency measurement unless you spend a lot of money. You could probably find a stand alone frequency counter at a fraction of the cost of a scope with the bandwidth to measure the 50Mhz you are looking for. Frequency counters typically have a higher resolution readout and accuracy than scopes, unless you go for the high end scopes. Bandwidth is very important when it comes to selecting the scope you consider purchasing. My rule of thumb is buy a scope that has double the frequency bandwidth of any frequency you want to examine. On the other hand if a frequency counter specifies it will read 200Mhz its going to be good for at least 200Mhz and not have the same bandwidth limitation of scopes. Obviously there are a lot more factors to consider one being sensitivity. Think of a scope as being more a tool to examine the voltage, period, ratio and shape of wave forms. If you want a scope to do everything in one box with a high bandwidth expect to pay high hundreds or thousands of dollars.
So I got a second generation Genesis for my birthday (July) in 94'. The Red sleve on the connector for the Sega CD is factory. It has both a black shell and the red cover that you take off before connecting.
Hi and thanks for the video ! I enjoyed it soooo much. I like that you speak true and not pretend to know like other guys do. Did you check the cable by any chance ? On this I would have go first by a good overall cleaning of the board, cartridge slot and check the cable. Might be a solution I don't know :)
Hi Steve, I know this is an old video but you could attempt an RGB mod on it. You confirmed that the RGB pins are getting a signal but not the analogue output. If it doesn't work, you could always use the rgb mod on the working one.
The Pinout diagram for the MB3514 chip shows pin 7 NTSC/PAL with the PAL having a line above that info. PAL and NTSC are television standards for different parts of the world. NTSC is used mostly in the USA and Japan, where PAL is used mostly in the UK. That pin tells the chip which TV standard to select for the market its being used. The line above PAL indicates for PAL that pin should be logic LOW or 0Volts, and logic HIGH or 5Volts for selecting NTSC standard assuming a 5Volts supply. As your model was sold for the UK market that pin is held LOW for the PAL standard in the UK. A pin description with a line over it means its active when logic LOW, often seen on Reset and Chip Enable pins.
It seems like a power issue to me. You keep looking at signal data, and clock signal and video output... But what I see happening there is a proper image coming up on the screen. So all of that other stuff is fine, followed by power cutting out.
Hey Steve ! Watched the video again. Did you change the power section capacitors as well ? Dunno looks power related issue to me. Like the game gears do when they have bad capacitors they show a lil something before turning all black. Might be an idea 😛 Apart of that the oscilloscope link is broken. Could you update it or just give here the model ? Thanks a lot again 🤘
First board is a "VA4", which was the first board without any discrete CPUs. The second one is a bit older, it's a "VA1 - PAL". It has two discrete CPUs (Motorola 68000 + Zilog Z80). The newer VA4 also has these CPUs but they are contained in the new SEGA-315-5960 ASIC. ...I would love to tell you that the VA4 is "better", but I guess it was only a bit cheaper to manufacture.
I had a MD2 with the same symptoms, tried everything, even replaced the main CPU from a donor board, nothing worked. Gave up in the end as I was starting to go mad the amount of time spent going over the board. Not worth it for a $40 console.
I have a black screening model 2 myself, from looking at the board one of the pins on a chip looks non shiny and dry compared to the others, one of these days I will just remove the solder and add more and see what happens.
If you have working TMSS, which you do, then you have working CPU to the ROM where TMSS is stored but not necessarily to the cartridge ROM also check the voltage regulator could be an amperage issue.
didnt see clear... is that rusty under capasitor? 41:57 above C30 letters? it is first. second - did you get back that capasitor, that you remove before you find last broken connection? and did you test this capasitor too? did you check voltage after that... how it names... like transistor, but with radiator? 7805 or how it names... maybe it is voltage fault.
Steve the MB or CXA chip is where the video signal video sends out the video, it goes from pin 20 through R49 Resistor, CE12 Cap, 101 EM2 filter to the rear socket. You fixed part of the issues it had, Take the cart slot off completely and check the traces under it, for solid continuity. might not be visible to the eyes, Its a common fault area. Could also try swap the EM filters, both are the same, its just one filters video other audio. Also re-flow the MB chip off the board and check to see if shorts go away. also with regards to the OSC1 Crystal MD 2 PAL clock should be around 3.5Mhz & NTSC Genesis 2 7.6Mhz Thinking about it, it also could be a v-ram problem that's linked to the encoder.
My old memory is getting a work out today LOL! Jump a wire from CE21 Cap negative side, to case of OSC1 crystal. Also another thing i forgot If you can get some thick white paper and soak it in IPA and make sure it gets a good grip in the cart slot, do that end to end and then try a game. 👍
@@Ratchet_effect 😊 Thanks Steve, really appreciate the info again! I felt like I was really close with this one, but I just hit a wall. I did clean the cart slot with a credit card folded around some card dipped in IPA, I just didn't film it. I'm pretty confident the cart slot is ok, I took it off and all traces and pads are good. I can definitely try the jumper from CE21 - what does/will that do?
It should then try force the md to output a signal, In some cases it has worked. The encoder chip needs an oscillator input to generate the portion of the video signal. Some times a helping hand is needed. You can try a 50/60Hz mod with 2 two caps and a resistor to make it switch but..I don't like it as it involves cutting traces. If you exhaust all avenues I'd be happy to take a look at it. I would document everything of corse so you'd get all the information and hopefully fix(s) with its working return. 👍
Hi m8 , did you ever fix this ? Cos my megadrive 2 has the same prob , spash screen , them black screen not reading games . serching google for answers i came across your video .
