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No video - French Master System Model 1 - M4 POWERBASE/NTSC 837-6700
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Hello fellow SMS fans,
I bought a french SMS model 1 and it doesn't output video, even with the RVB adapteur thingy I bought for it. It came to me already like this, with these cables soldered, the last owner didn't know anything about it, it was bought untested, Attached photos 1,2 and 3 are from when I got it, in the 3rd one I already got the pink cable out. So far I've unsoldered all the stuff he had done to it (seems one of the barrel holes has been drilled? I don't get this.) and bridged one of the faulty ceramic caps - green wire(it's totally broken) and it still doesn't output nothing, no video or sound, but the channel does change to AV when I plug it in. You can see the drilled barrel hole and the damaged trace in photo 8, maybe that's why he drilled it? I know my way around the soldering iron but I don't know much about electronics, if the ceramic cap bridge I'm doing it's no good, please tell me how to fix it another way as I don't have any of these around. Any idea on how to fix this French baguette? :/ Thanks a lot! This is how it is now: |
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No video - French Master System Model 1 - M4 POWERBASE/NTSC 837-6700
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This one's not looking good. Not gonna lie. And usually an unsuccessful repair means any damage has gone from bad to worse.
I'm not sure what you mean by "bridged one of the faulty ceramic caps"? There are photos of this model board here which you can use as a reference: https://www.smspower.org/Development/RGBMasterSystemM4POWERBASENTSC837-6700 I'm sure other people on the forum will chime in with help. |
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I think I might have a couple of ideas of what could be happening... but there's happening something here: syncronization signals seem to be correctly outputted if your TV switches automatically.
Csync is a valid composite video signal, just without data. To enter RGB mode, TVs require a voltage to switch. Check if the 5V signal at the connector is being outputted. Alternatively, it could also be that your adapter from scart to HDMI only accepts composite. What have been the conditions of the test? Have you tried with a cartridge in order to test the sound? Not all SMS have a game in their BIOS. |
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Hey there! I bridged the broken cap so the circuit would complete, now without the cap (it completely broke when I touched it) it won't even turn on. :(
I've tried with a cartridge, same thing, the TV is a CRT, a Trinitron, it's working with the other consoles. The RVB Adapteur is the cable needed for these french machines, it's missing the rgb modulator from the factory and that is included in the cable itself. :) Hopefully I can fix it. Thanks! |
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As said, check the 5V at the connector. Check also ground by the way, just for in case.
The French Master System just outputs RGB directly from the VDP, after all they didn't need the composite out. However it also means the VDP is directly exposed to the outside, with all the consequences this implies. If you have an oscilloscope, I would advise you to check the audio and any of the RGB outputs to observe if signal is being generated. |
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How can I test it? I'm pretty new to tinkering with this stuff. :> I do have a multimeter. And about the broken cap and it not powering on now? It was the one I bridged, it's so sad to buy stuff and this happening, now I understand why "untested"... |
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A multimeter won't do the job here. You need an oscilloscope, which is a device that allows to observe the signals being tested. If you had one, you should observe the signal at the distinct points of the transportation from the VDC to the connector. This way you could find the cause of the failure with ease. Acquiring an oscilloscope is an inversion for the future. So if you don't have one and are planning on fix devices in the future, you should consider having one. The only thing that you can do with a multimeter here are basically two jobs. First, with the console turned off, check the ground pin on the AV connector has continuity with any of the ICs ground. If not, find a spot to solder a wire from that pin to ground. Second, with the console turned on but without anything connected at the A/V port check the 5V signal on that connector. If not, wait for instructions, as the 5V source for this pin is not the same source as the one used for the ICs and would require to check the schematics again. By the way, schematics and pinouts can be found at the Development section of the website (not of the forums!) on the upper-right corner of the screen. Please, consider upgrading your equipment. And have good luck with your depuration. |
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I wanted to fix this one, I just do some really easy stuff like changing caps and modding my consoles, ain't looking to buy to fix, for example, this one was a shot in the dark and what a shot it was. :D No other way to check it/ fix it easily right? After the cap completely broke it won't turn on, is that normal? Thanks! :) |
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While a oscilloscope is a nice tool to have, it's not always essential for every repair.
@daeds can you point out the capacitor you speak of in a photo for me? |
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Hey there! It's this one, Thanks! |
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No video - French Master System Model 1 - M4 POWERBASE/NTSC 837-6700
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This ceramic capacitor is a filter capacitor between CSYNC and GND. Bridging it is probably forcing the TV into continuous blanking. This needs to be unbridged and the capacitor replaced with a new one.
