Genesisairs

[2600Ibarelyknewher]

I’m having a weird issue with my Genesis model 2 where only controller port two doesn’t work. On one game specifically “Thomas the tank engine and friends”,I don’t get any controller action from either side. I’ve desoldered and soldered them back on a couple times but to no avail. Here are some picks hopefully someone can help me bring this puppy back to life. 

Edited January 23, 2020 by 2600Ibarelyknewher
Added to

[2600Ibarelyknewher]

Bump 

[2600Ibarelyknewher]

I figured out by trial and error that sonic 3 and 2 the d pad and start button are responsive. I wonder how this could be when none of the buttons work on other games. 

[2600Ibarelyknewher]

Bump

[2600Ibarelyknewher]

Bump

[+Yurkie]

my guess is that you have one or more bad pins and or one or more bad pads trace on the motherboard. I would test continuity between the pins and points on the motherboard. Soldering the controller ports multiple times probably damaged the connection on the motherboard. 

[2600Ibarelyknewher]

5 hours ago, Yurkie said:

my guess is that you have one or more bad pins and or one or more bad pads trace on the motherboard. I would test continuity between the pins and points on the motherboard. Soldering the controller ports multiple times probably damaged the connection on the motherboard. 

I tested continuity between the pins and the resistors above them and I can’t seem to find any that are broken. Which pins would make the entire port not work if they were broken? 

[+Yurkie]

Test the edge of the pin where the controller plugs in to a point above where the pins solder to the motherboard.

[2600Ibarelyknewher]

I took your suggestion and tried each pin to where they solder and no issues found. I did find one trace that didn’t make a good connection to one of the resistors and fixed that. Still doesn’t work. It’s weird because the board is in such good shape. I even have a second Sega Genesis I took apart to compare and can’t find anything different between the two. Any suggestions you have are appreciated. 

Edited January 26, 2020 by 2600Ibarelyknewher

[2600Ibarelyknewher]

I reflowed all joints on the entire back of the board and it didn’t help, I fear the worst but hope for the best. 

Edited January 26, 2020 by 2600Ibarelyknewher

[2600Ibarelyknewher]

I was thinking of the idea of soldering all the pins from the controller port to their respective resistors via small wires. I may just be hacking it up worse, since I know they all have continuity. I’m just not going to give up till I know it’s not salvageable. 

Edited January 27, 2020 by 2600Ibarelyknewher

[2600Ibarelyknewher]

Bump

[2600Ibarelyknewher]

Bump

[+-^CrossBow^-]

If the traces are check out, then you are likely looking at logic issue possible to a flaky IC on the board. I've not looked at the Genesis 2 schematics, but given how integrated everything is, it would likely point to the main ASIC on the board. That is the big chip in the center...

 

I've not taken many model 2 units apart but I don't recall seeing CMK silkscreened on the PCB before?

 

[2600Ibarelyknewher]

36 minutes ago, -^CrossBow^- said:

If the traces are check out, then you are likely looking at logic issue possible to a flaky IC on the board. I've not looked at the Genesis 2 schematics, but given how integrated everything is, it would likely point to the main ASIC on the board. That is the big chip in the center...

 

I've not taken many model 2 units apart but I don't recall seeing CMK silkscreened on the PCB before?

 

I checked the pins from where the controller plugs into to the third pin of the resistors behind them. I’ve checked over the whole board and looked for damaged but can’t find any traces that are not functional. I don’t know how to read schematics, is there anything specific I should look for as to why just the second slot doesn’t work. I googled the “CMK” logo and couldn’t find any information on that either. I did not see any damage whatsoever on the board. Another thing to note that entire board feels and looks like a can of Soda was spilled and left to dry on it, it also has this weird stickiness you can’t seem to get off. It couldn’t be my solder work because the first controller always worked and it still does after all my attempts to resolve the issue. 

[+-^CrossBow^-]

Again, I'm not talking about an issue with the traces. I'm talking about the issue being the main asic itself in the center of the board. And on which side of the board is is all sticky? Bottom or top component side? If it is the bottom that could very well just be leftover flux from when it was assembled as over time that stuff seems to get more and more sticky with age. But if on the top side, then yeah...that would be a possible indication of spillage and then you really don't know what could have happened that you can't see.

 

[2600Ibarelyknewher]

The stickiness was on the bottom of the board so maby it’s normal after all to be sticky. Do you fee there is anything I can if it’s a chip issue? Short of actually trying to change it to a new one? 

[+-^CrossBow^-]

If the chips are at fault on a model 2, I don't normally mess with trying to replace them out since Model 2 units are cheaply had. In looking at different model 2 revisions, it looks like the CMK logo is on all the PAL board revisions and only on the 1.8 revision for the US. All others either don't have that, or have the diamond logo under the cartridge slot (Which, I have seen a few times). So it seems to be normal and is likely the logo for whomever was making the PCBs for Sega at the time.

 

pretty much all of the IC on that model 2 units are SMD so to replace them, you would need a hot air station to safely remove the old chips. The smaller SMD IC chips, you can get away with clipping the legs to remove the chip and then use a small chisel tip on a soldering iron to whisk off the remainder of the chip legs off the PCB pads and clean them up for new chip install. But the larger ASIC I wouldn't do this with and would only advise a hot air station be used to remove it and replace.

 

[2600Ibarelyknewher]

Well I guess maybe I should stop well I’m ahead since at least number 1 port works. I feel I’ve been had by the seller who sold this to me for 15 dollars Canadian but I did get the PSU and tv RF cable. I was told it only had an issue with the power port which was an easy fix. I am willing to basically use this as a learning experience so if theirs any other chips I can try to change that may be a fun project. Which other chips besides the main have anything to do with the second controller port?

Edited January 29, 2020 by 2600Ibarelyknewher

[+-^CrossBow^-]

If I'm looking at the model 2 schematic correctly. Player 2 port is the one labeled as PB...and all of that goes into pins 93 - 99 on the main large chip. So you can also verify if you have continuity from those pins off that large chip as well to the next component down the line. Eventually they should all meet up at the resistor bank behind the controller ports.

 

 

[2600Ibarelyknewher]

I’ve checked continuity from where the ports pins solder onto to motherboard back to these holes and then back to the chip. As suggested I lead these pins back to the 90s legs on the chip this is very hard with the equipment I have but I did get continuity for all these holes. These connect to the third pin on each of the resistors legs.