2:58 If you mind me asking, did you ever figure out what that capacitor was for? I thought to try the Triple Bypass mod for my MD2 VA0, but the cap is in the way. I wasn't sure what to do with it?
seeing the random cat hairs and whatnot under the microscope always makes me want to take the board and give it a bath in IPA lol. wouldn't be very effective, but the reflex is there.
The solder that was jumping the 2 pins on the chip may have meant to be there, ... You fixed the corrosion damaged pin/trace after removing the solder bridge. ... Just a guess
I honestly feel this unit has seen a few attempts at it's repair, and that short is not meant to be there, if it were the two pads would have been printed on as joined, if some revision required the pins to be connected later on, Then a jumper wire would have definitely been used..
Thats what I thought too. It looks like it's been through many hands. Any idea what that capacitor might be doing on the underside of the board, near the video output? I still don't think its factory!
Don't give up come back to it fix that Sega you do great work keep it up keep kicking butt I hope my channel my personal channel will grow as big as yours mine is MCS capsule tech but I subscribe to you on my personal cuz man you rock so relaxing when when you're soldering it's cool to watch
Sorry to see you had no luck l must say you have some patience but this is we’re you need a schematics l had a good friend like you Steve and he would spend hours on a pcb and by the end of the day his brain was fryed so he would look at it first thing next morning and 9 times out of 10 he would find the fault don’t give up mate l hope you fix it thanks for your video 👍😊
Wasn't there a short on C30? Remove that and see if the short is happening. BTW the RGB chips probably have different pinouts as often parts will change between revisions (due to availability) and the new chips require a layout change to accomodate the different pins. Crystal was showing the same 13MHz on each board, crystal speeds are divided down, so a factor of 4 on the nose seemed sensible. The cartridge port you buzzed out, and it was fine, but you got frustrated and took it off anyway even after reflowing the joints. When this level of frustration happens, step away from the soldering iron and reach for the Tetley. Then ask yourself if you really want to remove something that has goo continuity. I see others have recommended to remove the slot, but checking for and resolving any shorts should be first. Good luck fella, don't give up, but don't forget to put the kettle on when you need to either ;)
Love this, thank you! I have a habit of wanting to keep going, but you're right, a cup of tea is never a bad thing. I meant to go back to C30 as it did seem odd. I just got completely sidetracked. I've been dreaming about it ever since, so I will take it off and see if the short is still there. Thanks again! 👍
@@StezStixFix Capacitors, and semiconductors that test with pins that are shorted to ground need further investigation making sure the pin must not be grounded, so when you ever come across a short STOP EVERYTHING and set your goal to remove that short, Links Fuses and inductors BTW can show up as shorts, but if not sure, removing that component in this case the C30 capacitor is the first step, if the capacitor is removed and the short remains return the capacitor but only if it tests as if it is open, and then move on to any other component connected to the same track as C30 "ignore the ground track as were after the shorted component" just bare in mind the track connected to C30 could also be connected to a Via that goes to the other side of the board. A quick and dirty trick is using some IPA splashed on a suspect IC or Capacitor if you don't have a thermal camera at hand, as shorted components tend to get warmer than what they should be..
Thanks Bear! I do have a thermal camera and I actually used it on this but didn't film it. That was before I found the short on C30 though, BUT I only saw the voltage regulator and CPU warm up. Although I wasn't paying great attention to that area. Will check again! I hope its not the CPU.
I have the same issue with a super Nintendo. It just won't show anything on the tv. I believe it's the encoder chip or the main chip. Good luck, I hope you can make it work!
Looks like it's been mod in the past to either overclock or convert to ntsc. It was probably cocked up and the mod chip removed to go in a different machine. Like with the PlayStation some games never got released in the uk
Haha 😂, Hon kanske kan hjälpa dig med estetisk kabeldragning av högtalarkablarna.. 😊 Klart är att ju mer uppmärksamhet det ges, mer klick och pengar kommer in.
I looked again and i am not that convinced that it is moving... One think is certain. Something spilled on the board and I would look for more broken traces. Like the one you have located. also this trace next to your repair. I would re-do this one also. Anyway.... GOOD LUCK!
I have the same exact symptoms, the screen starts to display the "Sega..." text but then it's just a black screen. Would be super nice to get these things going again.
Word of caution in that some voltage regulators have heatsinks which may not be grounded, Also with the two pins Pal-In Pin 7 and Fsc-In pin 6 one or the other needs to be grounded so that the unused or undesirable input is muted, Note if the chip deals with digital signals ie "High or Low" grounding the pin ties to a low. NOW C30 is connected to a short, ergo all the components also connected to the same tracks as C30 "not the grounded side" all have to be tested including all IC's by it's removal, and if the short persists at C30 once a component is removed return that component back to the circuit as it's not the failed component, once the component is returned, remove the next component and test C30 until a component removes the short, once the short is removed order a replacement component for it, and install if you don't know what it is it may be left out if it is a capacitor, but if it's a resistor you will need to find out what it was.. ***HINT*** On booting @ 29:55 There is a distinct Hum which then goes silent and the screen goes black, this indicates the Video out and possibly The Red, Blue, Green Err-RGB Encoder might be OK for a monochrome output "Black and white" but once it needs to deal with Colour "It" or a connected faulty component connected to "it" is what is hindering a full Bootup.. You will fix this as long as replacement components are known and more importantly sourced..