Looking at the photos, there is a lot of bad soldering and joints around the AV Connector including a broken trace so we’re going to focus here as a starting point. The Master System AV Connector pinout can be found here: https://www.smspower.org/Development/AVPort This diagram is actually looking into the cable, so the pinout looking into the connector on the console will be flipped left to right. With the console turned off, check the connectivity of the following lines: RED - this pin of the AV connector connects to IC5 pin 26. GREEN - this pin of the AV connector connects to IC5 pin 27. BLUE - this pin of the AV connector connects to IC5 pin 28. CSYNC - this pin of the AV connector connects to IC5 pin 29, possibly through a 2.2K resistor. (This is the broken trace in photos 5 and 7) AUDIO - this pin of the AV connector connects to the negative leg of the 10uF electrolytic capacitor next to the AV connector. The positive leg of the capacitor is then connected to IC5 pin 10. +5V this pin of the AV connector should the +5V rail. GND this pin of the AV connector connects to the ground rail. As well as connectivity also check for bridging between the AV pins. Let’s start with that and go from there. |
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Thank you so much for helping me out, I will try to get my hand at the cap this week and try checking the connections, will need to have the cap put on first, right? Does the missing cap makes it not powering on? Cheers! EDIT1: Found out why it wasn't turning on, the bead inductor (?) on FB1 had some lead leaked in to the board! :| I already cleaned it up well and now it plugs in, should I replace it aswell? My multimeter plugs are too thick to go into the DIN8, can I use some electrical wire, rolled in the plugs, to check the connections? |
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No video - French Master System Model 1 - M4 POWERBASE/NTSC 837-6700
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You can try without the ceramic capacitor. The picture may be glitchy without it, or may not work at all. I'm not sure.
Inductors don't leak lead. That's probably just glue. As long as it shows continuity it's fine.
A paperclip, piece of wire, etc all will work. |
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Weird, maybe I got solder there while trying to unsolder the bad wires that came from the last owner? I will try the checking the connections later on and will let you know, so far, without bridging anything or testing, it turns on and changes channel but no sound or video. :( |
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Already did my testing with the multimeter, here are the results: RED - this pin of the AV connector connects to IC5 pin 26. - Connectivity OK GREEN - this pin of the AV connector connects to IC5 pin 27. - Connectivity OK BLUE - this pin of the AV connector connects to IC5 pin 28. - Connectivity OK CSYNC - this pin of the AV connector connects to IC5 pin 29, possibly through a 2.2K resistor. (This is the broken trace in photos 5 and 7) - No connectivity AUDIO - this pin of the AV connector connects to the negative leg of the 10uF electrolytic capacitor next to the AV connector. The positive leg of the capacitor is then connected to IC5 pin 10. - No connectivity on pin 10, connectivity on cap leg +5V this pin of the AV connector should the +5V rail. - Connecvity OK, tested from the 5v pin to a positive leg on a cap and tab 1 of the CON3 GND this pin of the AV connector connects to the ground rail. - Connectivity OK, tested on the metal shield and the GND tab of CON3 The bridging of the AV pins, how can I test that? Hopefully I can fix this with all your valuable help while learning something as I go. :) Thanks a lot! |
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1) Are you putting your TV in the RGB input ?
2) Is the RBV cable good ? if you move it a little conncted do you see something ? 3) is the image blue/no signal or black screen ? |
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Hey Nuno, I guess the cable is in working condition, I've opened and everything seems OK, it's basically a rgb modulator inside the box, The SCART is plugged in well and the TV changes to a black 4:3 screen, it does change to AV when I plug the console but, no image or sound, can't see to get interference while moving it. Tried it in both my Sony's and my other TV aswell to no avail. :( |
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No video - French Master System Model 1 - M4 POWERBASE/NTSC 837-6700
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You need to fix the connectivity between IC5 and the AV connector for the CSYNC line, and the connectivity between IC5 and the positive leg of the 10uF capacitor for the AUDIO line, to begin with.
For each one, follow the copper track through the jumpers and vias from IC5 towards the destination, testing for continuity with your multi-meter, until you find the break in continuity. When you find the break, solder in your own jumper to fix the break. |
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Scrape and solder a wire, right? :D Edit1: The cap near the AV port for the pin 10 is not working properly it's there where the circuit breaks, the rest talks with each other, I've traced it. Even if I try to check continuinty between the cap legs it wont work, from there forward nothing, but between the other leg and the av port it works. Cap has to be replaced. The csync it's my next step. :) |
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No video - French Master System Model 1 - M4 POWERBASE/NTSC 837-6700
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That's the spirit.
I may be misunderstanding you, but if you're saying you're reading an open circuit when measuring the two legs of the capacitor, that's not a fault. That's how it should measure. A capacitor blocks DC. A shorted capacitor is one that's faulty. Otherwise if you're saying there's a no connectivity between the positive leg of the capacitor and the track coming from IC pin 10, then yeah, that's a fault, and you'll need to fix that. |
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Yeah, read about it yesterday hehe. Yup, there is no connectivity, can it be the cap that it's broken, or the solder joints, for example? By the way, how can I solder the jumpers from beneath through the top, is it possible? The holes are blue. Thanks a lot for all the help, I'm learning a lot as I go. :) EDIT: I bridged it and now I have continuity in every pin, when I plug it in it changes channel to AV and I heard a beeeeeeeeep, Then, I plugged it off and on annd a white screen with some black squares appeared. This is without a game, with a game only black screen comes. When I get the video cable in and out I can see blue, red, green and some beeps aswel. What can I do next? :o |
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One final check I'll have you do is check that each pin of the AV connector has no connectivity with the other pins of the AV connector and +5V and GND.
How long did you have the system on for the tests? Was it long enough to boot? The next steps are going to be more difficult than fixing a couple of traces to the AV connector. There's no guarantee that someone telling you what to do over forum posts will lead to successful diagnosis and repair. |
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So, check continuity between every connector pin with each other and every pin with ground and the 5v rail? Where should I test the 5v and ground on the board? Really hoping I can fix it. :( |
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Anywhere, like the border for ground and the regulator for +5 volt rail. |
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