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Can you snap a picture of your PCB for us in hi-res please ?Are there any particular pins you would recommend beeping out or do they all want doing? I'm just asking as there are 384 of them and I think I'm going to go cross eyed as they're quite tricky to probe
I think @Darksoft has to help a bit here, it's clearly the GFX2 block which has issues so you should focus the search around the devices which control that bank.
Alternately you could drag solder/reflow the pins the FPGA/CPLD devices and see if that helps.
Thanks rtw. I've uploaded some PCB photos [here], they're towards the end of the gallery. Once open there is a 'sizes' button on the bottom right of the screen. Click 'TV & Computer (4K)' for full size.
I've just taken some overall photos of the whole board, let me know if you want a photo of anything in particular.
I've not drag soldered anything before, if I do I'll have to find a scrap board to practice on as I don't want to wreck this one.
I've just taken some overall photos of the whole board, let me know if you want a photo of anything in particular.
I've not drag soldered anything before, if I do I'll have to find a scrap board to practice on as I don't want to wreck this one.
Thanks for the video rtw, that's a better one than I had seen previously.
Looking at my iron my tip is far too big though. There are some tiny components that are close to the ICs that could be troublesome.
I started checking continuity between some of the pins on the multi and I am getting continuity and/or low ohms between some but I'm sure there are a few common pins and so I will get these results. Before I can go any further I really need the pinout of the connectors so I know which ones should be common and which ones shouldn't, it might also help to find which pins I should be checking for continuity between multi>mobo.
@Darksoft , can you help?
Looking at my iron my tip is far too big though. There are some tiny components that are close to the ICs that could be troublesome.
I started checking continuity between some of the pins on the multi and I am getting continuity and/or low ohms between some but I'm sure there are a few common pins and so I will get these results. Before I can go any further I really need the pinout of the connectors so I know which ones should be common and which ones shouldn't, it might also help to find which pins I should be checking for continuity between multi>mobo.
@Darksoft , can you help?
let me see what I can get, but a few ohms is bad. There shouldn't be any continuity at all between pins. Please make sure you try first for shortcuts with the multi pcb dismounted and if all looks good then you can test continuity with it mounted. I'm convinced that there are some small solder blobs in some pins causing your issue. Maybe a cold solder or similar with so many pins there sometimes somethings escape out of the quality control.
Thanks Pablo.
I could have sworn that I saw a pinout for the interboard connectors somewhere but maybe I was dreaming it. I had it in my head that there were quite a few common pins at the top and bottom of each connector. I'm definitely getting continuity between some of these pins with the multi-disconnected....
I could have sworn that I saw a pinout for the interboard connectors somewhere but maybe I was dreaming it. I had it in my head that there were quite a few common pins at the top and bottom of each connector. I'm definitely getting continuity between some of these pins with the multi-disconnected....
Hi Pablo,
Did you manage to find any information regarding the pinout? I still have the same issues
I need to know which pins I need to check continuity of between the cart and mobo when connected together. Which pins might affect the GFX issues I'm having?
Also, are you sure that there should be no continuity between any of the pins when the cart is disconnected? I ask because I have a lot of pins that have continuity between them.
If you look at the multi cart and took the pin numbering as follows:
.....then if I put one probe on J3 C1 I then have continuity between the following other pins in the J3 connector:
J3 C1 + J3 B1
J3 C1 + J3 C2
J3 C1 + J3 B2
J3 C1 + J3 C3
J3 C1 + J3 B3
J3 C1 + J3 C4
J3 C1 + J3 B4
J3 C1 + J3 B5
J3 C1 + J3 B6
J3 C1 + J3 B7
J3 C1 + J3 B8
J3 C1 + J3 B9
J3 C1 + J3 B10
J3 C1 + J3 B11
J3 C1 + J3 B12
J3 C1 + J3 B13
J3 C1 + J3 B14
As you can see, a few pins are common at the top of the connector and then the whole of the central column of pins (row B) down to row 14 are common to J3 C1
CONSOLE CONNECTOR B also seems to have the same pattern of continuity.
Are you saying that this shouldn't be the case and all pins should be isolated?