Thanks Bear! Some excellent information as usual 👌. I will definitely be going back to it. It's such a shame my other Mega Drive isn't the same board variation, otherwise I could pinch components off of it to confirm the fault. Hopefully it will be something that I can find info on online. Wish me luck 💪
Hi Bear, hoping you pick this up. I have been testing the components on the same track as the shorted cap C30. I finally got rid of the short by removing an inductor. Which immediately made me think that the inductor was bad, but with you mentioning (on another reply, I think) that an inductor can show up as a short, does that mean it could all be fine and that C30 may be showing a short, even though it actually isn't? Sorry for questions, I'm just getting myself all confused. Anyway, I have ordered up some inductors and will try swapping it out, but in the interim I thought I would pick your brains! Thanks, Steve.
C30 should be with no short, If you remove it and the short on the board disappears, C30 may need to be replaced, if it works reliably without it, then it should be fine. Test C30 for a short out of the Board and if it briefly beeps "or not at all" it can be placed back onto the board. The inductor is essentially a long wire coiled up, so it will beep and show a very low resistance "they would present as a short" ergo functioning as designed, in fact if it didn't beep it would need replacing. But just in case someone has placed it in the wrong place, remove it and try the Mega drive without it. Inductors are designed to mainly block unwanted signals, if the Mega drive still wont work and behaves much the same without it, Place the inductor back to where it was. I would then continue to disconnect every lead connected on the same tracks as C30 "One components lead at a time" and test each component for a short. Once you come across a component that continually beeps while it is out of circuit ***A short beep indicates a large capacitance capacitor which is normal BTW ergo it is not shorted*** to confirm it's a large capacitor swapping the leads once again may present a short beep*** Test the Mega drive across C30 to see if the short is gone, for each component you remove, if the short is gone "no constant Beep" replace the removed component. If I had your Mega Drive, and my thermal camera doesn't show any hot components, I would find a shorted capacitor connected to ground and follow the tracks to any IC connected to the shorted power rail, and remove them, if it's removal removes the short I would replace the IC at all costs with a new one be it an original or another compatible one, Last resort is a second hand IC. Mind you I have all the right tools "well bar a re-balling station so I do the re-balling in a very unusual way that is not quite 100% effective" So yeah if you have a hot air station and a set of ceramic tweezers remove the IC/s also connected to the shorted C30. And as I said.. I hope it's the Z80.
Thanks Bear. I don't want to give away too many spoilers, but the short on C30 (and the pads, once removed) was still there with every component (and IC) i took off, apart from the inductor. Removing the inductor removed the short on that rail! I'll be looking at it again tomorrow, so I may well find something else. I just kinda stopped in my tracks when the short disappeared but ill be spending more time on it. Thanks again for your help, its massively appreciated! 👍
I really enjoyed watching this Steve.
Very refreshing to see a man openly walk through his thoughts and emotions without fear of getting it wrong. Helped me realise I'm not the only one who doubts himself when taking on problems I don't always have the immediate answers to.
I'd love to see a follow up video, I get the feeling you're not going to give up on this! Thanks again. 😊
*just found the follow up 😅
😁 thanks Daniel! This one was a bit of a roller coaster! Glad you found the follow up!👍
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Was looking for ways on how to level up my repairing game past just replacing parts and learned a lot of tricks and things to buy from you and even your mistakes- thanks for doing these and not pretending like you know everything, these are my favorite
Hi Steve, that capacitor is most likely used for decoupling on a power rail and added as a modification at the manufacturers. It could be to solve a stability or intermittent issue.
You might find that it became a standard part of the PCB in later revisions of the board. This is common to see on boards as a modification to solve an issue.
Sometimes referred to as a "Bodge component". It could also have been left off of the PCB design by accident.
I could more or less watch you repair just about anything and enjoy it MASSIVELY. Thanks so much for some very entertaining and informative videos. I'm even becoming more comfortable with working on some of my own gear, and you're very much a part of the reason why, and I very much appreciate it!
Holy cow! I can appreciate how much effort you put into these Mega Drives. I saved up for a year to afford my one back in the 90’s..
Mate.. this is such a rollercoaster, I can hear the frustration/ sadness in your voice
Thanks Kip! Yeah, this was one hell of a ride. I spent far too many hours working on this! 😬
I'm an amateur on a budget. I'm used to watching pros do amazing videos on mods and repairs and I think I like your videos just as much. Great job, I feel like you were close.
I believe what you have there is a system that was once modded and someone has removed the mod then sold the unit. The cut traces, solder blobs on chip pins and the capacitor on the video output all scream a mod job. I would look up videos on how you do video mods to the system and see if you can trace back all the steps and see if something is still disconnected.
Also very possible. Might also explain the shutdown if there's something fucky going on with which region it thinks it is.
I was thinking the exact same thing. Often mods even require to cut certain traces. Which would explain at least some of it.
Usually something working then shutting off indicates a semiconductor getting warm and stop working.
But I honestly think it's the chip at this point.
Sega systems come from the factory or sega repair with strange additions like capacitors and things. I've seen it on alot of the older sega systems I've been in.
Rubbish. I've seen too many vintage hifi pcb's from equipment I'm 100% sure they were never opened having "modified redesign" from factory to know this could be a (let's call it) a "revision 0" board. Combine that with possible dodgy quality control on both pcb manufacturing and "friday afternoon factory repair" and there you have it.
