Reprise wrote:Ziggy587 wrote:And I recently repaired a Tengen Genesis cart for someone, apparently they're known for having issues with their PCBs.
Yeah, what is with those? I have bought Gauntlet IV FOUR times now and every single time the cartridge has been dead. The closest I have come to a working version is one that boots up and plays ok for the most part, but has a tendency to crash (and that was a version I bought specifically because the Ebay seller had claimed it was a cartridge they repaired and tested it). I ended up keeping that one in the end.
How hard are they to repair? I have a soldering iron, but haven't done any soldering in over 15 years.
marurun wrote:What needs to be repaired in them? Just caps, or is there other stuff wrong?
The problem is with the PCB, specifically the vias. The one that I had repaired was in fact Guantlet IV. The PCB is actually repairable, but it was quicker (and in turn less money someone had to pay me for the work) to replace the PCB. It's a simple PCB without any save RAM, and they can be had for cheap. All you have to do is desolder the mask ROM from the old PCB and solder it into the new PCB. Then solder in 2 caps. You can get the caps from the old board, but you might as well use new caps since they're dirt cheap anyway. The PCBs can be purchased from a variety of places. Just be sure the PCB has the correct specs. Board thickness should be 1.6mm, the edge connector should be hard gold (and not ENIG, which is fine but will wear out a lot faster) and the cart edge should be beveled. If the cart edge isn't beveled, you can easily fix that yourself with some sand paper, so it's not the end of the world.
Here's the exact PCB that I ended up using:
https://www.ebay.com/itm/333725888712There's plenty more available from a number of different websites, I only went with the above because of the price and availability at the time.
If you want to repair the Tengen PCB, it's really not hard. Just time consuming. If you're doing it for yourself, then that isn't an issue. If it's your cart, I would recommend trying to repair it first. Worst case scenario the repair doesn't work, and you're in no worse shape then when you started. You can still always transfer the mask ROM to a new PCB.
Anyway, the repair would be fixing the vias. No point on testing the vias to figure out which are bad and which are still good, you might as well fix them all since ones that are good now may go bad eventually. IIRC, what I would have done is scratch the solder mask off of the trace and around the via. Then use jumper wires (probably 30 AWG) to basically "replace" the vias. You may be able to scrape away the solder mask on both sides of the via and then bridge a blob of solder on both sides without a jumper wires, that may work, but I didn't test that theory. I'm not sure in what way the vias fail, just that they do. If the vias are large enough, you may be able to snake a jumper wire down through them, so that you can solder it to the trace on both sides. If not, then you would have to run the jumper wires elsewhere. Either method, just test it with the continuity setting on a multimeter to confirm that it worked.
You will have to remove the mask ROM in order to repair the board. Luckily, those Tengen PCBs are easy to desolder the mask ROM from. It has solder pads on one side for the mask ROM, and not through holes that would require a vacuum desolderer. So you can get away with using just a cheap desolder iron, such as this one:
https://www.amazon.com/ECG-J-045-DS-Ele ... 00068IJSG/