Did you manage to find any information regarding the pinout? I still have the same issues
I need to know which pins I need to check continuity of between the cart and mobo when connected together. Which pins might affect the GFX issues I'm having?
Also, are you sure that there should be no continuity between any of the pins when the cart is disconnected? I ask because I have a lot of pins that have continuity between them.
If you look at the multi cart and took the pin numbering as follows:
Code:
CONSOLE CONNECTOR C CONSOLE CONNECTOR A
J3 J1
C1 B1 A1 C1 B1 A1
C2 B2 A2 C2 B2 A2
C3 B3 A3 C3 B3 A3
"" "" "" "" "" ""
"" "" "" "" "" ""
C32 B32 A32 C32 B32 A32
CONSOLE CONNECTOR D CONSOLE CONNECTOR B
J4 J2
C1 B1 A1 C1 B1 A1
C2 B2 A2 C2 B2 A2
C3 B3 A3 C3 B3 A3
"" "" "" "" "" ""
"" "" "" "" "" ""
C32 B32 A32 C32 B32 A32J3 C1 + J3 B1
J3 C1 + J3 C2
J3 C1 + J3 B2
J3 C1 + J3 C3
J3 C1 + J3 B3
J3 C1 + J3 C4
J3 C1 + J3 B4
J3 C1 + J3 B5
J3 C1 + J3 B6
J3 C1 + J3 B7
J3 C1 + J3 B8
J3 C1 + J3 B9
J3 C1 + J3 B10
J3 C1 + J3 B11
J3 C1 + J3 B12
J3 C1 + J3 B13
J3 C1 + J3 B14
As you can see, a few pins are common at the top of the connector and then the whole of the central column of pins (row B) down to row 14 are common to J3 C1
CONSOLE CONNECTOR B also seems to have the same pattern of continuity.
Are you saying that this shouldn't be the case and all pins should be isolated?
Connector A+B is Program Rom
Connector B is Ensoniq
Connector C is Graphics
Connector D is Sound
You should check connector C and the following level shifters that go to it:
U9,U10,U11, U12,U13, U14, U16,U17,U18,U19,U20,U21.
Connector B is Ensoniq
Connector C is Graphics
Connector D is Sound
You should check connector C and the following level shifters that go to it:
U9,U10,U11, U12,U13, U14, U16,U17,U18,U19,U20,U21.
Ok, I've checked continuity between the pins on both sides of connector C on the cart>mobo and they're all showing continuity, even the pins that are cut which just goes to show that the removed pins are common (GND most likely) and cutting them on the mobo has no effect 
Here's a ProTip™ for anyone who needs to do similar checks on this type of setup. Trying to get the multimeter pins onto both sides of the cart/mobo was a royal PITA, especially when trying to probe the middle row. You either risked slipping off the pins and losing your position or risking bridging other pins with the probes and potentially getting mis-readings.
But, if you connect a couple of dupont wires to your probes you can easily put the connectors over each side of the pins which makes it 100x faster and it also isolates the pins being checked
So, with that verified ok I was going to see if I can look at this next:
Here's a ProTip™ for anyone who needs to do similar checks on this type of setup. Trying to get the multimeter pins onto both sides of the cart/mobo was a royal PITA, especially when trying to probe the middle row. You either risked slipping off the pins and losing your position or risking bridging other pins with the probes and potentially getting mis-readings.
But, if you connect a couple of dupont wires to your probes you can easily put the connectors over each side of the pins which makes it 100x faster and it also isolates the pins being checked
So, with that verified ok I was going to see if I can look at this next:
Do you mean a visual check or continuity checks between the multi connector C and the IC legs? If it's the latter I'm going to need a pin out...
Apologies for the late update. Darksoft sent me the schematics as promised and I started to beep out the U ICs but then some unfortunate Real-Life™ stuff got in the way.
As far as I can tell, I'm getting continuity where I should be.
Any other suggestions? I would really like to get this playable.
I've just had some free time though and I've finished beeping out continuity between the C connector and every leg of the ICs that the schematics show are connected to them. The IC legs are pretty fine so I used a needle to make sure I was probing the leg in question and not bridging other legs.
As far as I can tell, I'm getting continuity where I should be.
Any other suggestions? I would really like to get this playable.