It looks like pin 7 on the rgb chip is a selector pin to set the chip to ntsc or pal. If you ground it it's set to pal, if you set it high it's ntsc. It's not connected to anything on the working unit because leaving it floating has the same effect as grounding it because it's not set high. My first clue was that on the pinout diagram pal has a line over it. That means it's set to low for pal. I also realized how old this video is so I'm searching your channel to see if you figured it out. And I found it
I've binged a ton of your content now. This was the best and most informative by far.
meant to replay this video, my understanding is the Z80 controls sound, meant to see if the unit crashes at the point sound starts playing when compared to the working unit. There's also a diagnostic cartridge available, which may have helped. Anyway keep the video's coming they are always a good watch.
Found your channel during some time off work and having always enjoyed fault finding and fixing things I’ve proceeded to binge pretty much all your videos.
Having started on my own Megadrive 1 with a black screen of death I feel your pain on removing the cart slot but having found broken traces underneath was quite the feeling of success! Though I did a bit more trace damage than you did.
Keep up the good work.
those dark spots under the solder mask on the traces is usually a telltale sign of corrosion. Whenever you see it, always scrape it clear, tin it with solder, and apply fresh mask.
when my megadrive had the same issue, I reflowed every joint and cleaned the cart slot with wet and dry sand paper soaked in lighter fluid folded around an old credit card,, then tightened the pins with a fine watch makers screwdriver. That did the trick. However, there was always one cartridge that wouldn't work in it, but it would in my other console. It was an Aklaim made cartridge and I read they can have compatibility issues with some board revisions. Try doing the above and try different cartridges.
NGL when you said our friend Corrosion, I was half was half expecting The Sisters Of Mercy to kick in.
The reason mastersystem 2 were used to mod. Is because of the cartridge slot covers. They were easy to cut away the sides, so japanse cartridges would fit. These are round shaped at the corners in stead of European curved ones. If you look at the cartridge slot from the inside of the plastic housing, you will see cutlines were to remove the plastic.to enable Japanese, American cartridges. Therefore these system two's were the preferred system to use. This resulted in system 2 with a switch to switch between 50and 60 herz. And maybe there lies the problem with the black screen.
OMG you just brought an oscilloscope to the game!! Love how you follow your intuition....massively entertaining and motivational, thank you very much
Yeah, I really appreciate your effort and will to keep searching, work through the frustration. I really felt this episode!
@10.30 whilst you were removing the solder blob, the first leg on the left looked like it had pulled away from the board. Possibility.
10:30 Put the solderblob back on this two Leg and test it again?
I really enjoy watching your videos and I especially appreciate your patience and determination to find and fix issues.
Awesome video your train of thought is exactly like mine, congrats for the perseverance as I would have chucked it a long time ago lol fingers crossed for a revisit 🤞
Thanks Nick, I was very close to giving up a few times, but in the end I really didn't want to give up at all! Can't wait to give it another go 👍
Hey just wanted to let you know I found your channel today and I must say I love it! Keep them coming
Awesome! Thank you! 👍
Whew im glad you put a link to your underpants. Vital troubleshooting equipment!
When looking at a diagram a line above the pin name means it is active low. The pin is a switch low for NTSC high for PAL or vis versa. A permanently low signal can be achieved by tying it to ground and a high can be achieved by tying the rail to an appropriate power rail.
Also I would check the capacitor you found to be shorted to ground on both sides with it out of circuit. If that reads okay out of circuit then the chip that it goes to is more than likely faulty. It could be on a very low resistance line which newer CPU's and graphics chips have. However they are higher wattage devices and I doubt a megadrive would need any high wattages.
This is really useful info, thank you so much. I have been dreaming about that capacitor, as it was the only thing I think I left unsolved. I will definitely be going back to it. Thanks again, it's really appreciated! 👍
Fair play! You're great at making content - subbed - I admire your perseverance!
Your FNIRSI oscilloscope can measure 5mhz max. Keep the limitations in mind and this will be a very valuable tool. The bigger one, the 1014D can do way more, goes for under $200.
I had the same issue with a MD2. I looked everything.... Looking the pins of IC's on the schematic i had found that reset signal was "on" on the CPU (i dont remember It was the z80 or the motorola) but that order was sent by the IC6, the 315-5660... Never knew if i was right. Nice video!!!! 👍
I enjoy your videos, and your persistence. I appreciate that you show all, all, the attempts you made to fix this really sus board. Kudos
I think, although I’m not 100% sure that those chip legs were supposed to be soldered together. Pin 19 and 21 are both ground
It was my thoughts too.
You put so much energy into this. Sad to see it couldn’t be repaired….. yet.
Thanks for the spoiler.....
@@Charlie_Crown don’t read comments before watching.
@@OOOHBILLY your comment was visible just below the vid, in full view, unavoidable, ok buddy...
@@Charlie_Crown cool story bro
@@OOOHBILLY no, not a story, a fact, just a dirty great spoiler, unfortunately...
I have/had the same issue as you have( that is why I watched your vid), only I did not have any broken traces I also have the same cartridge slot as you have, and what helped for me was pushing down in the holes on top of the cartridge port on the pins with some tweezers so the pins would be compressed a bit and protrude some more in the cartridge slot. everywhere I have read that black screens is the cartridge slot, turns out it was right. ps. Do not push in the pins to far so they do not buckle.
Thanks for the info Unicron! Glad you got yours sorted 👍
Hi, I just bought a package of 2 megadrives and games and had the same issue on both consoles, no picture, no sound but power was on. I used electronic cleaning spray on the cartridge slot and the game and both work now. ( well I fear this wont be an easy fix for StezStix Fix too because he already had a picture for a milisecond )
Don't give up!
You are probably very close to fixing the console and it is quite entertaining to watch :)
Reminds me when I've spent 4 days on a Game Gear that did not read games. I have even read the service manual like 2-3 times. In the end, I have found a single broken trace when checking the connections of the cartridge connector by the service manual. You don't want to know how much time I have spent cleaning that cartridge connector thinking that it must be a dirty pin... :)
Haha, I know the feeling. I could tell I was getting closer with this one, but I had been working on it for 2 full days and had to send it somewhere. I'll definitely go back to it. I can't sleep at night! 😁
@@StezStixFix update?
Wondering if it might not be the power regulator. You get a very small window where the system is running but when everything else kicks in it's too demanding for the aged regulator and dies?
The fact that you get that licence screen seems to indicate that the video encoder is just fine, or at least "good enough" that it shouldn't be the cause of the system shutting down.
Did you ever end up figuring out what was wrong with this? I started messing around with electronics and soldering about a year ago and now I'm trying my luck at making a handheld Genesis, which I guess is a Nomad lol. I love watching your videos, they teach people to be persistent and to follow hunches that are often the answer to a problem.
Yes, he revisited this machine at ruclips.net/video/zPLaiYuC2Dc/видео.html
I know than I come here way too late for you but my comment can still be useful for anyone who watch this video ^^
For the capacitor, I've seen much uglier from factory. If the brand and/or series of the capacitor matches the other ones, it probably comes from factory as well. Also, the aspect of the soldering can be a clue : most of the time, brighter means later.
- @10:04 Yes, it's the Z80.
- Oscillators are often used with harmonics of the base frequency, not the base frequency itself.
- If the main quartz/oscillator is not working, you won't have anything on the screen. So, if you have "produced by/or under license..." wihout any difference with a working console, then many things are working properly.
- @28:59 Your iron is too hot, so it melts the glue of the trace and thus lift it. Also, the white/beige things near the pads show that the iron is hot enough to create bubbles within the PCB (delamination). Definitely too hot.
- About choosing an oscilloscope, be sure that it can see the signal properly : to see a 50MHz signal, then choosing an oscilloscope that can see at least twice this frequency, 100MHz here . Nowadays you have excellent 200Mhz rated products from Siglent or Rigol below 300€. For a tool like this it is very cheap.
- @44:56 For this kind of chip the choice of the video standard is done with the pin tied to Vcc OR ground. Check in the datasheet if available.
Out of curiosity, when it turned on then blanked out, did you ever put a thermal camera on it to check to see for anything overheating? That should always be the first step when turning something on.
Was there ever a part 3?
Yes, at ruclips.net/video/zPLaiYuC2Dc/видео.html
Agree Lee put the short back, good luck
Thanks Jonathan. Will definitely give that a try! 👍
@@StezStixFix If the short across the IC pins via what looks like a solder bridge, doesn't have a copper track under the solder bridge, then it's highly likely the bridge was made by mistake, there is also a slim chance the bridge is a revision, Mod or Hack via the manufacturer or some previous Gullible owner, I say Gullible because there are a few bad Mods and hack Videos out there, that do what is claimed but in doing so are probably the cause for also damaging ones unit..
Makes sense. I would prefer it to be standard, so if there have been any modifications, then I would be taking them out anyhow. I'm 99% certain the bridge wasn't supposed to be there. It was a blob, not a carefully soldered bridge. And there was no copper track underneath that I could see. Plus there is plenty of room above the chip to have another trace that joins to the trace next to it, so unless it was a mistake when manufacturing the board, I can't see it being right. I will be taking another look at the board tomorrow, so will analyse it properly!
GREAT! I'm so relieved you expected a copper track, Just goes show you're one seriously quick study, prompting me to mull over The Simpsons Mafia Dude as he conveys "I Like THAT" 😎
@@KorAllRBare 🤣
by look, the voltage is dropping when the power demand goes up. (hence the flash of picture and poof) i know you did a very good amount of eyeballing, but still i would say, check for any potential solder bridges, it could also be polarity is switched. You could also try measure VI curve. If you can.
the capacitor is there for over/ under load protection varible power needs
was put into later models to correct fluctuations in the circuit
That red strip covering the connector that goes into the mega CD 2 or mega CD 1
Star Trek quote here.
"When you eliminate the impossible, whatever remains, however improbable, must be the truth." - Spock
Actually, a quote from Sherlock Holmes
Hey Steve, the rule I have for electrolytic capacitors is if around two or three smaller caps measures a resistance above 1Ω then I replace them. New electrolytic caps should have very low resistance usually .5Ω or lower
Out of circuit, right?
Please explain, are you measuring them on diode mode? Are measuring them out of circuit? Are talking about SMD caps? I don’t think 0.5 Ohms for any cap is even possible, it’s usually way higher. Please explain, I’m trying to learn. Thank you
In my experience, when measuring the output frequency from oscillators you would do better with a dedicated frequency counter that can handle the frequencies involved.
Scopes can measure frequency but they tend to be some what limited in bandwidth and hence max frequency measurement unless you spend a lot of money.
You could probably find a stand alone frequency counter at a fraction of the cost of a scope with the bandwidth to measure the 50Mhz you are looking for.
Frequency counters typically have a higher resolution readout and accuracy than scopes, unless you go for the high end scopes.
Bandwidth is very important when it comes to selecting the scope you consider purchasing.
My rule of thumb is buy a scope that has double the frequency bandwidth of any frequency you want to examine.
On the other hand if a frequency counter specifies it will read 200Mhz its going to be good for at least 200Mhz and not have the same bandwidth limitation of scopes.
Obviously there are a lot more factors to consider one being sensitivity. Think of a scope as being more a tool to examine the voltage, period, ratio and shape of wave forms.
If you want a scope to do everything in one box with a high bandwidth expect to pay high hundreds or thousands of dollars.
Yes KB.. I checked the specs for that meter and it tops out at 5 Mhz. Good call. Cheers!
@@ovalwingnut Welcome.
So I got a second generation Genesis for my birthday (July) in 94'. The Red sleve on the connector for the Sega CD is factory. It has both a black shell and the red cover that you take off before connecting.
Hi and thanks for the video ! I enjoyed it soooo much. I like that you speak true and not pretend to know like other guys do.
Did you check the cable by any chance ? On this I would have go first by a good overall cleaning of the board, cartridge slot and check the cable.
Might be a solution I don't know :)
Hi Steve, I know this is an old video but you could attempt an RGB mod on it. You confirmed that the RGB pins are getting a signal but not the analogue output.
If it doesn't work, you could always use the rgb mod on the working one.
Great vid, it’s really a thriller. Looking forward to the follow up!
It's at ruclips.net/video/zPLaiYuC2Dc/видео.html
42:06 there is corrosion under the condensator. You should check above the c30 condensator.
Nice vid!
For what is that cartridge looking side of the board?
OMG, pure gold, a solid effort, and brutally entertaining.
Had the same issue with my MD. Black screen. It appeared the PSU became faulty. I replaced the filtering caps, the diodes and it worked again.
Minute 19:41 the trace next to the one you repaired looks also broken to me (the one above the upside down "4")
The Pinout diagram for the MB3514 chip shows pin 7 NTSC/PAL with the PAL having a line above that info. PAL and NTSC are television standards for different parts of the world.
NTSC is used mostly in the USA and Japan, where PAL is used mostly in the UK. That pin tells the chip which TV standard to select for the market its being used.
The line above PAL indicates for PAL that pin should be logic LOW or 0Volts, and logic HIGH or 5Volts for selecting NTSC standard assuming a 5Volts supply.
As your model was sold for the UK market that pin is held LOW for the PAL standard in the UK.
A pin description with a line over it means its active when logic LOW, often seen on Reset and Chip Enable pins.
11:58: Thanks I am gonna have nightmares now
The epic quest continues. Nice!
It seems like a power issue to me. You keep looking at signal data, and clock signal and video output... But what I see happening there is a proper image coming up on the screen. So all of that other stuff is fine, followed by power cutting out.
Aren’t parallel caps good for cleaning up signal noise? Surely that’s all that capacitor was for? And yeah it definitely looks like an addition.
For the crystal to measure, you need an oscilloscope. You came a long way, kudos for trying and failing live, not many show that.
Hey Steve ! Watched the video again.
Did you change the power section capacitors as well ? Dunno looks power related issue to me. Like the game gears do when they have bad capacitors they show a lil something before turning all black.
Might be an idea 😛
Apart of that the oscilloscope link is broken. Could you update it or just give here the model ?
Thanks a lot again 🤘
First board is a "VA4", which was the first board without any discrete CPUs. The second one is a bit older, it's a "VA1 - PAL". It has two discrete CPUs (Motorola 68000 + Zilog Z80).
The newer VA4 also has these CPUs but they are contained in the new SEGA-315-5960 ASIC.
...I would love to tell you that the VA4 is "better", but I guess it was only a bit cheaper to manufacture.
The cap on the back is "factory" by the way
correction: the VA1.8 used a Zilog Z80, your VA1 uses a Toshiba Z80 (as you have already found out yourself)
Hi Steve, enjoing your videos. Have you tried bridging the two legs again on that chip? Could be this was intentionally done in factory
I had a MD2 with the same symptoms, tried everything, even replaced the main CPU from a donor board, nothing worked.
Gave up in the end as I was starting to go mad the amount of time spent going over the board. Not worth it for a $40 console.
I have a black screening model 2 myself, from looking at the board one of the pins on a chip looks non shiny and dry compared to the others, one of these days I will just remove the solder and add more and see what happens.
If you have working TMSS, which you do, then you have working CPU to the ROM where TMSS is stored but not necessarily to the cartridge ROM also check the voltage regulator could be an amperage issue.
Problem solved ? Same on my Multimega after TMSS black screen only do you have check IC7 vram?
didnt see clear... is that rusty under capasitor? 41:57 above C30 letters? it is first. second - did you get back that capasitor, that you remove before you find last broken connection? and did you test this capasitor too? did you check voltage after that... how it names... like transistor, but with radiator? 7805 or how it names... maybe it is voltage fault.
Maybe if you join the 2 points in the Z80 chip what you separated first
29:04 last pad, bottom row. Trace looks broken at the via... maybe?
After you swapped the crystals, I could almost hear "f**k you sonic" as he appeared mocking you
17:27 that nick supposed to be there? 5th line above c9 diagonal, theres 3 but center looks nicked hard.
The somber music at the got got me 😂😢
Steve the MB or CXA chip is where the video signal video sends out the video, it goes from pin 20 through R49 Resistor, CE12 Cap, 101 EM2 filter to the rear socket.
You fixed part of the issues it had, Take the cart slot off completely and check the traces under it, for solid continuity. might not be visible to the eyes, Its a common fault area.
Could also try swap the EM filters, both are the same, its just one filters video other audio. Also re-flow the MB chip off the board and check to see if shorts go away. also with
regards to the OSC1 Crystal MD 2 PAL clock should be around 3.5Mhz & NTSC Genesis 2 7.6Mhz Thinking about it, it also could be a v-ram problem that's linked to the encoder.
My old memory is getting a work out today LOL! Jump a wire from CE21 Cap negative side, to case of OSC1 crystal. Also another thing i forgot
If you can get some thick white paper and soak it in IPA and make sure it gets a good grip in the cart slot, do that end to end and then try a game. 👍
@@Ratchet_effect 😊 Thanks Steve, really appreciate the info again! I felt like I was really close with this one, but I just hit a wall. I did clean the cart slot with a credit card folded around some card dipped in IPA, I just didn't film it. I'm pretty confident the cart slot is ok, I took it off and all traces and pads are good. I can definitely try the jumper from CE21 - what does/will that do?
Thanks Steve, will take a look at these things for sure. Really appreciate the info! 👍
It should then try force the md to output a signal, In some cases it has worked. The encoder chip needs an oscillator input to generate the portion of the video signal. Some times a helping hand is needed. You can try a 50/60Hz mod with 2 two caps and a resistor to make it switch but..I don't like it as it involves cutting traces. If you exhaust all avenues I'd be happy to take a look at it. I would document everything of corse so you'd get all the information and hopefully fix(s) with its working return. 👍
@@Ratchet_effect awesome, thanks Steve. I'll give it another go and then if I fail again, it's yours! 😁
Hi m8 , did you ever fix this ? Cos my megadrive 2 has the same prob , spash screen , them black screen not reading games . serching google for answers i came across your video .
2:58 If you mind me asking, did you ever figure out what that capacitor was for? I thought to try the Triple Bypass mod for my MD2 VA0, but the cap is in the way. I wasn't sure what to do with it?
@ 15:19 is that a damaged trace?
seeing the random cat hairs and whatnot under the microscope always makes me want to take the board and give it a bath in IPA lol. wouldn't be very effective, but the reflex is there.
The solder that was jumping the 2 pins on the chip may have meant to be there, ... You fixed the corrosion damaged pin/trace after removing the solder bridge. ... Just a guess
Thanks Lee. Good call. I didn't think to restore that just in case. I'll give it a go, nothing to lose 👍
Dave Jones at EEVBlog just did a video on why shorts like that are sometimes needed.
@@CygnusTM Thanks Todd, I'll check that out!
I honestly feel this unit has seen a few attempts at it's repair, and that short is not meant to be there, if it were the two pads would have been printed on as joined, if some revision required the pins to be connected later on, Then a jumper wire would have definitely been used..
Thats what I thought too. It looks like it's been through many hands. Any idea what that capacitor might be doing on the underside of the board, near the video output? I still don't think its factory!
Don't give up come back to it fix that Sega you do great work keep it up keep kicking butt I hope my channel my personal channel will grow as big as yours mine is MCS capsule tech but I subscribe to you on my personal cuz man you rock so relaxing when when you're soldering it's cool to watch
OKI! I cruised past their HQ in Tokyo a few years ago.
Can you share the magnifying apparatus you feature in this video?
Sorry to see you had no luck l must say you have some patience but this is we’re you need a schematics l had a good friend like you Steve and he would spend hours on a pcb and by the end of the day his brain was fryed so he would look at it first thing next morning and 9 times out of 10 he would find the fault don’t give up mate l hope you fix it thanks for your video 👍😊
The corrosion around the capacitor means it is leaking and therefore not working @ 6:12
Why don't you use your IR camera and once is powered on check if something there is overheating?
When you see signs of flux and cotton left by ear sticks or whatever they're called it's pretty sure that isn't factory and it was opened before
Wasn't there a short on C30? Remove that and see if the short is happening. BTW the RGB chips probably have different pinouts as often parts will change between revisions (due to availability) and the new chips require a layout change to accomodate the different pins. Crystal was showing the same 13MHz on each board, crystal speeds are divided down, so a factor of 4 on the nose seemed sensible. The cartridge port you buzzed out, and it was fine, but you got frustrated and took it off anyway even after reflowing the joints. When this level of frustration happens, step away from the soldering iron and reach for the Tetley. Then ask yourself if you really want to remove something that has goo continuity. I see others have recommended to remove the slot, but checking for and resolving any shorts should be first. Good luck fella, don't give up, but don't forget to put the kettle on when you need to either ;)
Love this, thank you! I have a habit of wanting to keep going, but you're right, a cup of tea is never a bad thing.
I meant to go back to C30 as it did seem odd. I just got completely sidetracked. I've been dreaming about it ever since, so I will take it off and see if the short is still there. Thanks again! 👍
@@StezStixFix Capacitors, and semiconductors that test with pins that are shorted to ground need further investigation making sure the pin must not be grounded, so when you ever come across a short STOP EVERYTHING and set your goal to remove that short, Links Fuses and inductors BTW can show up as shorts, but if not sure, removing that component in this case the C30 capacitor is the first step, if the capacitor is removed and the short remains return the capacitor but only if it tests as if it is open, and then move on to any other component connected to the same track as C30 "ignore the ground track as were after the shorted component" just bare in mind the track connected to C30 could also be connected to a Via that goes to the other side of the board. A quick and dirty trick is using some IPA splashed on a suspect IC or Capacitor if you don't have a thermal camera at hand, as shorted components tend to get warmer than what they should be..
Thanks Bear! I do have a thermal camera and I actually used it on this but didn't film it. That was before I found the short on C30 though, BUT I only saw the voltage regulator and CPU warm up. Although I wasn't paying great attention to that area. Will check again! I hope its not the CPU.
@@StezStixFix pretty sure the cpu is actually a common one ergo cheap to replace, but yeah hope its an easier component to replace..
I would have tested that cap while it was out. 👍
I dont understand why you not work with air, or comressed air to get rid of dust and equal dirty things
New sub here. I don't know what it is about you but I love your content keep it up
I have the same random capacitor on mine as well
Hey Mitchy. Yeah, I since found out that it's apparently a factory mod on some board revisions. I think to filter out some noise from the AV output.
Did we look at the reset button on this one?
I have the same issue with a super Nintendo. It just won't show anything on the tv. I believe it's the encoder chip or the main chip. Good luck, I hope you can make it work!
Thanks Petros! Hope you get your SNES working too! 😊
Looks like it's been mod in the past to either overclock or convert to ntsc. It was probably cocked up and the mod chip removed to go in a different machine. Like with the PlayStation some games never got released in the uk
Good try lots of effort I hope it gets there in the end what if it don't don't beat yourself up you tried the hardest
1st class video to watch thank you take care kind regards from me kenneth
Haha 😂, Hon kanske kan hjälpa dig med estetisk kabeldragning av högtalarkablarna.. 😊
Klart är att ju mer uppmärksamhet det ges, mer klick och pengar kommer in.
Hey Steve, about this trace leading to main chip... was this leg at the end moving? could you poke it again???
I looked again and i am not that convinced that it is moving... One think is certain. Something spilled on the board and I would look for more broken traces. Like the one you have located. also this trace next to your repair. I would re-do this one also.
Anyway.... GOOD LUCK!
I have the same exact symptoms, the screen starts to display the "Sega..." text but then it's just a black screen. Would be super nice to get these things going again.
Was that a later model console or did you guys get a different design over in Europe?
Word of caution in that some voltage regulators have heatsinks which may not be grounded, Also with the two pins Pal-In Pin 7 and Fsc-In pin 6 one or the other needs to be grounded so that the unused or undesirable input is muted, Note if the chip deals with digital signals ie "High or Low" grounding the pin ties to a low.
NOW C30 is connected to a short, ergo all the components also connected to the same tracks as C30 "not the grounded side" all have to be tested including all IC's by it's removal, and if the short persists at C30 once a component is removed return that component back to the circuit as it's not the failed component, once the component is returned, remove the next component and test C30 until a component removes the short, once the short is removed order a replacement component for it, and install if you don't know what it is it may be left out if it is a capacitor, but if it's a resistor you will need to find out what it was..
***HINT*** On booting @ 29:55 There is a distinct Hum which then goes silent and the screen goes black, this indicates the Video out and possibly The Red, Blue, Green Err-RGB Encoder might be OK for a monochrome output "Black and white" but once it needs to deal with Colour "It" or a connected faulty component connected to "it" is what is hindering a full Bootup..
You will fix this as long as replacement components are known and more importantly sourced..
Thanks Bear! Some excellent information as usual 👌. I will definitely be going back to it. It's such a shame my other Mega Drive isn't the same board variation, otherwise I could pinch components off of it to confirm the fault.
Hopefully it will be something that I can find info on online. Wish me luck 💪
Hi Bear, hoping you pick this up. I have been testing the components on the same track as the shorted cap C30. I finally got rid of the short by removing an inductor. Which immediately made me think that the inductor was bad, but with you mentioning (on another reply, I think) that an inductor can show up as a short, does that mean it could all be fine and that C30 may be showing a short, even though it actually isn't? Sorry for questions, I'm just getting myself all confused. Anyway, I have ordered up some inductors and will try swapping it out, but in the interim I thought I would pick your brains! Thanks, Steve.
C30 should be with no short,
If you remove it and the short on the board disappears, C30 may need to be replaced, if it works reliably without it, then it should be fine.
Test C30 for a short out of the Board and if it briefly beeps "or not at all" it can be placed back onto the board.
The inductor is essentially a long wire coiled up, so it will beep and show a very low resistance "they would present as a short" ergo functioning as designed, in fact if it didn't beep it would need replacing.
But just in case someone has placed it in the wrong place, remove it and try the Mega drive without it.
Inductors are designed to mainly block unwanted signals, if the Mega drive still wont work and behaves much the same without it, Place the inductor back to where it was.
I would then continue to disconnect every lead connected on the same tracks as C30 "One components lead at a time" and test each component for a short.
Once you come across a component that continually beeps while it is out of circuit
***A short beep indicates a large capacitance capacitor which is normal BTW ergo it is not shorted*** to confirm it's a large capacitor swapping the leads once again may present a short beep***
Test the Mega drive across C30 to see if the short is gone, for each component you remove, if the short is gone "no constant Beep" replace the removed component.
If I had your Mega Drive, and my thermal camera doesn't show any hot components, I would find a shorted capacitor connected to ground and follow the tracks to any IC connected to the shorted power rail, and remove them, if it's removal removes the short I would replace the IC at all costs with a new one be it an original or another compatible one, Last resort is a second hand IC.
Mind you I have all the right tools "well bar a re-balling station so I do the re-balling in a very unusual way that is not quite 100% effective"
So yeah if you have a hot air station and a set of ceramic tweezers remove the IC/s also connected to the shorted C30.
And as I said.. I hope it's the Z80.
@@StezStixFix An inductor is supposed to give you a short.
Thanks Bear. I don't want to give away too many spoilers, but the short on C30 (and the pads, once removed) was still there with every component (and IC) i took off, apart from the inductor. Removing the inductor removed the short on that rail!
I'll be looking at it again tomorrow, so I may well find something else. I just kinda stopped in my tracks when the short disappeared but ill be spending more time on it.
Thanks again for your help, its massively appreciated! 👍
Can you tell me what microscope you use please